^ 


^»ii? 


i 


Digitized  by  the  Internet  Archive 

in  2007  with  funding  from 

Microsoft  Corporation 


http://www.archive.org/details/anatdescsurgiOOgrayrich 


*4? 


TO 


SIR  BENJAMIN  COLLINS  BRODIE,  BART,.F.R.S,  D.C.L, 

SERJEANT-SURGEON  TO   THE   QUEEN, 
CORRESPONDING   MEMBER   OF   THE   INSTITUTE   OF   FRANCE, 


fflfis  Mark  is  $*tattbt 


IN   ADMIRATION   OF   HIS   GREAT  TALENTS, 


IN   REMEMBRANCE   OF   MANY   ACTS   OF   KINDNESS 


SHOWN   TO   THE   AUTHOR, 


FROM   AN   EARLY  PERIOD   OF   HIS   PROFESSIONAL   CAREER. 


BQS&k 


(in) 


AMERICAN  PUBLISHERS'  NOTICE. 


The  present  edition,  like  the  last  American  reprint,  has  been  passed 
through  the  press  under  the  supervision  of  Dr.  Richard  J.  Dunglison, 
who  has  carefully  corrected  whatever  errors  had  escaped  the  attention  of 
the  author,  and  has  made  such  changes  in  the  typographical  arrangement 
as  seemed  calculated  to  render  the  volume  more  convenient  for  consulta- 
tion and  reference. 

February,  1862. 


(  iv  ) 


PREFACE. 


In  preparing  a  Second  Edition  of  my  "  Descriptive  and  Surgical 
Anatomy,"  I  trust  that  I  have  corrected  any  inaccuracies  contained  in 
the  previous  one ;  every  page  has  been  carefully  revised ;  much  addi- 
tional matter  has  been  added  to  the  text;  and  several  new  Illustrations, 
executed  with  great  care  and  fidelity  by  Dr.  Westmacott,  have  been 
inserted. 

December,  1860. 


(v) 


viii  PREFACE. 

The  Veins  are  described  as  in  ordinary  anatomical  works;  and  illustrated  by  a 
series  of  engravings,  showing  those  in  each  region.  The  veins  of  the  spine  are 
described  and  illustrated  from  the  well-known  work  of  Breschet. 

The  Lymphatics  are  described,  and  figured  in  a  series  of  illustrations  copied 
from  the  elaborate  work  of  Mascagni. 

Tlie  Nervous  System  and  Organs  of  Sense.  A  concise  and  accurate  description  of 
this  important  part  of  anatomy  has  been  given,  illustrated  by  sixty-six  engravings, 
showing  the  spinal  cord  and  its  membranes ;  the  anatomy  of  the  brain,  in  a  series 
of  sectional  views;  the  origin,  course,  and  distribution  of  the  cranial,  spinal,  and 
sympathetic  nerves;  and  the  anatomy  of  the  organs  of  sense. 

The  Viscera.  A  detailed  description  of  this  essential  part  of  anatomy  has  been 
given,  illustrated  by  fifty-five  large,  accurately-lettered  engravings. 

Regional  Anatomy.  The  anatomy  of  the  perineum,  of  the  ischio-rectal  region, 
and  of  femoral  and  inguinal  hernia,  is  described  at  the  end  of  the  work;  the 
region  of  the  neck,  the  axilla,  the  bend  of  the  elbow,  Scarpa's  triangle,  and  the 
popliteal  space,  in  the  section  on  the  arteries;  the  laryngo-tracheal  region,  with 
the  anatomy  of  the  trachea  and  larynx.  The  regions  are  illustrated  by  many 
engravings. 

Microscopical  Anatomy.  A  brief  account  of  the  microscopical  anatomy  of  some 
of  the  tissues,  and  of  the  various  organs,  has  also  been  introduced. 

The  Author  gratefully  acknowledges  the  great  services  he  has  derived  in  the 
execution  of  this  work,  from  the  assistance  of  his  friend,  Dr.  H.  V.  Carter,  late 
Demonstrator  of  Anatomy  at  St.  George's  Hospital.  All  the  drawings  from  which 
the  engravings  were  made,  were  executed  by  him.  In  the  majority  of  cases,  they 
have  been  copied  from,  or  corrected  by,  recent  dissections  made  jointly  by  the 
Author  and  Dr.  Carter. 

The  Author  has  also  to  thank  his  friend,  Mr.  T.  Holmes,  for  the  able  assistance 
afforded  him  in  correcting  the  proof-sheets  in  their  passage  through  the  press. 

The  engravings  have  been  executed  by  Messrs.  Butterworth  and  Heath ;  and 
the  Author  cannot  omit  thfanking  these  gentlemen  for  the  great  care  and  fidelity 
displayed  in  their  execution. 

Wilton-Street,  Belgrave-Squark. 
August,  1858. 


CONTENTS. 


Osteology. 


Structure   and   Physical   Properties  of 

Bone     .... 
Chemical  Composition  of  Bone 
Form  of  Bones 
Surfaces  of  Bones 
Microscopic  Structure 
Vessels  of  Bone 
Periosteum 
Marrow     . 

Development  of  Bone 
Growth  of  Bone 
Number  of  Bones 

The  Spine. 

General  Characters  of  a  Yertebra  . 
Characters  of  the  Cervical  Vertebrae 
Peculiar  Cervical  Vertebra; 

Atlas 

Axis 

Vertebra  Prominens 
Characters  of  the  Dorsal  Vertebrae 
Peculiar  Dorsal  Vertebrae 
Characters  of  the  Lumbar  Vertebrae 
Structure  and  Development  of  the  Verte- 
brae         

Atlas    . 

Axis    . 

Seventh  Cervical 

Lumbar  Vertebrae 
Progress  of  Ossification  in  the  Spine 
Sacral  and  Coccygeal  Vertebrae 

Sacrum 

Coccyx      

Of  the  Spine  in  general     . 


The  Skull. 

Division  of  Bones  of 
Bones  of  the  Cranium 

Occipital  Bone  . 

Parietal  Bones  . 

Frontal  Bone     . 

Temporal  Bones 

Sphenoid  Bone 

Sphenoidal  Spongy  Bones 

Ethmoid  Bone   . 

Development  of  the  Cranium 

The  Fontanelles 

"Wormian  Bones 

Congenital  Fissures  and  Gaps 
Bones  of  the  Face     . 

Nasal  Bones 

Superior  Maxillary  Bone  . 

Lachrymal  Bones 

Malar  Bones 

Palate  Bones 


33 

33 
34 
35 
36 

37 
:is 
38 
38 

•Id 
40 


40 
41 
42 
42 
43 
44 
44 
45 
47 

47 
49 
49 
49 
49 
49 
50 
50 
54 
55 


57 
57 

57 
Gl 
83 
(17 
72 
7(1 
77 
79 
79 
80 
80 
so 
Bl 
83 
86 
87 
88 


PAOB 

Inferior  Turbinated  Bones         .        .       91 

Vomer       .... 

92 

Inferior  Maxillary  Bone     . 

92 

Changes  produced  by  age 

95 

Sutures  of  the  Skull 

97 

Vertex  of  the  Skull 

98 

Base  of  the  Skull,  Internal  Surface 

.     100 

Anterior  Fossae    . 

100 

Middle  Fossae 

.     100 

Posterior  Fossae  . 

.     101 

Base  of  Skull,  External  Surface 

.     102 

Lateral  Kegion  of  the  Skull 

105 

Temporal  Fossae 

.     105 

Zygomatic  Fossae 

.     106 

Spheno-maxillary  Fossae  . 

.     106 

Anterior  Begion  of  Skull 

.     106 

Orbits 

108 

Nasal  Fossae     .... 

.     109 

Os  Hyoides       .... 

111 

The  Thorax. 

The  Sternum     .        .        .        .                 .     112 

Development  of  the  Sternum 

.     114 

The  Ribs  .... 

.     116 

Peculiar  Ribs   . 

-     118 

Costal  Cartilages 

.     120 

The  Upper  Extremity. 

The  Clavicle 121 

Development  of  the  Clavicle 

123 

The  Scapula 

123 

Development  of  the  Scapula 
The  Humerus  . 

127 
129 

Development  of  the  Humerus 

133 

The  Forearm    . 

133 

The  Ulna 

133 

The  Radius 

138 

The  Hand 

140 

The  Carpus 

140 

Bones  of  Upper  Row 

141 

Bones  of  Lower  Row 

143 

The  Metacarpus 

146 

Peculiar  Metacarpal  Bones 

146 

Phalanges 

147 

Development  of  the  Hand 

148 

The  Lower  Extremity. 

Os  Innominatum 149 

149 

Pubes 

153 

Development  of  the  Os  Innominatum 

154 

The  Pelvis 

155 

Boundaries  of  Pelvis         .... 

155 

( 

ix) 

CONTENTS. 


Position  of  Pelvis 

Axes  of  Pelvis  ..... 

Differences  between  the  Male  and  Female 

Pelvis 

The  Femur 

Development  of  the  Femur 

The  Leg 

Patella      ....... 

Tibia 

Development  of  Tibia       .... 

Fibula 

Development  of  Fibula     .... 
The  Foot 


PAGE 

157   Tarsus       .... 

157  Oalcaneum  or  Os  Calcis   . 
Cuboid      .... 

158  Astragalus 

158   Scaphoid  .... 
163   Internal  Cuneiform  . 

163  Middle  Cuneiform     . 

164  External  Cuneiform 

165  j  Metatarsal  Bones 

168  j  Peculiar  Metatarsal  Bones 
168  j  Phalanges 
170   Development  of  the  Foot 
170  i  Sesamoid  Bones 


PAGE 

170 
170 
173 
173 
175 
175 
176 
176 
177 
177 
178 
178 
179 


The  Articulations. 


General  Anatomy  of  the  Joints         .        .  181 

Cartilage 181 

Fibro-cartilage 183 

Ligament 183 

Synovial  Membrane    ....  183 

Synovia       .        .        .        .        .        .  184 

Forms  of  Articulation      ....  184 

Synarthrosis 184 

Amphiarthrosis 185 

Diarthrosis 185 

Movements  of  Joints        ....  187 

Gliding  Movement      ....  187 

Angular  Movement     ....  187 

Circumduction 187 

Potation 187 

Articulations  of  the  Trunk. 
Articulations  of  the  Vertebral  Column     .  188 
Atlas  with  the  Axis  .  191 
Spine  with  Cranium  194 
Temporo-maxillary  Articulation       .         .  195 
Articulation  of  the  Ribs  with  the  Verte- 
brae          197 

Articulations  of   the   Cartilages   of   the 

Ribs  with  the  Sternum           .         .         .  200 

Ligaments  of  the  Sternum        .        .        .  202 


Articulations  of  the  Pelvis  with  the  Spine  203 
Inter-pubic 205 

Articulations  of  the  Upper  Extremity. 

Sterno-clavicular 207 

Scapuloclavicular 208 

Ligaments  of  the  Scapula         .        .         .     210 

Shoulder-joint 210 

Elbow-joint 211 

Radio-ulnar  Articulation  ....     213 

Wrist-joint 216 

Articulations  of  the  Carpus  .  .  .217 
Carpo-metacarpal  Articulations  .  .  218 
Metacarpo-phalangeal  Articulations  .  220 
Articulation  of  the  Phalanges  .        .         .     220 

Articulations  of  the  Lower  Extremity. 

Hip-joint 221 

Knee-joint 223 

Articulation  between  the  Tibia  and  Fibula     226 

Ankle-joint 228 

Articulations  of  the  Tarsus  .  .  .  229 
Tarso-metatarsal  Articulations  .  .233 
Articulations  of  the  Metatarsus  .  .  233 
Metatarso-phalangeal  Articulations  .     233 

Articulation  of  the  Phalanges  .        .        .     234 


Muscles  and  Fascia3. 


General  Anatomy  of  Muscle    . 
Tendons  . 
Aponeuroses    . 
Fasciae     . 

Muscles  and  Fasciae  op  the  Head 
and  Face. 

Subdivision  into  Groups   .... 
Epicranial  Region. 


235 
237 
237 

237 


238 


Dissection 

Occipito-frontalis      .... 

.    239 

.     240 

Auricular  Region. 

Dissection 

Attollens  Aurem       .... 
Attrahens  Aurem      .... 
Retrahens  Aurem      .... 
Actions 

.  241 
.     241 

.  242 
.  242 
.     242 

Palpebral  Region. 

Dissection 

Orbicularis  Palpebrarum  . 

.  242 
.     242 

Corrugator  Supercilii 
Tensor  Tarsi     . 
Actions     . 


Orbital  Region. 

Dissection 

Levator  Palpebrae  Superioris   . 

Rectus   Superior,  Inferior,  Internal  and 

External 

Superior  Oblique 

Inferior  Oblique 

Actions 

Surgical  Anatomy 

Nasal  Region. 

Pyramidalis  Nasi 

Levator  Labii  Superioris  Alaeque  Nasi 

Dilator  Naris    . 

Compressor  Naris 

Narium  Minor 
Depressor  Ahe  Nasi 
Actions     . 


243 
243 
243 


243 

243 

244 
245 
245 
245 
245 


246 
2-1 G 
246 
246 
246 
246 
246 


CONTENTS. 


XI 


Superior  Maxillary  Region. 


Levator  Labii  Snperioris 
Levator  Anguli  Oris 
Zygomatici 
Actions     . 


Inferior  Maxillary  Region. 

Dissection 

Levator  Labii  Inferioris  . 
Depressor  Labii  Inferioris 
Depressor  Anguli  Oris     . 

Intermaxillary  Region. 
Dissection 
Orbicularis  Oris 
Buccinator 
Eisorius    . 
Actions     . 


Temporo- Maxillary  Region. 

Masseter 

Temporal  Fascia       .... 
Dissection  of  Temporal  Muscle 
Temporal 

Pterygo-Maxillary  Region. 

Dissection 

Internal  Pterygoid  .... 
External  Pterygoid  .... 
Actions 


Muscles  and  Fasciae  of  the  Neck. 
Subdivision  into  Groups  .... 

Superficial  Cervical  Region. 

Dissection 

Superficial  Cervical  Fascia 

Platysma  Myoides    .... 

Deep  Cervical  Fascia 

Sterno-cleido-mastoid 

Boundaries  of  the  Triangles  of  the  Neck 

Surgical  Anatomy     .... 

Actions 


Infra-hyoid  Region. 
Dissection         .... 
Sterno-hyoid      .... 
Sterno-thyroid  .... 
Thyro-hyoid,  Omo-hyoid    . 
Actions 


PAC1E 

247 
247 
247 

247 


247 
247 
248 
248 


248 
248 
249 
249 
249 


249 
250 
250 
251 


251 
251 
252 
252 


252 


253 
253 
253 
254 
254 
255 
256 
256 


256 
256 
257 
258 
258 


Supra-hyoid  Region. 

Dissection 

Digastric 

Stylo-hyoid,  Mylo-hyoid,  Genio-hyoid 
Actions 


Lingual  Region. 
Dissection         .... 
Genio-hyo-glossus,  Hyo-glossus 
Stylo-glossus,  Lingualis    . 
Palato-glossus  .... 
Actions 


Pharyngeal  Region. 

Dissection 

Inferior  Constrictor 

Middle  Constrictor,  Superior  Constrictor 

Stylo-pharyngeus 

Actions 


258 
259 
259 
260 


260 
260 
261 
262 
262 


262 
262 
263 

263 
264 


Palatal  Region. 

Dissection         .... 
Levator  Palati 

Tensor  Palatfi,  Azygos  Uvulae  . 
Palato-glossus,  Palato-pharyugeus 
Actions,  Surgical  Anatomy 

Anterior  Vertebral  Region. 
Bectus  Capitis  Anticus  Major 
Pectus  Capitis  Anticus  Minor 
Bectus  Lateralis       .... 
Longus  Colli 

Lateral  Vertebral  Region. 
Scalenus  Anticus,  Scalenus  Medius 
Scalenus  Posticus     .... 
Actions 


Muscles  and  Fascle  of  the  Trunk. 
Subdivision  into  Groups   .... 

Muscles  of  the  Back. 
Subdivision  into  Layers    .... 

First  Layer. 
Dissection 
Trapezius 

Ligamentum  Nuchae 
Latissimus  Dorsi 

Second  Layer, 
Dissection 

Levator  Anguli  Scapulae 
Bhomboideus  Minor 
Bhomboideus  Major 
Actions     . 

Third  Layer. 
Dissection 

Serratus  Posticus  Superior 
Serratus  Posticus  Inferior 
Vertebral  Aponeurosis     . 
Splenius  Capitis  and  Splenius  Colli 
Actions     . 

Fourth  Layer, 
Dissection 
Erector  Spinae  . 
Sacyo-lumbalis  . 
Musculus  Accessorius  ad  Sacro-lumbalem 
Cervicalis  Ascendens 
Longissimus  Dorsi    . 
Transversalis  Colli   . 
Trachelo-mastoid 
Spinalis  Dorsi,  Spinalis  Cervicis 
Complexus 
Biventer  Cervicis 

Fifth  Layer. 

Dissection 

Semispinalis  Dorsi,  Semispinalis  Colli 
Multifidus  Spinae       .... 
Botatores  Spinae       .... 

Supra-spinales 

Inter-spinales 

Extensor  Coccygis,  Inter-transversales 
Bectus  Posticus  Major     . 
Bectus  Posticus  Minor    . 
Obliquus  Superior    .... 
Obliquus  Inferior      .... 
Actions 


PAdK 

264 
265 
265 
265 
266 


266 
267 
267 
267 


268 

268 
268 


269 


269 


269 
269 
270 
270 


272 
272 
272 
273 
273 


273 
273 
274 
274 
274 
274 


278 

276 
276 
276 
276 
276 
277 
277 
277 
277 
277 


278 
278 
278 
278 
279 
279 
279 
279 
279 
280 
280 
280 


Xll 


CONTENTS. 


Muscles  of  the  Abdomen. 

Dissection 

Obliquus  Externus 

Obliquus  Interims 

Transversalis    . 

Lumbar  Fascia 

Rectus  Abdominis 

Pyramidalis,  Quadratus  Lumborum 

Linea  Alba,  Lineae  Semilunares 

Linear  Transversa?     . 

Actions 


PAGE 

281 
281 
283 
284 
285 
286 
287 
287 
287 
287 


Muscles  and  Fasciae  of  the  Thorax. 

Intercostal  Fasciae    ......  288 

External  Intercostals        ....  288 

Internal  Intercostals         ....  288 

Infra-costales,  Triangularis  Sterni    .        .  289 

Levatores  Costarum         ....  289 

Actions 289 


Diaphragm 
Actions 


Diaphragmatic  Region. 


Muscles  and  Fascia  of  the  Upper 
Extremity. 

Subdivision  into  Groups  .... 
Dissection  of  Pectoral  Region  and  Axilla 
Fasciae  of  the  Thorax       .... 


Anterior  Thoracic  Region 
Pectoralis  Major 
Costo-coracoid  Membrane 
Pectoralis  Minor 
Subclavius 
Actions     . 


Lateral  Thoracic  Region. 
Serratus  Magnus  .... 
Actions 


Deltoid 
Action 


Acromial  Region. 


Anterior  Scapular  Region. 
Subscapular  Aponeurosis 

Subscapularis 

Actions 


Posterior  Scapular  Region 
Supra-spinous  Aponeurosis 
Supra-spinatus 
Infra-spinous  Aponeurosis 
Infra-spinatus   . 
Teres  Minor 
Teres  Major 
Actions     .... 


Anterior  Humeral  Region. 

Deep  Fascia  of  Arm 
<  oraco-brachialis,  Biceps 
Brachialis  Anticus    .... 
Actions 


289 
292 


293 
293 
294 


294 
296 
296 
296 
297 


298 
298 


299 

299 


299 
•299 
300 


300 
300 
300 
300 
301 
301 
302 


302 
303 
304 
304 


Posterior  Humeral  Region. 

Triceps      .        .         .  .         .        .  304 

Subanconeus 304 

Actions 304 


Muscles  of  Forearm. 

PAOK 

Deep  Fascia  of  Forearm  .        .        .     305 

Anterior  Brachial  Region,  Superficial 

Layer. 

Pronator  Radii  Teres       ....  306 

.  306 

.  307 

.  307 

.  307 


Flexor  Carpi  Radialis 
Palmaris  Longus 
Flexor  Carpi  Ulnaris 
Flexor  Digitorum  Sublimis 

Anterior  Brachial  Region,  Deep  Layer. 
Flexor  Profundus  Digitorum    .        .        .     308 

.  309 
.  309 
.     310 


Flexor  Longus  Poinds 
Pronator  Quadratus 

Actions     . 


Radial  Region. 
Dissection 
Supinator  Longus 
Extensor  Carpi  Radialis  Longior 
Extensor  Carpi  Radialis  Brevior 


310 
310 
310 
311 


Posterior  Brachial  Region,  Superficial 
Layer. 
Extensor  Communis  Digitorum         .        .     312 
Extensor  Minimi  Digiti     ....     312 
Extensor  Carpi  Ulnaris    ....     312 
Anconeus 312 

Posterior  Brachial  Region,  Deep  Layer. 
Supinator  Brevis       .....     313 


Extensor  Ossis  Metacarpi  Pollicis    . 

.     313 

Extensor  Primi  Internodii  Pollicis  . 

.     313 

Extensor  Secundi  Internodii  Pollicis 

.     313 

Extensor  Indicis       .... 

.     314 

.     314 

Muscles  and  Fasciae  of  the  Ham 

I. 

Dissection 

.     315 

Anterior  Annular  Ligament 

.     315 

Posterior  Annular  Ligament     . 

.     315 

Palmar  Fascia          .... 

.     316 

Muscles  of  the  Hand. 

Radial  Group 

.     316 

Ulnar  Group 

.     318 

.     319 

Middle  Palmar  Group 

.     319 

.     320 

Surgical  Anatomy  of  the  Muscles  q, 

f  the 

Upper  Extremity. 

Fractures  of  the  Clavicle 

.     320 

Acromion  Process 

.     321 

Coracoid  Process  . 

.     321 

Humerus 

.     321 

Ulna      . 

.     322 

Olecranon 

.     322 

Radius  . 

.     323 

Muscles  and  Fascia  of  the  Low 

ER 

Extremity. 

Subdivision  into  Groups    . 

.     324 

Iliac  Region. 

Dissection 

.     325 

Iliac  Fascia 

.     325 

Psoas  Magnus,  Psoas  Parvus  . 

.     326 

.     326 

.     327 

CONTENTS. 


Xlll 


Anterior  Femoral  Region. 


PAGE 

327 

Fasciae  of  the  Thigh          .... 

327 

Superficial  Fascia 

327 

Deep  Fascia,  Fascia  Lata 

328 

Saphenous  Opening 

329 

Iliac  and  Pubic  Portions  of  Fascia  Lata  . 

329 

Tensor  Vaginas  Femoris,  Sartorius  . 

329 

Quadriceps  Extensor  Cruris     . 

330 

Rectus  Femoris,  Vastus  Externus    . 

330 

Vastus  Internus  and  Crureus   . 

331 

331 

331 

Internal  Femoral  Region. 

332 

332 

332 

Adductor  Longus 

333 

Adductor  Brevis,  Adductor  Magnus 

333 

334 

Gluteal  Region. 

334 

Gluteus  Maximus 

334 

Gluteus  Medius 

335 

Gluteus  Minimus 

336 

Pyriformis         ...... 

336 

Obturator  Internus,  Gemelli    . 

337 

Quadratus  Femoris,  Obturator  Externus 

337 

338 

Posterior  Femoral  Region. 

339 

Biceps,  Semitendinosus     .... 

339 

Semimembranosus 

340 

340 

Surgical  Anatomy  of  Hamstring  Tendons 

340 

Muscles  and  Fascia}  of  Leg. 

Dissection  of  Front  of  Leg 

340 

Fascia  of  the  Leg 

340 

Muscles  of  the  Leg 

341 

Anterior  Tibio-fibular  Region. 

Tibialis  Anticus 

341 

Extensor  Proprius  Pollicis 

342 

Extensor  Longus  Digitorum    . 

342 

Peroneus  Tertius 

342 

342 

Posterior  Tibio-fibular  Region, 
Superficial  Layer. 

PAGE 

Dissection 343 

Gastrocnemius 343 

Soleus,  Tendo  Achillis,  Plantaris     .        .  344 

Actions 344 

Posterior  Tibio-fibular  Region, 
Deep  Layer. 

Deep  Fascia  of  Leg 345 

Popliteus 345 

Flexor  Longus  Pollicis     ....  346 
Flexor  Longus  Digitorum,  Tibialis  Pos- 
ticus        346 

Actions 347 

Fibular  Region. 

Peroneus  Longus 347 

Peroneus  Brevis 348 

Actions 348 

Surgical  Anatomy  of   Tendons  around 

Ankle 348 

Muscles  and  Fascial  of  Foot. 

Anterior  Annular  Ligament     .        .        .  348 

Internal  Annular  Ligament      .         .         .  349 

External  Annular  Ligament     .         .         .  349 

Plantar  .Fascia 349 

Muscles  of  the  Foot,  Dorsal  Region. 

Extensor  Brevis  Digitorum      .        .        .  350 


Plantar  Region. 

Subdivision  into  Groups   . 

Subdivision  into  Layers    . 

First  Layer  . 
Second  Layer 
Third  Layer    . 

Interossei 


350 
350 
350 
352 
353 
354 


Surgical  Anatomy  of  the  Muscles  of  the 
Lower  Extremity. 

Fracture  of  the  Femur      ....    353 
the  Patella     .        .        .        .356 
the  Tibia        .        .        .        .356 
the  Fibula,    with    Displace- 
ment of  the  Tibia    .        .357 


The  Arteries. 


General  Anatomy. 
Subdivision  into  Pulmonary  and  Systemic 
Distribution  of — Where  found  . 
Mode  of  Division — Anastomoses 
Structure  of  Arteries 
Sheath — Vasa  Vasorum  . 
Capillaries         .... 


Aorta. 
Arch  of  Aorta 
Dissection 

Ascending  Part  of  Arch  . 
Transverse  Part  of  Arch  . 
Descending  Part  of  Arch 
Peculiarities 
Surgical  Anatomy  . 
Branches  .... 
Peculiarities  of  Branches 


358 
358 
358 
359 
360 
360 


361 
362 
363 
364 
364 
364 
365 
365 


Coronary  Arteries. 

Peculiarities 366 

Arteria  Innominata. 

Relations 366 

Peculiarities 366 

Surgical  Anatomy 367 

Common  Carotid  Arteries. 

Course  and  Relations         ....  367 

Peculiarities 370 

Surgical  Anatomy 370 

External  Carotid  Artery. 

Relations 371 

Surgical  Anatomy 372 

Branches 372 


XIV 


CONTENTS. 


Superior  Thyroid  Artery. 

Course  and  Relations 
Surgical  Anatomy    . 

Lingual  Artery. 
Course  and  Relations 
Branches  .... 
Surgical  Anatomy     . 

Facial  Artery, 
Course  and  Relations 
Branches  .... 
Peculiarities 
Surgical  Anatomy    . 

Occipital  Artery. 
Course  and  Relations 
Branches  . 


PAOE 

372 
372 


373 
373 
374 


374 
375 
376 
376 


Posterior  Auricular  Artery. 


376 
377 


Branches 377 

Ascending  Pharyngeal  Artery. 
Branches  . 


Thyroid  Axis     . 
Supra-scapular  Artery 
Transversalis  Colli     . 
Internal  Mammary    . 
Superior  Intercostal . 
Deep  Cervical  Artery 

Surgical  Anatomy  of  the  Axilla 

Axillary  Artery. 
First  Portion    .... 
Second  Portion 

Third  Portion  .... 
Peculiarities,  Surgical  Anatomy 
Branches  . 


378 


378 
378 
379 


Temporal  Artery. 
Course  and  Relations 

Branches  

Surgical  Anatomy    . 

Internal  Maxillary  Artery. 

Course  and  Relations        .  379 

Peculiarities     ......  379 

Branches  from  First  Portion    .         '.  '     379 

Second  Portion         .  .     381 

Third  Portion  .         .  .381 

Surgical  Anatomy  of  the  Triangles  of  the 

Neck. 

Anterior  Triangular  Space. 

Inferior  Carotid  Triangle  .        .        .  333 

Superior  Carotid  Triangle        .        ."  .'     383 

Submaxillary  Triangle      .        .        '.  [     383 

Posterior  Triangular  Space. 

Occipital  Triangle    .         .        .  334 

Subclavian  Triangle          .        .  334 

Internal  Carotid  Artery. 
Cervical  Portion 
Petrous  Portion 
Cavernous  Portion   . 
Cerebral  Portion 
Peculiarities,  Surgical  Anatomy 

Branches 

Ophthalmic  Artery  .         .         " 
Cerebral  Branches  of  Internal  Carotid     '. 
Arteries  of  the  Upper  Extremity. 


Brachial  Artery. 

Relations 

Bend  of  the  Elbow    . 
Peculiarities  of  Brachial  Artery 
Surgical  Anatomy    . 
Branches 

Radial  Artery. 

Relations 

Deep  Palmar  Arch  . 
Peculiarities,  Surgical  Anatomy 
Branches 

Ulnar  Artery. 
Relations  ..... 
Superficial  Palmar  Arch  . 
Peculiarities  of  Ulnar  Artery   . 
Surgical  Anatomy    . 
Branches  

Descending  Aorta 

Thoracic  Aorta. 

Relations 

Surgical  Anatomy     . 
Branches  . 


386 
386 
386 
386 
386 
387 
387 
390 


Subclavian  Arteries. 
First  Part  of  Right  Subclavian  Artery 
First  Part  of  Left  Subclavian  Alter 
Second  Part  of  Subclavian  Artery 
Third  Part  of  Subclavian  Artery 
Peculiarities 
Surgical  Anatomy    . 
Branches  . 

Vertebral  Artery 

Basilar  Artery  . 

Circle  of  Willis  . 


391 
392 
393 
393 
393 
394 
395 
396 
397 
397 


Abdominal  Aorta. 

Relations 

Surgical  Anatomy    . 
Branches  

Cceliac  Axis,  Gastric  Artery 

Hepatic  Artery 

Splenic  Artery  . 

Superior  Mesenteric  Artery 

Inferior  Mesenteric  Artery 

Supra-renal  Arteries 

Renal  Arteries  . 

Spermatic  Arteries 

Phrenic  Arteries 

Lumbar  Arteries 

Middle  Sacral  Artery 

Common  Iliac  Arteries 
Course  and  Relations 
Peculiarities,  Surgical  Anatomy 

Internal  Iliac  Artery. 
Course  and  Relations 
Peculiarities,  Surgical  Anatomy 

Branches 

Vesical  Arteries 
Hemorrhoidal  Arteries 
Uterine  and  Vaginal  Arteries 
Obturator  Artery 


PAOK 

398 
398 
398 
399 
400 
400 

401 


402 
403 
403 
404 
404 


405 
407 
407 
408 
409 


410 
410 
411 
412 


413 
414 
414 
414 
415 

416 


417 
417 
417 


419 
420 
420 
421 
422 
423 
423 
425 
426 
426 
427 
427 
427 
428 


429 
429 


430 
431 

4:52 
432 

4:12 
4:2 

4i.2 


CONTENTS. 


xv 


Internal  Pudic  Artery 

Sciatic  Artery 

Gluteal,    Ilio-lumbar,    and    Lateral 
Sacral  Arteries       . 

External  Iliac  Artery. 
Course  and  Relations        . 

Surgical  Anatomy 

Branches 

Epigastric  Artery     . 

Circumflex  Iliac  Artery    . 

Femoral  Artery. 
Course  and  Relations        . 

Scarpa's  Triangle 

Peculiarities 

Surgical  Anatomy 

Branches 

Profunda  Artery 

Popliteal  Artery. 

Popliteal  Space 

Course  and  Relations        . 
Peculiarities,  Surgical  Anatomy 
Branches 


PAOE 

433 
435 

436 


437 
437 
437 
437 
438 


438 
438 
440 
440 
441 
442 

443 
444 
445 
445 


Anterior  Tibial  Artery. 

Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches 


Dorsalis  Pedis  Artery. 
Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches  


Posterior  Tibial  Artery. 
Course  and  Relations 
Peculiarities,  Surgical  Anatomy 
Branches  


Peroneal  Artery. 
Course  and  Relations 
Peculiarities     .... 


Plantar  Arteries. 
Internal  Plantar 
External  Plantar 

Pulmonary  Artery. 
Right  and  Left  Pulmonary 


PAOB 

446 
447 
448 


449 
449 
449 


450 
450 
451 


451 
452 


452 
452 


454 


The  Veins. 


General  Anatomy. 

Subdivision  into    Pulmonary,   Systemic, 

and  Portal 455 

Anastomoses  of  Yeins      ....  455 
Superficial  Veins,  Deep  Yeins  or  Venae 

Comites 455 

Sinuses,  their  Structure    ....  455 

Structure  of  Veins 456 

Valves  of  Veins 457 

Vessels  and  Nerves  of  Veins  .        .        .  457 

Veins  of  the  Head  and  Neck. 

Facial  Vein 458 

Temporal  Vein 459 

Internal  Maxillary  Vein   ....  459 

Temporo-maxillary  Vein  ....  459 

Posterior  Auricular  Vein,  Occipital  Vein  459 

Veins  of  the  Neck. 

External  Jugular  Vein      ....  460 

Posterior  External  Jugular  Vein     .        .  460 

Anterior  Jugular  Vein     ....  460 

Internal  Jugular  Vein      ....  460 

Lingual,  Pharyngeal,  and  Thyroid  Veins  461 

Vertebral  Veins 461 

Veins  of  the  Diploe 461 

Cerebral  Veins. 

Superficial  Cerebral  Veins        .        .        .  462 

Deep  Cerebral  Veins        ....  463 

Cerebellar  Veins       .        .        .        .        .  463 

Sinuses  of  the  Dura  Mater. 

Superior  Longitudinal  Sinus     .         .         .  463 
Inferior  Longitudinal,  Straight,  Lateral, 

and  Occipital  Sinuses    ....  464 

Cavernous  Sinuses 465 

Circular  Sinus 465 

Inferior  Petrosal,  and  Transverse  Sinuses  466 

Superior  Petrosal  Sinus   ....  466 


Veins  of  the  Upper  Extremitt. 

Superficial  Veins 
Deep  Veins 
Axillary  Vein    . 
Subclavian  Vein 
Innominate  Veins 

Peculiarities  of . 
Internal  Mammary  Vein  . 
Inferior  Thyroid  Veins 
Superior  Intercostal  Veins 
Superior  Vena  Cava 
Azygos  Veins  . 
Spinal  Veins     . 


Veins  of  the  Lower  Extremity 

Internal  Saphenous  Vein  . 
External  Saphenous  Vein 
Popliteal  Vein  . 
Femoral  Vein  . 
External  Iliac  Vein 
Internal  Iliac  Vein 
Common  Iliac  Vein 
Inferior  Vena  Cava 

Peculiarities 
Lumbar  and  Spermatic  Veins  . 
Ovarian,  Renal,  Supra-renal  Veins 
Phrenic  Veins  .... 
Hepatic  Veins  .... 


Portal  System  of  Veins. 

Inferior  and  Superior  Mesenteric  Veins 

Splenic  and  Gastric  Veins 

Portal  Vein 

Cardiac  Veins. 
Coronary  Sinus         .... 

Pulmonary  Veins. 
Distribution  of  .... 


466 
466 
468 
468 
468 
469 
469 
469 
470 
470 
470 
471 


473 
473 
474 
474 
474 
474 
475 
475 
476 
476 
476 
476 
477 


477 
477 

477 


479 


479 


CONTENTS. 


The  Lymphatics. 


General  Anatomy. 


PAGE 

Structure  of, 481 

Subdivision  into  Deep  and  Superficial      .  481 

Coats  of  Lymphatics        ....  481 

Valves  of  Lymphatics      ....  482 

Lymphatic  or  Conglobate  Glands     .         .  482 

Structure  of  Lymphatic  Glands        .         .  482 

Thoracic  Duct 483 

Right  Lymphatic  Duct     ....    484 

Lymphatics  of  Head,  Face,  and  Neck. 

Superficial  Lymphatic  Glands  of  Head    .  484 
Lymphatics  of  Head       .         .  484 
of  the  Face         .  484 
Deep  Lymphatics  of  the  Face          .        .  484 
of  the  Cranium     .         .  485 
Lymphatic  Glands  of  the  Neck        .        .  485 
Superficial  Cervical  Glands      .         .         .  486 
Deep  Cervical  Glands        ....  486 
Superficial    and    Deep     Cervical    Lym- 
phatics    486 

Lymphatics  of  the  Upper  Extremity. 

Superficial  Lymphatic  Glands  . 

Deep  Lymphatic  Glands  .... 

Axillary  Glands 

Superficial    Lymphatics    of   Upper    Ex- 
tremity ....... 

Deep  Lymphatics  of  Upper  Extremity    . 

Lymphatics  of  the  Lower  Extremity. 

Superficial  Inguinal  Glands 
Deep  Lymphatic  Glands  . 
Anterior  Tibial  Gland 
Deep  Popliteal  Glands 
Deep  Inguinal  Glands 
Gluteal  and  Ischiatic  Glands     . 
Superficial    Lymphatics    of  Lower    Ex- 
tremity .... 

Internal  Group  . 

External  Group 
Deep  Lymphatics  of  Lower  Extremity    . 

Lymphatics  of  Pelvis  and  Abdomen. 

Deep  Lymphatic  Glands  of  Pelvis   . 
External  Iliac  Glands 
Internal  Iliac  Glands 


487 
487 
487 


488 


488 
488 
488 
489 
489 
489 

489 
489 
489 
489 


490 
490 
490 


Sacral  Glands 

PAGE 

490 

Lumbar  Glands          .... 

490 

Lymphatics  of  Pelvis  and  Abdomen 

490 

Superficial  Lymphatics   of  Wall  of  Ab- 

domen 

490 

of  Gluteal  Region 

490 

of  Scrotum  and  Perineum  . 

490 

of  Penis       .... 

490 

of    Labia,     Nymphse,     and 

Clitoris 

491 

Deep    Lymphatics    of   Pelvis    and    Ab- 

domen    

491 

Lymphatics  of  Bladder     .... 

492 

of  Rectum     .... 

492 

of  Uterus       .... 

492 

of  Testicle    .... 

492 

of  Kidney     .... 

492 

of  Liver        .... 

492 

Lymphatic  Glands  of  Stomach 

492 

Lymphatics  of  Stomach  .... 

492 

Lymphatic  Glands  of  Spleen    . 

493 

Lymphatics  of  Spleen       .... 

493 

Lymphatic  System  of  the  Intestines. 

Lymphatic    Glands    of   Small    Intestine 

(Mesenteric  Glands)      .... 

493 

Lymphatic  Glands  of  Large  Intestine 

493 

Lymphatics  of  Small  Intestine  (Lacteals) 

493 

of  Large  Intestine 

493 

Lymphatics  of  Thorax. 

Deep  Lymphatic  Glands  of  Thorax 

493 

Intercostal  Glands     .... 

493 

Internal  Mammary  Glands 

493 

Anterior  Mediastinal  Glands     . 

493 

Posterior  Mediastinal  Glands     . 

493 

Superficial    Lymphatics     on    Front     of 

Thorax           .        .         . 

494 

Deep  Lymphatics  of  Thorax    . 

494 

Intercostal  Lymphatics     .... 

494 

Internal  Mammary  Lymphatics 

494 

Lymphatics  of  Diaphragm 

494 

Bronchial  Glands 

494 

Lymphatics  of  Lung        .... 

494 

Cardiac  Lymphatics          .... 

494 

Thymic  Lymphatics          .... 

494 

Thyroid  Lymphatics          .... 

494 

Lymphatics  of  (Esophagus 

494 

Nervous  System. 


General  Anatomy. 

Subdivision  into  Cerebro-spinal  Axis, 
Ganglia,  and  Nerves  .... 
Constituent  Elements  of  Nervous  System 
Fibrous  Nervous  Substance  .  ... 
Vesicular  Nervous  Substance  . 
Chemical  Composition  .... 
Microscopic  Structure  of  Tubular  Fibres 

of  Gelatinous  Fibres 

of  Vesicular  Nervous  Substance 


Where  found. 


Ganglia. 
Structure 


495 
495 
495 
495 
495 
496 
496 
496 


497 


Nerves. 


Subdivision  into  Cerebro-spinal  and  Sym- 
pathetic        .        .                ...  497 
General  Anatomy  of  the  Nerves       .         .  498 

TJie  Spinal  Cord  and  its  Membranes. 

Dissection 500 

Membranes  of  the  Cord    ....  500 

Dura  Mater 500 

Arachnoid 501 

Pia  Mater 502 

Lisramcntum  Denticulatum        .         .  502 

SpinafCord       .                 ....  502 


CONTENTS. 


xvn 


PAflE 

Fissures  of  Cord  ....  503 
Columns  of  Cord  ....  503 
Structure  of  Cord  ....  504 
Mode  of  Arrangement  of  Gray  and 

White  Matter        .        .        .        .504 
"White  Matter  of  Cord.   Structure     .     504 
Gray    Substance    of    Cord.     Struc- 
ture         505 

The  Central  Canal     .        .        .        .506 

The  Brain  and  its  Membranes. 

Membranes  of  the  Brain  ....    507 

Dura  Mater. 


Structure           .... 

.     507 

Arteries,  Veins,  Nerves    . 

.    507 

Glanduhe  Pacchioni 

.     507 

Processes  of  the  Dura  Mater  . 

.     508 

Falx  Cerebri    . 

.     508 

Tentorium  Cerebelli 

.     508 

Falx  Cerebelli 

-.     508 

Arachnoid  Membrant 

Subarachnoid  Space 

.  *509 

Cerebro-spinal  Fluid 

.     509 

Pia  Mater. 

The  Brain. 

Subdivision  into  Cerebrum,   Cerebellum, 


Pons  Varolii,  Medulla  Oblongata 

510 

Weight  of  Brain       .... 

510 

Medulla  Oblongata. 

Anterior  Pyramids    .... 

511 

Lateral  Tract,  and  Olivary  Body 

.     511 

Restiform  Bodies      .... 

511 

Posterior  Pyramids  .... 

511 

Posterior  Surface  of  Medulla  Oblongata 

512 

Structure  of  Medulla  Oblongata 

512 

of  Anterior  Pyramid 

512 

of  Lateral  Tract. 

512 

of  Olivary  Body 

512 

of  Restiform  Body    . 

513 

Septum  of  Medulla  Oblongata  . 

513 

Gray  Matter  of  Medulla  Oblongata  . 

513 

Pons  Varolii. 

Structure  

.     514 

Transverse  Fibres     .... 

514 

Longitudinal  Fibres  .... 

514 

Septum 

515 

Cerebrum. 

Upper  Surface  of  Cerebrum     . 

515 

Convolutions  and  Sulci     . 

515 

Base  of  the  Brain      ..... 

517 

General  Arrangement  of  the  Parts  com- 

posing the  Cerebrum     . 

520 

Interior  of  the  Cerebrum  . 

520 

Corpus  Callosum 

521 

Lateral  Ventricles 

522 

Boundaries    of,  and   Parts    forming  the 

Lateral  Ventricles 

523 

Septum  Lucidum 

525 

Fornix 

525 

Velum  Interpositum  . 

526 

Thalami  Optici  .... 

526 

Third  Ventricle 

2 

527 

Anterior,  Middle,  and  Posterior  Commis- 
sures      

Gray  Matter  of  Third  Ventricle 
Pineal  Gland    . 
Corpora  Quatlrigemina 
Valve  of  Vieussens  . 
Corpora  Geniculata . 
Structure  of  Cerebrum 

1.  Diverging  or  Peduncular  Fibres 

2.  Transverse  Commissural  Fibres 

3.  Longitudinal  Commissural  Fibres 

Cerebellum. 

Its  Position,  Size,  Weight,  etc. 
Cerebellum,  Upper  Surface 
Under  Surface 
Lobes  of  the  Cerebellum  . 
Fourth  Ventricle 
Boundaries  of  Ventricle    . 
Lining  Membrane.     Choroid  Plexus 
Gray  Matter  of  Cerebellum 
Structure  of  the  Cerebellum 

Its  Lamina; 

Corpus  Dentatum 
Peduncles  of  Cerebellum  . 

Cranial  Nerves. 

Subdivision  into  Groups    . 

Nerves  of  Special  Sense     . 

of  Common  Sensation 
of  Motion 

Mixed  Nerves    . 
Olfactory  Nerve 
Optic  Nerve     . 
Tracts    . 
Commissure   . 
Auditory  Nerve 
Third  Nerve 
Fourth  Nerve  . 
Sixth  Nerve 
Relations  of  the  Orbital  Nerves 

in  the  Cavernous  Sinus 

in  the  Sphenoidal  Fissure  . 

in  the  Orbit 
Facial  Nerve    .... 

Branches  of 
Ninth  or  Hypoglossal  Nerve    . 
Fifth  Nerve      .... 
Casserian  Ganglion  . 
Ophthalmic  Nerve    . 
Lachrymal,  Frontal,  and  Nasal  Branches 
Superior  Maxillary  Nerve 
Inferior  Maxillary  Nerve  . 
Auriculotemporal,    Gustatory,    and    In- 
ferior Dental  Branches .         .         .      550, 
Ophthalmic  Ganglion 
Sphenopalatine  Ganglion 
Otic  Ganglion  . 
Submaxillary  Ganglion 
Eighth  Pair 

Glosso-pharyngeal 

Pneumogastric  . 

Spinal  Accessory 


Spinal  Nerves. 
Roots  of  the  Spinal  Nerves 

Origin  of  Anterior  Roots  . 

of  Posterior  Roots 

Ganglia  of  the  Spinal  Nerves   . 


561 
56L 
561 
562 


XY1U 


CONTENTS. 


Anterior  Branches  of  the  Spinal  Nerves  .  562 

Posterior  Branches  of  the  Spinal  Nerves  562 

Cervical  Nerves. 

Roots  of  the  Cervical  Nerves  .         .         .  562 

Anterior  Branches  of  the  Cervical  Nerves  563 

Cervical  Plexus. 

Superficial    Branches  #>f    the    Cervical 

Plexus 564 

Deep  Branches  of  the  Cervical  Plexus      .  565 

Posterior  Branches  of  the  Cervical  Nerves  565 

Brachial  Plexus. 

Branches  above  the  Clavicle. 

Posterior  Thoracic,  Supra-scapular       567,  568 

Branches  below  the  Clavicle. 
Anterior    Thoracic,     and     Subscapular 

Nerves 568,  569 

Circumflex,     and     Musculo  -  cutaneous 

Nerves 569 

Internal,  and  Lesser  Internal  Cutaneous 

Nerves 570 

Median  Nerve 571 

Ulnar  Nerve 573 

Musculo-spiral  Nerve        ....  574 

Radial  Nerve 575 

Posterior  Interosseous  Nerve    .        .  575 

Dorsal  Nerves. 

Roots  of  the  Dorsal  Nerves      .        .        .  576 

Intercostal  Nerves 576 

Upper  Intercostal  Nerves         .         .         .  576 

Intercosto-humeral  Nerves        .         .         .  577 

Lower  Intercostal  Nerves         .         .         .  577 

Peculiar  Dorsal  Nerves    ....  577 

First  Dorsal  Nerve    ....  577 

Last  Dorsal  Nerve    ....  577 

Lumbar  Nerves. 

Roots  of  Lumbar  Nerves  ....  578 

Posterior  Branches  of  Lumbar  Nerves     .  578 

Anterior  Branches  of  Lumbar  Nerves      .  578 

Lumbar  Plexus. 

Branches  of  Lumbar  Plexus     .         .         .  578 

Uio-hypogastric  Nerve      ....  578 

Ilio-inguinal,  and  Genito-crural  Nerves     .  580 

External  Cutaneous,  and  Obturator  Nerves  580 

Accessory  Obturator  Nerve      .         .        .  582 

Anterior  Crural  Nerve     ....  582 

Branches  of 582 

Middle  Cutaneous 583 

Internal  Cutaneous,  Long  Saphenous        .  583 

Muscular  and  Articular  Branches     .  584 

Sacral  and  Coccygeal  Nerves. 

Roots  of  origin  of 584 

Posterior  Sacral  Nerves  ....  584 


Anterior  Sacral  Nerves     . 

Posterior  Branch  of  Coccygeal  Nerve 

Anterior  Branch  of  Coccygeal  Nerve 

Sacral  Plexus. 

Superior  Gluteal  Nerve    . 
Pudic  and  Small  Sciatic  Nerves 
Great  Sciatic  Nerve .... 
Internal  Popliteal  Nerve  . 
Posterior  Tibial  Nerve 
Plantar  Nerves         .... 
External  Popliteal  or  Peroneal  Nerve 
Anterior  Tibial  Nerve 
Musculo-cutaneous  Nerve 

Sympathetic  Nerve. 

Subdivision  of 

Branches   of   the  Ganglia, 
scription  of   . 


General  De- 


PAOB 

585 
585 
585 


586 
586 
588 
588 
589 
589 
590 
590 
591 


592 
592 


Cephalic  Portion  of  Sympathetic 
Ganglia  of 

Cervical  Portion  of  the  Sympathetic. 

Superior  Cervical  Ganglion 
Middle  Cervical  Ganglion 
Inferior  Cervical  Ganglion 
Carotid  and  Cavernous  Plexuses 

Cardiac  Nerves. 

Superior,  Middle,  and   Inferior   Cardiac 

Nerves 

Deep  Cardie  Plexus  .... 

Superficial  Cardiac  Plexus 

Anterior  and  Posterior  Coronary  Plexus 

Thoracic  Part  of  the  Sympathetic. 

Great  Splanchnic  Nerve  .         .         . 
Lesser  Splanchnic  Nerve 
Smallest  Splanchnic  Nerve 
Epigastric  or  Solar  Plexus 
Semilunar  Ganglia    .... 
Phrenic,  Supra-renal,  and  Renal  Plexuses 
Spermatic,  Cceliac,  and  Gastric  Plexuses 
Hepatic,  Splenic,  and  Superior  Mesen- 
teric Plexuses       .        .        .        . 
Aortic,  and  Inferior  Mesenteric  Plexuses 


594 


594 
595 
595 
595 


596 
596 
597 
597 


597 
598 
598 
598 
598 
598 
599 

599 
599 


Lumbar  Portion  of  Sympathetic.      600 


Branches  of 

Pelvic  Portion  of  Sympathetic 

Hypogastric  Plexus 

Inferior  Hypogastric  or  Pelvic  Plexus 

Inferior  Hemorrhoidal  Plexus 

Vesical  Plexus 

Prostatic  Plexus      .... 

Vaginal  Plexus         ..... 

Uterine  Nerves         .... 


600 
600 

600 
600 
601 
601 
601 
601 
601 


CONTENTS. 


xix 


Organs  of  Sense. 


Skin 

Derma  or  true  Skin  . 

Corium 

Papillary  Layer 
Epidermis  or  Cuticle 
Vessels  and  Nerves  of  the  Skin 


Appendages  of  the  Skin. 


Nails 
Hairs 
Sebaceous 


md  Sudoriferous  Glands 


Tongue. 


Papillae  of,  and  their  Structure 
Follicles,  and  Mucous  Glands  of 
Fibrous  Septum  of   . 
Muscular  Fibres  of   . 
Arteries  and  Nerves  of     . 

Nose. 

Cartilages  of     . 
Muscles  of        ...        . 
Skin,  Mucous  Membrane . 
Arteries,  Veins,  and  Nerves     . 


Nasal  Fossa?. 
Mucous  Membrane  of       ... 
Peculiarities  of,  in  Superior,  Middle,  and 

Inferior  Meatuses 

Arteries,  Veins,  and  Nerves   of  Nasal 

Fossae 

Eye. 


Situation,  Form  of    . 

Tunics  of 

Sclerotic  and  its  Structure 
Cornea  and  its  Structure  . 
Choroid  and  its  Structure 
Ciliary  Processes      .... 

Iris 

Membrana  Pupillaris,  Ciliary  Ligament 

Ciliary  Muscle 

Retina 

Structure  of  Retina 

Jacob's  Membrane 

Granular  Layer 

Nervous  Layer  .... 

Radiating  Fibres  of  the  Retina 
Arteria  Centralis  Retina; 
Structure  of  Retina,  at  Yellow  Spot 

Humors  of  the  Eye. 

Aqueous  Humor 

Anterior  Chamber     . 

Posterior  Chamber    . 
Vitreous  Body .... 
Crystalline  Lens  and  its  Capsule 
Changes  produced  in  the  Lens  by  Age 


615 


PAGE 

602 
603 
603 
604 
605 


605 
606 
607 


609 
610 
610 
610 
611 


612 
612 
612 
613 


613 
613 


614 


614 
615 
616 
616 
617 
618 
619 
620 
620 
620 
621 
621 
621 
621 
622 
622 
622 


622 
622 
622 
623 
623 
624 


Suspensory  Ligament  of  Lens  .        .  624 

Canal  of  Petit 684 

Vessels  of  the  Globe  of  the  Eye       .        .  024 

Nerves  of  Eyeball .625 

Appendages  of  the  Eye 

Eyebrows  .        .        .        .        .        .  &25 

Eyelids 625 

Structure  of  the  Eyelids  .        .        .        .625 

Tarsal  Cartilages 625 

Meibomian  Glands 626 

Eyelashes  .  ....  626 

Conjunctiva 626 

Caruncula  Lacrymalis       ....  627 

Lachrymal  Apparatus. 

Lachrymal  Gland 628 

Canals 628 

Sac 628 

Nasal  Duct 628 

Ear. 

Pinna  or  Auricle 628 

Structure  of  Auricle  ....  628 

Ligaments  of  the  Pinna  ....  629 

Muscles  of  the  Pinna        ....  630 

Arteries,  Veins,  and  Nerves  of  the  Pinna  631 

Auditory  Canal 631 

Middle  Ear  or  Tympanum. 

Openings  in  Cavity  of       ...  632 

Walls  of 632,  633,  634 

Eustachian  Tube 634 

Membrana  Tympani  ....  634 

Structure  of 634 

Ossicles  of  the  Tympanum  .  .  .  634 
Ligaments  of  the  Ossicula  .  .  .  635 
Muscles  of  the  Tympanum  .  .  .  636 
Mucous  Membrane  of  Tympanum  .  .  636 
Arteries,  Veins,  and  Nerves  of  Tym- 
panum        636,  637 


Internal  Ear  or  Labyrinth. 

Vestibule 

Semicircular  Canals 

Superior  Semicircular  Canal 
Posterior  Semicircular  Canal     . 
External  Semicircular  Canal 

Cochlea 

Central  Axis  or  Modiolus 
Spiral  Canal       .... 

Lamina  Spiralis         .... 

Scala  Tympani,  Scala  Vestibuli 

Membranous  Labyrinth     . 

Utricle  and  Saccule 

Membranous  Semicircular  Canals 

Structure  of  the  (Membranous)  Labyrinth 

Vessels  of  the  Labyrinth 

Auditory  Nerve,  Vestibular  Nerve,  Coch 
lear  Nerve 


637 
638 
638 
638 
638 
639 
639 
639 
640 
640 
640 
641 
641 
641 
641 

642 


CONTENTS. 


VISCERA. 


Organs  of  Digestion  and  their  Appendages. 


Alimentary  Canal 
Its  Subdivisions 
The  Mouth 
The  Lips  . 
The  Cheeks 
The  Gums 


Teeth. 


General  Characters  of 

Permanent  Teeth     .... 

Incisors,  Canine,  Bicuspid,  Molars    . 

Temporary  or  Milk  Teeth 

Structure  of  the  Teeth 

Ivory  or  Dentine,  Chemical  Composition 

Enamel,  Cortical  Substance 

Development  of  the  Teeth 

of  the  Permanent  Teeth    . 
Growth  of  the  Teeth 
Eruption  of  the  Teeth 

Palate. 

Hard  Palate 

Soft  Palate 

Uvula,  Pillars  of  the  Soft  Palate 
Mucous     Membrane,    Aponeurosis,    and 
Muscles  of  Soft  Palate 

Tonsils. 
Arteries,  Veins,  and  Nerves  of  Tonsils     . 

Salivary  Glands. 

Parotid  Gland. 
Steno's  Duct     .         .         . 
Vessels  and  Nerves  of  Parotid  Gland 

Submaxillary  Gland. 
Wharton's  Duct                 * 
Vessels    and     Nerves    of    Submaxillary 
Gland 

Sublingual  Gland. 
Vessels  and  Nerves  of      ... 
Structure  of  Salivary  Glands    . 


Structure  of 


Pharynx. 


(Esophagus. 


PAGE 

643 
643 
643 
643 

644 
644 


645 
646 
646 
647 
648 
648 
649 
649 
649 
651 
651 


652 
652 
652 

653 


653 


654 

655 


655 


655 


655 
655 


656 


Kelations,  Surgical  Anatomy,  and  Struc- 
ture of 


Abdomen. 


Boundaries 
Apertures  of     . 
Regions     . 


657 


658 
659 
659 


Peritoneum. 
Reflections  traced     . 
Foramen  of  Winslow 


660 
661 


Lesser  Omentum       .... 

PAGE 

.     662 

Great  Omentum 

.     662 

Gastro-splenic  Omentum  . 

.     662 

Mesentery 

.     662 

Mesocaecum,  Mesocolon    . 

.     663 

Stomach. 

663 

Splenic  end,  Pyloric  end  . 

.     663 

Cardiac  and  Pyloric  Orifices    . 

.     663 

Greater  and  Lesser  Curvatures 

.     683 

664 

Ligaments  of    . 

.     664 

Alterations  in  Position 

.     664 

Pylorus 

.     665 

Structure  of  Stomach 

.     665 

Serous  and  Muscular  Coats 

.     666 

Mucous  Membrane   . 

.     666 

Gastric  Follicles 

.     666 

Vessels  and  Nerves  of  Stomach 

.     667 

Small  Intestines. 

Duodenum         .... 

.     667 

Ascending  portion 

.     667 

Descending  portion    . 

.     667 

Transverse  portion     . 

.     667 

Vessels  and  Nerves  of  Duodenum 

.     668 

.     668 

,     668 

Structure  of  Small  Intestines   . 

.     668 

Serous,  Muscular,  and  Cellular  Coats        .     668 

Mucous  Membrane    . 

.     668 

Epithelium  and  Valvuke  Conniventes       .    668 

Villi — their  Structure 

.     669 

Simple  Follicles,  Duodenal  Glands 

.     669 

Solitary  Glands 

.     969 

Aggregate  Glands     . 

.     670 

Large  Intestine. 

.     670 

Appendix  Vermiformis  Caeci 

.     671 

Ileo-caecal  Valve 

.     671 

,     672 

Ascending 

.     672 

Transverse 

.     672 

Descending 

.     672 

Sigmoid  Flexure 

.     672 

672 

Upper  portion    . 

.     673 

Middle  portion  . 

.     673 

Lower  portion    . 

.     673 

Structure  of  Large  Intestine     . 

.     673 

Serous  and  Muscular  Coats 

.     673 

Cellular  and  Mucous  Coats 

.     674 

Epithelium,  Simple  Follicles     . 

.     674 

Solitary  Glands 

.     675 

Liver. 

Size,  Weight,  Position  of 

.     675 

Its  Surfaces  and  Borders 

.     675 

Changes  of  Position 

.     675 

CONTENTS. 


xxi 


PAGE 

Ligaments  of  the  Liver    ....  675 

Longitudinal,  Lateral.  Coronary        .  676 

Round  Ligament        ....  676 

Fissures  of  the  Liver         ....  676 

Longitudinal 67G 

Fissure  of  Ductus  Yenosus,  Portal  Fis- 
sure         677 

Fissures  for  Gall-bladder  and  Vena  Cava  677 

Lobes  of  the  Liver 677 

Eight,  Left        ....     677,  G78 
Lobus  Quadratus,  L.  Spigelii,  L.  Cauda- 

tus 678 

Vessels  of  Liver 678 

Lymphatics,  Nerves          ....  678 

Structure  of  Liver 678 

Serous  Coat 678 

Fibrous  Coat 679 

Lobules 679 

Hepatic  Cells 679 

Biliary  Ducts,  Portal  Vein       .         .         .680 

Hepatic  Artery,  Hepatic  Veins        .        .  680 

Gall-bladder. 

Structure 681 

Biliary  Ducts 681 

Hepatic  Ducts 681 

Cystic,     and     Common     Choledoch 

Ducts 682 

Structure  of  Biliary  Ducts         .        .  682 

Pancreas. 

Dissection 682 

Relations 683 

Duct 683 

Structure,  Vessels,  and  Nerves                 .  684 

Spleen. 

Relations .        .        .        .        .        .        .684 

Size  and  Weight       .        .        .        .        .684 

Structure  of  Serous  and  Fibrous  Coats    .  685 

Proper  Substance 685 

Malpighian  Corpuscles     ....  686 

Splenic  Artery  and  its  distribution  .        .  687 

Capillaries  of  Spleen         ....  688 

Veins  of  Spleen 688 

Lymphatics  and  Nerves   .                 .        .  689 


Thorax. 

PAllE 

Boundaries  of 689 

Superior  Opening,  Base    ....  689 

Parts  passing  through  Upper  Opening    .  689 

Pericardium. 

Structure 689 

Fibrous  Layer,  Serous  Layer    .        .        .  680 

Heart. 

Position,  Size 691 

Subdivision  into  Four  Cavities         .        .  691 

Circulation  of  Blood  in  Adult  .        .        .  691 
Auriculo-ventricular,     and     Ventricular 

Grooves 691 

Right  Auricle. 

Openings 693 

Valves 693 

Relics  of  Foetal  Structure        .        .        .693 

Musculi  Pectinati 693 

Right  Ventricle. 

Openings 694 

Tricuspid  Valve 694 

Semilunar  Valves 695 

Chorda?  Tendineae  and  Columnae  Carnea; .  695 

Left  Auricle. 

Sinus  and  Appendix         .        .        .        .  695 

Openings,  Musculi  Pectinati    .        .        .  696 

Left  Ventricle. 

Openings 697 

Mitral  and  Semilunar  Valves    .        .        .  697 

Endocardium 697 

Structure  of  Heart. 

Fibrous  Rings 697 

Muscular  Structure 698 

of  Auricles         ....  698 

of  Ventricles      .        .        .        .698 

Vessels  and  Nerves  of  Heart    .        .        .  699 

Peculiarities  in  Vascular  System  of  Foetus  699 

Foramen  Ovale,  Eustachian  Valve  .        .  699 

Ductus  Arteriosus 699 

Umbilical  or  Hypogastric  Arteries  .        .699 

Fcetal  Circulation 700 

Changes  in  Vascular  System  at  Birth      .  702 


Organs  of  Yoice  and  Eespiration. 


Tlie  Larynx. 

Cartilages  of  the  Larynx 

Thyroid  Cartilage 

Cricoid  and  Arytenoid  Cartilages 

Cartilages  of  Santorini  andWrisberg 

Epiglottis.     Its  Structure 

Ligaments  of  the  Larynx 

Ligaments  connecting  the  Thyroid  Carti 

lage  with  the  Os  Hyoides 
Ligaments  connecting  the  Thyroid  Carti 

lage  with  the  Cricoid    ... 
Ligaments  connecting  the  Arytenoid  Car- 
tilages to  the  Cricoid    . 
Ligaments  of  the  Epiglottis     . 
Upper  Aperture  of  the  Larynx 
Cavity  of  the  Larynx 

Glottis 

False  Vocal  Cords    .... 


703 
703 
704 
705 
705 
705 

705 

706 

706 
706 
706 
707 
707 
707 


True  Vocal  Cords     .... 

708 

Ventricle  of  Larynx,  Sacculus  Laryngis 

708 

Muscles  of  Larynx    ..... 

708 

Crico-thyroid     .... 

708 

Crico-arytaenoideus  posticus 

708 

lateralis 

709 

Thyro-arytaenoideus   . 

709 

Muscles  of  the  Epiglottis  . 

709 

Thyro-epiglottideus   . 

710 

Arytaeno-epiglottideus,  superior 

710 

inferior 

710 

Actions  of  Muscles  of  Larynx 

710 

Mucous  Membrane  of  Larynx  . 

710 

Glands,  Vessels  and  Nerves  of 

711 

Trachea. 

Relations 

712 

Bronchi 

712 

xxu 


CONTENTS. 


PAOK 

Struciure  of  Trachea         ....     712 
Surgical  Anatomy  of    Laryngotracheal 
Eegion .     713 

The  Pleura. 

Eeflections 715 

Vessels  and  Nerves  .        .        .        .716 

Mediastinum. 
Anterior  Mediastinum       ....     716 
Middle  Mediastinum  ....     716 

Posterior  Mediastinum     .         .         .         .716 

The  Lungs. 

Surfaces,  Lobes 717 

Eoot  of  Lung 719 

Weight,  Color,   and  Properties  of  Sub- 
stance of  Lung      719 

Structure  of  Lung 719 

Serous  Coat,  and  Subserous  AreolarTissue  719 


PABB 

Parenchyma  and  Lobules  of  Lung   .        .  719 
Bronchi,  Arrangement  of  in  Substance  of 

Lung 719 

Structure  of  Smaller  Bronchial  Tubes      .  720 

The  Air-cells 720 

Pulmonary  Artery 720 

Pulmonary  Capillaries  and  Veins     .         .  720 

Bronchial  Arteries  and  Veins  .         .         .  720 

Lymphatics  and  Nerves  of  Lung      .         .  721 

Thyroid  Gland. 

Structure 721 

Vessels  and  Nerves          ....  721 

Chemical  Composition      ....  722 

Tliymus  Gland. 

Structure 722 

Vessels  and  Nerves          ....  723 

Chemical  Composition      ....  723 


The  Urinary  Organs. 


Kidneys. 
Eelations 

Dimensions,  Weight 
Cortical  Substance  . 
Medullary  Substance 
Minute  Structure 
Malpighian  Bodies  . 
Ureter,  Pelvis,  Infundibula 
Eenal  Artery,  Eenal  Veins 
Lymphatics  and  Nerves   . 

Ureters. 

Situation,  Course,  Eelations 
Structure 


Supra-renal  Capsules. 


Eelations 


724 
724 
724 
725 
725 
726 
726 
726 
727 


727 
727 


727 


Structure 

Vessels  and  Nerves 

Pelvis. 
Boundaries  and  Contents 

Bladder. 
Shape,  Position,  Eelations 
Subdivisions 
Ligaments 
Structure  . 
Interior  of  Bladder 
Vessels  and  Nerves 

Male  Urethra. 
Membranous  Portion 
Spongy  Portion 
Structure  . 


728 

728 


728 


729 
730 
730 
731 
731 
732 


733 
733 

733 


Male  Generative  Organs. 


Prostate  Gland          .... 

735 

Structure  

735 

Vessels  and  Nerves   . 

736 

Cowper's  Glands       .         . 

736 

Prostatic  Secretion  .... 

736 

Penis. 

Eoot 

736 

Glans  Penis 

736 

Body         ....... 

736 

Corpora  Cavernosa  .... 

737 

Structure  

737 

Corpus  Spongiosum 

737 

The  Bulb 

737 

Structure  of  Corpus  Spongiosum 

738 

Erectile  Tissue          .... 

738 

Arteries  of  the  Penis 

738 

Lymphatics  of  the  Penis  . 

738 

Nerves  of  the  Penis 

738 

•                       The  Testes. 

Form  and  Situation 

739 

Size  and  Weight       .... 

739 

Scrotum 

739 

Other  Coverings  of  the  Testis  . 

739 

Proper  Coverings  of  the  Testis 

739 

Tunica  Vaginalis 

740 

Tunica  Albuginea 

740 

Mediastinum  Testis  . 

740 

Tunica  Vasculosa 

740 

Structure  of  the  Testis 

741 

Lobules  of  the  Testis 

741 

Number,  Size,  Shape,  Position 

741 

Structure  of  the  Lobuli  Testis 

741 

Tubuli  Seminiferi      .... 

.     741 

Arrangement  in  Lobuli     . 

741 

in  Mediastinum  Testis 

741 

in  Epididymis 

741 

Vasculum  Aberrans 

741 

Vas  Deferens,  Course,  Eelations 

742 

Structure  

742 

Vessels  and  Nerves  of  the  Coverings  o 

F 

the  Testis 

742 

Spermatic  Cord. 

Its  Composition        .... 

742 

Eelations  of  in  Inguinal  Canal 

742 

Arteries  of  the  Cord 

742 

Veins  of  the  Cord     .... 

743 

Lymphatics  and  Nerves  of  the  Cord 

743 

CONTENTS. 


xxin 


Vesicvlce  Seminales. 


Form  and  Size 
Relations  . 
Structure  . 


PAOE 

743 

744 
744 


Ejaculatory  Ducts     . 

Structure  of 
The  Semen 
Descent  of  the  Testes 

Gubernaculum  Testis 


PAOK 

744 

744 
744 
744 

745 


Female  Organs  of  Generation. 


Mons  Veneris,  Labia  Majora    . 
Labia  Minora,  Clitoris,  Meatus  Urinarius 
Hymen,  Glands  of  Bartholine  . 
Bladder     .        .        .        .        • 

Urethra 

Rectum     ....... 


Vagina. 


Relations 
Structure 


Uterus. 


Situation,  Form,  Dimensions 

Fundus,  Body  and  Cervix 

Ligaments 

Cavity  of  the  Uterus 

Structure  .... 

Vessels  and  Nerves  . 

Its  Form,  Size,  and  Situation 

in  the  Foetus 

at  Puberty 


746 

747 
747 

748 
748 
749 


749 
749 


750 
750 
750 
750 
751 
751 
752 
752 
752 


during  and  after  Menstruation 

752 

after  Parturition 

752 

in  Old  Age 

752 

Appendages  oftlie  Uterus. 

Fallopian  Tubes        .... 

752 

Structure  . 

752 

Ovaries     . 

752 

Structure  . 

753 

Graafian  Vesicles 

753 

Ovum 

754 

Discharge  of  the  Ovum 

754 

Corpus  Luteum 

754 

Ligament  of  the  Ovary 

755 

Round  Ligaments     . 

755 

Vessels  and  Nerves  of  Appendages 

755 

Mammary  Glands. 

Structure  of  Mamma 

.     756 

Vessels  and  Nerves 

.     757 

Surgical  Anatomy  of  Inguinal  Hernia. 


Dissection 

758 

Inguinal  Hernia. 

Superficial  Fascia 

Superficial  Vessels  and  Nerves 

758 
758 

Varieties  of 

.     764 

Deep  Layer  of  Superficial  Fascia 

758 

Oblique  Inguinal  Hernia. 

Aponeurosis  of  External  Oblique 

759 

External  Abdominal  Ring 

760 

Course  and  Coverings  of  .        ... 

764 

Pillars  of  the  Ring  . 

760 

Seat  of  Stricture       .... 

764 

Intercolumnar  Fibres 

760 

Scrotal  Hernia          .... 

765 

Fascia 

760 

Bubonocele 

765 

Poupart's  Ligament 

760 

Congenital  Hernia    .... 

765 

Gimbernat's  Ligament 

761 

Infantile  Hernia 

765 

Internal  Oblique  Muscle 

761 

Triangular  Ligament 
Cremaster 

761 
761 

Direct  Inguinal  Hernia. 

Trans versalis  Muscle 

762 

Course  and  Coverings  of  the  Hernia 

765 

Spermatic  Canal 
Fascia  Transversalis 

762 

Seat  of  Stricture       .... 

765 

# 

763 

Incomplete  Direct  Hernia 

766 

Internal  Abdominal  Ring 

763 

Comparative  Frequency  of  Oblique  ant 

Subserous  Areolar  Tissue 

763 

Direct  Hernia        .... 

76G 

Epigastric  Artery     . 

764 

Diagnosis  of  Oblique  and  Direct  Hernia 

766 

Peritoneum 

764 

Surgical  Anatomy  of  Femoral  Hernia. 


Dissection 

766 

Superficial  Fascia     .... 

766 

Cutaneous  Vessels    .... 

766 

Internal  Saphenous  Vein       '  . 
Superficial  Inguinal  Glands 

767 

767 

Cutaneous  Nerves    .... 

767 

Deep  Layer  of  Superficial  Fascia    . 

768 

Cribriform  Fascia     .... 

768 

Fascia  Lata 

768 

Iliac  Portion      .... 

768 

Pubic  Portion   .... 

769 

Saphenous  Opening  .... 

769 

Crural  Arch 

Gimbernat's  Ligament 

Crural  Sheath  . 

Deep  Crural  Arch    . 

Crural  Canal     . 

Femoral  or  Crural  Ring 

Position  of  Parts  around  the  Ring 

Septum  Crurale 

Descent  of  Femoral  Hernia 

Coverings  of  Femoral  Hernia  . 

Varieties  of  Femoral  Hernia    . 

Seat  of  Stricture 


769, 


769 
770 
770 
771 
771 
771 
771 
772 
773 
773 
773 
774 


XXIV 


CONTENTS. 


Surgical  Anatomy  of  Perineum  and  Ischio-rectal  Region. 


Ischio-rectal  Region. 

Dissection 
Boundaries  of  . 
Superficial  Fascia 
External  Sphincter 
Internal  Sphincter 
Ischio-rectal  Fossa 
Position  of  Parts  contained  in 

Perineum. 

Boundaries,  and  Extent    . 
Superficial  Layer  of  Superficial  Fascia 
Deep  Layer  of  Superficial  Fascia     . 
Course  taken  by  the  Urine  in  Rupture 

of  the  Urethra       .... 
Muscles  of  the  Perineum  (Male) 
Accelerator  Urina?    . 

Erector  Penis 

Transversus  Perinei 
Superficial  Perineal  Vessels  and  Nerves 
Transversus  Periaei  Artery 
Muscles  of  the  Perineum  (Female) 
Sphincter  Vaginae     .... 
Erector  Clitoridis      .... 


PAGE 

775 
775 
775 
776 
77G 
776 
776 


777 
777 

777 

778 
778 
778 
77'.) 
779 
780 
780 
780 
780 
780 


Transversus  Perinei 
Compressor  Urethra; 
Levator  Ani 
Deep  Perineal  Fascia 

Anterior  Layer 

Posterior  Layer 
Parts  between  the  two  Layers 
Compressor  Urethra; 
Cowper's  Glands 
Pudic  Vessels  and  Nerves 
Artery  of  the  Bulb  . 
Levator  Ani 

Relations,  Actions     . 
Coccygeus,  Relations,  Actions 
Position  of  Viscera  at  Outlet  of  Pelvis 
Parts   concerned  in  the    Operation    of 

Lithotomy 

Parts  divided  in  the  Operation 
Parts  to  be  avoided  in  the  Operation 
Abnormal    Course    of    Arteries    in    the 

Perineum 
Pelvic  Fascia    . 

Obturator  Fascia 

Recto-vesical  Fascia 


780 

780 

780 

781 

781 

781 

781 

781 

781 

781' 

781 

781 

782 

782 

782 

783 

784 
784 

785 
785 
786 
786 


Surgical 

Anatomy  of  Muscles  of  the  Extremities 

320 

—354 

a 

"             Talipes    .... 

* 

.     348 

"             Arteries 

"             Triangles  of  the  Neck   . 

364—450 
.    382 

u 

"             Axilla     .... 

401 

u 

"             Bend  of  Elbow 

407 

u 

"              Scarpa's  Triangle 

. 

438 

u 

11 

"             Popliteal  Space 
"              (Esophagus 

• 

443 

657 

« 

"             Laryngotracheal  Region 

713 

•  ( 

"             Inguinal  Hernia 

7G2 

u 

(( 

"             Femoral  Hernia 

•"             Perineum 

"             Prostate  Gland 

• 

\ 

766 
775 

782 

- 

"             Base  of  Bladder 

, 

783 

LIST  OF  ILLUSTRATIONS. 


4S*  The  Illustrations,  when  copied  from  any  other  work,  have  the  author's  name  affixed  ;  when  no  such  acknow- 
ledgment is  made,  the  drawing  is  to  be  considered  original.    Those  marked  with  *  are  new  in  this  edition. 


FIG 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8 

14, 
15. 
16. 
17 
20. 
21. 
22. 
23. 
24. 
25. 
26. 
27. 
28. 
29. 
30. 
31. 
32. 
33. 
34. 
35. 
36. 
37. 
38. 
39. 
40. 
41. 
42. 
43. 
44. 
45. 
46. 
47. 
48. 
49. 
50. 
51. 


Osteology. 


A  Cervical  Vertebra 

Atlas        .... 

Axis         .... 

*Seventh  Cervical  Vertebra 

A  Dorsal  Vertebra 

Peculiar  Dorsal  Vertebrae 

A  Lumbar  Vertebra 
to  13.  Development  of  the  Vertebrae 

Sacrum,  anterior  surface 

*  Vertical  Section  of  the  Sacrum 

Sacrum,  posterior  surface 
to  19.  Development  of  Sacrum     . 

Coccyx,  anterior  and  posterior  surfaces 

Lateral  View  of  Spine    . 

Occipital  Bone,  outer  surface 

Occipital  Bone,  inner  surface 

Occipital  Bone,  development  of 

Parietal  Bone,  external  surface 

Parietal  Bone,  internal  surface 

Frontal  Bone,  outer  surface 

Frontal  Bone,  inner  surface 

*Frontal  Bone  at  Birth  . 

Temporal  Bone,  outer  surface 

Temporal  Bone,  inner  surface 

Temporal  Bone,  petrous  portion 

Temporal  Bone,  development  of 

Sphenoid  Bone,  superior  surface 

Sphenoid  Bone,  anterior  surface 

Sphenoid  Bone,  posterior  surface 

Plan  of  the  Development  of  Sphenoid 

Ethmoid  Bone,  outer  surface 

Perpendicular  Plate  of  Ethmoid 

*Ethmoid  Bone,  inner  surface  of  right  lateral  mass 

*Skull  at  Birth,  showing  the  anterior  and  posterior  Fontanelles 

*Lateral  Fontanelles 

Nasal  Bone,  outer  surface 

Nasal  Bone,  inner  surface 

Superior  Maxillary  Bone,  outer  surface 

Superior  Maxillary  Bone,  inner  surface 

Development  of  Superior  Maxillary  Bone 

Lachrymal  Bone,  outer  surface  . 

Malar  Bone,  outer  surface 

Malar  Bone,  inner  surface 

Palate  Bone,  internal  view 


Quain 


Quain 


Quain 


Quain 


Quain 


(  xxv  ) 


XXVI 


LIST   OF   ILLUSTRATIONS. 


FIG. 

52.  Palate  Bone,  posterior  view 

53.  Inferior  Turbinated  Bone,  inner  surface 

54.  Inferior  Turbinated  Bone,  outer  surface 

55.  Vomer      ..... 

56.  Inferior  Maxillary  Bone,  outer  surface   . 

57.  Inferior  Maxillary  Bone,  inner  surface  . 

58.  *Side-view  of  the  Lower  Jaw,  at  Birth 

59.  *Side-view  of  the  Lower  Jaw,  at  Puberty 

60.  *Side-view  of  the  Lower  Jaw,  in  the  Adult 

61.  *Side-view  of  the  Lower  Jaw,  in  Old  Age 

62.  Base  of  Skull,  inner  surface 

63.  Base  of  Skull,  outer  surface 

64.  *Side-view  of  the  Skull  . 

65.  Anterior  Region  of  Skull 

66.  Nasal  Fossae,  roof,  floor,  and  wall 

67.  Nasal  Fossae,  inner  wall  or  septum 

68.  Hyoid  Bone,  anterior  surface 

69.  Sternum  and  Costal  Cartilages,  anterior  surface 

70.  Sternum,  posterior  surface 
71  to  74.  Development  of  Sternum 

75.  A  Rib      . 

76.  Vertebral  Extremity  of  a  Rib    . 
77  to  81.  Peculiar  Ribs 

82.  Clavicle,  anterior  surface 

83.  Clavicle,  inferior  surface 

84.  Scapula,  anterior  surface  or  venter 

85.  Scapula,  posterior  surface  or  dorsum 

86.  Plan  of  the  Development  of  the  Scapula 

87.  Humerus,  anterior  view  . 

88.  Humerus,  posterior  surface 

89.  Plan  of  the  Development  of  the  Humerus 

90.  Bones  of  the  Forearm,  anterior  surface 

91.  Bones  of  the  Forearm,  posterior  surface 

92.  Plan  of  the  Development  of  the  Ulna    . 

93.  Plan  of  the  Development  of  the  Radius 

94.  Bones  of  the  Hand,  dorsal  surface 

95.  Bones  of  the  Hand,  palmar  surface 

96.  Plan  of  the  Development  of  the  Hand    . 

97.  Os  innominatum,  external  surface 

98.  Os  Innominatum,  internal  surface 

99.  Plan  of  the  Development  of  the  Os  Innominatum 

100.  *Male  Pelvis  (adult)       .... 

101.  *Female  Pelvis  (adult)    .  . 

102.  *Vertical  Section  of  the  Pelvis,  with  lines  indicating  the  Axes  of  the 

103.  Right  Femur,  anterior  surface    . 

104.  Right  Femur,  posterior  surface  . 

105.  *Diagram  showing  the  Structure  of  the  Neck  of  the  Femur 

106.  Plan  of  the  Development  of  the  Femur 

107.  Right  Patella,  anterior  surface  . 

108.  Right  Patella,  posterior  surface 

109.  Tibia  and  Fibula,  anterior  surface 

110.  Tibia  and  Fibula,  posterior  surface 

111.  Plan  of  the  Development  of  the  Tibia 

112.  Plan  of  the  Development  of  the  Fibula 

113.  Bones  of  the  Foot,  dorsal  surface 

114.  Bones  of  the  Foot,  plantar  surface 

115.  Plan  of  the  Development  of  the  Foot 


Pelvis 


Ward 


LIST   OF   ILLUSTRATIONS. 


XXTll 


Articulations. 

FIO. 

116.  Vertical  Section  of  Two  Vertebra;  and  their  Ligaments,  front  view 

117.  Occipito-atloid  and  Atlo-axoid  Ligaments,  front  view  . 

118.  Occipito-atloid  and  Atlo-axoid  Ligaments,  posterior  view 

119.  Articulation  between  Odontoid  Process  and  Atlas 

120.  Occipito-axoid  and  Atlo-axoid  Ligaments 

121.  Temporo-maxillary  Articulation,  external  view 

122.  Temporo-maxillary  Articulation,  internal  view 

123.  Temporo-maxillary  Articulation,  vertical  section 

124.  Costo-vertebral  and  Costo-transverse  Articulations,  anterior  view 

125.  Costo-transverse  Articulation     ..... 

126.  Costo-sternal,  Costo-xiphoid,  and  Intercostal  Articulations,  anterior 

127.  Articulations  of  Pelvis  and  Hip,  anterior  view 

128.  Articulations  of  Pelvis  and  Hip,  posterior  view 

129.  Vertical  Section  of  the  Symphysis  Pubis 

130.  Sterno-clavicular  Articulation     ..... 

131.  Shoulder-Joint,  Scapuloclavicular  Articulation,  and  proper  Ligament 

132.  Elbow-Joint,  showing  anterior  and  internal  Lateral  Ligaments 

133.  Elbow-Joint,  showing  posterior  and  external  Lateral  Ligaments 

134.  Ligaments  of  "Wrist  and  Hand,  anterior  view    . 

135.  Ligaments  of  Wrist  and  Hand,  posterior  view  . 

136.  Vertical  Section  of  Wrist,  showing  the  Synovial  Membranes 

137.  Articulations  of  the  Phalanges 

138.  Hip-Joint,  laid  open 

139.  Knee-Joint,  anterior  view 

140.  Knee-Joint,  posterior  view 

141.  Knee-Joint,  showing  internal  Ligaments 

142.  Head  of  Tibia,  with  semilunar  Cartilages,  &c,  seen  from  above 

143.  Ankle-Joint,  Tarsal  and  Tarso-metatarsal  Articulations,  internal  view 

144.  Ankle-Joint,  Tarsal  and  Tarso-metatarsal  Articulations,  external  view 

145.  Ligaments  of  Plantar  surface  of  the  Foot  . 

146.  Svnovial  Membranes  of  the  Tarsus  and  Metatarsus 

Muscles  and  Fascise. 

147.  Plan  of  Dissection  of  the  Head,  Face,  and  Neck 

148.  Muscles  of  the  Head,  Face,  and  Neck  . 

149.  Muscles  of  the  right  Orbit 

150.  Relative  position  and  attachment  of  the  Muscles  of  the  left  Eyeball 

151.  Temporal  Muscle  .... 

152.  Pterygoid  Muscles  .  .  . 

153.  Muscles  of  the  Neck,  and  Boundaries  of  the  Triangles 

154.  Muscles  of  the  Neck,  anterior  view 

155.  Muscles  of  the  Tongue,  left  side 

156.  Muscles  of  the  Pharynx,  external  view  . 

157.  Muscles  of  the  Soft  Palate 

158.  The  Prevertebral  Muscles  .... 

159.  Plan  of  Dissection  of  the  Muscles  of  the  Back  . 

160.  Muscles  of  tjie  Back — first,  second,  and  part  of  the  third  layers 

161.  Muscles  of  the  back — deep  layers 

162.  Plan  of  Dissection  of  Abdomen 

163.  External  Oblique  Muscle 

164.  Internal  Oblique  Muscle 

165.  Transversalis,  Rectus,  and  Pyramidalis  Muscles 

166.  Transverse  Section  of  Abdomen  in  Lumbar  Region 

167.  Diaphragm,  under  surface 

168.  Dissection  of  Upper  Extremity  . 


view 


Arnold 


Arnold 


s  of  Scapula 


Arnold 
do. 


Arnold 


uam 


Quain 


XXV111 


LIST   OF   ILLUSTRATIONS. 


Fia. 

169.  Muscles  of  the  Chest  and  Front  of  the  Arm,  superficial  view 

170.  Muscles  of  the  Chest  and  Front  of  the  Arm,  with  the  boundaries  of  the  Axilla 

171.  Muscles  on  the  Dorsum  of  the  Scapula  and  the  Triceps 

172.  Front  of  the  Forearm,  superficial  muscles 

173.  Front  of  the  Forearm,  deep  muscles 

174.  Posterior  surface  of  Forearm,  superficial  muscles 

175.  Posterior  surface  of  Forearm,  deep  muscles 

176.  *Transverse  section  through  the  Wrist,  showing  Posterior  Annular 

Canals  for  the  passage  of  the  Extensor  Tendons 

177.  Muscles  of  the  Hand,  palmar  surface     . 

178.  Dorsal  Interossei  of  Hand 

179.  Palmar  Interossei  of  Hand 

180.  Fracture  of  the  Middle  of  the  Clavicle    . 

181.  Fracture  of  the  Surgical  Neck  of  the  Humerus 

182.  Fracture  of  the  Humerus  above  the  Condyles   . 

183.  Fracture  of  the  Olecranon 

184.  Fracture  of  shaft  of  the  Radius  . 

185.  Fracture  of  the  lower  end  of  the  Radius 

186.  Plan  of  Dissection  of  Lower  Extremity,  front  view 

187.  Muscles  of  the  Iliac  and  Anterior  Femoral  Eegions 

188.  Muscles  of  the  Internal  Femoral  Region 

189.  Plan  of  Dissection  of  Lower  Extremity,  posterior  view 

190.  Muscles  of  the  Hip  and  Thigh    . 

191.  Muscles  of  the  Front  of  the  Leg 

192.  Muscles  of  the  back  of  the  Leg,  superficial  layer 

193.  Muscles  of  the  back  of  the  Leg,  deep  layer 

194.  Muscles  of  the  sole  of  the  Foot,  first  layer 

195.  Muscles  of  the  sole  of  the  Foot,  second  layer    . 

196.  Muscles  of  the  sole  of  the  foot,  third  layer 

197.  Dorsal  Interossei  of  Foot 

198.  Plantar  Interossei  of  Foot 

199.  Fracture  of  the  neck  of  the  Femur  within  the  Capsular  Ligament 

200.  Fracture  of  the  Femur  below  the  Trochanters  . 

201.  Fracture  of  the  Femur  above  the  Condyles 

202.  Fracture  of  the  Patella  .... 

203.  Oblique  fracture  of  the  shaft  of  the  Tibia 

204.  Fracture  of  the  Fibula,  with  displacement  of  the  Tibia 

Arteries. 

205.  Arch  of  the  Aorta  and  its  branches 

206.  Plan  of  the  branches  of  the  Arch  of  the  Aorta 

207.  Surgical  Anatomy  of  the.  Arteries  of  the  Neck 

208.  Plan  of  the  branches  of  the  External  Carotid    . 

209.  Arteries  of  the  Face  and  Scalp  . 

210.  The  Internal  Maxillary  Artery,  and  its  branches 

211.  Plan  of  the  branches  of  the  Internal  Maxillary  Artery 

212.  Internal  Carotid  and  Vertebral  Arteries 

213.  Ophthalmic  Artery  and  its  branches 

214.  Arteries  of  the  base  of  the  Brain 

215.  Plan  of  the  branches  of  the  Right  Subclavian  Artery 

216.  Scapular  and  Circumflex  Arteries 

217.  Axillary  Artery,  and  its  branches 

218.  Surgical  Anatomy  of  the  Brachial  Artery      "    . 

219.  Surgical  Anatomy  of  the  Radial  and  Ulnar  Arteries 

220.  Ulnar  and  Radial  Arteries,  deep  view    . 

221.  Arteries  of  the  back  of  the  Forearm  and  Hand 

222.  Abdominal  Aorta  and  its  branches 


PAGE 

295 

he  Axilla 

297 

301 

306 

•  309 

. 

311 

311 

Ligament,  and 

315 

. 

317 

. 

319 

.     . 

320 

Hind 

321 

do. 

321 

do. 

322 

do. 

322 

do. 

323 

do. 

324 

327 

328 

Q 

uain 

332 
335 
336 
341 
343 
345 
351 
352 
353 
354 
354 

Hind 

355 

do. 

355 

do. 

356 

do. 

356 

do. 

356 

do. 

357 

362 

362 

369 

369 

374 

380 

380 

385 

387 

389 

395 

399 

401 

406 

410 

413 

415 

41,9 

LIST   OF    ILLUSTRATIONS. 


.   XXIX 


FIG. 

223.  C celiac  Axis  and  its  branches,  the  Liver  having  been  raised,  and  the  Lesser  Omen- 

tum removed  ........ 

224.  Cceliac  Axis  and  its  branches,  the  Stomach  having  been  raised,  and  the  Transverse 

Mesocolon  removed  ..... 

225.  Superior  Mesenteric  Artery  and  its  branches    . 

226.  Inferior  Mesenteric  Artery  and  its  branches 

227.  Arteries  of  the  Pelvis     ..... 

228.  229.  Variations  in  Origin  and  Course  of  Obturator  Artery 

230.  Arteries  of  the  Gluteal  and  Posterior  Femoral  Regions 

231.  Surgical  Anatomy  of  the  Femoral  Artery 

232.  Popliteal,  Posterior  Tibial,  and  Peroneal  Arteries 

233.  Surgical  Anatomy  of  the  Anterior  Tibial  and  Dorsalis  Pedis  Arteries 

234.  Plantar  Arteries,  superficial  view 

235.  Plantar  Arteries,  deep  view        .... 

Yeins. 

236.  Veins  of  the  Head  and  Neck      ........ 

237.  Veins  of  the  Diploe,  as  displayed  by  the  removal  of  the  outer  table  of  the  Skull  Breschet 

238.  Vertical  Section  of  the  Skull,  showing  the  Sinuses  of  the  Dura  Mater 

239.  Sinuses  at  the  Base  of  the  Skull  ..... 

240.  Superficial  Veins  of  the  Upper  Extremity         .... 

241.  Vena?  Cavae  and  Azygos  Veins,  with  their  Formative  Branches 

242.  Transverse  Section  of  a  Dorsal  Vertebra,  showing  the  Spinal  Veins  Breschet 

243.  Vertical  Section  of  two  Dorsal  Vertebra?,  showing  the  Spinal  Veins 

244.  Internal  or  long  Saphenous  Vein  and  its  Branches 

245.  External  or  short  Saphenous  Vein         .  .  . 

246.  Portal  Vein  and  its  Branches     ..... 


421 

422 
424 
426 
429 
433 
435 
439 
446 
448 
453 
453 


458 
462 
464 
465 
466 
469 
472 
472 
473 
474 
478 


Lymphatics. 

247.  Thoracic  and  Right  Lymphatic  Ducts   .... 

248.  Superficial  Lymphatics  and  Glands  of  the  Head,  Face,  and  Neck 

249.  Deep  Lymphatics  and  Glands  of  the  Neck  and  Thorax 

250.  Superficial  Lymphatics  and  Glands  of  the  Upper  Extremity   . 

251.  Superficial  Lymphatics  and  Glands  of  the  Lower  Extremity   . 

252.  Deep  Lymphatic  Vessels  and  Glands  of  the  Abdomen  and  Pelvis 

Nervous  System. 

253.  Spinal  Cord  and  its  Membranes  .... 

254.  Transverse  Section  of  the  Spinal  Cord  and  its  Membranes 

255.  Spinal  Cord,  side  view.     Plan  of  the  Fissures  and  Columns     . 

256.  Transverse  Sections  of  the  Cord     ...  . 

257.  *Transverse  Section  of  the  Gray  Substance  of  the  Spinal  Cord,  i 

near  the  middle  of  the  Dorsal  Region  .  .  .        j 

258.  *Transverse  Section  of  the  Gray  Substance  of  the  Spinal  Cord,  -i 

through  the  middle  of  the  Lumbar  Enlargement     .  .         j 

259.  *Longitudinal  Section  of  the  White  and  Gray  Substance  of  the  i 

Spinal  Cord,  through  the  middle  of  the  Lumbar  Enlargement    j 

260.  Medulla  Oblongata  and  Pons  Varolii,  anterior  surface 

261.  Posterior  Surface  of  Medulla  Oblongata 

262.  Transverse  Section  of  Medulla  Oblongata 

263.  Columns  of  the  Medulla  Oblongata,  and  their  Connection  with  the  l 

Cerebrum  and  Cerebellum     .....) 

264.  Upper  Surface  of  the  Brain,  the  Pia  Mater  having  been  removed 

265.  Base  of  the  Brak  ...... 

266.  Section  of  the  Brain,  made  on  a  level  with  the  Corpus  Callosum 


Mascagni 
do. 
do. 
do. 
do. 


Arnold 

Quain 

Arnold 


do. 
do. 


Arnold 
Altered  from 
Arnold 


483 
485 
486 
487 
489 
491 


501 
501 
503 
504 


J.  L.  Clarke      505 


505 

506 

511 
512 
512 

513 

516 
518 
521 


XXX 


LIST   OF   ILLUSTRATIONS. 


267.  Lateral  Ventricles  of  the  Brain  .......  522 

268.  Fornix,  Velum  Interpositum,  and  Middle  or  Descending  Cornu  of  the  Lateral  Ventricle  524 

269.  Third  and  Fourth  Ventricles       ........  527 

270.  Upper  Surface  of  the  Cerebellum  ......  530 

271.  Under  Surface  of  the  Cerebellum  .  .  .  .  -         .  .  531 

272.  Vertical  Section  of  the  Cerebellum        .....        Arnold  533 


Cranial  Nerves. 

273.  Optic  Nerves  and  Optic  Tracts  .... 

274.  Course  of  the  Fibres  in  the  Optic  Commissure 

275.  Nerves  of  the  Orbit,  seen  from  above     .... 

276.  Nerves  of  the  Orbit  and  Ophthalmic  Ganglion,  side  view 

277.  Course  and  Connections  of  the  Facial  Nerve  in  the  Temporal  Bone 

278.  Nerves  of  the  Scalp,  Face,  and  Side  of  the  Neck 

279.  Hypoglossal  Nerve,  Cervical  Plexus,  and  their  Branches         .  . 

280.  Distribution  of  the  Second  and  Third  Divisions  of  the  Fifth  Nerve  i 

and  Submaxillary  Ganglion  ....        J 

281.  Spheno-Palatine  Ganglion  and  its  Branches 

282.  Otic  Ganglion  and  its  Branches  .... 

283.  Origin  of  the  Eighth  Pair,  their  Ganglia  and  Communications 

284.  Course  and  Distribution  of  the  Eighth  Pair  of  Nerves 


Bowman 
After  Arnold 
After  Arnold 
After  Bidder 


After  Arnold 
Bendz 


536 
537 
538 
539 
540 
542 
544 


■After  Arnold    549 


553 
554 
555 
556 


Spinal  Nerves. 

285.  Plan  of  the  Brachial  Plexus       .... 

286.  Cutaneous  Nerves  of  Upper  Extremity,  anterior  view 

287.  Cutaneous  Nerves  of  Upper  Extremity,  posterior  view 

288.  Nerves  of  the  Upper  Extremity,  front  view 

289.  Supra-scapular,  Circumflex,  and  Musculo-spiral  Nerves 

290.  Lumbar  Plexus  and  its  Branches 

291.  Cutaneous  Nerves  of  Lower  Extremity,  front  view  • 

292.  Nerves  of  the  Lower  Extremity,  front  view 

293.  Cutaneous  Nerves  of  Lower  Extremity,  posterior  view 

294.  Nerves  of  the  Lower  Extremity,  posterior  view 

295.  Plantar  Nerves    ...... 

296.  Sympathetic  Nerve         ..... 


.  567 

.  569 

.  570 

.  572 

.  574 

Altered  from  Quain  579 

.  581 

.  581 

.  587 

.  587 

.  589 

.  593 


Organs  of  Sense. 

297.  Sectional  View  of  the  Skin,  magnified   ....... 

298.  Upper  Surface  of  the  Tongue     ........ 

299.  Three  kinds  of  Papillae  of  the  Tongue,  magnified  .  .       Bowman 

300.  Cartilages  of  the  Nose     .......         Arnold 

301.  Bones  and  Cartilages  of  Septum  of  Nose,  right  side     .  .  .  do. 

302.  Nerves  of  Septum  of  Nose,  right  side    .....  do. 

303.  Vertical  Section  of  the  Eyeball,  enlarged  .  .  ... 

304.  Choroid  and  Iris,  enlarged  .....        Altered  from  Zinn 

305.  Veins  of  the  Choroid,  enlarged  ......       Arnold 

306.  Arteries  of  the  Choroid  and  Iris,  enlarged         .  .  .  .do. 

307.  Arteria  Centralis  Betinae,  Yellow  Spot,  etc.,  the  anterior  half  of  the  Eyeball  being 

removed,  enlarged     .....•••• 

308.  Crystalline  Lens,  hardened  and  divided,  enlarged  .  .  .      Arnold 

309.  Meibomian  Glands,  etc.,  seen  from  the  Inner  Surface  of  the  Eyelids   .  do. 

310.  Lachrymal  Apparatus,  right  side  ....... 

311.  Pinna  or  Auricle,  outer  surface  ........ 

312.  Muscles  of  the  Pinna       .......      Arnold 


602 
608 
608 
611 
612 
614 
615 
617 
618 
619 

621 

624 
626 
627 
629 
630 


LIST   OP   ILLUSTRATIONS 


XXXI 


Scarpa 

PAGE 

631 

. 

633 

Arnold 

635 

Scemmerrmg 

638 

Arnold 

639 

Breschet 

641 

313.  Front  View  of  the  Organ  of  Hearing,  right  side 

314.  View  of  Inner  Wall  of  Tympanum,  enlarged 

315.  Small  Bones  of  the  Ear,  seen  from  the  outside,  enlarged 

316.  Osseous  Labyrinth,  laid  open,  enlarged 

317.  Cochlea  laid  open,  enlarged        .... 

318.  Membranous  Labyrinth  detached,  enlarged 

Organs  of  Digestion  and  their  Appendages. 

319.  Sectional  View  of  the  Nose,  Mouth,  Pharynx,  etc.     . 

320.  Permanent  Teeth,  external  view 

321.  Temporary  or  Milk  Teeth,  external  view 

322.  Vertical  Section  of  a  Molar  Tooth 

323.  Vertical  Section  of  a  Bicuspid  Tooth,  magnified  .  .         After  Retzius 
324  to  329.  Development  of  Teeth     .....  Goodsir 

330.  Salivary  Glands  ...... 

331.  The  Regions  of  the  Abdomen  and  their  contents 

332.  Reflections  of  the  Peritoneum,  as  seen  in  a  Vertical  Section  of  •»        Altered  from 

the  Abdomen  .....  }  Quain 

333.  Mucous  Membrane  of  the  Stomach  and  Duodenum,  with  the  Bile  Ducts 

334.  Muscular  Coat  of  the  Stomach  ....... 

335.  Minute  Anatomy  of  Mucous  Membrane  of  Stomach    .  .         Dr.  Sprott  Boyd 

336.  Two  Villi,  magnified       ........ 

337.  Patch  of  Peyer's  Glands,  from  the  lower  part  of  the  Ileum 

338.  A  portion  of  Peyer's  Glands,  magnified  .  .  .  .        Boehm 

339.  Caecum  and  Colon  laid  open,  to  show  the  Ilio-caecal  Valve 

340.  Minute  Structure  of  Large  Intestine     .....        Boehm 

341.  Liver,  upper  surface        ........ 

342.  Liver,  under  surface        ........ 

343.  Longitudinal  section  of  an  Hepatic  Vein  ....       Kieman 

344.  Longitudinal  section  of  a  small  Portal  Vein  and  Canal  .  .    •         do. 

345.  Transverse  section  of  a  small  Portal  Canal  and  its  vessels       .  .  do. 

346.  Pancreas  and  its  Relations         ........ 

347.  Transverse  section  of  the  Spleen,  showing  the  Tubercular  Tissue,  and  the  Splenic 

Vein  and  its  branches  ........ 

348.  Malpighian  Corpuscles,  and  their  Relation  with  the  Splenic  Artery  and  its  branches 

349.  One  of  the  Splenic  Corpuscles,  showing  its  Relations  with  flic  Bloodvessels  . 

350.  Transverse  section  of  the  Human  Spleen,  showing  the  distribution  of  the  Splenic 

Artery  and  its  branches       ........ 


644 
645 
647 
648 
648 
650 
054 
658 

660 

664 
665 
666 
669 
670 
670 
671 
674 
676 
677 
679 
679 
680 
683 

685 
686 
687 

688 


Organs  of  Circulation. 

351.  *Front  view  of  the  Thorax,  showing  the  relation  of  the  Thoracic  Viscera  to  the  walls 

of  the  Chest  ..........  690 

352.  Right  Auricle  and  Ventricle  laid  open,  the  anterior  walls  of  both  being  removed      .  692 

353.  Left  Auricle  and  Ventricle  laid  open,  the  anterior  walls  of  both  being  removed        .  696 

354.  Plan  of  the  Fcetal  Circulation    ........  700 


,  Organs  of  Voice  and  Eespiration. 

355.  Side  view  of  the  Thyroid  and  Cricoid  Cartilages 

356.  Cartilages  of  the  Larynx,  posterior  view  .... 

357.  *Larynx  and  adjacent  parts,  seen  from  above  .... 

358.  *Vertical  section  of  the  Larynx  and  upper  part  of  the  Trachea 

359.  Muscles  of  Larynx,  side  view,  right  Ala  of  Thyroid  Cartilage  removed 

360.  Interior  of  the  Larynx,  seen  from  above,  enlarged 

361.  Front  view  of  Cartilages  of  Larynx,  the  Trachea  and  Bronchi 


Willis 


703 
704 
706 
707 
709 
709 
711 


xxxn 


LIST    OF    ILLUSTRATIONS. 


362.  *Transverse  section  of  the  Trachea,  just  above  its  Bifurcation,  with  a  bird's-eye  view 

of  the  interior  ........ 

363.  Surgical  Anatomy  of  the  Laryngotracheal  Region       .... 

364.  Transverse  section  of  the  Thorax,  showing  the  relative  position  of  the  Yiscera,  and 

the  reflections  of  the  Pleura  ...... 

365.  *Front  view  of  the  Thorax,  showing  the  relation  of  the  Thoracic  Viscera  to  the  walls 

of  the  Chest  .  .  .  .  .  . 

366.  Front  view  of  the  Heart  and  Lungs       ...... 


712 

714 

715 

717 
718 


The  Urinary  and  Generative  Organs. 

367.  Vertical  section  of  the  Kidney  .... 

368.  Plan  to  show  the  minute  structure  of  the  Kidney         .  .  .     Bowman 

369.  Vertical  section  of  Bladder,  Penis,  and  Urethra        •   . 

370.  Bladder  and  Urethra  laid  open,  seen  from  above 

371.  Testis  in  situ,  the  Tunica  Vaginalis  having  been  laid  open 

372.  Vertical  section  of  the  Testicle,  to  show  the  arrangement  of  the  ducts 

373.  Base  of  the  Bladder,  with  the  Vasa  Deferentia  and  Vesiculae  Seminales      Haller 

374.  Vulva  and  External  Female  Organs  of  Generation       ..... 

375.  Section  of  Female  Pelvis,  showing  position  of  Viscera  .... 

376.  Uterus  and  its  Appendages,  anterior  view         ....        Wilson 

377.  *Section  of  the  Ovary  of  a  Virgin,  showing  the  Stroma  and  Graafian  Vesicles 

378.  *Section  of  the  Graafian  Vesicle  ....  After  Van  Baer 

379.  *Ovum  of  the  Sow  ......  After  Barry 

380.  Inguinal  Hernia,  Superficial  Dissection  ..... 

381.  Inguinal  Hernia,  showing  the  Internal  Oblique,  C  remaster,  and  Spermatic  Canal 

382.  Inguinal  Hernia,  showing  the  Transversalis  Muscle,  the  Transversalis  Fascia,  and 

the  Internal  Abdominal  Ring  .... 

383.  Femoral  Hernia,  Superficial  Dissection 

384.  Femoral  Hernia,  showing  Fascia  Lata,  and  Saphenous  Opening 

385.  Femoral  Hernia,  Iliac  Portion  of  Fascia  Lata  removed,  and  Sheath  of  Femoral  Vessels 

and  Femoral  Canal  exposed 

386.  Hernia ;  the  Relations  of  the  Femoral  and  Internal  Abdominal  Rings,  seen  from 

within  the  Abdomen,  right  side         ...... 

387.  388.  Variations  in  Origin  and  Course  of  Obturator  Artery 

389.  Plan  of  Dissection  of  Perineum  and  Ischio-rectal  Region 

390.  Perineum;  the  Integument  and  Superficial  Layer  of  Superficial  Fascia  reflected 

391.  The  Superficial  Muscles  and  Vessels  of  the  Perineum  .  . 

392.  Deep  Perineal  Fascia ;  on  the  Left  Side  the  Anterior  Layer  has  been  removed 

393.  A  view  of  the  Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis 

394.  A  transverse  section  of  the  Pelvis,  showing  the  Pelvic  Fascia  .     After  Wilson 

395.  Side  view  of  the  Pelvic  Viscera  of  the  Male  Subject,  showing  the  Pelvic  and  Perineal 

Fasciae     .......... 


725 
725 
729 
732 
740 
741 
743 
746 
748 
753 
753 
753 
754 
759 
761 

763 

767 
768 

770 

772 
772 
776 
778 
779 
780 
783 
784 

785 


ANATOMY, 

DESCRIPTIVE  AND  SURGICAL. 


Osteology. 

In  the  construction  of  the  human  body,  it  would  appear  essential,  in  the  first 
place,  to  provide  some  dense  and  solid  texture  capable  of  forming  a  framework 
for  the  support  and  attachment  of  the  softer  parts  of  the  frame,  and  of  forming 
cavities  for  the  protection  of  the  more  important  vital  organs;  and  such  a 
structure  we  find  provided  in  the  various  bones,  which  form  what  is  called  the 
Skeleton  (oxexxu>,  to  dry  tip). 

Structure  and  Physical  Properties  of  Bone.  Bone  is  one  of  the  hardest  structures 
of  the  animal  body ;  it  possesses  also  a  certain  degree  of  toughness  and  elasticity. 
Its  color,  in  a  fresh  state,  is  of  a  pinkish-white  externally,  and  deep  red  within. 
On  examining  a  section  of  any  bone,  it  is  seen  to  be  composed  of  two  kinds 
of  tissue,  one  of  which  is  dense  and  compact  in  texture,  like  ivory;  the  other 
consisting  of  slender  fibres  and  lamellae,  which  join  to  form  a  reticular  structure; 
this,  from  its  resemblance  to  lattice-work,  is  called  cancellated.  The  compact 
tissue  is  always  placed  on  the  exterior  of  a  bone;  the  cancellous  tissue  is  always 
internal.  The  relative  quantity  of  these  two  kinds  of  tissue  varies  in  different 
bones,  and  in  different  parts  of  the  same  bone,  as  strength  or  lightness  is  requisite. 
Close  examination  of  the  compact  tissue  shows  it  to  be  extremely  porous,  so  that 
the  difference  in  structure  between  it  and  the  cancellous  tissue  depends  merely 
upon  the  different  amount  of  solid  matter,  and  the  size  and  number  of  the  spaces 
in  each;  in  the  compact  tissue  the  cavities  being  small,  and  the  solid  matter 
between  them  abundant,  whilst  in  the  cancellous  tissue  the  spaces  are  large,  and 
the  solid  matter  diminished  in  quantity. 

Chemical  Analysis.  Bone  consists  of  an  organic  or  animal,  and  an  inorganic 
or  earthy  material,  intimately  combined  together:  the  animal  matter  giving  to 
bone  its  elasticity  and  toughness,  the  earthy  part  its  hardness  and  solidity.  The 
animal  constituent  may  be  separated  from  the  earthy  by  steeping  bone  in  a  dilute 
solution  of  nitric  or  muriatic  acid :  by  this  process  the  earthy  constituents  are 
gradually  dissolved  out,  leaving  a  tough  semi-transparent  substance,  which  retains, 
in  every  respect,  the  original  form  of  the  bone.  This  is  often  called  cartilage, 
but  differs  from  it  in  being  softer,  more  flexible,  and,  when  boiled  under  a  high 
pressure,  it  is  almost  entirely  resolved  into  gelatine.  Cartilage  does,  however, 
form  the  animal  basis  of  bone  in  certain  parts  of  the  skeleton.  Thus,  according 
to  Tomes  and  De  Morgan,  it  occurs  in  the  petrous  part  of  the  temporal  bone;  and, 
according  to  Dr.  Sharpey,  on  the  articular  ends  of  adult  bones,  lying  underneath 
the  natural  cartilage  of  the  joint.  The  earthy  constituent  may  be  obtained  by 
subjecting  a  bone  to  strong  heat  in  an  open  fire  with  free  access  of  air.  By  these 
means  the  animal  matter  is  entirely  consumed,  the  earthy  part  remaining  as  a 
white  brittle  substance  still  preserving  the  original  shape  of  the  bone.  Both 
constituents  present  the  singular  property  of  remaining  unaltered  in  chemical 
composition  after  a  lapse  of  centuries. 
3 


34 


OSTEOLOGY. 


The  organic  constituent  of  bone  forms  about  one-third,  or  33.3  per  cent.;  the 
inorganic  matter,  two-thirds,  or  66.7  per  cent. :  as  is  seen  in  the  subjoined  analysis 
by  Berzelius: — 


Organic  Matter, 

Gelatine  and  Bloodvessels 

.     33.30 

1  Phosphate  of  Lime    . 

.     51.04 

Inorganic 

Carbonate  of  Lime    . 

.     11.30 

or 

Fluoride  of  Calcium 

.       2.00 

Earthy  Matter, 

Phosphate  of  Magnesia 

.       1.16 

V  Soda  and  Chloride  of  Sodium   . 

.       1.20 

100.00 

Some  chemists  add  to  this  about  one  per  cent,  of  fat. 

The  relative  proportions  of  the  two  constituents  of  bone  are  found  to  differ  in 
different  hones  of  the  skeleton,  as  shown  by  Dr.  Owen  Eees.  Thus,  the  bones  of 
the  head,  and  the  long  bones  of  the  extremities,  contain  more  earthy  matter  than 
those  of  the  trunk;  and  those  of  the  upper  extremity  somewhat  more  than  the 
corresponding  bones  of  the  lower  extremity.  The  humerus  contains  more  earthy 
matter  than  the  bones  of  the  forearm ;  and  the  femur  more  than  the  tibia  and 
fibula.  The  vertebras,  ribs,  and  clavicle  contain  nearly  the  same  proportion  of 
earthy  matter.  The  metacarpal  and  metatarsal  bones  contain  about  the  same 
proportion  as  those  of  the  trunk. 

Much  difference  exists  in  the  analyses  given  by  chemists  as  to  the  proportion 
between  the  two  constituents  of  bone  at  different  periods  of  life.  According  to 
Schreger,  and  others,  there  is  considerable  increase  in  the  earthy  constituents  of 
the  bones  with  advancing  years.  Dr.  Eees  states  that  this  is  especially  marked 
in  the  long  bones,  and  the  bones  of  the  head,  which,  in  the  foetus,  do  not  contain 
the  excess  of  earthy  matter  found  in  those  of  the  adult.  But  the  bones  of  the 
trunk  in  the  foetus,  according  to  this  analyst,  contain  as  much  earthy  matter  as 
those  of  the  adult.  On  the  other  hand,  the  analyses  of  Stark  and  Yon  Bibra 
show  that  the  proportions  of  animal  and  earthy  matter  are  almost  precisely  the 
same  at  different  periods  of  life.  According  to  the  analyses  of  Yon  Bibra, 
Yalentin,  and  Dr.  Kees,  the  compact  substance  contains  more  earthy  matter  than 
the  cancellous.  The  comparative  analysis  of  the  same  bones  in  both  sexes  shows 
no  essential  difference  between  them. 

There  are  facts  of  some  practical  interest,  bearing  upon  the  difference  which 
seems  to  exist  in  the  amount  of  the  two  constituents  of  bone  at  different  periods 
of  life.  Thus,  in  the  child,  where  the  animal  matter  predominates,  it  is  not 
uncommon  to  find,  after  an  injury  to  the  bones,  that  they  become  bent  or  only 
partially  broken,  from  the  large  amount  of  flexible  animal  matter  which  they 
contain.  Again,  also  in  aged  people,  where  the  bones  contain  a  large  proportion 
of  earthy  matter,  the  animal  matter  at  the  same  time  being  deficient  in  quantity 
and  quality,  the  bones  are  more  brittle,  their  elasticity  is  destroyed,  and,  hence, 
fracture  takes  place  more  readily.  Some  of  the  diseases,  also,  to  which  bones 
are  liable,  mainly  depend  on  the  disproportion  between  the  two  constituents  of 
bone.  Thus,  in  the  disease  called  rickets,  so  common  in  the  children  of  scrofulous 
parents,  the  bones  become  bent  and  curved,  either  from  the  superincumbent 
weight  of  the  body,  or  under  the  action  of  certain  muscles.  This  depends  upon 
some  deficiency  of  the  nutritive  system,  by  which  bone  becomes  minus  its  normal 
proportion  of  earthy  matter,  whilst  the  animal  matter  is  of  unhealthy  quality. 
In  the  vertebra  of  a  rickety  subject,  Dr.  Bostock  found  in  100  parts  79.75  animal, 
and  20.25  earthy  matter. 

Form  of  Bones.  The  various  mechanical  purposes  for  which  bones  are  employed 
in  the  animal  economy  require  them  to  be  of  very  different  forms.  All  the  scien- 
tific principles  of  Architecture  and  Dynamics  are  more  or  less  exemplified  in  the 
construction  of  this  part  of  the  human  body.     The  power  of  the  arch  in  resisting 


^ 


GENERAL  ANATOMY  OF  BONE.  35 

superincumbent  pressure  is  well  exhibited  in  various  parts  of  the  skeleton,  such 
as  the  human  foot,  and  more  especially  in  the  vaulted  roof  of  the  cranium. 

Bones  are  divisible  into  four  classes :  Long,  Short,  Flat,  and  Irregular. 

The  Long  Bones  are  found  chiefly  in  the  limbs,  where  they  form  a  system  of 
levers,  which  have  to  sustain  the  weight  of  the  trunk,  and  to  confer  extensive 
powers  of  locomotion.  A  long  bone  consists  of  a  lengthened  cylinder  or  shaft, 
and  two  extremities.  The  shaft  is  a  hollow  cylinder,  the  walls  consisting  of  dense 
compact  tissue  of  great  thickness  in  the  middle,  and  becoming  thinner  towards  the 
extremities ;  the  spongy  tissue  is  scanty,  and  the  bone  is  hollowed  out  in  its  interior 
to  form  the  medullary  canal.  The  extremities  are  generally  somewhat  expanded 
for  greater  convenience  of  mutual  connection,  for  the  purposes  of  articulation,  and 
to  afford  a  broad  surface  for  muscular  attachment.  Here  the  bone  is  made  up  of 
spongy  tissue  with  only  a  thin  coating  of  compact  substance.  The  long  bones  are, 
the  clavicle,  humerus,  radius,  ulna,  femur,  tibia,  fibula,  metacarpal  and  metatarsal 
bones,  and  the  phalanges. 

Short  Bones.  Where  a  part  is  intended  for  strength  and  compactness,  and  the 
motion  at  the  same  time  slight  and  limited,  it  is  divided  into  a  number  of  small 
pieces  united  together  by  ligaments,  and  the  separate  bones  are  short  and  com- 
pressed, such  as  the  bones  of  the  carpus  and  tarsus.  These  bones,  in  their  struc- 
ture, are  spongy  throughout,  excepting  at  their  surface,  where  there  is  a  thin  crust 
of  compact  substance. 

Flat  Bones.  Where  the  principal  requirement  is  either  extensive  protection,  or 
the  provision  of  broad  surfaces  for  muscular  attachment,  we  find  the  osseous  struc- 
ture remarkable  for  its  slight  thickness,  becoming  expanded  into  broad  flat  plates, 
as  is  seen  in  the  bones  of  the  skull  and  shoulder-blade.  These  bones  are  composed 
of  two  thin  layers  of  compact  tissue,  inclosing  between  them  a  variable  quantity 
of  cancellous  tissue.  In  the  cranial  bones,  these  layers  of  compact  tissue  are 
familiarly  known  as  the  tables  of  the  skull ;  the  outer  one  is  thick  and  tough,  the 
inner  one  thinner,  denser,  and  more  brittle,  and  hence  termed  the  vitreous  table. 
The  intervening  cancellous  tissue  is  called  the  diploe.  The  flat  bones  are,  the 
occipital,  parietal,  frontal,  nasal,  lachrymal,  vomer,  scapulee,  ossa  innominata,  sternum, 
and  ribs. 

The  Irregular  or  Mixed  bones  are  such  as,  from  their  peculiar  form,  cannot  be 
grouped  under  either  of  the  preceding  heads.  Their  structure  is  similar  to  that  of 
other  bones,  consisting  of  a  layer  of  compact  tissue  externally,  and  of  spongy 
cancellous  tissue  within.  The  irregular  bones  are,  the  vertebrse,  sacrum,  coccyx, 
temporal,  sphenoid,  ethmoid,  superior  maxillary,  inferior  maxillary,  palate,  inferior 
turbinated,  and  hyoid. 

Surfaces  of  Bones.  If  the  surface  of  any  bone  is  examined,  certain  eminences 
and  depressions  are  seen,  to  which  descriptive  anatomists  have  given  the  following 
names. 

A  prominent  process  projecting  from  the  surface  of  a  bone,  which  it  has  never 
been  separate  from,  or  movable  upon,  is  termed  an  apophysis  (from  drtoyveis,  an 
excrescence) ;  but  if  such  process  is  developed  as  a  separate  piece  from  the  rest  of 
the  bone  to  which  it  is  afterwards  joined,  it  is  termed  an  epiphysis  (from  hnlyvais, 
an  accretion). 

These  eminences  and  depressions  are  of  two  kinds:  articular  and  non-articular. 
Well-marked  examples  of  articular  eminences  are  found  in  the  heads  of  the 
humerus  and  femur;  and  of  articular  depressions,  in  the  glenoid  cavity  of 
the  scapula,  and  the  acetabulum.  Non-articular  eminences  are  designated 
according  to  their  form.  Thus,  a  broad,  rough,  uneven  elevation  is  called  a 
tuberosity;  a  small,  rough  prominence,  a  tubercle;  a  sharp,  slender,  pointed 
eminence,  a  spine;  a  narrow,  rough  elevation,  running  some  way  along  the  surface, 
a  ridge,  or  line. 

The  non-articular  depressions  are  also  of  very  variable  form,  and  are  described 
as  fossre,  grooves,  furrows,  fissures,  notches,  etc.  These  non-articular  eminences 
and  depressions  serve  to  increase  the  extent  of  surface  for  the  attachment  of  liga 


3G  OSTEOLOGY. 

inents  and  muscles,  and  are  usually  well  marked  in  proportion  to  the  muscularity 
of  the  subject. 

Microscojjcc  Structure.  If  a  thin  transverse  section  from  the  shaft  of  a  long 
bone  be  examined  with  a  power  of  about  20  diameters,  a  number  of  aper- 
tures, surrounded  by  a  series  of  concentric  rings,  are  observed,  with  small,  dark 
spots  grouped  around  them,  also  in  a  concentric  manner.  The  apertures  are 
sections  of  the  Haversian  canals  (so  called  after  their  discoverer,  Clopton  Havers); 
the  concentric  rings  are  sections  of  the  lamellae,  which  are  developed  around  the 
Haversian  canals ;  the  dark  spots  are  small  cavities  in  the  substance  of  the  bone, 
called  lacunse. 

The  Haversian  canals  are  channelled  out  of  the  compact  substance  for  the  pur- 
pose of  conveying  bloodvessels  for  its  nutrition.  They  vary  in  size  from  the 
2^0  to  the  tj^'ott  °f  an  mcn  m  diameter,  the  average  size  being  about  z\-$.  They 
are  generally  round  or  oval,  sometimes  angular.  Those  nearest  to  the  outer  sur- 
face, where  the  bone  is  most  compact,  are  very  small ;  but,  towards  the  medullary 
canal,  they  gradually  acquire  a  larger  size,  and  open  into  it,  or  into  the  cells  of  tlm 
cancellous  tissue.  The  Haversian  canals  are  lined  by  a  delicate  membrane  con- 
tinuous with  the  periosteum ;  the  smallest  canals  contain  a  single  capillary  vessel ; 
those  larger  in  size  contain  a  network  of  vessels:  whilst  the  largest  contain  blood- 
vessels and  marrow.  If  a  thin  longitudinal  section  of  the  shaft  of  a  long  bone  be 
examined,  the  Haversian  canals  will  be  found  to  run  in  the  long  axis  of  the  bone, 
and  parallel  with  each  other,  communicating  freely  by  transverse  or  oblique  canals, 
so  as  to  form,  for  the  most  part,  rectangular  meshes.  Some  of  these  canals  open 
on  the  outer  surface,  to  admit  bloodvessels  from  the  periosteum ;  others  communi- 
cate with  the  medullary  canal,  receiving  bloodvessels  from  the  interior  of  this  part. 
By  this  means,  the  Haversian  canals  establish  a  free  communication  between  the 
bloodvessels  of  the  periosteum,  and  those  of  the  medullary  membrane. 

If  a  higher  power  is  now  applied  to  the  same  transverse  section,  each  Haversian 
canal  appears  surrounded  by  a  series  of  concentric  rings,  varying  in  number  from 
eight  to  fifteen ;  these  rings  are  termed  the  lamellve,  and  their  appearance  is  pro- 
duced by  transverse  sections  of  concentric  layers  of  bone  that  have  been  developed 
around  the  Haversian  canal,  the  last  formed  layer  being  deposited  on  that  surface 
next  to  the  bloodvessel.  This  concentric  arrangement  is  not  complete  around  all 
the  canals;  for  here  and  there  one  set  of  lamellae  may  be  seen  ending  between  two 
adjacent  ones.  Besides  the  lamellae  surrounding  the  Haversian  canals,  some  are 
disposed  parallel  with  the  outer  and  inner  surfaces  of  the  bone ;  these  are  termed 
circumferential  lamellae,  and  may  be  considered  as  concentric  with  the  medullary 
canal.  Others,  again,  penetrate  between  the  Haversian  systems ;  these  are  termed 
interstitial  lamellae.  Each  Haversian  canal,  together  with  its  concentric  lamellae 
of  bone,  lacunae,  etc.,  is  called  an  Haversian  system,  the  bloodvessel  contained  in 
the  central  canal  being  the  source  of  nutrition  to  the  lamellae  which  surround  it. 
Nearly  the  whole  of  the  compact  tissue  is  made  up  of  these  Haversian  systems, 
each  one  being,  to  a  certain  extent,  independent  of  the  rest.  In  a  longitudinal 
section,  the  lamellae  are  seen  running  in  lines  parallel  with  the  Haversian  canal 
which  they  surround,  except  when  the  section  passes  transversely  or  obliquely 
across  a  canal,  in  which  case  an  appearance  is  seen,  somewhat  similar  to  that 
observed  in  a  transverse  section.  This  lamellated  structure  may  be  easily  demon- 
strated on  a  piece  of  bone  softened  in  dilute  acid,  when  the  lamellae  may  be  peeled 
from  the  surface  of  the  bone  in  a  longitudinal  direction.  According  to  Dr.  Sharpey, 
the  lamella3,  in  structure,  consist  of  fine  transparent  fibres  decussating  each  other, 
so  as  to  form  a  delicate  network,  the  fibres  apparently  coalescing  at  their  point 
of  junction.  The  lamellae  are  perforated,  in  certain  situations,  by  bundles  of 
fibres  which  penetrate  them  in  a  more  or  less  oblique  direction,  serving  to  securely 
approximate  the  several  plates.  The  lamellae  are  also  perforated  by  numerous 
minute  apertures  placed  at  regular  distances  apart,  which  are,  probably,  transverse 
sections  of  the  canaliculi.  In  this  fibrous  basis  of  the  lamellae,  the  inorganic 
elements  of  bone  are  intimately  united. 


GENERAL  ANATOMY  OF  BONE.  37 

A  transverse  section  of  compact  bone  sometimes  exhibits  certain  vacuities  or 
spaces,  termed,  by  Messrs.  Tomes  and  De  Morgan,  Haversian  spaces.  These 
spaces  are  found  at  al\  periods  of  life,  but  especially  in  young  and  growing  bones. 
They  are  characterized  by  an  irregular  or  jagged  outline,  and  are  apparently 
produced  by  the  absorption  of  parts  of  several  Haversian  systems,  which  have 
been,  to  a  greater  or  less  extent,  removed  in  order  to  form  them.  These  spaces 
may  exist  in  various  conditions:  in  some,  the  process  of  absorption  is  evidently 
going  on;  in  others,  the  spaces  are  lined  by  newly-formed  lamellae  which  fill 
up  the  peripheral  portion  of  the  space;  in  others,  the  lamellas  fill  in  the  whole 
of  the  space,  leaving  a  Haversian  canal  in  the  centre.  It  would  thus  appear, 
that  portions  of  the  Haversian  systems  are,  from  time  to  time,  removed  by 
absorption,  and  a  new  system  of  lamellae  re-formed  in  place  of  those  previously 
existing.  Sometimes,  these  spaces  may  be  seen  filled  in,  at  one  part,  by  the 
deposition  of  lamellas;  while,  at  another  part,  they  are  extending  themselves  by 
absorption. 

We  have  already  said,  that  the  dark  spots  seen  in  and  between  the  lamellae, 
arranged  in  concentric  circles  around  the  Haversian  canals,  are  the  lacunse. 
They  are  minute  cavities  existing  in  the  osseous  substance,  having  numerous  fine 
^  tubes  called  canaliculi  issuing  from  all  parts  of  their  circumference.  In  fresh 
bones,  each  lacuna  contains  a  delicate  cell,  with  pellucid  contents,  and  a  single 
nucleus ;  and  from  the  cell  numerous  fine  processes  are  given  off,  which  fill  the 
canaliculi.  These  are  the  bone  cells,  discovered  by  Virchow.  The  lacunae  are 
oval  flattened  spaces,  lying  parallel  to  the  direction  of  the  lamellae.  The  canaliculi 
issuing  from  them  are  extremely  minute,  their  diameter  ranging  from  T1kw  to 
5 noun  °f  aT1  inch.  They  communicate  freely  with  the  canaliculi  of  adjoining 
lacunae,  some  opening  into  the  Haversian  canals,  or  in  the  cancelli  of  the  spongy 
substance,  and  some  upon  the  free  surface  of  the  bone.  By  this  communication 
between  the  lacunae  and  canaliculi  traversing  the  entire  substance  of  the  bone, 
the  plasma  of  the  blood  is  carried  into  every  part. 

Vessels  of  Bone.  The  bloodvessels  of  bone  are  very  numerous.  Those  of  the 
compact  tissue  are  derived  from  a  close  and  dense  network  of  vessels,  which  ramify 
in  a  fibrous  membrane  termed  the  periosteum,  which  covers  the  surface  of  the  bone 
in  nearly  every  part.  From  this  membrane,  vessels  pass  through  the  minute  orifices 
in  the  compact  tissue,  running  through  the  canals  which  traverse  its  substance. 
The  cancellous  tissue  is  supplied  in  a  similar  way,  but  by  a  less  numerous  set  of 
larger  vessels,  which,  perforating  the  outer  compact  tissue,  are  distributed  to  the 
cavities  of  the  spongy  portion  of  the  bone.  In  the  long  bones,  numerous  apertures 
may  be  seen  at  the  ends  near  the  articular  surfaces,  some  of  which  give  passage  to 
the  arteries  referred  to;  but  the  greater  number,  and  these  are  the  largest  of  them, 
are  for  the  veins  of  the  cancellous  tissue  which  run  separately  from  the  arteries. 
The  medullary  canal  in  the  shafts  of  the  long  bones  is  supplied  by  one  large 
artery, — or  sometimes  more, — which  enters  the  bone  at  the  nutritious  foramen 
(situated,  in  most  cases,  near  the  centre  of  the  shaft),  and  perforates  obliquely  the 
compact  substance.  This  vessel,  usually  accompanied  by  one  or  two  veins,  sends 
branches  upwards  and  downwards,  to  supply  the  medullary  membrane,  which 
lines  the  central  cavity  and  the  adjoining  canals.  The  ramifications  of  this  vessel 
anastomose  with  the  arteries  both  of  the  cancellous  and  compact  tissues.  In  most 
of  the  flat,  and  in  many  of  the  short  spongy  bones,  one  or  more  large  apertures 
are  observed,  which  transmit,  to  the  centre  of  the  bone,  vessels  which  correspond 
to  the  medullary  arteries  and  veins. 

The  veins  emerge  from  the  long  bones  in  three  places  (Kolliker).  1.  By  a  large 
vein  which  accompanies  the  nutrient  artery;  2.  by  numerous  large  and  small  veins 
at  the  articular  extremities;  3.  by  many  small  veins  which  arise  in  the  compact 
substance.  In  the  flat  cranial  bones,  the  veins  are  large,  very  numerous,  and  run 
in  tortuous  canals  in  the  diploic  tissue,  the  sides  of  which  are  constructed  of  a  thin 
lamella  of  bone,  perforated  here  and  there  for  the  passage  of  branches  from  the 
adjacent  cancelli.     The  veins  thus  inclosed  and  supported  by  the  osseous  structure, 


38  OSTEOLOGY. 

have  exceedingly  thin  coats;  and  when  the  bony  structure  is  divided,  thej 
remain  patulous,  and  do  not  contract  in  the  canals  in  which  they  are.  contained. 
Hence  the  constant  occurrence  of  purulent  absorption  after  amputation,  in  those 
cases  where  the  stump  becomes  inflamed,  and  the  cancellous  tissue  is  infiltrated 
and  bathed  in  pus. 

Lymphatic  vessels  have  been  traced,  by  Cruikshank,  into  the  substance  of  bone, 
but  Kolliker  doubts  their  existence.  Nerves  are  distributed  freely  to  the  perios- 
teum, and  accompany  the  nutritious  arteries  into  the  interior  of  the  bone.  They 
are  said,  by  Kolliker,  to  be  most  numerous  in  the  articular  extremities  of  the 
long  bones,  in  the  vertebrae,  and  the  larger  flat  bones. 

Periosteum.  The  bones  are  covered  by  a  tough  fibrous  membrane,  the  periosteum, 
which  adheres  to  their  surface  in  nearly  every  part,  excepting  at  their  cartilaginous 
extremities,  and  where  strong  tendons  are  attached.  ,It  is  highly  vascular;  and, 
from  it,  numerous  vessels  pass  into  minute  orifices  which  cover  the  entire  surface 
of  the  bone.  It  consists  of  two  layers  closely  united  together;  the  outer  one 
formed  chiefly  of  connective  tissue,  and  occasionally  a  few  fat-cells ;  the  inner  one, 
of  elastic  fibres  of  the  finer  kind,  which  form  dense  elastic  membranous  networks, 
superimposed  in  several  layers  (Kolliker).  In  young  bones,  this  membrane  is 
thick,  very  vascular,  intimately  connected  at  either  end  of  the  bone  with  the 
epiphysal  cartilage ;  but  less  closely  connected  with  the  shaft,  from  which  it  is 
separated  by  a  layer  of  soft  blastema,  in  which  ossification  proceeds  on  the  exterior 
of  the  young  bone.  Later  in  life,  the  periosteum  is  thinner,  less  vascular,  and 
more  closely  connected  with  the  adjacent  bone,  this  adhesion  growing  stronger  as 
age  advances.  The  periosteum  serves  as  a  nidus  for  the  ramification  of  the  vessels 
previous  to  their  distribution  in  the  bone ;  hence  the  liability  of  bone  to  exfolia- 
tion or  necrosis,  when,  from  injury,  it  is  denuded  of  this  membrane. 

Marrow.  The  medullary  canal  of  adult  long  bones,  the  cavities  of  the  cancellous 
tissue,  and  the  larger  Haversian  canals,  are  filled  with  a  substance  called  marrow, 
and  lined  by  a  highly  vascular  areolar  tissue,  the  medullary  membrane,  or  internal 
periosteum.  It  is  by  means  of  the  vessels  which  ramify  through  this  membrane, 
that  the  nourishment  of  the  medulla  and  contiguous  osseous  tissue  is  effected. 

The  marrow  differs  in  composition  at  different  periods  of  life,  and  in  different 
bones.  In  young  bones,  it  is  a  transparent  reddish  fluid,  of  tenacious  consistence, 
free  from  fat;  and  contains  numerous  minute  roundish  polynucleated  cells.  In 
the  shafts  of  adult  long  bones,  the  marrow  is  of  a  yellow  color,  and  contains,  in 
100  parts,  96.0  fat,  1.0  areolar  tissue  and  vessels,  and  3.0  of  fluid  with  extractive 
matters ;  whilst,  in  the  flat  and  short  bones,  in  the  articular  ends  of  the  long  bones, 
in  the  bodies  of  the  vertebras,  the  base  of  the  cranium,  and  in  the  sternum  and 
ribs,  it  is  of  a  red  color,  and  contains,  in  100  parts,  75.0  water,  and  25.0  solid 
matter,  consisting  of  albumen,  fibrin,  extractive  matter,  salts,  and  a  mere  trace  of 
fat.  It  consists  of  fat-cells  with  a  large  quantity  of  fluid,  containing  numerous 
polynucleated  cells,  similar  to  those  found  in  foetal  marrow. 

Development  of  Bone.  From  the  peculiar  uses  to  which  bone  is  applied  in 
forming  a  hard  skeleton  or  framework  for  the  softer  materials  of  the  body,  and  in 
inclosing  and  protecting  some  of  the  more  important  vital  organs,  we  find  its 
development  takes  place  at  a  very  early  period.  Hence,  the  parts  that  appear 
soonest  in  the  embryo  are  the  vertebral  column  and  the  skull,  the  great  central 
column,  to  which  the  other  parts  of  the  skeleton  are  appended.  At  an  early  period 
of  embryonic  life,  the  parts  destined  to  become  bone  consist  of  a  congeries  of  cells, 
connected  together  by  an  amorphous  blastema  which  constitutes  the  simplest  form 
of  cartilage.  This  temporary  cartilage,  as  it  is  termed,  is  an  exact  miniature  of 
the  bone  which,  in  due  course,  is  to  take  its  place ;  and  as  the  process  of  ossification 
is  slow,  and  not  completed  until  adult  life,  it  increases  in  bulk  by  an  interstitial 
development  of  new  cells.  The  next  step  in  this  process  is  the  ossification  of  the 
intercellular  substance,  and  of  the  cells  composing  the  cartilage.  Ossification 
commences  in  the  interior  of  the  cartilage  at  certain  points,  called  points  or  centres 
of  ossification,  from  which  it  extends  into  the  surrounding  substance.     This  mode 


GENERAL   ANATOMY   OF   BONE.  39 

of  ossification  is  called  intra-cartilaginous,  to  distinguish  it  from  that  which  takes 

{)lace  in  a  membranous  tissue,  quite  different  in  its  nature  from  cartilage.  The 
atter  mode  of  ossification  is  called  intra-membranous.  Examples  of  it  are  seen, 
according  to  Kolliker,  in  the  upper  half  of  the  expanded  portion  of  the  occipital 
bone ;  the  parietal  and  frontal  bones ;  the  squamous  portion  and  tympanic  ring  of 
the  temporal  bone ;  the  internal  lamella  of  the  pterygoid  process  of  the  sphenoid ; 
the  cornua  sphenoidalia ;  in  all  the  bones  of  the  face,  excepting  the  inferior  turbi- 
nated ;  and,  according  to  Brack,  in  the  clavicle. 

The  period  of  ossification  is  different  in  different  bones.  The  order  of  succes- 
sion may  be  thus  arranged  (Kolliker) : — 

In  the  second  month,  first,  in  the  clavicle,  and  lower  jaw  (fifth  to  seventh  week); 
then,  in  the  vertebrae,  humerus,  femur,  the  ribs,  and  the  cartilaginous  portion  of 
the  occipital  bone. 

At  the  end  of  the  second,  and  commencement  of  the  third  month,  the  frontal 
bone,  the  scapula,  the  bones  of  the  forearm  and  leg,  and  upper  jaw,  make  their 
appearance. 

In  the  third  month,  the  remaining  cranial  bones,  with  few  exceptions,  begin  to 
ossify,  the  metatarsus,  the  metacarpus,  and  the  phalanges. 

In  the  fourth  month,  the  iliac  bones,  and  the  ossicula  auditus. 

In  the  fourth  or  fifth  month,  the  ethmoid,  sternum,  pubis,  and  ischium. 

From  the  sixth  to  the  seventh  month,  the  calcaneum,  and  astragalus. 

In  the  eighth  month,  the  hyoid  bone. 

At  birth,  the  epiphyses  of  all  cylindrical  bones,  occasionally  with  the  exception 
of  those  of  the  femur  and  tibia ;  all  the  bones  of  the  carpus ;  the  five  smaller 
ones  of  the  tarsus ;  the  patella ;  sesamoid  bones ;  and  the  last  pieces  of  the  coccyx, 
are  still  unossified. 

From  the  time  of  birth  to  the  fourth  year,  osseous  nuclei  make  their  appearance 
also  in  these  parts. 

At  twelve  years,  in  the  pisiform  bone. 

The  number  of  ossific  centres  is  different  in  different  bones.  In  most  of  the  short 
bones,  ossification  commences  by  a  single  point  in  the  centre,  and  proceeds  towards 
the  circumference.  In  the  long  bones,  there  is  a  central  point  of  ossification  for  the 
shaft  or  diaphysis ;  and  one  or  more  for  each  extremity,  the  epiphyses.  That  for  the 
shaft  is  the  first  to  appear ;  those  for  the  extremities  appear  later.  For  a  long  period 
after  birth,  a  thin  layer  of  unossified  cartilage  remains  between  the  diaphysis  and 
epiphyses,  until  their  growth  is  finally  completed,  their  junction  taking  place  either 
at  the  period  of  puberty,  or  towards  the  end  of  the  period  of  growth.  The  union  of 
the  epiphyses  with  the  shaft  takes  place  in  the  inverse  order  to  that  in  which  their 
ossification  began ;  for,  although  ossification  commences  latest  in  those  epiphyses 
towards  which  the  nutritious  artery  in  the  several  bones  is  directed,  they  become 
joined  to  the  diaphyses  sooner  than  the  epiphyses  at  the  opposite  extremity,  with 
the  exception  of  the  fibula,  the  lower  end  of  which  commences  to  ossify  at  an 
earlier  period  than  the  upper  end,  but,  nevertheless,  is  joined  to  the  shaft  earliest. 

The  order  in  which  the  epiphyses  become  united  to  the  shaft  appears  to  be 
regulated  by  the  direction  of  the  nutritious  artery  of  the  bone.  Thus  the  arteries 
of  the  bones  of  the  arm  and  forearm  are  directed  towards  the  elbow,  and  the 
epiphyses  of  the  bones  forming  this  joint  become  united  to  the  shaft  before  those 
at  the  opposite  extremity.  In  the  lower  extremities,  on  the  contrary,  the 
nutritious  arteries  pass  in  a  direction  from  the  knee;  that  is  upwards  in  the  femur, 
downwards  in  the  tibia  and  fibula ;  and  in  them  it  is  observed,  that  the  upper 
epiphysis  of  the  femur,  and  the  lower  epiphyses  of  the  tibia  and  fibula,  become 
first  united  to  the  shaft. 

Where  there  is  only  one  epiphysis,  the  medullary  artery  is  directed  towards  that 
end  of  the  bone  where  there  is  no  additional  centre :  as,  towards  the  acromial  end 
in  the  clavicle ;  towards  the  distal  end  of  the  metacarpal  bone  of  the  thumb  and  great 
toe;  and  towards  the  proximal  end  of  the  other  metacarpal  and  metatarsal  bones. 

A  knowledge  of  the  exact  periods  when  the  epiphyses  become  joined  to  the 


tJ^sI. 


40 


OSTEOLOGY. 


shaft  aids  the  surgeon  in  the  diagnosis  of  many  of  the  injuries  to  which  the  joints 
are  liable ;  for  it  not  unfrequently  happens  that,  on  the  application  of  severe  force 
to  a  joint,  the  epiphyses  become  separated  from  the  shaft,  and  such  injuries  may 
be  mistaken  for  fracture. 

Growth  of  Bone.  Increase  in  the  length  of  a  bone  is  provided  for  by  the  deve- 
lopment of  new  bone  in  the  cartilage  at  either  end  of  the  shaft  (diaphysis);  and  in 
the  thickness,  by  the  deposition  of  soft  ossifying  blastema  in  successive  layers 
upon  the  inner  surface  of  the  periosteum. 

The  entire  skeleton  in  an  adult  consists  of  204  distinct  bones.     These  are — 


Vertebral  column  (sacrum  and  coccyx  included) 

26 

Cranium    ........ 

8 

Ossicula  auditus         ...... 

6 

Face 

14 

Os  hyoides,  sternum,  and  ribs   .... 

26 

Upper  extremities     ...... 

64 

Lower  extremities 

60 

204 

In  this  enumeration,  the  patellae  and  other  sesamoid  bones,  as  well  as  the 
Wormian  bones,  are  excluded,  as  are  also  the  teeth,  which  differ  from  bone  both 
in  structure,  development,  and  mode  of  growth. 


THE    SPINE. 

The  Spine  is  a  flexuous  column,  formed  of  a  series  of  bones  called  Vertebrse. 

The  Vertebrae  are  thirty-three  in  number,  exclusive  of  those  which  form  the  skull, 
and  have  received  the  names  cervical,  dorsal  lumbar,  sacral,  and  coccygeal,  according 
to  the  position  which  they  occupy ;  seven  being  found  in  the  cervical  region,  twelve 
in  the  dorsal,  five  in  the  lumbar,  five  in  the  sacral,  and  four  in  the  coccygeal. 

This  number  is  sometimes  found  increased  by  an  additional  segment  in  one 
region,  or  the  number  may  be  diminished  in  one  region,  the  deficiency  being 
supplied  by  an  additional  segment  in  another.  These  observations  do  not  apply 
to  the  cervical  portion  of  the  spine,  the  number  of  segments  forming  which  is 
seldom  increased  or  diminished. 

The  Vertebrae  in  the  three  uppermost  regions  of  the  spine  are  separate  segments 
throughout  the  whole  of  life ;  but  those  found  in  the  sacral  and  coccygeal  regions  are, 
in  the  adult,  firmly  united,  so  as  to  form  two  bones — five  entering  into  the  formation 
of  the  upper  bone  or  sacrum,  and  four  into  the  terminal  bone  of  the  spine  or  coccyx. 

General  Characters  of  a  Vertebra. 

Each  vertebra  consists  of  two  essential  parts,  an  anterior  solid  segment  or 
body,  and  a  posterior  segment,  the  arch.  The  arch  is  formed  of  two  pedicles 
and  two  laminae,  supporting  seven  processes ;  viz.,  four  articular,  two  transverse, 
and  one  spinous  process. 

The  Bodies  of  the  vertebrae  are  piled  one  upon  the  other,  forming  a  strong 
pillar,  for  the  support  of  the  cranium  and  trunk;  the  arches  forming  behind  these 
a  hollow  cylinder  for  the  protection  of  the  spinal  cord.  The  different  segments 
are  connected  together  by  means  of  the  articular  processes,  and  the  transverse 
and  spinous  processes  serve  as  levers  for  the  attachment  of  muscles  which  move 
the  different  parts  of  the  spine.  Lastly,  between  each  pair  of  vertebrae  apertures 
exist  through  which  the  spinal  nerves  pass  from  the  cord.  Each  of  these  con- 
stituent parts  must  now  be  separately  examined. 


/ 


CHARACTERS   O^  THE    CERVICAL   VERTEBRJE. 


41 


The  Body  is  the  largest  and  most  solid  part  of  a  vertebra.  Above  and  below,  it 
is  slightly  concave,  presenting  a  rim  around  its  circumference ;  and  its  surfaces  are 
rough,  for  the  attachment  of  the  intervertebral  fibro-cartilages.  In  front  it  is  convex 
from  side  to  side,  concave  from  above  downwards.  Behind,  flat  from  above  down- 
wards and  slightly  concave  from  side  to  side.  Its  anterior  surface  is  perforated  by 
a  few  small  apertures,  for  the  passage  of  nutrient  vessels ;  whilst  on  the  posterior 
surface  is  a  single  irregular-shaped  aperture,  or  occasionally  several  large  apertures, 
for  the  exit  of  veins  from  the  body  of  the  vertebra,  the  vense  basis  vertebrse. 

The  Pedicles  project  backwards,  one  on  each  side,  from  the  upper  part  of  the 
body  of  the  vertebra,  at  the  line  of  junction  of  its  posterior  and  lateral  surfaces. 

The  concavities  above  and  below  the  pedicles  are  the  intervertebral  notches ;  they 
are  four  in  number,  two  on  each  side,  the  inferior  ones  being  generally  the  deeper. 
When  the  vertebrae  are  articulated,  the  notches  of  each  contiguous  pair  of  bones 
form  the  intervertebral  foramina,  which  communicate  with  the  spinal  canal  and 
transmit  the  spinal  nerves. 

The  Laminse  are  two  broad  plates  of  bone,  which  complete  the  vertebral  arch 
behind,  inclosing  a  foramen  which  serves  for  the  protection  of  the  spinal  cord ; 
they  are  connected  to  the  body  by  means  of  the  pedicles.  Their  upper  and  lower 
borders  are  rough,  for  the  attachment  of  the  ligamenta  subjlava. 

The  Articular  Processes,  four  in  number,  two  on  each  side,  spring  from  the 
junction  of  the  pedicles  with  the  laminae.  The  two  superior  project  upwards, 
their  articular  surfaces  being  directed  more  or  less  backwards,  the  two  inferior 
project  downwards,  their  articular  surfaces  looking  more  or  less  forwards. 

The  Spinous  Process  projects  backwards  from  the  junction  of  the  two  laminae, 
and  serves  for  the  attachment  of  muscles. 

The  Transverse  Processes,  two  in  number,  project  one  at  each  side  from  the 
point  where  the  articular  processes  join  the  pedicle.  They  also  serve  for  the 
attachment  of  muscles. 

Characters  of  the  Cervical  Vertebrae. 

The  Body  (fig.  1)  is  smaller  than  in  any  other  region  of  the  spine,  and  broader 
from  side  to  side  than  from  before  backwards.  The  anterior  and  posterior  surfaces 
are  flattened  and  of  equal  depth ;  the  former  is  placed  on  a  lower  level  than  the 


Fig.  1. — A  Cervical  Vertebra. 


Anterior  Talercle  of  Trans.Troc 

foramen  fm-  Vertebral  Art 
TostencrTulcrch  of  Trans .  P roc, 


Transverse  Process. 

^Superior  Articular  Prores*. 
-Life  riorArtlcala  r  Srccest. 


latter,  and  its  inferior  border  is  prolonged  downwards  so  as  to  overlap  the  upper 
and  fore  part  of  the  vertebra  below.  Its  upper  surface  is  concave  transversely, 
and  presents  a  projecting  lip  on  each  side ;  its  lower  surface  being  convex  from 
side  to  side,  concave  from  before  backwards,  and  presenting  laterally  a  shallow 
concavity,  which  receives  the  corresponding  projecting  lip  of  the  adjacent  verte- 
bra.    The  pedicles  are  directed  obliquely  outwards,  and  the  superior  intervertebral 


42 


OSTEOLOGY. 


notches  are  deeper,  but  narrower,  than  the  inferior.  The  laminse  are  narrow, 
long,  thinner  above  than  below,  and  overlap  each  other;  inclosing  the  spinal 
foramen,  which  is  very  large,  and  of  a  triangular  form.  The  spinous  processes 
are  short,  bifid  at  the  extremity,  to  afford  greater  extent  of  surface  for  the  attach- 
ment of  muscles,  the  two  divisions  being  often  of  unequal  size.  They  increase 
in  length  from  the  fourth  to  the  seventh.  The  transverse  processes  are  short, 
directed  downwards,  outwards,  and  forwards,  are  bifid  at  their  extremity,  and 
marked  by  a  groove  along  their  upper  surface,  which  runs  downwards  and  out- 
wards from  the  superior  intervertebral  notch,  and  serves  for  the  transmission  of 
one  of  the  cervical  nerves.  The  transverse  processes  are  pierced  at  their  base  by 
a  foramen,  for  the  transmission  of  the  vertebral  artery,  vein,  and  plexus  of  nerves. 
Each  process  is  formed  by  two  roots ;  the  anterior  root  arises  from  the  side  of  the 
body,  and  corresponds  to  the  ribs ;  the  posterior  root  springs  from  the  junction  of 
the  pedicle  with  the  lamina,  and  corresponds  with  the  transverse  processes  in  the 
dorsal  region.  It  is  by  the  junction  of  these  two  processes,  that  the  vertebral 
foramen  is  formed.  The  extremities  of  each  of  these  roots  form  the  anterior  and 
posterior  tubercles  of  the  transverse  processes.  The  articular  processes  are  oblique: 
the  superior  are  of  an  oval  form,  flattened,  and  directed  upwards  and  backwards; 
the  inferior  downwards  and  forwards. 

The  peculiar  vertebrae  in  the  cervical  region  are  the  first  or  Atlas;  the  second  or 
Axis;  and  the  seventh  or  Vertebra  prorninens.  The  great  modifications  in  the  form 
of  the  atlas  and  axis  are-  to  admit  of  the  nodding  and  rotatory  movements  of  the 
head. 

The  Atlas  (fig.  2)  is  so  named  from  supporting  the  globe  of  the  head.     The  chief 


Fig.  2. — 1st  Cervical  Vertebra  or  Atlas. 
Tubercle- 


Trans.  Prooc 


Toramen  for 
Vertebral  Art?. 


Groove  fcr  Verz>e£.  Art  ? 
ajid'l.'-'  Cerv.Nerva 


Spin.  Proc, 


peculiarities  of  this  bone  are,  that  it  has  neither  body  nor  spinous  process.  The 
body  is  detached  from  the  rest  of  the  bone,  and  forms  the  odontoid  process  of 
the  second  vertebra,  the  parts  corresponding  to  the  pedicles  pass  in  front  and 
join  to  form  the  anterior  arch.  The  atlas  consists  of  an  anterior  arch,  a  posterior 
arch,  and  two  lateral  masses.  The  anterior  arch  forms  about  one-fifth  of  the 
bone ;  its  anterior  surface  is  convex,  and  presents  about  its  centre  a  tubercle,  for 
the  attachment  of  the  Longus  colli  muscle ;  posteriorly  it  is  concave,  and  marked 
by  a  smooth  oval  or  circular  facet,  for  articulation  with  the  odontoid  process  of 
the  axis.  The  posterior  arch  forms  about  two-fifths  of  the  circumference  of  the 
bone ;  it  terminates  behind  in  a  tubercle,  which  is  the  rudiment  of  a  spinous 
process,  and  gives  origin  to  the  Eectus  capitis  posticus  minor.  The  diminutive 
size  of  this  process  prevents  any  interference  in  the  movements  between  it  and 
the  cranium.  The  posterior  part  of  the  arch  presents  above  a  rounded  edge ; 
whilst  in  front,  immediately  behind  each  superior  articular  process,  is  a  groove, 
sometimes  converted  into  a  foramen  by  a  delicate  bony  spiculum  which  arches 


CERVICAL   VERTEBRAE.  43 

backwards  from  the  posterior  extremity  of  the  superior  articular  process.  These 
grooves  represent  the  superior  intervertebral  notches,  and  are  peculiar  from  being 
situated  behind  the  articular  processes,  instead  of  before  them,  as  in  the  other 
vertebne.  Thej  serve  for  the  transmission  of  the  vertebral  artery,  which,  ascending 
through  the  foramen  in  the  transverse  process,  winds  round  the  lateral  mass  in  a 
direction  backwards  and  inwards.  They  also  transmit  the  sub-occipital  nerves. 
On  the  under  surface  of  the  posterior  arch,  in  the  same  situation,  are  two  other 
grooves,  placed  behind  the  lateral  masses,  and  representing  the  inferior  interver- 
tebral notches  of  other  vertebrae ;  they  are  much  less  marked  than  the  superior. 
The  lateral  masses  are  the  most  bulky  and  solid  parts  of  the  atlas,  in  order  to 
support  the  weight  of  the  head ;  they  present  two  articulating  processes  above, 
and  two  below.  The  two  superior  are  of  large  size,  oval,  concave,  and  approach 
towards  one  another  in  front,  but  diverge  behind ;  they  are  directed  upwards, 
inwards,  and  a  little  backwards,  forming  a  kind  of  cup  for  the  condyles  of  the 
occipital  bone,  and  are  admirably  adapted  to  the  nodding  movements  of  the  head. 
Not  unfrequentl}7'  they  are  partially  subdivided  by  a  more  or  less  deep  indentation 
which  encroaches  upon  each  lateral  margin ;  the  inferior  articular  processes  are 
circular  in  form,  flattened,  or  slightly  concave,  and  directed  downwards,  inwards, 
and  a  little  backwards,  articulating  with  the  axis,  and  permitting  the  rotatory 
movements.  Just  below  the  inner  margin  of  each  superior  articular  surface,  is  a 
small  tubercle,  for  the  attachment  of  a  ligament  which,  stretching  across  the  ring 
of  the  atlas,  divides  it  into  two  unequal  parts ;  the  anterior  or  smaller  segment 
receiving  the  odontoid  process  of  the  axis,  the  posterior  allowing  the  transmission 
of  the  spinal  cord  and  its  membranes.  This  part  of  the  spinal  canal  is  of  con- 
siderable size,  to  afford  space  for  the  spinal  cord ;  and  hence  lateral  displacement 
of  the  atlas  may  occur  without  compression  of  the  spinal  cord.  (This  ligament 
and  the  odontoid  process  are  marked  in  figure  2  in  dotted  outline.)  The  trans- 
verse processes  are  of  large  size,  for  the  attachment  of  special  muscles  which 
assist  in  rotating  the  head — long,  not  bifid,  perforated  at  their  base  by  a  canal 
for  the  vertebral  artery,  which  is  directed  from  below,  upwards  and  backwards. 
The  Axis  (fig.  3)  is  so  named  from  forming  the  pivot  upon  which  the  head 

Fig.  3. — 2d  Cervical  Vertebra  or  Axis. 
Odontoid  JPros , 


Rovgh  Surf,  for  CAee'A  Lig^- 
Artic.Swrf.fer  Trant.Ligt  • 


Spin.  Free.  J 


Artie.  Surf.foT Atlas 


A— Body 


Trant.Proe. 
Infer.  A.  rtic.  Pro*. 


rotates.  The  most  distinctive  character  of  this  bone  is  the  strong  prominent 
process,  tooth-like  in  form  (hence  the  name  odontoid),  which  rises  perpendi- 
cularly from  the  upper  part  of  the  body.  The  body  is  of  a  triangular  form ; 
deeper  in  front  than  behind,  and  prolonged  downwards  anteriorly  so  as  to  overlap 
the  upper  and  fore  part  of  the  adjacent  vertebra.  It  presents  in  front  a  median 
longitudinal  ridge,  separating  two  lateral  depressions  for  the  attachment  of  the 
Longi  colli  muscles.     The  odontoid  process  presents  two  articulating  surfaces: 


44 


OSTEOLOGY. 


one  in  front  of  an  oval  form,  for  articulation  with  the  atlas ;  another  behind,  for 
the  transverse  ligament;  the  latter  frequently  encroaches  on  the  sides  of  the 
process ;  the  apex  is  pointed.  Below  the  apex  this  process  is  somewhat  enlarged, 
and  presents  on  either  side  a  rough  impression  for  the  attachment  of  the  odontoid 
or  check  ligaments,  which  connect  it  to  the  occipital  bone ;  the  base  of  the  process, 
where  attached  to  the  body,  is  constricted,  so  as  to  prevent  displacement  from  the 
transverse  ligament,  which  binds  it  in  this  situation  to  the  anterior  arch  of  the 
atlas.  Sometimes,  however,  this  process  does  become  displaced,  especially  in 
children,  where  the  ligaments  are  more  relaxed ;  instant  death  is  the  result.  The 
pedicles  are  broad  and  strong,  especially  their  anterior  extremities  which  coalesce 
with  the  sides  of  the  body  and  the  root  of  the  odontoid  process.  The  laminae  are 
thick  and  strong,  and  the  spinal  foramen  very  large.  The  superior  articular 
surfaces  are  round,  slightly  convex,  directed  upwards  and  outwards,  and  are 
peculiar  in  being  supported  on  the  body,  pedicles,  and  transverse  processes.  The 
inferior  articular  surfaces,  have  the  same  direction  as  those  of  the  other  cervical 
vertebras.  The  superior  intervertebral  notches  are  very  shallow,  and  lie  behind 
the  articular  processes ;  the  inferior  in  front  of  them,  as  in  the  other  cervical 
vertebras.  The  transverse  processes  are  very  small,  not  bifid,  and  perforated  by 
the  vertebral  foramen,  which  is  directed  obliquely  upwards  and  outwards.  The 
spinous  process  is  of  large  size,  very  strong,  deeply  channelled  on  its  under 
surface,  and  presents  a  bifid  tubercular  extremity  for  the  attachment  of  muscles, 
which  serve  to  rotate  the  head  upon  the  spine. 

Seventh  Cervical  (fig.  4).  The 
most  distinctive  character  of  this 
vertebra  is  the  existence  of  a  very 
long,  and  prominent  spinous  pro- 
cess; hence  the  name  Vertebra 
prominens.  This  process  is  thick, 
nearly  horizontal  in  direction,  not 
bifurcated,  and  has  attached  to  it 
the  ligamentum  nuchas.  The 
transverse  process  is  usually  of 
large  size,  especially  its  posterior 
root,  its  upper  surface  has  usually 
a  shallow  groove,  and  seldom  pre- 
sents more  than  a  trace  of  bifur- 
cation at  its  extremity.  The  ver- 
tebral foramen  is  sometimes  as 
large  as  in  the  other  cervical  ver- 
tebrae, usually  smaller,  on  one  or 
both  sides,  and  sometimes  want- 
On  the  left  side,  it  occasion - 


Pig.  4. 


-7th  Cervical  Vertebra  or  Vertebra 
Prominens. 


Bcdy. 


msr. 


Spinous  .Prscj/S 


ally  gives  passage  to  the  vertebral 
artery;  more  frequently  the  ver- 
tebral vein  traverses  it  on  both 

sides ;  but  the  usual  arrangement  is  for  both  artery  and  vein  to  pass  through  the 

foramen  in  the  transverse  process  of  the  sixth  cervical. 


Characters  of  the  Dorsal  Vertebrae. 

The  bodies  of  the  dorsal  vertebrae  (fig.  5)  resemble  those  in  the  cervical  and 
lumbar  regions  at  the  respective  ends  of  this  portion  of  the  spine ;  but  in  the 
middle  of  the  dorsal  region  their  form  is  very  characteristic,  being  heart-shaped, 
and  broader  in  the  antero-posterior  than  in  the  lateral  direction.  They  are 
thicker  behind  than  in  front,  flat  above  and  below,  convex  and  prominent  in 
front,  deeply  concave  behind,  slightly  constricted  in  front  and  at  the  sides,  and 
marked  on-  each  side,  near  the  root   of  the  pedicle,  by  two  demi-facets,  one 


DORSAL   YERTEBRJE. 


45 


above,  the  other  below.  These  are  covered  with  cartilage  in  the  recent  state; 
and,  when  articulated  with  the  adjoining  vertebrae,  form  oval  surfaces  for  the 
reception  of  the  heads  of  the  corresponding  ribs.  The  pedicles  are  directed 
backwards,  and  the  inferior  intervertebral  notches  are  of  large  size,  and  deeper 
than  in  any  other  region  of  the  spine.  The  laminse  are  broad  and  thick,  and 
the  spinal  foramen  small,  and  of  a  circular  form.  The  articular  processes  are  flat, 
nearly  vertical  in  direction,  and  project  from  the  upper  and  lower  part  of  the 
pedicles,  the  superior  being  directed  backwards  and  a  little  outwards  and  upwards, 
the  inferior  forwards  and  a  little  inwards  and  downwards.  The  transverse  pro- 
cesses arise  from  the  same  parts  of  the  arch  as  the  posterior  roots  of  the  trans- 
verse processes  in  the  neck ;  they  are  thick,  strong,  and  of  great  length,  directed 
obliquely  backwards  and  outwards,  presenting  a  clubbed  extremity,  lipped  on  its 
anterior  part  by  a  small  concave  surface,  for  articulation  with  the  tubercle  of  a 
rib.  Besides  the  articular  facet  for  the  rib,  two  indistinct  tubercles  may  be  seen 
rising  from  the  extremity  of  the  transverse  processes,  one'  near  the  upper,  the 
other  near  the  lower  border.  In  many  they  are  comparatively  of  small  size,  and 
serve  only  for  the  attachment  of  muscles.  But  in  some  animals,  they  attain  con- 
siderable magnitude  either  for  the  purpose  of  more  closely  connecting  the  seg- 
ments of  this  portion  of  the  spine,  or  for  muscular  and  ligamentous  attachment. 
The  spinous  processes  are  long,  triangular  in  form,  directed  obliquely  downwards, 
and  terminate  by  a  tubercular  margin.  They  overlap  one  another  from  the  fifth, 
to  the  eighth,  but  are  less  oblique  in  direction  above  and  below. 


Fig.  5. — A  Do i  sal  Vertebra. 


Superior  Artie.  1'rocest 

jffil 

Facet  fr  Tulercle  ofJZii 


Demi  facet  for  head  cf  Eil 


Demi  facet  furliea.d,  of  Jill 


lW        Infer.  Artie. Froc. 


The  peculiar  dorsal  vertebrae  are  the  first,  ninth,  tenth,  eleventh,  and  twelfth 
(fig.  6). 

The  First  Dorsal  Vertebra  presents,  on  each  side  of  the  body,  a  single  entire 
articular  facet  for  the  head  of  the  first  rib,  and  a  half  facet  for  the  upper  half  of 
the  second.  The  upper  surface  of  the  body  is  like  that  of  a  cervical  vertebra, 
being  broad  transversely,  concave,  and  lipped  on  each  side.  The  articular  sur- 
faces are  oblique,  and  the  spinous  process  thick,  long,  and  almost  horizontal. 

The  Ninth  Dorsal  has  no  demi-facet  below.  In  some  subjects,  the  ninth  has 
two  demi-facets  on  each  side ;  then  the  tenth  has  a  demi-facet  at  the  upper  part, 
none  below. 

The  Tenth  Dorsal  has  an  entire  articular  facet  on  each  side  above ;  no  demi 
facet  below. 


46 


OSTEOLOGY. 


In  the  Eleventh  Dorsal,  the  body  approaches  in  its  form  and  size  to  the  lumbar 
vertebras.!  The  articular  facets  for  the  heads  of  the  ribs,  one  on  each  side,  are  of 
large  size,  and  placed  chiefly  on  the  pedicles,  which  are  thicker  and  stronger  in  this 
and  the  next  vertebra,  than  in  any  other  part  of  the  dorsal  region.  The  transverse 
processes  are  very  short,  tubercular  at  their  extremities,  and  have  no  articular 
facets  for  the  tubercles  of  the  ribs.  The  spinous  process  is  short,  nearly  horizontal 
in  direction,  and  presents  a  slight  tendency  to  bifurcation  at  its  extremity. 

Fig.  6. — Peculiar  Dorsal  Vertebrae. 


An.  entire  faeet  <t7>ov4 
A  Demi  facet   lelow 


— A  Demi  facet  aiove 


— On*  entire  farev 


n  entire  facet 
Vo facet on  Trans.Pror. 
•/tts  n/ dime/it  a  r/r 


n  entire  facet 
No  facet  tin.Tra  ?is  jir. 

Infer.Artic.  Proe 
convene  and turned 
outward 


The  Twelfth  Dorsal  has  the  same  general  characters  as  the  eleventh ;  but  may 
be  distinguished  from  it  by  the  inferior  articular  processes  being  convex  and 
turned  outwards,  like  those  of  the  lumbar  vertebra? ;  by  the  general  form  of  the 
body,  lamime,  and  spinous  process,  approaching  to  that  of  the  lumbar  vertebrae; 
and  by  the  transverse  processes  being  shorter,  and  the  tubercles  at  their  extremi- 
ties more  marked. 


LUMBAR   VERTEBRA.  4T 


Characters  of  the  Lumbar  Vertebra. 

The  Lumbar  Vertebrae  (fig.  7)  are  the  largest  segments  of  the  vertebral  column. 
The  body  is  large,  broader  from  side  to  side  than  from  before  backwards,  and 
about  equal  in  depth  in  front  and  behind,  flattened  or  slightly  concave  above  and 
below,  concave  behind,  and  deeply  constricted  in  front  and  at  the  sides,  presenting 
prominent  margins  which  afford  a  broad  basis  for  the  support  of  the  superincum- 
bent weight.     The  pedicles  are  very  strong,  directed  backwards  from  the  upper 

Fig.  7. — A  Lumbar  Vertebra. 
Super.  Artec.  Proc. 


part  of  the  bodies;  consequently  the  inferior  intervertebral  notches  are  of  large 
size.  The  laminse  are  short,  but  broad  and  strong ;  and  the  •  foramen  triangular, 
larger  than  in  the  dorsal,  smaller  than  in  the  cervical  region.  The  superior  articular 
processes  are  concave,  and  look  almost  directly  inwards;  the  inferior,  convex,  look 
outwards  and  a  little  forwards ;  the  former  are  separated  by  a  much  wider  interval 
than  the  latter,  embracing  the  lower  articulating  processes  of  the  vertebra  above. 
The  transverse  processes  are  long,  slender,  directed  transversely  outwards  in  the 
upper  three  lumbar  vertebras,  slanting  a  little  upwards  in  the  lower  two.  By 
some  anatomists  they  are  considered  homologous  with  the  ribs.  Of  the  two  tuber- 
cles noticed  in  connection  with  the  transverse  processes  in  the  dorsal  region,  the 
superior  ones  become  connected  in  this  region  with  the  back  part  of  the  superior 
articular  processes,  the  inferior  ones  with  the  posterior  part  of  the  base  of  the 
transverse  processes.  Although  in  man  they  are  comparatively  small,  in  some 
animals  they  attain  considerable  size,  and  serve  to  lock  the  vertebrae  more  closely 
together.  The  spinous  processes  are  thick  and  broad,  somewhat  quadrilateral, 
horizontal  in  direction,  thicker  below  than  above,  and  terminate  by  a  rough 
uneven  border. 

The  Fifth  Lumbar  vertebra  is  characterized  by  having  the  body  much  thicker 
in  front  than  behind,  which  accounts  for  the  prominence  of  the  sacro-vertebral 
articulation,  by  the  smaller  size  of  its  spinous  process,  by  the  wide  interval 
between  the  inferior  articulating  processes,  and  by  the  greater  size  and  thickness 
of  its  transverse  processes. 

Structure  and  Development  of  the  Vertebrae. 

The  structure  of  a  vertebra  differs  in  different  parts.  The  body  is  composed 
of  light  spongy  cancellous  tissue,  having  a  thin  coating  of  compact  tissue  on  its 
external  surface  perforated  by  numerous  orifices,  some  of  large  size,  for  the  passage 


48 


OSTEOLOGY. 


of  vessels,  its  interior  being  traversed  by  one  or  two  large  canals  for  the  reception 
of  veins,  which  converge  towards  a  single  large  irregular  aperture  or  several  small 

ones  at  the  posterior  part  of  the  body 


Fig.  8. — Development  of  a  Vertebra. 
By  o  primary  eertfret 

plY  t  for  Body  (i$  zivcA) 


J for  each  Lamina  (6*-  uteJj 


Pijf.  9. 


J}y  4  Secnn.dt.vr u  Centres 


1  for  each 
Traiin.Proo. 
ft  v» 


2  tomttimes  /  J  for  Spin.proc  (I6y  r*j 


Fitf.  10. 


1  far  upper  su rfat 
of  body 

1for  u  it  dor  »urfae*\ 
of   body 


II 


Fie.  11.— Atlas. 


12.— Axis. 


f  for  anter.  area  (1''yr) 

/  for  eeuth      )lj.      ; .  .» 

—  ,J  ,  I  before  Om-tn 

lateral,  mats)    J 


Fig.  13. — Lumbar  Vertebra. 
2    additional  ce-nt  ret 


Zfor  odontoid proe  f6r*>  mo  J 


//or  ear  A  lateral  mass   I    ^ 


mo.) 


\3? 
for  tubercles   on  Sup. 


of  each  bone.  The  arch  and  processes 
projecting  from  it  have,  on  the  con- 
trary, an  exceedingly  thick  covering 
of  compact  tissue. 

Development.  Each  vertebra  is  form- 
ed of  three  primary  cartilaginous  por- 
tions (fig.  8);  one  for  each  lamina  and 
its  processes,  and  one  for  the  body. 
Ossification  commences  in  the  laminae 
about  the  sixth  week  of  foetal  life,  in 
the  situation  where  the  transverse  pro- 
cesses afterwards  project,  the  ossific 
granules  shooting  backwards  to  the 
spine,  forwards  to  the  body,  and  out- 
wards into  the  transverse  and  articular 
processes.  Ossification  in  the  body 
makes  its  appearance  in  the  middle  of 
the  cartilage  about  the  eighth  week. 
At  birth,  these  three  pieces  are  per- 
fectly separate.  During  the  first  year, 
the  laminae  become  united  behind,  by 
a  portion  of  cartilage  in  which  the 
spinous  process  is  ultimately  formed, 
and  thus  the  arch  is  completed.  About 
the  third  year,  the  body  is  joined  to 
the  arch  on  each  side,  in  such  a  man- 
ner that  the  body  is  formed  from  the 
three  original  centres  of  ossification, 
the  amount  contributed  by  the  pedicles 
increasing  in  extent  from  below  up- 
wards. Thus  the  bodies  of  the  sacral 
vertebrae  are  formed  almost  entirely 
from  the  central  nuclei,  the  bodies  of 
the  lumbar  segments  are  formed  late- 
rally and  behind  by  the  pedicles.  In 
the  dorsal  region  the  pedicles  advance 
as  far  forwards  as  the  articular  depres- 
sions for  the  heads  of  the  ribs,  forming 
these  cavities  of  reception ;  and  in  the 
neck  the  whole  of  the  lateral  portions 
of  the  bodies  are  formed  by  the  ad- 
vance of  the  pedicles.  Before  puberty, 
no  other  changes  occur  excepting  a 
gradual  increase  in  the  growth  of  these 
primary  centres,  the  upper  and  under 
surface  of  the  bodies,  and  the  ends  of 
the  transverse  and  spinous  processes, 
being  tipped  with  cartilage,  in  which 
ossific  granules  are  not  as  yet  depo- 
sited. At  sixteen  years  (fig.  9),  four 
secondary  centres  appear,  one  for  the 
tip  of  each  transverse  process,  and  two 
(sometimes  united  into  one)  for  the  end 
of  the  spinous   process.     At   twenty- 


DEVELOPMENT  OF  THE  VERTEBRAE.         49 

one  years  (fig.  10),  a  thin  circular  plate  of  bone  is  formed  in  the  thin  layer  of  carti- 
lage situated  on  the  upper  and  under  surface  of  the  body,  the  former  being  the 
thicker  of  the  two.  All  these  become  joined ;  and  the  bone  is  completely  formed 
about  the  thirtieth  year  of  life. 

Exceptions  to  this  mode  of  development  occur  in  the  first,  second,  and  seventh 
cervical,  and  in  the  vertebrae  of  the  lumbar  region. 

The  Atlas  (fig.  11)  is  developed  by  two  primary  centres,  and  by  one  or  more 
epiphyses.  The  two  primary  centres  consist  of  the  two  lateral  of  neural  masses, 
ossification  of  which  commences  before  birth,  near  the  articular  processes,  and 
extending  backwards,  they  are  separated  from  one  another  behind,  at  birth,  by  a 
narrow  interval  filled  in  with  cartilage.  Between  the  second  and  third  years, 
they  unite  either  directly  or  through  the  medium  of  an  epiphysal  centre,  developed 
in  the  cartilage  near  their  point  of  junction.  The  anterior  arch,  at  birth,  is  alto- 
gether cartilaginous,  and  this  portion  of  the  atlas  is  completed  by  the  gradual 
extension  forwards  and  ultimate  junction  of  the  two  neural  processes.  Occasion- 
ally a  separate  nucleus  is  developed  in  the  anterior  arch,  which,  extending  laterally, 
joins  the  neural  processes  in  front  of  the  pedicles ;  or,  there  are  two  nuclei  deve- 
loped in  the  anterior  arch,  one  on  either  side  of  the  median  line;  they  join  to  form 
a  single  mass,  which  is  afterwards  united  to  the  lateral  portions  in  front  of  the 
articulating  processes. 

The  Axis  (fig.  12)  is  developed  by  six  centres.  The  body  and  arch  of  this  bone 
are  formed  in  the  same  manner  as  the  corresponding  parts  in  the  other  vertebras : 
one  centre  for  the  lower  part  of  the  body,  and  one  for  each  lamina.  The  odontoid 
process,  which  is  really  the  centrum  or  body  of  the  axis,  consists  originally  of  an 
extension  upwards  of  the  cartilaginous  mass,  in  which  the  lower  part  of  the  body 
is  formed.  At  about  the  sixth  month  of  foetal  life,  two  osseous  nuclei  make  their 
appearance  in  the  base  of  this  process :  they  are  placed  laterally,  and  join  before 
birth  to  form  a  conical-shaped  bilobed  mass,  deeply  cleft  above;  the  interval 
between  the  cleft  and  the  summit  of  the  process  is  formed  by  a  wedge-shaped 
piece  of  cartilage ;  the  base  of  the  process  being  separated  from  the  body  by  a 
cartilaginous  interval,  which  gradually  becomes  ossified,  sometimes  by  a  separate 
epiphysal  nucleus.  Finally,  as  Mr.  Humphry  has  lately  demonstrated,  the  apex 
of  the  odontoid  process  has  a  separate  nucleus. 

The  Seventh  Cervical.  The  anterior  or  costal  part  of  the  transverse  process  of 
the  seventh,  cervical  is  developed  from  a  separate  osseous  centre  at  about  the 
sixth  month  of  fcetal  life,  and  joins  the  body  and  posterior  division  of  the  trans- 
verse process  between  the  fifth  and  sixth  years.  Sometimes  this  process  continues 
as  a  separate  piece,  and  becoming  lengthened  outwards  constitutes  what  is  known 
as  a  cervical  rib. 

The  Lumbar  Vertebrse  (fig.  13)  have  two  additional  centres  (besides  those  peculiar 
to  the  vertebras  generally),  for  the  tubercles,  which  project  from  the  back  part  of 
the  superior  articular  processes.  The  transverse  process  of  the  first  lumbar  is 
sometimes  developed  as  a  separate  piece,  which  may  remain  permanently  uncon- 
nected with  the  remaining  portion  of  the  bone ;  thus  forming  a  lumbar  rib,  a 
peculiarity  which  is  sometimes,  though  rarely,  met  with. 

Progress  of  Ossification  in  the  Spine  generally.  Ossification  of  the  laminas 
of  the  vertebras  commences  at  the  upper  part  of  the  spine,  and  proceeds  gradually 
downwards;  heDce  the  frequent  occurrence  of  spina  bifida  in  the  lower  part  of 
the  spinal  column.  Ossification  of  the  bodies,  on  the  other  hand,  commences  a 
little  below  the  centre  of  the  spinal  column,  about  the  ninth  or  tenth  dorsal 
vertebra,  and  extends  both  upwards  and  downwards.  Although,  however,  the 
ossific  nuclei  make  their  first  appearance  in  the  lower  dorsal  vertebras,  the  lumbar 
and  first  sacral  are  those  in  which  these  nuclei  are  largest  at  birth. 

Attachment  of  Muscles.  To  the  Atlas  are  attached  the  Longus  colli,  Rectus 
anticus  minor,  Rectus  lateralis,  Rectus  posticus  minor,  Obliquus  superior  and 
inferior,  Splenitis  colli,  Levator  anguli  scapulas,  Interspinous,  and  Intertransverse. 

To  the  Axis  are  attached  the  Longus  colli,  Obliquus  inferior,  Rectus  posticus 
4 


50 


OSTEOLOGY. 


major,  Semispinals  colli,  Multifidus  spinas,  Levator  anguli  scapulas,  Splenius  colli, 
Transversalis  colli,  Scalenus  posticus,  Intertransversales,  Interspinales. 

To  the  remaining  Vertebras  generally  are  attached,  anteriorly,  the  Rectus  anticus 
major,  Longus  colli,  Scalenus  anticus  and  posticus,  Psoas  magnus,  Psoas  parvus, 
Quadratus  lumborum,  Diaphragm,  Obliquus  internus  and  Transversalis, — poste- 
riorly, the  Trapezius,  Latissimus  dorsi,  Levator  anguli  scapulas,  Rhomboideus 
major  and  minor,  Serratus  posticus  superior  and  inferior,  Splenius,  Sacro-lumbalis, 
Longissimus  dorsi,  Spinalis  dorsi,  Cervicalis  ascendens,  Transversalis  colli, 
Trachelo-mastoid,  Complexus,  Serni-spinalis  dorsi  and  colli,  Multifidus  spinas, 
Interspinales,  Supraspinales,  Intertransversales,  Levatores  costarum. 

Saceal  and  Coccygeal  Vertebrae. 

The  Sacral  and  Coccygeal  Vertebras  consist,  at  an  early  period  of  life,  of  nine 
separate  pieces,  which  are  united  in  the  adult,  so  as  to  form  two  bones,  five 
entering  into  the  formation  of  the  sacrum,  four  of  the  coccyx. 

The  Sacrum  (fig.  14),  so  called  from  its  having  been  offered  in  sacrifice,  and 
hence  considered  sacred,  is  a  large  triangular  bone,  situated  at  the  lower  part  of 


Fig.  14. — Sacrum:  Anterior  Surface. 
Promontory 


the  vertebral  column,  and  at  the  upper  and  back  part  of  the  pelvic  cavity,  where 
it  is  inserted  like  a  wedge  between  the  two  ossa  innominata;  its  upper  part, 
or  base,  articulating  with  the  last  lumbar  vertebra,  its  apex  with  the  coccyx. 
The  sacrum  is  curved  upon  itself,  and  placed  very  obliquely,  its  upper  extremity 
projecting  forwards,  forming,  with  the  last  lumbar  vertebra,  a  very  prominent 
angle,  called  the  promontory  or  sacro-vertebral  angle,  whilst  its  central  part  is 
directed  backwards,  so  as  to  give  increased  capacity  to  the  pelvic  cavity.     It 


SACRUM. 


51 


Fig.  15. — Vertical  Section  of  the  Sacrum. 


presents  for  examination  an  anterior  and  posterior  surface,  two  lateral  surfaces,  a 
base,  an  apex,  and  a  central  canal. 

Tlie  Anterior  Surface  is  concave  from  above  downwards,  and  slightly  so  from 
side  to  side.  In  the  middle  are  seen  four  transverse  ridges,  indicating  the  original 
division  of  the  bone  into  five  separate  pieces.  The  portions  of  bone  intervening 
between  the  ridges  correspond  to  the  bodies  of  the  vertebrae.  The  body  of  the 
first  segment  is  of  large  size,  and  in  form  resembles  that  of  a  lumbar  vertebra;  the 
succeeding  ones  diminish  in  size  from  above  downwards,  are  flattened  from  before 
backwards,  and  curved  so  as  to  accom- 
modate themselves  to  the  form  of  the 
sacrum,  being  concave  in  front,  convex 
behind.  At  each  end  of  the  ridges,  above 
mentioned,  are  seen  the  anterior  sacral 
foramina,  analogous  to  the  intervertebral 
foramina,  four  in  number  on  each  side, 
somewhat  rounded  in  form,  diminishing 
in  size  from  above  downwards,  and  di- 
rected outwards  and  forwards;  they 
transmit  the  anterior  branches  of  the 
sacral  nerves.  External  to  these  fora- 
mina is  the  lateral  mass,  consisting,  at 
an  early  period  of  life,  of  separate  seg- 
ments, which  correspond  to  the  anterior 
transverse  processes ;  these  become  blend- 
ed, in  the  adult,  with  the  bodies,  with 
each  other,  and  with  the  posterior  trans- 
verse processes.  Each  lateral  mass  is 
traversed  by  four  broad  shallow  grooves, 
which  lodge  the  anterior  sacral  nerves  as 
they  pass  outwards,  the  grooves  being 
separated  by  prominent  ridges  of  bone, 
which  give  attachment  to  the  slips  of  the 
Pyriformis  muscle. 

If  a  vertical  section  is  made  through 
the  centre  of  the  bone  (fig.  15),  the  bodies 
are  seen  to  be  united  at  their  circumfe- 
rence by  bone,  a  wide  interval  being  left 
centrally,  which,  in  the  recent  state,  is 
filled  by  intervertebral  substance.  In 
some  bones,  this  union  is  more  complete 
between  the  lower  segments  than  between 
the  upper  ones. 

The  Posterior  Surface  (fig.  16)  is  convex,  and  much  narrower  than  the  anterior. 
In  the  middle  line,  are  three  or  four  tubercles,  which  represent  the  rudimentary 
spinous  processes  of  the  sacral  vertebrae.  Of  these  tubercles,  the  first  is  usually 
prominent,  and  perfectly  distinct  from  the  rest ;  the  second  and  third  are  either 
separate,  or  united  into  a  tubercular  ridge,  which  diminishes  in  size  from  above 
downwards;  the  fourth  usually,  and  the  fifth  always,  remaining  undeveloped.  Ex- 
ternal to  the  spinous  processes  on  each  side  are  the  laminse,  broad  and  well  marked 
in  the  three  first  pieces;  sometimes  the  fourth,  and  generally  the  fifth,  being  un- 
developed ;  in  this  situation  the  lower  end  of  the  sacral  canal  is  exposed.  External 
to  the  laminae  is  a  linear  series  of  indistinct  tubercles  representing  the  articular 
processes;  the  upper  pair  are  large,  well  developed,  and  correspond  in  shape  and 
direction  to  the  superior  articulating  processes  of  a  lumbar  vertebra;  the  second 
and  third  are  small ;  the  fourth  and  fifth  (usually  blended  together)  are  situated 
on  each  side  of  the  sacral  canal :  they  are  called  the  sacral  cornua,  and  articulate 
with  the  cornua  of  the  coccyx.     External  to  the  articular  processes  are  the  four 


52 


OSTEOLOGY. 


posterior  sacral  foramina ;  they  are  smaller  in  size,  and  less  regular  in  form  than 
the  anterior,  and  transmit  the  posterior  branches  of  the  sacral  nerves.  On  the 
outer  side  of  the  posterior  sacral  foramina  is  a  series  of  tubercles,  the  rudimentary 


Fig.  16. — Sacrum:  Posterior  Surface. 


posterior  transverse  processes  of  the  sacral  vertebra?.  The  first  pair  of  transverse 
tubercles  are  of  large  size,  very  distinct,  and  correspond  with  each  superior  angle 
of  the  bone ;  the  second,  small  in  size,  enter  into  the  formation  of  the  sacro-iliac 
articulation ;  the  third  give  attachment  to  the  oblique  sacro-iliac  ligaments ;  and 
the  fourth  and  fifth  to  the  great  sacro-ischiatic  ligaments.  The  interspace  between 
the  spinous  and  transverse  processes  on  the  back  of  the  sacrum,  presents  a  wide 
shallow  concavity,  called  the  sacral  groove;  it  is  continuous  above  with  the 
vertebral  groove,  and  lodges  the  origin  of  the  Erector  spina?. 

The  Lateral  surface,  broad  above,  becomes  narrowed  into  a  thin  edge  below. 
Its  upper  half  presents  in  front  a  broad  ear-shaped  surface  for  articulation  with 
the  ilium.  This  is  called  the  auricular  or  ear-shaped  surface,  and  in  the  fresh 
state  is  coated  with  cartilage.  It  is  bounded  posteriorly  by  deep  and  uneven 
impressions,  for  the  attachment  of  the  posterior  sacro-iliac  ligaments.  The  lower 
half  is  thin  and  sharp,  and  gives  attachment  to  the  greater  and  lesser  sacro-ischiatic 
ligaments,  and  to  some  fibres  of  the  Gluteus  maximus;  below,  it  presents  a  deep 
notch,  which  is  converted  into  a  foramen  by  articulation  with  the  transverse 
process  of  the  upper  piece  of  the  coccyx,  and  transmits  the  anterior  branch  of  the 
fifth  sacral  nerve. 

The  Base  of  the  sacrum,  which  is  broad  and  expanded,  is  directed  upwards  and 
forwards.  In  the  middle  is  seen  an  oval  articular  surface,  which  corresponds  with 
the  under  surface  of  the  body  of  the  last  lumbar  vertebra,  bounded  behind  by 
the  large  triangular  orifice  of  the  sacral  canal.  This  orifice  is  formed  behind  by 
the  spinous  process  and  laminae  of  the  first  sacral  vertebra,  whilst  projecting  from 


DEVELOPMENT   OF   SACRUM. 


53 


Fig.  17. — Development  of  Sacrum. 

Formed  ly  union,    of    £  Verteb  ra. 
2      characteristic  points. 

2  Additional   centres 
far   the  first  3 pieces  * 


at  birth 


it  on  each  side  are  the  superior  articular  processes;  they  are  oval,  concave, 
directed  backwards  and  inwards,  like  the  superior  articular  processes  of  a  lumbar 
vertebra;  in  front  of  each  articular  process  is  an  intervertebral  notch,  which 
forms  the  lower  half  of  the  last  intervertebral  foramen.  Lastly,  on  each  side  of 
the  articular  surface  is  a  broad  and  flat  triangular  surface  of  bone,  which  extends 
outwards,  and  is  continuous  on  each  side  with  the  iliac  fossa. 

The  Apex,  directed  downwards  and  forwards,  presents  a  small  oval  concave 
surface  for  articulation  with  the  coccyx. 

The  Sacral  Canal  runs  throughout  the  greater  part  of  the  bone ;  it  is  large 
and  triangular  in  form  above,  small  and  flattened  from  before  backwards  below. 
In  this  situation  its  posterior  wall  is  incomplete,  from  the  non-development  of  the 
lamina?  and  spinous  processes.  It  lodges  the  sacral  nerves,  and  is  perforated  by 
the  anterior  and  posterior  sacral  foramina, 
through  which  these  pass  out. 

Structure.  It  consists  of  much  loose 
spongy  tissue  within,  invested  exter- 
nally by  a  thin  layer  of  compact  tissue. 

Differences  in  the  Sacrum  of 
the  Male  and  Female.  The  sacrum 
in  the  female  is  usually  wider  than  in 
the  male;  and  it  is  much  less  curved, 
the  upper  half  of  the  bone  being  nearly 
straight,  the  lower  half  presenting  the 
greatest  amount  of  curvature.  The 
bone  is  also  directed  more  obliquely 
backwards;  which  increases  the  size  of 
the  pelvic  cavity,  and  forms  a  more  pro- 
minent sacro-vertebral  angle.  In  the 
male,  the  curvature  is  more  evenly  dis- 
tributed over  the  whole  length  of  the 
bone,  and  is  altogether  greater  than  in 
the  female. 

Peculiarities  of  the  Sacrum. 
This  bone,  in  some  cases,  consists  of 
six  pieces;  occasionally  the  number  is 
reduced  to  four.  Sometimes  the  bodies 
of  the  first  and  second  segments  are 
not  joined,  or  the  laminae  and  spinous 
processes  have  not  coalesced.  Occa- 
sionally, the  upper  pair  of  transverse 
tubercles  are  not  joined  to  the  rest  of 
the  bone  on  one  or  both  sides;  and, 
lastly,  the  sacral  canal  may  be  open  for 
nearly  the  lower  half  of  the  bone,  in 
consequence  of  the  imperfect  develop- 
ment of  the  laminae  and  spinous  pro- 
cesses. The  sacrum,  also,  varies  con- 
siderably with  respect  to  its  degree  of 
curvature.  From  the  examination  of 
a  large  number  of  skeletons,  it  would 
appear,  that,  in  one  set  of  cases,  the 
anterior  surface  of  this  bone  was  nearly 
straight,  the  curvature,  which  was 
very  slight,  affecting  only  its  lower  end. 
In  another  set  of  cases,  the  bone  was 
curved  throughout  its  whole  length, 
but  especially  towards  its  middle.     In 


Fig.  18. 


at  4J  y'rs 


Fig.  19. 


.     nr    tJl 

at  2o   r-.  y. 


54 


OSTEOLOGY. 


a  third  set,  the  degree  of  curvature  was  less  marked,  and  affected  especially  the 
lower  third  of  the  bone. 

Development  (fig.  17).  The  sacrum,  formed  by  the  union  of  five  vertebra?,  has 
thirty-five  centres  of  ossification. 

The  bodies  of  the  sacral  vertebra?  have  each  three  ossific  centres ;  one  for  the 
central  part,  and  one  for  the  epiphysal  plates  on  its  upper  and  under  surface. 

The  laminse  of  the  sacral  vertebra?  are  each  developed  by  two  centres ;  these 
meet  behind  to  form  the  arch,  and  subsequently  join  the  body. 

The  lateral  masses  have  six  additional  centres,  two  for  each  of  the  first  three 
vertebra?.  These  centres  make  their  appearance  above  and  to  the  outer  side  of 
the  anterior  sacral  foramina  (fig.  17),  and  are  developed  into  separate  segments, 
which  correspond  with  the  anterior  transverse  processes  (fig.  18);  they  are  subse- 
quently blended  with  each  other,  and  with  the  bodies  and  the  posterior  transverse 
processes,  to  form  the  lateral  mass. 

Lastly,  each  lateral  surface  of  the  sacrum  is  developed  by  two  epiphysal  plates 
(fig.  19);  one  for  the  articular  surface,  and  one  for  the  remaining  part  of  the  thin 
lateral  edge  of  the  bone. 

Period  of  Development.  At  about  the  eighth  or  ninth  week  of  foetal  life,  ossifi- 
cation of  the  central  part  of  the  bodies  of  the  first  three  vertebra?  commences ; 
and,  at  a  somewhat  later  period,  that  of  the  last  two.  Between  the  sixth  and 
eighth  months,  ossification  of  the  lamina?  takes  place :  and,  at  about  the  same 
period,  the  characteristic  osseous  tubercles  for  the  three  first  sacral  vertebra?  make 
their  appearance.  The  lamina?  join  to  form  the  arch,  and  are  united  to  the  bodies, 
first,  in  the  lowest  vertebra?.  This  occurs  about  the  second  year,  the  uppermost 
segment  appearing  as  a  single  piece  about  the  fifth  or  sixth  year.  About  the  six- 
teenth year,  the  epiphyses  for  the  upper  and  under  surfaces  of  the  bodies  are 
formed :  and,  between  the  eighteenth  and  twentieth  years,  those  for  each  lateral 
surface  of  the  sacrum  make  their  appearance.     At  about  this  period,  the  last 

two  segments  are  joined  to  one  another;  and  this  pro- 
cess gradually  extending  upwards,  all  the  pieces 
become  united,  and  the  bone  completely  formed  from 
the  twenty-fifth  to  the  thirtieth  year  of  life. 

Articulations.  With  four  bones;  the  last  lumbar 
vertebra,  coccyx,  and  the  two  ossa  innominata. 

Attachment  of  Muscles.  The  Pyriformis  and 
Coccygeus  on  either  side ;  behind,  the  Gluteus  maxi- 
mus,  and  Erector  spina?. 

The  Coccyx. 

The  Coccyx  (x6xxv%,  cuckoo),  so  called  from  resem- 
bling a  cuckoo's  beak  (fig.  20),  is  usually  formed 
of  four  small  segments  of  bone,  the  most  rudi- 
mentary parts  of  the  vertebral  column.  In  each 
of  the  first  three  segments  may  be  traced  a  rudi- 
mentary body,  articular  and  transverse  processes; 
the  last  'piece  (sometimes  the  third)  being  merely 
a  rudimentary  nodule  of  bone,  without  distinct 
processes.  All  the  segments  are  destitute  of  lami- 
na? and  spinous  processes;  and,  consequently,  of 
spinal  canal,  and  intervertebral  foramina.  The  first 
segment  is  the  largest,  resembles  the  loAvermost 
sacral  vertebra,  and  often  exists  as  a  separate  piece ; 
the  last  three,  diminishing  in  size  from  above  down- 
wards, are  usually  blended  together  so  as  to  form 
a  single  bone.  The  gradual  diminution  in  the 
size  of  the  pieces  gives  this  bone  a  triangular 
form,  articulating  by  its  base  with  the  end  of  the 


Fig.  20.— Coccyx. 
Cornva 


jlnterior  Surfars 


JPotterior  S-u-rfca 


THE    SPINE.  55 

sacrum.  It  presents  for  examination  an  anterior  and  posterior  surface,  two  borders, 
a  base,  and  an  apex.  The  anterior  surface  is  slightly  concave,  and  marked  with 
three  transverse  grooves,  indicating  the  points  of  junction  of  the  different  pieces. 
It  has  attached  to  it  the  anterior  sacro-coecygeal  ligament,(the  Levator  ani  muscle, 
and  supports  the  lower  end  of  the  rectum.  The  posterior  surface  is  convex, 
marked  by  transverse  grooves  similar  to  those  on  the  anterior  surface;  and  presents 
on  each  side  a  linear  row  of  tubercles,  the  rudimentary  articular  processes  of  the 
coccygeal  vertebra.  Of  these,  the  superior  pair  are  very  large ;  and  are  called 
the  cornua  of  the  coccyx;  they  project  upwards,  and  articulate  with  the  cornua  of 
the  sacrum,  the  junction  between  these  two  bones  completing  the  fifth  sacral 
foramen  for  the  transmission  of  the  posterior  branch  of  the  fifth  sacral  nerve. 
The  lateral  borders  are  thin,  and  present  a  series  of  small  eminences,  which  re- 
present the  transverse  processes  of  the  coccygeal  vertebrae.  Of  these,  the  first  on 
each  side  is  of  large  size,  flattened  from  before  backwards ;  and  often  ascends  to 
join  the  lower  part  of  the  thin  lateral  edge  of  the  sacrum,  thus  completing  the 
fifth  sacral  foramen :  the  others  diminish  in  size  from  above  downwards,  and  are 
often  wanting.  The  borders  of  the  coccyx  are  narrow,  and  give  attachment  on 
each  side  to  the  sacro-sciatic  ligaments  and  Coccygeus  muscle.  The  base  presents 
an  oval  surface  for  articulation  with  the  sacrum.  The  apex  is  rounded,  and  has 
attached  to  it  the  tendon  of  the  external  Sphincter  muscle.  It  is  occasionally 
bifid,  and  sometimes  deflected  to  one  or  other  side. 

Development.  The  coccyx  is  developed  by  four  centres,  one  for  each  piece. 
Occasionally,  one  of  the  first  three  pieces  of  this  bone  is  developed  by  two  centres, 
placed  side  by  side.  The  ossific  nuclei  make  their  appearance  in  the  following 
order:  in  the  first  segment,  at  birth;  in  the  second  piece,  at  from  five  to  ten  years; 
in  the  third,  from  ten  to  fifteen  years ;  in  the  fourth,  from  fifteen  to  twenty  years. 
As  age  advances,  these  various  segments  become  united  in  the  following  order : 
the  first  two  pieces  join;  then  the  third  and  fourth;  and,  lastly,  the  bone  is  com- 
pleted by  the  union  of  the  second  and  third.  At  a  late  period  of  life,  especially 
in  females,  the  coccyx  becomes  joined  to  the  end  of  the  sacrum. 

Articulation.  With  the  sacrum. 

Attachment  of  Muscles.  On  either  side,  the  Coccygeus;  behind,  the  Gluteus 
maxim  us ;  at  its  apex,  the  Sphincter  ani ;  and  in  front,  the  Levator  ani. 

Of  the  Spine  in  general. 

The  spinal  column,  formed  by  the  junction  of  the  vertebras,  is  situated  in  the 
median  line,  at  the  posterior  part  of  the  trunk :  its  average  length  is  about  two 
feet  two  or  three  inches;  the  lumbar  region  contributing  seven  parts  of  that 
length,  the  dorsal  eleven,  and  the  cervical  five. 

Viewed  in  front,  it  presents  two  pyramids  joined  together  at  their  bases,  the 
upper  one  being  formed  by  all  the  vertebrae  from  the  second  cervical  to  the  last 
lumbar ;  the  lower  one  by  the  sacrum,  and  coccyx.  Viewed  somewhat  more  closely, 
the  uppermost  pyramid  is  seen  to  be  formed  of  three  smaller  pyramids.  Of  these, 
the  most  superior  one  consists  of  the  six  lower  cervical  vertebrae;  its  apex  being 
formed  by  the  axis  or  second  cervical ;  its  base,  by  the  first  dorsal.  The  second 
pyramid,  which  is  inverted,  is  formed  by  the  four  upper  dorsal  vertebrae,  the  base 
being  at  the  first  dorsal,  the  smaller  end  at  the  fourth.  The  third  pyramid  com- 
mences at  the  fourth  dorsal,  and  gradually  increases  in  size  to  the  fifth  lumbar. 

Viewed  laterally  (fig.  21),  the  spinal  column  presents  several  curves,  which 
correspond  to  the  different  regions  of  the  column,  and  are  called  cervical,  dorsal, 
lumbar,  and  pelvic.  The  cervical  curve  commences  at  the  apex  of  the  odontoid 
process,  and  terminates  at  the  middle  of  the  second  dorsal  vertebra ;  it  is  convex 
in  front,  but  the  least  marked  of  all  the  curves.  The  dorsal  curvature,  which  is 
concave  forwards,  commences  at  the  middle  of  the  second,  and  terminates  at  the 
middle  of  the  twelfth  dorsal.  Its  most  prominent  point  behind  corresponds  to 
the  body  of  the  seventh  or  eighth  vertebra.  The  lumbar  curve  commences  at  the 
middle  of  the  last  dorsal,  and  terminates  at  the  sacro-.vertebral  angle.   It  is  convex 


56 


OSTEOLOGY. 


Fig.  21. — Lateral  View  of  Spine. 

lsl  Cervical 
orAtlat. 


6-\ 


IV  Dorsal. 


%A 


/? 


1?  Lumbar.^r^, 


u- 


^mm 


anteriorly;  the  convexity  of  the  lower 
three  vertebrae  being  much  greater  than 
that  of  the  upper  ones.  The  'pelvic  curve 
commences  at  the  sacro- vertebral  articula- 
tion, and  terminates  at  the  point  of  the 
coccyx.  It  is  concave  posteriorly.  These 
curves  are  partly  due  to  the  shape  of  the 
bodies  of  the  vertebrae,  and  partly  to  the 
intervertebral  substances,  as  will  be  ex- 
plained in  the  Articulations  of  the  Spine. 

The  spine  has  also  a  slight  lateral 
curvature,  the  convexity  of  which  is  di- 
rected toward  the  right  side.  This  is 
most  probably  produced,  as  Bichat  first 
explained,  from  the  effect  of  muscular 
action;  most  persons  using  the  right  arm 
in  preference  to  the  left,  especially  in 
making  long-continued  efforts,  when  the 
body  is  curved  to  the  right  side.  In 
support  of  this  explanation,  it  has  been 
found,  by  Beclard,  that  in  one  or  two  in- 
dividuals who  were  left-handed,  the  lateral 
curvature  was  directed  to  the  left  side. 

The  spinal  column  presents  for  exami- 
nation an  anterior,  a  posterior,  and  two 
lateral  surfaces;  a  base,  summit,  and  ver- 
tebral canal. 

The  anterior  surface  presents  the  bodies 
of  the  vertebrae  separated  in  the  recent  state 
by  the  intervertebral  disks.  The  bodies 
are  broad  in  the  cervical  region,  narrow 
in  the  upper  part  of  the  dorsal,  and  broadest 
in  the  lumbar  region.  The  whole  of  this 
surface  is  convex  transversely,  concave  from 
above  downwards  in  the  dorsal  region,  and 
convex  in  the  same  direction  in  the  cervical 
and  lumbar  regions. 

The  posterior  surface  presents  in  the 
median  line  the  spinous  processes.  These 
are  short,  horizontal,  with  bifid  extremi- 
ties in  the  cervical  region.  In  the  dorsal 
region,  they  are  directed  obliquely  above, 
assume  almost  a  vertical  direction  in  the 
middle,  and  are  horizontal,  like  the  spines 
of  the  lumbar  vertebras,  below.  They 
are  separated  by  considerable  intervals  in 
the  loins,  by  narrower  intervals  in  the 
neck,  and  are  closely  approximated  in 
the  middle  of  the  dorsal  region.  Oc- 
casionally one  of  these  processes  deviates 
a  little  from  the  median  line,  a  fact  to 
be  remembered,  as  irregularities  of  this 
sort  are  attendant  on  fractures  or  dis- 
placements of  the  spine.  On  either  side  of 
the  spinous  processes,  extending  the  whole 
length  of  the  column,  is  the  vertebral 
groove,  formed  by  the  laminaa  in  the  cer- 


THE    SKULL.  5T 

vical  and  lumbar  regions,  where  it  is  shallow,  and  by  the  laminrc  and  transverse 
processes  in  the  dorsal  region,  where  it  is  deep  and  broad.  In  the  recent  state, 
these  grooves  lodge  the  deep  muscles  of  the  back.  External  to  the  vertebral 
grooves  are  the  articular  processes,  and  still  more  externally  the  transverse  pro- 
cesses. In  the  dorsal  region,  the  latter  processes  stand  backwards,  on  a  place  con- 
siderably posterior  to  the  same  processes  in  the  cervical  and  lumbar  regions.  In 
the  cervical  region,  the  transverse  processes  are  placed  in  front  of  the  articular 
processes,  and  between  the  intervertebral  foramina.  In  the  lumbar,  they  are  placed 
also  in  front  of  the  articular  process,  but  behind  the  intervertebral  foramina.  In 
the  dorsal  region,  they  are  posterior  both  to  the  articular  processes  and  foramina. 
The  lateral  surfaces  are  separated  from  the  posterior  by  the  articular  processes 
in  the  cervical  and  lumbar  regions,  and  by  the  transverse  processes  in  the  dorsal. 
These  surfaces  present  in  front  the  sides  of  the  bodies  of  the  vertebras,  marked  in 
the  dorsal  region  by  the  facets  for  articulation  with  the  heads  of  the  ribs.  More 
posteriorly  are  the  intervertebral  foramina,  formed  by  the  juxtaposition  of  the  inter- 
vertebral notches,  oval  in  shape,  smallest  in  the  cervical  and  upper  part  of  the  dorsal 
regions,  and  gradually  increasing  in  size  to  the  last  lumbar.  They  are  situated 
between  the  transverse  processes  in  the  neck,  and  in  front  of  them  in  the  back  and 
loins,  and  transmit  the  spinal  nerves.  The  base  of  the  vertebral  column  is  formed 
by  the  under  surface  of  the  body  of  the  fifth  lumbar  vertebra;  and  the  summit  by 
the  upper  surface  of  the  atlas.  The  vertebral  canal  follows  the  different  curves 
of  the  spine ;  it  is  largest  in  those  regions  in  which  the  spine  enjoys  the  greatest 
freedom  of  movement,  as  in  the  neck  and  loins,  where  it  is  wide  and  triangular ; 
and  narrow  and  rounded  in  the  back,  where  motion  is  more  limited. 

THE  SKULL. 

The  Skull,  or  superior  expansion  of  the  vertebral  column,  is  composed  of  four 
vertebras,  the  elementary  parts  of  which  are  specially  modified  in  form  and  size, 
and  almost  immovably  connected,  for  the  reception  of  the  brain,  and  special 
organs  of  the  senses.  These  vertebras  are  the  occipital,  parietal,  frontal,  and  nasal. 
Descriptive  anatomists,  however,  divide  the  skull  into  two  parts,  the  Cranium  and 
the  Face.  The  Cranium  (xponos,  a  helmet)  is  composed  of  eight  bones:  viz.,  the 
occipital,  two  parietal,  frontal,  two  temporal,  sphenoid,  and  ethmoid.  The  face  is 
composed  of  fourteen  bones:  viz.,  the  two  nasal,  two  superior  maxillary,  two  lachry- 
mal, two  malar,  two  palate,  two  inferior  turbinated,  vomer,  inferior  maxillary.  The 
ossicula  auditus,  the  teeth,  and  Wormian  bones,  are  not  included  in  this  enumeration. 

Occipital. 

Two  Parietal. 

Cranium,  8  bones.       )     zJon  ~"  , 

Two  Temporal. 

Sphenoid. 

Ethmoid. 

Skull,  22  bones.    (  /     Two  Nasal. 


Face,  14  bones. 


Two  Superior  Maxillary. 

Two  Lachrymal. 

Two  Malar. 

Two  Palate. 

Two  Inferior  Turbinated. 

Vomer. 

Inferior  Maxillary. 

BONES   OF  THE  CRANIUM. 

The  Occipital  Bone. 

The  Occipital  Bone  (fig.  22)  is  situated  at  the  back  part  and  base  of  the  cranium, 
is  trapezoid  in  form,  curved  upon  itself,  and  presents  for  examination  two  sur- 
faces, four  borders,  and  four  angles. 


58 


OSTEOLOGY. 


The  External  Surface  is  convex.  Midway  between  the  summit  of  the  bone 
and  the  posterior  margin  of  the  foramen  magnum  is  a  prominent  tubercle,  the 
external  occipital  protuberance,  for  the  attachment  of  the  Ligamentum  nuchas;  and 
descending  from  it,  as  far  as  the  foramen,  a  vertical  ridge,  the  external  occipital 
crest.  This  tubercle  and  crest  vary  in  prominence  in  different  skulls.  Passing 
outwards  from  the  occipital  protuberance  on  each  side  are  two  semicircular  ridges, 
the  superior  curved  lines ;  and  running  parallel  with  these  from  the  middle  of  the 
crest,  are  the  two  inferior  curved  lines.  The  surface  of  the  bone  above  the  supe- 
rior curved  lines  is  smooth  on  each  side,  and  in  the  recent  state  is  covered  by  the 
Occipito-frontalis  muscle,  whilst  the  ridges,  as  well  as  the  surface  of  the  bone 
between  them,  serve  for  the  attachment  of  numerous   muscles.     The  superior 


22.— Occipital  Bone.     Outer  Surface. 


t>f Hiarynx 


curved  line  gives  attachment  internally  to  the  Trapezius,  externally  to  the  Occi- 
pito-frontalis, and  Sterno-cleido-mastoid,  to  the  extent  shown  in  the  figure.  The 
depressions  between  the  curved  lines  to  the  Complexus  internally,  the  Splenius 
capitis  and  Obliquus  superior  externally.  The  inferior  curved  line,  and  the 
depressions  below  it,  afford  insertion  to  the  Rectus  capitis  posticus,  major  and  minor. 
The  foramen  magnum  is  a  large  oval  aperture,  its  long  diameter  extending 
from  before  backwards.  It  transmits  the  spinal  cord  and  its  membranes,  the 
spinal  accessory  nerves,  and  the  vertebral  arteries.  Its  back  part  is  wide  for  the 
transmission  of  the  cord,  and  the  corresponding  margin  rough  for  the  attachment 
of  the  dura  mater  inclosing  it ;  the  forepart  is  narrower,  being  encroached  upon 
by  the  condyles ;  it  has  projecting  towards  it  from  below  the  odontoid  process, 
and  its  margins  are  smooth  and  bevelled  internally  to  support  the  medulla 
oblongata.  On  each  side  of  the  foramen  magnum  are  the  condyles  for  articulation 
with  the  atlas;  they  are  convex,  oblong  or  reniform  in  shape,  and  directed  down- 
wards and  outwards;  they  converge  in  front,  and  encroach  slightly  upon  the 
anterior  segment  of  the  foramen.     On  the  inner  border  of  each  condvle  is  a  rough 


OCCIPITAL  BONE. 


59 


tubercle  for  the  attachment  of  the  ligaments  (check)  which  connect  this  bone  with 
the  odontoid  process  of  the  axis ;  whilst  external  to  them  is  a  rough  tubercular 
prominence,  the  transverse  or  jugular  process  (the  representative  of  the  trans- 
verse process  of  a  vertebra),  channelled  in  front  by  a  deep  notch,  which  forms 
part  of  the  jugular  foramen.  The  under  surface  of  this  process  affords  attach- 
ment to  the  Rectus  capitis  lateralis ;  its  upper  or  cerebral  surface  presents  a  deep 
groove,  which  lodges  part  of  the  lateral  sinus,  whilst  its  prominent  extremity  is 
marked  by  a  quadrilateral  rough  surface,  covered  with  cartilage  in  the  fresh  state, 
and  articulating  with  a  similar  surface  on  the  petrous  portion  of  the  temporal 
bone.  On  the  outer  side  of  each  condyle,  near  its  forepart,  is  a  foramen,  the 
anterior  condyloid ;  it  is  directed  downwards,  outwards,  and  forwards,  and  trans- 
mits the  hypoglossal  nerve.  This  foramen  is  sometimes  double.  Behind  each 
condyle  is  a  fossa,'  perforated  at  the  bottom  by  a  foramen,  the  posterior  condyloid, 
for  the  transmission  of  a  vein  to  the  lateral  sinus.  In  front  of  the  foramen 
magnum  is  a  strong  quadrilateral  plate  of  bone,  the  basilar  process,  wider  behind 
than  in  front ;  its  under  surface,  which  is  rough,  presenting  in  the  median  line  a 
tubercular  ridge,  the  pharyngeal  spine,  for  the  attachment  of  the  tendinous  raphe 
and  Superior  constrictor  of  the  pharynx ;  and  on  each  side  of  it  are  rough  depressions 
for  the  attachment  of  the  Rectus  capitis  anticus  major,  and  Rectus  capitis  minor. 

Fig.  23. — Occipital  Bone  :  Inner  Surface. 
Su/ieri'or  Angle 

•  ''Of, 


Inferior  Ant/lp  V« 

The  Internal  or   Cerebral  Surface  (fig.  23)  is  deeply  concave.     The  posterior 

1  This  fossa  presents  many  variations  in  size.  It  is  usually  shallow,  and  the  foramen  small ; 
occasionally  wanting,  on  one,  or  both  sides.  Sometimes  both  fossa  and  foramen  are  large,  but 
confined  to  one  side  only ;  more  rarely,  the  fossa  and  foramen  are  very  large  on  both  sides. 


60  OSTEOLOGY. 

or  occipital  part  is  divided  by  a  crucial  ridge  into  four  fossae.  The  two  superior, 
the  smaller,  receive  the  posterior  lobes  of  the  cerebrum,  and  present  slight  emi- 
nences and  depressions  corresponding  to  their  convolutions.  The  two  inferior, 
which  receive  the  lateral  lobes  of  the  cerebellum,  are  larger  than  the  former,  and 
comparatively  smooth ;  both  are  marked  by  slight  grooves  for  the  lodgment  of 
arteries.  At  the  point  of  meeting  of  the  four  divisions  of  the  crucial  ridge  is  an 
eminence,  the  internal  occipital  protuberance.  It  nearly  corresponds  to  that  on 
the  outer  surface,  and  is  perforated  by  one  or  more  large  vascular  foramina. 
From  this  eminence,  the  superior  division  of  the  crucial  ridge  runs  upwards  to 
the  superior  angle  of  the  bone ;  it  presents  occasionally  a  deep  groove  for  the 
superior  longitudinal  sinus,  the  margins  of  which  give  attachment  to  the  falx 
cerebri.  The  inferior  division,  the  internal  occipital  crest,  runs  to  the  posterior 
margin  of  the  foramen  magnum,  on  the  edge  of  which  it  becomes  gradually  lost: 
this  ridge,  which  is  bifurcated  below,  serves  for  the  attachment  of  the  falx  cere- 
belli.  The  transverse  grooves  pass  outwards  to  the  lateral  angles;  they  are 
deeply  channelled,  for  the  lodgment  of  the  lateral  sinuses,  their  prominent  margins 
affording  attachment  to  the  tentorium  cerebelli.1  At  the  point  of  meeting  of  these 
grooves  is  a  depression,  the  "  Torcular  Herophili,"*  placed  a  little  to  one  or  the 
other  side  of  the  internal  occipital  protuberance.  More  anteriorly  is  the  foramen 
magnum,  and  on  each  side  of  it,  but  nearer  its  anterior  than  its  posterior  part, 
the  internal  openings  of  the  anterior  condyloid  foramina ;  the  internal  openings 
of  the  posterior  condyloid  foramina  being  a  little  external  and  posterior  to  them, 
protected  by  a  small  arch  of  bone.  In  front  of  the  foramen  magnum  is  the  basilar 
process,  presenting  a  shallow  depression,  the  basilar  groove,  which  slopes  from 
behind,  upwards  and  forwards,  and  supports  the  medulla  oblongata ;  and  on  each 
side  of  the  basilar  process  is  a  narrow  channel,  which,  when  united  with  a  similar 
channel  on  the  petrous  portion  of  the  temporal  bone,  forms  a  groove,  which  lodges 
the  inferior  petrosal  sinus. 

Angles.  The  superior  angle  is  received  into  the  interval  between  the  posterior 
superior  angles  of  the  two  parietal  bones ;  it  corresponds  with  that  part  of  the 
skull  in  the  foetus  which  is  called  the  posterior  fontanelle.  The  inferior  angle  is 
represented  by  the  square-shaped  surface  of  the  basilar  process.  At  an  early 
period  of  life,  a  layer  of  cartilage  separates  this  part  of  the  bone  from  the  sphenoid ; 
but  in  the  adult,  the  union  between  them  is  osseous.  The  lateral  angles  correspond 
to  the  outer  ends  of  the  transverse  grooves,  and  are  received  into  the  interval 
between  the  posterior  inferior  angles  of  the  parietal  and  the  mastoid  portion  of 
the  temporal. 

Borders.  The  superior  extends  on  each  side  from  the  superior  to  the  lateral 
angle,  is  deeply  serrated  for  articulation  with  the  parietal  bone,  and  forms  by 
this  union  the  lambdoid  suture.  The  inferior  border  extends  from  the  lateral  to 
the  inferior  angle ;  its  upper  half  is  rough,  and  articulates  with  the  mastoid  por- 
tion of  the  temporal,  forming  the  masto-occipital  suture :  the  inferior  half  articu- 
lates with  the  petrous  portion  of  the  temporal,  forming  the  petro-occipital  suture : 
these  two  portions  are  separated  from  one  another  by  the  jugular  process.  In 
front  of  this  process  is  a  deep  notch,  which,  with  a  similar  one  on  the  petrous 
portion  of  the  temporal,  forms  the  foramen  lacerum  posterius.  This  notch  is 
occasionally  subdivided  into  two  parts  by  a  small  process  of  bone,  and  presents  an 
aperture  at  its  upper  part,  the  internal  opening  of  the  posterior  condyloid  foramen. 

Structure.  The  occipital  bone  consists  of  two  compact  laminae,  called  the  outer 
and  inner  tables,  having  between  them  the  diploic  tissue ;  this  bone  is  especially 

'  Usually  one  of  the  transverse  grooves  is  deeper  and  broader  than  the  other ;  this  seems  in 
nearly  equal  proportion  on  the  two  sides;  occasionally  both  grooves  are  of  equal  depth  and 
breadth,  or  both  equally  indistinct.  The  broader  of  the  two  transverse  grooves  is  nearly  always 
continuous  with  the  vertical  groove  for  the  superior  longitudinal  sinus,  and  occupies  the  corre- 
sponding side  of  the  median  line. 

2  The  columns  of  blood  coming  in  different  directions  were  supposed  to  be  pressed  together  at 
this  point. 


OCCIPITAL   BONE. 


61 


JJt/  4-  centres 


at  lirfJL 

the   1,  pit  res 
*cj>a  rale 


thick,  at  the  ridges,  protuberances,  condyles,  and  anterior  part  of  the  basilar 
process;  whilst  at  the  bottom  of  the  fossae,  especially  the  inferior,  it  is  thin,  semi- 
transparent,  and  destitute  of  diploe. 

Development  (fig.  24).  The  occipital  bone  has  four  centres  of  development ; 
one  for  the  posterior  or  occi- 
pital part,  Which  is  formed  in  F'S-  24. -Development  of  Occipital  Boue. 
membrane ;  one  for  the  basilar 
portion;  and  one  for  each 
condyloid  portion,  which  are 
formed  in  cartilage. 

The  centre  for  the  occipi- 
tal portion  appears  about  the 
tenth  week  of  foetal  life ;  and 
consists,  according  to  Blandin 
and  Cruveilhier,  of  a  small 
oblong  plate  which  appears 
in  the  situation  of  the  occi- 
pital protuberance.1  The 
condyloid  portions  then 
ossify,  and  lastly  the  basilar 
portion.  At  birth,  the  bone 
consists  of  four  parts,  separate  from  one  another,  the  occipital  portion  being  fissured 
in  the  direction  above  indicated.  At  about  the  fourth  year,  the  occipital  and  the 
two  condyloid  pieces  join;  and  about  the  sixth  year  the  bone  consists  of  a  single 
piece.  At  a  later  period  between  the  eighteenth  and  twenty-fifth  years,  the 
occipital  and  sphenoid  become  united,  forming  a  single  bone. 

Articulations.  With  six  bones ;  two  parietal,  two  temporal,  sphenoid,  and  atlas. 

Attachment  of  Muscles.  To  the  superior  curved  line  are  attached  the  Occipito- 
frontalis,  Trapezius,  and  Sterno-cleido-mastoid.  To  the  space  between  the  curved 
lines,  the  Complexus,  Splenius  capitis,  and  Obliquus  superior;  to  the  inferior 
curved  line,  and  the  space  between  it  and  the  foramen  magnum,  the  Kectus 
posticus  major  and  minor ;  to  the  transverse  process,  the  Rectus  lateralis ;  and  to 
the  basilar  process,  the  Recti  antici  majores  and  minores,  and  Superior  Constrictor 
of  the  pharynx. 


/    for  occipital 
portion 


I  for  each  condyloid 
portion 

or  otLthlar  portion 


The  Parietal  Boxes. 

The  Parietal  Bones  {paries,  a  wall)  form  by  their  union  the  sides  and  roof  of 
the  skull ;  each  bone  is  of  an  irregular  quadrilateral  form,  and  presents  for  ex- 
amination two  surfaces,  four  borders  and  four  angles. 

Surfaces.  The  external  surface  (fig.  25)  is  convex,  smooth,  and  marked  about 
its  centre  by  an  eminence,  called  the  parietal  eminence,  which  indicates  the  point 
where  ossification  commenced.  Crossing  the  centre  of  the  bone  in  an  arched 
direction  is  a  curved  ridge,  the  temporal  ridge,  for  the  attachment  of  the  temporal 
fascia.  Above  this  ridge,  the  surface  of  the  bone  is  rough  and  porous,  and  covered 
by  the  aponeurosis  of  the  Occipito-frontalis.;  below  it  the  bone  is  smooth,  forms 
part  of  the  temporal  fossa,  and  affords  attachment  to  the  Temporal  muscle.  At 
the  back  part  of  the  superior  border,  close  to  the  sagittal  suture,  is  a  small 
foramen,  the  parietal  foramen,  which  transmits  a  vein  to  the  superior  longitudinal 
sinus.     Its  existence  is  not  constant,  and  its  size  varies  considerably. 

The  internal  surface  (fig.  26),  concave,  presents  eminences  and  depressions  for 
lodging  the  convolutions  of  the  cerebrum,  and  numerous  furrows  for  the  ramifica- 
tions of  the  meningeal  arteries ;  the  latter  run  upwards  and  backwards  from  the 

1  BGclard  considers  this  segment  to  have  four  centres  of  ossification,  arranged  in  pairs,  two 
above,  and  two  below  the  curved  lines,  and  Meckel  describes  eight,  four  of  which  correspond  in 
situation  with  those  above  described :  of  the  other  four,  two  are  placed  in  juxta-position,  at  the 
upper  angle  of  the  bone,  and  the  remaining  two,  one  at  each  side,  in  the  lateral  angles. 


62 


OSTEOLOGY. 


anterior  inferior  angle,  and  from  the  central  and  posterior  part  of  the  lower 
border  of  the  bone.  Along  the  upper  margin  is  part  of  a  shallow  groove,  which, 
when  joined  to  the  opposite  parietal,  forms  a  channel  for  the  superior  longitudinal 
sinus,  the  elevated  edges  of  which  afford  attachment  to  the  falx  cerebri.  Near 
the  groove  are  seen  several  depressions;  they  lodge  the  Pacchionian  bodies. 
The  internal  opening  of  the  parietal  foramen  is  also  seen  when  that  aperture 
exists. 

Fig.  25. — Left  Parietal  Bone  :  External  Surface. 
•    ..T(tt,cs        <wilh         ot,„„ 


Borders.  The  superior,  the  longest  and  thickest,  is  dentated  to  articulate  with 
its  fellow  of  the  opposite  side,  forming  the  sagittal  suture.  The  inferior  is 
divided  into  three  parts;  of  these,  the  anterior  is  thin  and  pointed,  bevelled  at  the 
expense  of  the  outer  surface,  and  overlapped  by  the  tip  of  the  great  wing  of  the 
sphenoid;  the  middle  portion  is  arched,  bevelled  at  the  expense  of  the  outer 
surface,  and  overlapped  by  the  squamous  portion  of  the  temporal ;  the  posterior 
portion  being  thick  and  serrated  for  articulation  with  the  mastoid  portion  of  the 
temporal.  The  anterior  border,  deeply  serrated,  is  bevelled  at  the  expense  of  the 
outer  surface  above,  and  of  the  inner  below ;  it  articulates  with  the  frontal  bone, 
forming  the  coronal  suture.  The  posterior  border,  deeply  denticulated,  articulates 
with  the  occipital,  forming  the  lambdoid  suture. 

Angles.  The  anterior  superior,  thin  and  pointed,  corresponds  with  that  portion 
of  the  skull  which  in  the  foetus  is  membranous,  and  is  called  the  anterior  fon- 
tanels. The  anterior  inferior  angle  is  thin  and  lengthened,  being  received  in  the 
interval  between  the  great  wing  of  the  sphenoid  and  the  frontal.  Its  inner 
surface  is  marked  by  a  deep  groove,  sometimes  a  canal,  for  the  anterior  branch  of 
the  middle  meningeal  artery.  The  posterior  superior  angle  corresponds  with  the 
junction  of  the  sagittal  and  lambdoid  sutures.  In  the  foetus  this  part  of  the  skull 
is  membranous,  and    is    called  the  posterior  fontanelle.     The  ptosterior   inferior 


PARIETAL   BONE 


63 


angle  articulates  with  the  mastoid  portion  of  the  temporal  bone,  and  generally 
presents  on  its  inner  surface  a  broad  shallow  groove  for  lodging  part  of  the  lateral 
sinus. 

Development.  The  parietal  bone  is  formed  in  membrane,  being  developed  by- 
owe  centre,  which  corresponds  with  the  parietal  eminence,  and  makes  its  first 
appearance  about  the  fifth  or  sixth  week  of  foetal  life.     Ossification  gradually 

Fig.  26. — Left  Parietal  Bone  :  Internal  Surface. 


J     Amjle 


Toitl.IiiJiir.Aui 


Ant.  Infer.  Avqle 


extends  from  the  centre  to  the  circumference  of  the  bone,  the  angles  are  conse- 
quently the  parts  last  formed,  and  it  is  in  their  situation,  that  the  fontanelles  exist, 
previous  to  the  completion  of  the  growth  of  the  bone. 

Articulations.  With  five  bones;  the  opposite  parietal,  the  occipital,  frontal, 
temporal,  and  sphenoid. 

Attachment  of  Muscles.  To  one  only,  the  Temporal. 

The  Frontal  Bone. 

This  bone,  which  resembles  a  cockle-shell  in  form,  consists  of  two  portions — . 
a  vertical  or  frontal  portion,  situated  at  the  anterior  part  of  the  cranium,  forming 
the  forehead ;  and  a  horizontal  or  orbito-nasal  portion,  which  enters  into  the  forma- 
tion of  the  roof  of  the  orbits  and  nose. 

Vertical  Portion.  External  Surface  (fig.  27).  In  the  median  line,  traversing 
the  bone  from  the  upper  to  its  lower  part,  is  occasionally  seen  a  slightly  elevated 
ridge,  and  in  young  subjects  a  suture,  which  represents  the  point  of  union  of  the 
two  lateral  halves  of  which  the  bone  consists  at  an  early  period  of  life ;  in  the 
adult,  this  suture  usually  disappears,  excepting  below.  On  either  side  of  this 
ridge,  a  little  below  the  centre  of  the  bone,  is  a  rounded  eminence,  the  frontal 
eminence.  These  eminences  vary  in  size  in  different  individuals,  and  are  occa- 
sionally unsymmetrical  in  the  same  subject.     They  are  especially  prominent  iix 


64 


OSTEOLOGY. 


cases  of  well-marked  cerebral  development.  The  whole  surface  of  the  bone  above 
this  part  is  smooth,  and  covered  by  the  aponeurosis  of  the  Occipito-frontalis 
muscle.  Below  the  frontal  eminence,  and  separated  from  it  by  a  slight  groove,  is 
the  superciliary  ridge,  broad  internally  where  it  is  continuous  with  the  nasal 
eminence,  but  less  distinct  as  it  arches  outwards.  These  ridges  are  caused  by  the 
projection  outwards  of  the  frontal  sinuses.  Beneath  the  superciliary  ridge  is  the 
supra-orbital  arch,  a  curved  and  prominent  margin,  which  forms  the  upper 
boundary  of  the  orbit,  and  separates  the  vertical  from  the  horizontal  portion  of 
the  bone.  The  outer  part  of  the  arch  is  sharp  and  prominent,  affording  to  the 
eye,  in  that  situation,  considerable  protection  from  injury ;  the  inner  part  is  less 
prominent.     At  the  inner  third  of  this  arch  is  a  notch,  sometimes  converted  into 


Fig.  27. — Frontal  Bone  :  Outer  Surface. 


Exlernal 
Angular  hrot. 


Natal 


a  foramen  by  a  bony  process  or  ligament,  and  called  the  supra-orbital  notch  or 
foramen.  It  transmits  the  supra-orbital  artery,  veins,  and  nerve.  A  small 
aperture  is  seen  in  the  upper  part  of  the  notch,  which  transmits  a  vein  from  the 
diploe  to  join  the  ophthalmic  vein.  The  supra-orbital  arch  terminates  externally 
in  the  external  angular  process,  and  internally  in  the  interal  angular  process. 
The  external  angular  process  is  strong,  prominent,  and  articulates  with  the  malar 
bone :  running  upwards  and  backwards  from  it  is  a  sharp  curved  crest,  the  tem- 
poral ridge,  for  the  attachment  of  the  temporal  fascia;  and  beneath  it  a  slight 
concavity,  that  forms  the  anterior  part  of  the  temporal  fossa,  and  gives  origin  to 
the  Temporal  muscle.  The  internal  angular  processes  are  less  marked  than  the 
external,  and  articulate  with  the  lachrymal  bones.  Between  the  two  is  a  rough, 
uneven  interval,  the  nasal  notch,  which  articulates  in  the  middle  line  with  the 
nasal,  and  on  either  side  with  the  nasal  process  of  the  superior  maxillary  bone. 
The  notch  is  continuous  below,  with  a  long  pointed  process,  the  nasal  spine. 


FRONTAL   BONE. 


G5 


Vertical  Portion.  Internal  Surface  (fig.  28).  Along  the  middle  line  is  a  vertical 
groove,  the  edges  of  which  unite  below  to  form  a  ridge,  the  frontal  crest ;  the 
groove  lodges  the  superior  longitudinal  sinus,  whilst  its  edges  afford  attachment 
to  the  falx  cerebri.  The  crest  terminates  below  at  a  small  opening,  the  foramen 
csecum,  which  is  generally  completed  behind  the  ethmoid.  This  foramen  varies 
in  size  in  different  subjects,  is  usually  partially,  or  completely,  impervious,  lodges 
a  process  of  the  falx  cerebri,  and,  when  open,  transmits  a  vein  from  the  lining 
membrane  of  the  nose  to  the  superior  longitudinal  sinus.  On  either  side  of  the 
groove,  the  bone  is  deeply  concave,  presenting  eminences  and  depressions  for  the 
convolutions  of  the  brain,  and  numerous  small  furrows  for  lodging  the  ramifica- 
tions of  the  anterior  meningeal  arteries.  Several  small,  irregular  fossae  are  also 
seen  on  either  side  of  the  groove,  for  the  reception  of  the  Pacchionian  bodies. 


Fig.  28. — Frontal  Bone.     Inner  Surface. 


1 


with  Sup.  Max 

with  Na 


with  PcrpeniLeular  ylatc  cf  Ethmoid 


Frontal    j&'inus 

Earpa  ndtd  base   of  JVhural  Spnie, 
Jnrnuriij  part  <>f  Roirf  ef   /yose 


Horizontal  Portion;  external  Surface.  This  portion  of  the  bone  consists  of 
two  thin  plates,  which  form  the  vault  of  the  orbits,  separated  from  one  another  by 
the  ethmoidal  notch.  Each  orbital  vault  consists  of  a  smooth,  concave,  triangular 
plate  of  bone,  marked  at  its  anterior  and  external  part,  immediately  beneath  the 
external  angular  process,  by  a  shallow  depression,  the  lachrymal  fossa,  for  lodging 
the  lachrymal  gland;  and  at  its  anterior  and  internal  part,  by  a  depression,  some- 
times a  small  tubercle,  for  the  attachment  of  the  fibrous  pulley  of  the  Superior 
oblique  muscle.  The  ethmoidal  notch  separates  the  two  orbital  plates:  it  is 
quadrilateral,  and  filled  up,  when  the  bones  are  united,  by  the  cribriform  plate  of 
the  ethmoid.  The  margins  of  this  notch  present  several  half-cells,  which,  when 
united  with  corresponding  half-cells  on  the  upper  surface  of  the  ethmoid,  complete 
the  ethmoidal  cells :  two  grooves  are  also  seen  crossing  these  edges  transversely ; 
5 


66 


OSTEOLOGY. 


they  are  converted  into  canals  by  articulation  with  the  ethmoid,  and  are  called 
the  anterior  and  posterior  ethmoidal  canals;  they  open  on  the  inner  wall  of  the 
orbit.  The  anterior  one  transmits  the  nasal  nerve  and  anterior  ethmoidal  vessels; 
the  posterior  one,  the  posterior  ethmoidal  vessels.  In  front  of  the  ethmoidal 
notch  is  the  nasal  spine,  a  sharp-pointed  eminence  which  projects  downwards  and 
forwards,  and  articulates  in  front  with  the  crest  of  the  nasal  bones ;  behind,  it  is 
marked  by  two  grooves,  separated  by  a  vertical  ridge :  the  ridge  articulates  with 
the  perpendicular  lamella  of  the  ethmoid,  the  grooves  form  part  of  the  roof  of  the 
nasal  fossa?.  On  either  side  of  the  base  of  the  nasal  spine  are  the  openings  of  the 
frontal  sinuses.  These  are  two  irregular  cavities,  which  extend  upwards  and 
outwards,  a  variable  distance,  between  the  two  tables  of  the  skull,  and  are  separated 
from  one  another  by  a  thin  bony  septum.  They  give  rise  to  the  prominences 
above  the  root  of  the  nose,  called  the  nasal  eminences  and  superciliary  ridges.  In 
the  child  they  are  generally  absent,  and  they  become  gradually  developed  as  age 
advances.  These  cavities  vary  in  size  in  different  persons,  are  larger  in  men  than 
in  women,  and  are  frequently  of  unequal  size  on  the  two  sides,  the  left  being 
commonly  the  larger.  Occasionally  they  are  subdivided  by  incomplete  bony 
laminae.  They  are  lined  by  mucous  membrane ;  and  communicate  with  the  nose 
by  the  infundibulum,  and  occasionally  with  each  other  by  apertures  in  the  septum. 
The  Internal  Surface  of  the  horizontal  portion  presents  the  convex  upper 
surfaces  of  the  orbital  plates,  separated  from  each  other  in  the  middle  line  by  the 
ethmoidal  notch,  and  marked  by  eminences,  and  depressions  for  the  convolutions 
of  the  anterior  lobes  of  the  brain. 

Borders.  The  border  of  the  vertical  portion  is  thick,  strongly  serrated,  bevelled 
at  the  expense  of  the  internal  table  above,  where  it  rests  upon  the  parietal,  at  the 
expense  of  the  external  table  at  each  side,  where  it  receives  the  lateral  pressure  of 
those  bones:  this  border  is  continued  below,  into  a  triangular  rough  surface,  which 
articulates  with  the  great  wing  of  the  sphenoid.  The  border  of  the  horizontal 
portion  is  thin,  serrated,  and  articulates  with  the  lesser  wing  of  the  sphenoid. 

Structure.  The  vertical  portion,  and  external  angular  processes,  are  very  thick, 
consisting  of  diploic  tissue  contained  between  two  compact  laminae.  The  hori- 
zontal portion  is  thin,  translucent,  and  composed  entirely  of  compact  tissue ;  hence 
the  facility  with  which  instruments  can  penetrate  the  cranium  through  this  part 
of  the  orbit. 

Development   (fig.    29).      The   frontal   bone   is   formed   in   membrane,   being 

developed  by  tico  centres,  one  for  each 
lateral  half,  which  make  their  appearance, 
at  an  early  period  of  foetal  life,  in  the  situ- 
ation of  the  orbital  arches.  From  this 
point,  ossification  extends,  in  a  radiating 
manner,  upwards  into  the  forehead,  and 
backwards  over  the  orbit.  At  birth,  it 
consists  of  two  pieces,  which  afterwards 
become  united  along  the  middle  line,  by 
a  suture  which  runs  from  the  vertex  to 
the  root  of  the  nose.  This  suture  be- 
comes obliterated  within  a  few  years  after 
birth ;  but  it  occasionally  remains  through- 
out life. 

Articulations.    With  twelve  bones :  two 
parietal,    sphenoid,    ethmoid,    two    nasal, 
two  superior  maxillary,  two  lachrymal,  and  two  malar. 

Attachment  of  Muscles.  To  three  pairs:  the  Corrugator  supercilii,  Orbicularis 
palpebrarum,  and  Temporal. 


Fig.  29.— Frontal  Bone  at  Birth. 
Developed  by  two  lateral  Halves. 


TEMPORAL   BONE. 


GT 


The  Temporal  Bones. 

The  Temporal  Bones  are  so  called  because  they  occupy  that  part  of  the  head 
on  which  the  hair  first  begins  to  turn  gray,  thus  indicating  the  age.  They  are 
situated  at  the  side  and  base  of  the  skull,  and  present  for  examination  a  squamous, 
mastoid,  and  petrous  portion. 

The  Squamous  Portion  {squama,  a  scale),  the  most  anterior  and  superior  part  of 
the  bone  (fig.  30),  is  scale-like  in  form,  thin  and  translucent  in  texture.  Its  outer 
surface  is  smooth,  convex,  and  grooved  at  its  back  part  for  the  deep  temporal 
arteries ;  it  affords  attachment  to  the  Temporal  muscle,  and  forms  part  of  the 
temporal  fossa.  At  its  back  part  may  be  seen  a  curved  ridge,  part  of  the  tem- 
poral ridge ;  it  serves  for  the  attachment  of  the  temporal  fascia,  limits  the  origin 
of  the  Temporal  muscle,  and  marks  the  boundary  between  the  squamous  and 
mastoid  portions  of  the  bone.     Projecting  from  the  lower  part  of  the  squamous 

Fig.  30. — Left  Temporal  Bone.     Outer  Surface. 


teiZfot 


portion  is  a  long  arched  outgrowth  of  bone,  the  zygomatic  process.  It  is  at  first 
directed  outwards,  its  two  surfaces  looking  upwards  and  downwards ;  it  then  appears 
as  if  twisted  upon  itself,  and  takes  a  direction  forwards,  its  surfaces  now  looking 
inwards  and  outwards.  The  superior  border  of  this  process  is  long,  thin,  and 
sharp,  and  serves  for  the  attachment  of  the  temporal  fascia.  The  inferior,  short, 
thick,  and  arched,  has  attached  to  it  some  fibres  of  the  Masseter  muscle.  Its  outer 
surface  is  convex  and  subcutaneous ;  its  inner  is  concave,  and  also  affords  attachment 
to  the  Masseter.  The  extremity,  broad,  and  deeply  serrated,  articulates  with  the 
malar  bone.  This  process  is  connected  to  the  temporal  bone  by  three  divisions, 
called  the  roots  of  the  zygomatic  process,  an  anterior,  middle,  and  posterior.  The 
anterior,  which  is  short,  but  broad  and  strong,  runs  transversely  inwards  into  a 
rounded  eminence,  the  eminentia  articularis.  This  eminence  forms  the  front 
boundary  of  the  glenoid  fossa,  and  in  the  recent  state  is  covered  with  cartilage. 
The  middle  root  forms  the  outer  margin  of  the  glenoid  cavity ;  running  obliquely 


68 


OSTEOLOGY. 


inwards  it  terminates  at  the  commencement  of  a  well-marked  fissure,  the  Glaserian 
fissure ;  whilst  the  posterior  root,  which  is  strongly  marked,  runs  from  the  upper 
border  of  the  zygoma,  in  an  arched  direction,  upwards  and  backwards,  forming  the 
posterior  part  of  the  temporal  ridge.  At  the  junction  of  the  anterior  root  with 
the  zygoma  is  a  projection,  called  the  tubercle,  for  the  attachment  of  the  external 
lateral  ligament  of  the  lower  jaw ;  and  between  the  anterior  and  middle  roots  is 
an  oval  depression,  forming  part  of  the  glenoid  fossa  (y*.^,  a  shallow  pit),  for  the 
reception  of  the  condyle  of  the  lower  jaw.  This  fossa  is  bounded,  in  front,  by  the 
eminentia  articularis ;  behind,  by  the  vaginal  process ;  and,  externally,  by  the 
auditory  process,  and  middle  root  of  the  zygoma ;  and  is  divided  into  two  parts 
by  a  narrow  slit,  the  Glaserian  fissure :  the  anterior  part,  formed  by  the  squamous 
portion  of  the  bone,  is  smooth,  and  covered  in  the  recent  state  with  cartilage,  and 
articulates  with  the  condyle  of  the  lower  jaw.  This  part  of  the  glenoid  fossa  is 
separated  from  the  auditory  process,  by  a  small  tubercle,  the  post- glenoid  process, 

Fig.  31. — Left  Temporal  Bone.     Inner  Surface. 
■parietal 


Aqticduetux   Veshhuli. 

jDepTCXsivii   far  DuTCr-vuitrr 

Meatus  Atiduonas  i  ttternus 


"'Ln^ejor  Superior  Brnfimrmfar  Ca,n*l 
•  Jliatus   FaLlopii 

Opcmnyfor  Smaller  Petrosal  Mrt-c 
Dcnrfsuan  for  Cassertan  gaiujhcm 
BriUlf  passed  thrcuyh  Carotid  Ctuud 


the  representative  of  a  prominent  tubercle  which,  in  some  of  the  mammalia, 
descends  behind  the  condyle  of  the  jaw,  and  prevents  it  being  displaced  backwards 
during  mastication  (Humphry).  The  posterior  part  of  the  glenoid  fossa  is  formed 
chiefly  by  the  vaginal  process  of  the  petrous  portion,  and  lodges  part  of  the  parotid 
gland.  The  Glaserian  fissure,  which  leads  into  the  tympanum,  lodges  the  pro- 
cessus gracilis  of  the  malleus,  and  transmits  the  Laxator  tympani  muscle  and  the 
anterior  tympanic  artery.  The  chorda  tympani  nerve  passes  through  a  separate 
canal  parallel  to  the  Glaserian  fissure  (canal  of  Huguier),  on  the  outer  side  of  the 
Eustachian  tube,  in  the  retiring  angle  between  the  squamous  and  petrous  portions 
of  the  temporal  bone. 

The  internal  surface  of  the  squamous  portion  (fig.  31)  is  concave,  presents 
numerous  eminences  and  depressions  for  the  convolutions  of  the  cerebrum,  and 
two  well-marked  grooves  for  branches  of  the  middle  meningeal  artery. 

Borders.  The  superior  border  is  thin,  bevelled  at  the  expense  of  the  internal 
surface,  so  as  to  overlap  the  lower  border  of  the  parietal  bone,  forming  the 


TEMPORAL   BONE.  09 

squamous  suture.  The  anterior  inferior  border  is  thick,  serrated,  and  hovelled 
alternately  at  the  expense  of  the  inner  and  outer  surfaces,  for  articulation  with 
the  great  wing  of  the  sphenoid. 

The  Mastoid  Portion  (paatos,  a  nipple  or  teat)  is  situated  at  the  posterior  part  of 
the  bone ;  its  outer  surface  is  rough,  and  perforated  by  numerous  foramina.  One 
of  these,  of  large  size,  situated  at  the  posterior  border  of  the  bone,  is  termed  the 
mastoid  foramen;  it  transmits  a  vein  to  the  lateral  sinus  and  a  small  artery. 
The  position  and  size  of  this  foramen  arc  very  variable,  being  sometimes  situated 
in  the  occipital  bone,  or  in  the  suture  between  the  temporal  and  the  occipital. 
The  mastoid  portion  is  continued  below  into  a  conical  projection,  the  mastoid  pro- 
cess, the  size  and  form  of  which  vary  somewhat  in  different  individuals.  This 
process  serves  for  the  attachment  of  the  Sterno-mastoid,  Splenius  capitis,  and 
Trachelo-mastoid  muscles.  On  the  inner  side  of  the  mastoid  process  is  a  deep 
groove,  the  digastric  fossa,  for  the  attachment  of  the  Digastric  nmscle;  and  running 
parallel  with  it,  but  more  internal,  the  occipital  groove,  which  lodges  the  occipital 
artery.  The  internal  surface  of  the  mastoid  portion  presents  a  deeply  curved 
groove,  which  lodges  part  of  the  lateral  sinus ;  and  into  it  may  be  seen  opening 
the  mastoid  foramen.  A  section  of  the  mastoid  process  shows  it  to  be  hollowed 
out  into  a  number  of  cellular  spaces,  communicating  with  each  other,  called  the 
mastoid  cells  ;  they  open  by  a  single  or  double  orifice  into  the  back  of  the  tym- 
panum ;  are  lined  by  a  prolongation  of  its  lining  membrane ;  and,  probably,  form 
some  secondary  part  of  the  organ  of  hearing.  The  mastoid  cells,  like  the  other 
sinuses  of  the  cranium,  are  not  developed  until  after  puberty ;  hence  the  promi- 
nence of  this  process  in  the  adult. 

Borders.  The  superior  border  of  the  mastoid  portion  is  broad  and  rough,  its 
serrated  edge  sloping  outwards,  for  articulation  with  the  posterior  inferior  angle 
of  the  parietal  bone.  The  posterior  border,  also  uneven  and  serrated,  articulates 
with  the  inferior  border  of  the  occipital  bone  between  its  lateral  angle  and  jugular 
process. 

The  Petrous  Portion  («irpo?,  a  rock),  so  named  from  its  extreme  density  and 
hardness,  is  a  pyramidal  process  of  bone,  wedged  in  at  the  base  of  the  skull  between 
the  sphenoid  and  occipital  bones.  Its  direction  from  without  is  forwards,  inwards, 
and  a  little  downwards.  It  presents  for  examination  a  base,  an  apex,  three  sur- 
faces, and  three  borders ;  and  contains,  in  its  interior,  the  essential  parts  of  the 
organ  of  hearing.  The  base  is  applied  against  the  internal  surface  of  the  squamous 
and  mastoid  portions,  its  upper  half  being  concealed ;  but  its  lower  half  is  exposed 
by  their  divergence,  which  brings  into  view  the  oval  expanded  orifice  of  a  canal 
leading  into  the  tympanum,  the  meatus  auditorius  externus.  This  canal  is  situated 
between  the  mastoid  process  and  the  posterior  and  middle  roots  of  the  zygoma ; 
its  upper  margin  is  smooth  and  rounded,  but  the  greater  part  of  its  circumference 
is  surrounded  by  a  curved  plate  of  bone,  the  auditory  process,  the  free  margin  of 
which  is  thick  and  rough  for  the  attachment  of  the  cartilage  of  the  external  ear. 

The  apex  of  the  petrous  portion,  rough  and  uneven,  is  received  into  the  angular 
interval  between  the  spinous  process  of  the  sphenoid,  and  the  basilar  process  of 
the  occipital;  it  presents  the  anterior  orifice  of  the  carotid  canal,  and  forms  the 
posterior  and  external  boundary  of  the  foramen  lacerum  medium. 

The  anterior  surface  of  the  petrous  portion  (fig.  31)  forms  the  posterior 
boundary  of  the  middle  fossa  of  the  skull.  This  surface  is  continuous  with  the 
squamous  portion,  to  which  it  is  united  by  a  suture,  the  temporal  Suture,  the 
remains  of  which  are  distinct  at  a  late  period  of  life.  This  surface  presents  six 
points  for  examination.  1.  An  eminence  near  the  centre  which  indicates  the 
situation  of  the  superior  semicircular  canal.  2.  On  the  outer  side  of  this  eminence 
is  a  depression,  indicating  the  position  of  the  tympanum,  the  layer  of  bone  which 
separates  the  tympanum  from  the  cranial  cavity  being  extremely  thin.  3.  A 
shallow  groove,  sometimes  double,  leading  backwards  to  an  oblique  opening,  the 
hiatus  Fallopii,  for  the  passage  of  the  petrosal  branch  of  the  Vidian  nerve.  4. 
A  smaller  opening,  occasionally  seen  external  to  the  latter  for  the  passage  of  the 


10 


OSTEOLOGY. 


smaller  petrosal  nerve.  5.  Near  the  apex  of  the  bone  is  seen  the  termination  of 
the  carotid  canal,  the  wall  of  which  in  this  situation  is  deficient  in  front.  6.  Above 
this  canal  is  a  shallow  depression  for  the  reception  of  the  Casserian  ganglion. 

The  posterior  surface  forms  the  front  boundary  of  the  posterior  fossa  of  the 
skull,  and  is  continuous  with  the  inner  surface  of  the  mastoid  portion  of  the  bone. 
It  presents  three  points  for  examination.  1.  About  its  centre  is  a  large  orifice, 
the  meatus  auditorius  internus.  This  aperture  varies  considerably  in  size ;  its 
margins  are  smooth  and  rounded;  and  it  leads  into  a  short  canal,  about  four  lines 
in  length,  which  runs  directly  outwards.  The  end  of  the  canal  is  closed  by  a 
vertical  plate,  divided  by  a  horizontal  crest  into  two  unequal  portions.  It  trans- 
mits the  auditory  and  facial  nerves,  and  auditory  artery.  2.  Behind  the  meatus 
auditorius  is  a  small  slit,  almost  hidden  by  a  thin  plate  of  bone,  leading  to  a 
canal,  the  aquoeductus  vestibuli ;  it  transmits  a  small  artery  and  vein,  and  lodges 
a  process  of  the  dura  mater.     3.  In  the  interval  between  these  two  openings,  but 

Fig.  32. — Petrous  Portion.     Inferior  Surface. 


fon&MluiUufimn  tab* 
and  Te^ar^mpani^,^^ 

Levator    palati 


Rough  Quadrilateral, Su-rfa+e 
°J»™y  of  carrtd  camd 
Canal/or  Jaeohon,  nerve 
^uMacrus  Corhleic 
Canal far  Arnold'*  nerve- 
Jugular  fossa 
Vagcnal  _prace<K 
Styloid  praeess- 
Stylo- mastoid  foramen 
Jugular  Surface 
Auricular  fissure 


STYLO-PHARYNGEOS 


above  them,  is  an  angular  depression  which  lodges  a  process  of  the  dura  mater, 
and  transmits  a  small  vein  into  the  cancellous  tissue  of  the  bone. 

The  inferior  or  basilar  surface  (fig.  32)  is  rough  and  irregular,  and  forms  part 
of  the  base  of  the  skull.  Passing  from  the  apex  to  the  base,  this  surface  presents 
eleven  points  for  examination.  1.  A  rough  surface,  quadrilateral  in  form,  which 
serves  partly  for  the  attachment  of  the  Levator  palati,  and  Tensor  tympani  muscles. 
2.  The  opening  of  the  carotid  canal,  a  large  circular  aperture,  which  ascends  at 
first  vertically  upwards,  and  then,  making  a  bend,  runs  horizontally  forwards  and 
inwards.  It  transmits  the  internal  carotid  artery,  and  the  carotid  plexus.  3.  The 
aquseductus  cochleae,  a  small  triangular  opening,  lying  on  the  inner  side  of  the 
latter,  close  to  the  posterior  border  of  the  petrous  portion ;  it  transmits  a  vein  from 
the  cochlea,  which  joins  the  internal  jugular.  4.  Behind  these  openings  is  a  deep 
depression,  the  jugular  fossa,  which  varies  in  depth  and  size  in  different  skulls;  it 


TEMPORAL   BONE. 


U 


lodges  the  internal  jugular  vein,  and,  with  a  similar  depression  on  the  margin  of 
the  occipital  bone,  forms  the  foramen  lacerum  posterius.  5.  A  small  foramen  for 
the  passage  of  Jacobson's  nerve  (the  tympanic  branch  of  the  glossopharyngeal). 
This  is  seen  in  front  of  the  bony  ridge  dividing  the  carotid  canal  from  the  jugular 
fossa.  6.  A  small  foramen  seen  on  the  inner  wall  of  the  jugular  fossa,  for  the 
entrance  of  the  auricular  branch  of  the  pncumogastric  (Arnold's)  nerve.  7.  Behind 
the  jugular  fossa  is  a  smooth  square-shaped  facet,  the  jugular  surface ;  it  is  covered 
with  cartilage  in  the  recent  state,  and  articulates  with  the  jugular  process  of  the 
occipital  bone.  8.  The  vaginal  process,  a  very  broad  sheath-like  plate  of  bone, 
which  extends  from  the  carotid  canal  to  the  mastoid  process ;  it  divides  behind 
into  two  laminae,  receiving  between  them  the  9th  point  for  examination,  the  styloid 
process ;  a  long  sharp  spine,  about  an  inch  in  length,  continuous  with  the  vaginal 
process,  between  the  laminae  of  which  it  is  received,  and  directed  downwards, 
forwards,  and  inwards.  It  varies  in  size  and  shape ;  and  sometimes  consists  of 
several  pieces  united  by  cartilage.  It  affords  attachment  to  three  muscles,  the 
Stylo-pharyngeus,  Stylo-glossus,  and  Stylo-hyoideus ;  and  two  ligaments,  the  stylo- 
hyoid, and  stylo-maxillary.  10.  The  stylo-mastoid  foramen,  a  rather  large  orifice, 
placed  between  the  styloid  and  mastoid  processes ;  it  is  the  termination  of  the 
aquaeductus  Fallopii,  and  transmits  the  facial  nerve,  and  stylo-mastoid  artery. 
11.  The  auricular  fissure,  situated  between  the  vaginal  and  mastoid  processes,  for 
the  exit  of  the  auricular  branch  of  the  pneumogastric  nerve. 

Borders.  The  superior,  the  longest,  is  grooved  for  the  superior  petrosal  sinus, 
and  has  attached  to  it  the  tentorium  cerebelli :  at  its  inner  extremity  is  a  semilunar 
notch,  upon  which  reclines  the  fifth  nerve.  The  posterior  border  is  intermediate 
in  length  between  the  superior  and  the  anterior.  Its  inner  half  is  marked  by  a 
groove,  which,  when  completed  by  its  articulation  with  the  occipital,  forms  the 
channel  for  the  inferior  petrosal  sinus.  Its  outer  half  presents  a  deep  excavation, 
the  jugular  fossa,  which,  with  a  similar  notch  on  the  occipital,  forms  the  foramen 
lacerum  posterius.  A  projecting  eminence  of  bone  occasionally  stands  out  from 
the  centre  of  the  notch,  and  divides  the  foramen  into  two  parts.  The  anterior 
border  is  divided  into  two  parts,  an  outer,  joined  to  the  squamous  portion  by  a 
suture,  the  remains  of  which  are  distinct ;  an  inner,  free,  articulating  with  the 
spinous  process  of  the  sphenoid.  At  the  angle  of  junction  of  these  two  parts,  are 
seen  two  canals,  separated  from  one  another  by  a  thin  plate  of  bone,  the  processus 
cochleariformis ;  they  both  lead  into  the  tympanum,  the  upper  one  transmitting 
the  Tensor  tympani  muscle,  the  lower 
one  the  Eustachian  tube.  ^h 

Structure.  The  squamous  portion  is 
like  that  of  the  other  cranial  bones, 
the  mastoid  portion  cellular,  and  the 
petrous  portion  dense  and  hard. 

Development  (fig.  33).  The  tempo- 
ral bone  is  developed  by  four  centres, 
exclusive  of  those  for  the  internal  ear 
and  the  ossicula,  viz.: — one  for  the 
squamous  portion  including  the  zygo- 
ma, one  for  the  petrous  and  mastoid 
parts,  one  for  the  styloid,  and  one  for 
the  auditory  process  (tympanic  bone). 
The  first  traces  of  the  development  of 
this  bone  appear  in  the  squamous  por- 
tion, about  the  time  when  osseous 
matter  is  deposited  in  the  vertebne ; 
the  auditory  process  succeeds  next; 
it  consists  of  an  elliptical  portion  of 
bone,  forming  about  three-fourths  of 
a  circle,  the  deficiency  being  above;  it       *f°*  StyU&pm*. 


33. — Development  of  Temporal  Bone. 
By  four  Centres. 


1  for  Squamous 
portum  induaiiiM ■'  r^i. 
Zuqomai. 
g&  mo. 


I  fjr  Audctoru 

jirottsa 


for  Petrous 
8r  Xo,stijid 
portions 


72 


OSTEOLOGY. 


is  grooved  along  its  concave  surface  for  the  attachment  of  the  membrana  tympani, 
and  becomes  united  by  its  extremities  to  the  squamous  portion  during  the  last 
months  of  intrauterine  life.  The  petrous  and  mastoid  portions  then  become 
ossified,  and^  lastly  the  styloid  process,  which  remains  separate  a  considerable 
period,  and  is  occasionally  never  united  to  the  rest  of  the  bone.  At  birth,  the 
temporal  bone,  excluding  the  styloid  process,  is  formed  of  three  pieces,  the 
squamous  and  zygomatic,  the  petrous  and  mastoid,  and  the  auditory.  The 
auditory  process  joins  with  the  squamous  at  about  the  ninth  month.  The  petrous 
and  mastoid  join  with  the  squamous  during  the  first  year,  and  the  styloid  process 
becomes  united  between  the  second  and  third  years.  The  subsequent  changes  in  this 
bone  are  the  extension  outwards  of  the  auditory  process,  so  as  to  form  the  meatus 
auditorius ;  the  glenoid  fossa  becomes  deeper ;  and  the  mastoid  part,  which  at  an 
early  period  of  life  is  quite  flat,  enlarges  from  the  development  of  numerous 
cellular  cavities  in  its  interior. 

Articulations.  With  five  bones,  occipital,  parietal,  sphenoid,  inferior  maxillary 
and  malar. 

Attachment  of  Muscles.  To  the  squamous  portion,  the  Temporal;  to  the  z3rgoma, 
the  Masseter;  to  the  mastoid  portion,  the  Occipito-frontalis,  Sterno-mastoid, 
Splenius  capitis,  Trachelo-mastoid,  Digastricus  and  Eetrahens  aurem;  to  the 
styloid  process,  the  Stylo-pharyngeus,  Stylo-hyoideus  and  Stylo-gloss  us ;  and  to 
the  petrous  portion,  the  Levator  palati,  Tensor  tympani,  and  Stapedius. 


The  Sphenoid  Bone. 

The  Sphenoid  bone  (atyijv,  a  wedge;  ftSo?.  likeness)  is  situated  at  the  anterior  part 
of  the  base  of  the  skull,  articulating  with  all  the  other  cranial  bones,  which  it 
binds  firmly  and  solidly  together.  In  its  form  it  somewhat  resembles  a  bat,  with 
its  wings  extended ;  and  is  divided  into  a  central  portion  or  body,  two  greater 
and  two  lesser  wings  extending  outwards  on  each  side  of  the  body ;  and  two 
processes,  the  pterygoid  processes,  which  project  from  it  below. 

The  Body  is  of  large  size,  quadrilateral  in  form,  and  hollowed  out  in  its  interior 
so  as  to  form  a  mere  shell  of  bone.  It  presents  for  examination  four  surfaces — 
a  superior,  an  inferior,  an  anterior,  and  a  posterior. 

The  superior  surface  (fig.  34).  From  before,  backwards,  is  seen  a  prominent 
spine,  the  ethmoidal  spine,  for  articulation  with  the  ethmoid ;  behind  this  a  smooth 


Fig.  34. — Sphenoid  Bone.    Superior  Surface. 

maau  cu^a  pro***    mmddaI  s  M 


X-o<n£, 


Jlopcbwcn  Optieu 
Tovatiion  Zacrrwm 
Qnrcn'us.  or  Sjjtwrwi.-iairUiicrc 
J'uramtm  JtctotiJo.vi,-' 
„  Vtfoliii 

„  OuaJt, 


SPHENOID   BONE. 


73 


surface  presenting,  in  the  median  line,  a  slight  longitudinal  eminence,  with  a 
depression  on  each  side,  for  lodging  the  olfactory  nerves.  A  narrow  transverse 
groove,  the  optic  groove,  bounds  the  above-mentioned  surface  behind ;  it  lodges 
the  optic  commissure,  and  terminates  on  either  side  in  the  optic  foramen,  for  the 
passage  of  the  optic  nerve  and  ophthalmic  artery.  Behind  the  optic  groove  is  a 
small  eminence,  olive-like  in  shape,  the  olivary  process ;  and  still  more  posteriorly, 
a  deep  depression,  the  pituitary  fossa,  or  sella  Turcica,  which  lodges  the  pituitary 
body.  This  fossa  is  perforated  by  numerous  foramina,  for  the  transmission  of 
nutrient  vessels  to  the  substance  of  the  bone.  It  is  bounded  in  front  by  two  small 
eminences,  one  on  either  side,  called  the  middle  clinoid  processes  (xxlvr;,  a  bed), 
and  behind  by  a  square-shaped  plate  of  bone,  terminating  at  each  superior  angle 
in  a  tubercle,  the  posterior  clinoid  processes,  the  size  and  form  of  which  vary 
considerably  in  different  individuals.  These  processes  deepen  the  pituitary  fossa, 
and  serve  for  the  attachment  of  prolongations  from  the  tentorium.  The  sides  of 
the  plate  of  bone  supporting  the  posterior  clinoid  processes  are  notched,  for  the 
passage  of  the  sixth  pair  of  nerves ;  and  behind,  it  presents  a  shallow  depression, 
which  slopes  obliquely  backwards,  and  is  continuous  with  the  basilar  groove  of 
the  occipital  bone ;  it  supports  the  medulla  oblongata.  On  either  side  of  the  body 
is  a  broad  groove,  curved  somewhat  like  the  italic  letter/;  it  lodges  the  internal 
carotid  artery  and  the  cavernous  sinus,  and  is  called  the  cavernous  groove.     The 

Fig.  35. — Sphenoid  Bone.    Anterior  Surface. 


posterior  surface,  quadrilateral  in  form,  articulates  with  the  basilar  process  of  the 
occipital  bone.  During  childhood,  a  separation  between  these  bones  exists  by 
means  of  a  layer  of  cartilage ;  but  in  after-life  this  becomes  ossified,  ossification 
commencing  above,  and  extending  downward,  and  the  two  bones  are  then  im- 
movably connected  together.  The  anterior  surface  (fig.  35)  presents,  in  the 
middle  line,  a  vertical  lamella  of  bone,  which  articulates  in  front  with  the  per- 
pendicular plate  of  the  ethmoid,  forming  part  of  the  septum  of  the  nose.  On 
either  side  of  it  are  the  irregular  openings  leading  into  the  sphenoidal  sinuses. 
These  are  two  large  irregular  cavities,  hollowed  out  of  the  interior  of  the  body 
of  the  sphenoid  bone,  and  separated  from  one  another  by  a  more  or  less  complete 
perpendicular  bony  septum.  Their  form  and  size  vary  considerably;  they  are 
seldom  symmetrical,  and  are  often  partially  subdivided  by  irregular  osseous 
laminae.  Occasionally  they  extend  into  the  basilar  process  of  the  occipital  nearly 
as  far  as  the  foramen  magnum.  The  septum  is  seldom  quite  vertical,  commonly 
being  bent  to  one  or  the  other  side.     These  sinuses  do  not  exist  in  children ;  but 


U  OSTEOLOGY. 

they  increase  in  size  as  age  advances.  They  are  partially  closed,  in  front  and 
below,  by  two  thin  curved  plates  of  bone,  the  sphenoidal  turbinated  bones, 
leaving  a  round  opening  at  their  upper  parts,  by  which  they  communicate  with 
the  upper  and  back  part  of  the  nose,  and  occasionally  with  the  posterior  ethmoidal 
cells.  The  lateral  margins  of  this  surface  present  a  serrated  edge,  which  articu- 
lates with  the  os  planum  of  the  ethmoid,  completing  the  posterior  ethmoidal  cells ; 
the  lower  margin,  also  rough  and  serrated,  articulates  with  the  orbital  process  of 
the  palate  bone ;  and  the  upper  margin  with  the  orbital  plate  of  the  frontal  bone. 
The  inferior  surface  presents,  in  the  middle  line,  a  triangular  spine,  the  rostrum, 
which  is  continuous  with  the  vertical  plate  on  the  anterior  surface,  and  is  received 
into  a  deep  fissure  between  the  alas  of  the  vomer.  On  each  side  may  be  seen  a 
projecting  lamina  of  bone,  which  runs  horizontally  inwards  from  near  the  base  of 
the  pterygoid  process :  these  plates,  termed  the  vaginal  processes,  articulate  with 
the  edges  of  the  vomer.  Close  to  the  root  of  the  pterygoid  process  is  a  groove, 
formed  into  a  complete  canal  when  articulated  with  the  sphenoidal  process  of  the 
palate  bone ;  it  is  called  the  pterygo-palatine  canal,  and  transmits  the  pterygo- 
palatine vessels  and  pharyngeal  nerve. 

The  Greater  Wings  are  two  strong  processes  of  bone,  which  arise  at  the  sides 
of  the  body,  and  are  curved  in  a  direction  upwards,  outwards,  and  backwards ; 
being  prolonged  behind  into  a  sharp-pointed  extremity,  the  spinous  jwocess  of  the 
sphenoid.  Each  wing  presents  three  surfaces  and  a  circumference.  The  superior 
or  cerebral  surface  forms  part  of  the  middle  fossa  of  the  skull;  it  is  deeply 
concave,  and  presents  eminences  and  depressions  for  the  convolutions  of  the  brain. 
At  its  anterior  and  internal  part  is  seen  a  circular  aperture,  the  foramen 
rotundum,  for  the  transmission  of  the  second  division  of  the  fifth  nerve.  Behind 
and  external  to  this,  is  a  large  oval  foramen,  the  foramen  ovale,  for  the  transmission 
of  the  third  division  of  the  fifth,  the  small  meningeal  artery,  and  the  small  petrosal 
nerve.  At  the  inner  side  of  the  foramen  ovale,  a  small  aperture  may  occasionally 
be  seen  opposite  the  root  of  the  pterygoid  process;  it  is  the  foramen  Vesalii. 
transmitting  a  small  vein.  Lastly,  in  the  apex  of  the  spine  of  the  sphenoid  is  a 
short  canal,  sometimes  double,  the  foramen  spinosum ;  it  transmits  the  middle 
meningeal  artery.  The  external  surface  is  convex,  and  divided  by  a  transverse 
ridge,  the  pterygoid  ridge,  into  two  portions.  The  superior  or  larger,  convex 
from  above  downwards,  concave  from  before  backwards,  enters  into  the  formation 
of  the  temporal  fossa,  and  attaches  part  of  the  Temporal  muscle.  The  inferior 
portion,  smaller  in  size  and  concave,  enters  into  the  formation  of  the  zygomatic 
fossa,  and  affords  attachment  to  the  External  pterygoid  muscle.  It  presents,  at 
its  posterior  part,  a  sharp-pointed  eminence  of  bone,  the  spinous  process,  to  which 
are  connected  the  internal  lateral  ligament  of  the  lower  jaw,  and  the  Laxator 
tympani  muscle.  The  pterygoid  ridge,  dividing  the  temporal  and  zygomatic 
portions,  gives  attachment  to  part  of  the  External  pterygoid  muscle.  At  its  inner 
extremity  is  a  triangular  spine  of  bone,  which  serves  to  increase  the  extent  of 
origin  of  this  muscle.  The  anterior  or  orbital  surface,  smooth  and  quadrilateral 
in  form,  assists  in  forming  the  outer  wall  of  the  orbit.  It  is  bounded  above  by  a 
serrated  edge,  for  articulation  with  the  frontal  bone ;  below,  by  a  rounded  border, 
which  enters  into  the  formation  of  the  spheno-maxillary  fissure;  internally,  it 
enters  into  the  formation  of  the  sphenoidal  fissure ;  whilst  externally  it  presents  a 
serrated  margin,  for  articulation  with  the  malar  bone.  At  the  upper  part  of  the 
inner  border  is  a  notch,  for  the  transmission  of  a  branch  of  the  ophthalmic  artery ; 
and  at  its  lower  part  a  small  pointed  spine  of  bone,  which  serves  for  the  attachment 
of  part  of  the  lower  head  of  the  External  rectus  muscle.  One  or  two  small  foramina 
may  occasionally  be  seen,  for  the  passage  of  arteries;  they  are  called  the  external 
orbitar  foramina.  Circumference :  from  the  body  of  the  sphenoid  to  the  spine, 
commencing  from  behind,  the  outer  half  of  this  margin  is  serrated,  for  articula- 
tion with  the  petrous  portion  of  the  temporal  bone ;  whilst  the  inner  half  forms 
the  anterior  boundary  of  the  foramen  lacerum  medium,  and  presents  the  posterior 
aperture  of  the  Vidian  canal.     In  front  of  the  spine,  the  circumference  of  the 


SPHENOID   BONE 


75 


great  wing  presents  a  serrated  edge,  bevelled  at  the  expense  of  the  inner  table 
below,  and  of  the  external  above,  which  articulates  with  the  squamous  portion  of 
the  temporal  bone.  At  the  tip  of  the  great  wing  a  triangular  portion  is  seen, 
bevelled  at  the  expense  of  the  internal  surface,  for  articulation  with  the  anterior 
inferior  angle  of  the  parietal  bone.  Internal  to  this  is  a  broad  serrated  surface, 
for  articulation  with  the  frontal  bone :  this  surface  is  continuous  internally  with 
the  sharp  inner  edge  of  the  orbital  plate,  which  assists  in  the  formation  of  the 
sphenoidal  fissure. 

The  Lesser  Wings  (processes  of  Ingrassias)  are  two  thin  triangular  plates  of 
bone,  which  arise  from  the  upper  and  lateral  parts  of  the  body  of  the  sphenoid ; 
and,  projecting  transversely  outwards,  terminate  in  a  more  or  less  acute  point. 
The  superior  surface  of  each  is  smooth,  flat,  broader  internally  than  externally, 
and  supports  the  anterior  lobe  of  the  brain.  The  inferior  surface  forms  the  back 
part  of  the  roof  of  the  orbit,  and  the  upper  boundary  of  the  sphenoidal  fissure  or 
foramen  lacerum  anterius.  This  fissure  is  of  a  triangular  form,  and  leads  from 
the  cavity  of  the  cranium  into  the  orbit ;  it  is  bounded  internally  by  the  body  of 
the  sphenoid ;  above,  by  the  lesser  wing ;  below,  by  the  orbital  surface  of  the 
greater  wing ;  and  is  converted  into  a  foramen  by  the  articulation  of  this  bone 
with  the  frontal.  It  transmits  the  third,  fourth,  ophthalmic  division  of  the  fifth  and 
sixth  nerves,  and  the  ophthalmic  vein.  The  anterior  border  of  the  lesser  wing  is 
serrated,  for  articulation  with  the  frontal  bone ;  the  posterior,  smooth  and  rounded, 
is  received  into  the  fissure  of  Sylvius  of  the  brain.  The  inner  extremity  of  this 
border  forms  the  anterior  clinoid  process.  The  lesser  wing  is  connected  to  the 
side  of  the  body  by  two  roots;  the  upper  thin  and  flat,  the  lower  thicker,  obliquely 
directed,  and  presenting  on  its  outer  side,  near  its  junction  with  the  body,  a  small 
tubercle,  for  the  attachment  of  the  common  tendon  of  the  muscles  of  the  eye. 
Between  the  two  roots  is  the  optic  foramen,  for  the  transmission  of  the  optic  nerve 
and  ophthalmic  artery. 

The  Pterygoid  processes  (rttipvZ,  a  wing,  rl8oi}  likeness),  one  on  each  side  (fig.  36), 
descend  perpendicularly  from 

the  point  where  the  body  and  FiS-  36.— Sphenoid  Bone.     Posterior  Surface, 

great  wing  unite.  Each  pro- 
cess consists  of  an  external 
and  an  internal  plate,  separ- 
ated behind  by  an  interven- 
ing notch,  the  pterygoid  fossa ; 
but  joined  partially  in  front. 
The  external  pterygoid  plate  is 
broad  and  thin,  turned  a  little 
outwards,  and  forms  part  of 
the  inner  wall  of  the  zygo- 
matic fossa.  It  gives  attach- 
ment, by  its  outer  surface,  to 
the  External  pterygoid;  its 
inner  surface  forms  part  of 
the  pterygoid  fossa,  and  gives 
attachment  to  the  Internal 
pterygoid.  The  internal  pterygoid  plate  is  much  narrower  and  longer,  curving 
outwards,  at  its  extremity,  into  a  hook-like  process  of  bone,  the  hamular  process, 
around  which  turns  the  tendon  of  the  Tensor  palati  muscle.  At  the  base  of  this 
plate  is  a  small,  oval,  shallow  depression,  the  scaphoid  fossa,  from  which  arises  the 
Tensor  palati,  and  above  which  is  seen  the  posterior  orifice  of  the  Vidian  canal. 
The  outer  surface  of  this  plate  forms  part  of  the  pterygoid  fossa,  the  inner  sur- 
face forming  the  outer  boundary  of  the  posterior  aperture  of  the  nares.  The 
two  pterygoid  plates  are  separated  below  by  an  angular  interval,  in  which  the 
pterygoid  process,  or  tuberosity,  of  the  palate  bone  is  received.  The  anterior 
surface  of  the  pterygoid  process  is  very  broad  at  its  base,  and  forms  the  pos- 


76 


OSTEOLOGY. 


Fig.  37. — Plan  of  the  Development  of 
Sphenoid.     By  Ten  Centres. 


/  frreaci  Teste*  vniiq  la  Ant '- '/"irr  'J  body 


\       lfvr-tad,  inC.ptery.pl- 
tfir  tool  great  iving  tr  exz._ptcrygpkt.tc 

lJcrruuJi  Splitncidal  turbinated  bone 


terior  wall  of  the  sphenomaxillary  fossa;  it  supports  Meckel's  ganglion.  It 
presents,  above,  the  anterior  orifice  of  the  Vidian  canal ;  and,  below,  a  rough 
margin,  which  articulates  with  the  perpendicular  plate  of  the  palate  bone. 

Development.  The  sphenoid  bone  is  developed  by  ten  centres,  six  for  the  pos- 
terior sphenoidal  division,  and  four  for  the  anterior  sphenoidal.  The  six  centres 
for  the  posterior  sphenoidal  division  are,  one  for  each  greater  wing  and  external 

pterygoid  plate ;  one  for  each  internal  ptery- 
goid plate;  two  for  posterior  part  of  the 
body.  The  four  for  the  anterior  sphe- 
noidal are,  one  for  each  lesser  wing  and 
anterior  part  of  the  body;  and  one  for 
each  sphenoidal  turbinated  bone.  Ossifi- 
cation takes  place  in  these  pieces  in  the 
following  order:  the  greater  wing  and  ex- 
ternal pterygoid  plate  are  first  formed, 
ossific  granules  being  deposited  close  to  the 
foramen  rotundum  on  each  side,  at  about 
the  second  month  of  foetal  life ;  ossification 
spreading  outwards  into  the  great  wing, 
and  downwards  into  the  external  pterygoid 
plate.  Each  internal  pterygoid  plate  is 
then  formed,  and  becomes  united  to  the  external  about  the  middle  of  foetal  life. 
The  two  centres  for  the  posterior  part  of  the  body  appear  as  separate  nuclei,  side 
by  side,  beneath  the  sella  Turcica ;  they  join  about  the  middle  of  foetal  life  into 
a  single  piece,  which  remains  ununited  to  the  rest  of  the  bone  until  after  birth. 
Each  lesser  wing  is  formed  by  a  separate  centre,  which  appears  on  the  outer  side 
of  the  optic  foramen,  at  about  the  third  month;  they  become  united  and  join 
with  the  body  at  about  the  eighth  month  of  foetal  life.  At  about  the  end  of  the 
third  year,  ossification  has  made  its  appearance  in  the  sphenoidal  spongy  bones. 
At  birth,  the  sphenoid  consists  of  three  pieces ;  viz.,  the  greater  wing  and 
pterygoid  processes  on  each  side ;  the  lesser  wings  and  body  united.  At  the  first 
year  after  birth,  the  greater  wings  and  body  are  united.  From  the  tenth  to  the 
twelfth  year,  the  spongy  bones  are  partially  united  to  the  sphenoid,  their  junction 
being  complete  by  the  twentieth  year.     Lastly,  the  sphenoid  joins  the  occipital. 

Articulations.  The  sphenoid  articulates  with  all  the  bones  of  the  cranium,  and 
five  of  the  face ;  the  two  malar,  two  palate,  and  vomer.  The  exact  extent  of  articu- 
lation with  each  bone  is  shown  in  the  accompanying  figures. 

Attachment  of  Muscles.  The  Temporal,  External  pterygoid,  Internal  pterygoid, 
Superior  constrictor,  Tensor  palati,  Laxator  tympani,  Levator  palpebr«3,  Obliquus 
superior,  Superior  rectus,  Internal  rectus,  Inferior  rectus,  External  rectus. 


The  Sphenoidal  Spongy  Bones. 

The  Sphenoidal  Spongy  Bones  are  two  thin,  curved  plates  of  bone,  which  exist 
as  separate  pieces  until  puberty,  and  occasionally  are  not  joined  to  the  sphenoid 
in  the  adult.  They  are  situated  at  the  anterior  and  inferior  part  of  the  body  of 
the  sphenoid,  an  aperture  of  variable  size  being  left  in  their  anterior  wall  through 
which  the  sphenoidal  sinuses  open  into  the  nasal  fossse.  They  are  irregular  in 
form,  and  taper  to  a  point  behind,  being  broader  and  thinner  in  front.  Their 
inner  surface,  which  looks  towards  the  cavity  of  the  sinus,  is  concave ;  their  outer 
surface  convex.  Each  bone  articulates  in  front  with  the  ethmoid,  externally  with 
the  palate ;  behind,  its  point  is  placed  above  the  vomer,  and  is  received  between 
the  root  of  the  pterygoid  process  on  the  outer  side,  and  the  rostrum  of  the  sphe- 
uoid  on  the  inner. 


ETHMOID   BONE. 


77 


The  Ethmoid  Bone. 

The  Ethmoid  (^u6j,  a  sieve)  is  an  exceedingly  light  spongy  bone,  of  a  cubical 
form,  situated  at  the  anterior  part  of  the  base  of  the  cranium,  between  the  two 
orbits,  at  the  root  of  the  nose, 


Fig.  38. — Ethmoid  Bone.     Outer  Surface  of  Right  Lateral 
Mass  (enlarged). 


and  contributing  to  form  each 
of  these  cavities.  It  consists 
of  three  parts :  a  horizontal 
plate,  which  forms  part  of  the 
base  of  the  cranium ;  a  per- 
pendicular plate,  which  forms 
part  of  the  septum  nasi ;  and 
two  lateral  masses  of  cells. 

The  Horizontal  or  Cribri- 
form Plate  (fig.  38)  forms 
part  of  the  anterior  fossa  of 
the  base  of  the  skull,  and  is 
received  into  the  ethmoid 
notch  of  the  frontal  bone  be- 
tween the  two  orbital  plates. 
Projecting  upwards  from  the 
middle  line  of  this  plate,  is  a 
thick  smooth  triangular  pro- 
cess of  bone,  the  crista  galli, 
so  called  from  its  resemblance 
to  a  cock's  comb.  Its  base  joins  the  cribriform  plate.  Its  posterior  border,  long, 
thin,  and  slightly  curved,  serves  for  the  attachment  of  the  falx  cerebri.  Its 
anterior  border,  short  and  thick,  articulates  with  the  frontal  bone,  and  presents 
two  small  projecting  alae,  which  are  received  into  corresponding  depressions  in 
the  frontal,  completing  the  foramen  cascum  behind.  Its  sides  are  smooth,  and 
sometimes  bulging,  when  it  is  found  to  inclose  a  small  sinus.  On  each  side  of 
the  crista  galli,  the  cribriform  plate  is  narrow,  and  deeply  grooved,  to  support 
the  bulb  of  the  olfactory  nerves,  and  is  perforated  by  foramina  for  the  passage  of 
its  filaments.  These  foramina  are  arranged  in  three  rows ;  the  innermost,  which 
are  the  largest  and  least  numerous,  are  lost  in  grooves  on  the  upper  part  of  the 
septum;  the  foramina  of  the  outer  row  are  continued  on  to  the  surface  of  the  upper 
spongy  bone.  The  foramina  of  the  middle  row  are  the  smallest ;  they  perforate  the 
bone,  and  transmit  nerves  to  the  roof  of  the  nose.  At  the  front  part  of  the  cribri- 
form plate,  on  each  side 

Shown  by 


if.'turbiaatetl  ti. 


of  the  crista  galli,  is  a 
small  fissure,  which 
transmits  the  nasal 
branch  of  the  ophthal- 
mic nerve;  and  at  its 
posterior  part  a  trian- 
gular notch,  which  re- 
ceives the  ethmoidal 
spine  of  the  sphenoid. 

The  Perpendicular 
Plate  (fig.  39)  is  a  thin 
flattened  lamella  of 
bone,  which  descends 
from  the  under  surface 
of  the  cribriform  plate, 
and  assists  in  forming 
the  septum  of  the  nose. 
It  is  much  thinner  in 
the   middle  than  at  the 


Fig.  39. — Perpendicular  Plate  of  Ethmoid  (enlarged), 
removing  the  Right  Lateral  Mass. 


vn'tA  Ethmoid, 


73 


OSTEOLOGY. 


circumference,  and  is  generally  deflected  a  little  to  one  side.  Its  anterior  border 
articulates  with  the  frontal  spine  and  crest  of  the  nasal  bones.  Its  posterior, 
divided  into  two  parts,  is  connected  by  its  upper  half  with  the  rostrum  of  the 
sphenoid ;  by  its  lower  half  with  the  vomer.  The  inferior  border  serves  for  the 
attachment  of  the  triangular  cartilage  of  the  nose.  On  each  side  of  the  perpen- 
dicular plate  numerous  grooves  and  canals  are  seen,  leading  from  foramina  on 
the  cribriform  plate ;  they  lodge  filaments  of  the  olfactory  nerves. 

The  Lateral  Masses  of  the  ethmoid  consist  of  a  number  of  thin-walled  cellular 
cavities,  the  ethmoidal  cells,  interposed  between  two  vertical  plates  of  bone,  the 
outer  one  of  which  forms  part  of  the  orbit,  and  the  inner  one  part  of  the  nasal 
fossa  of  the  corresponding  side.  In  the  disarticulated  bone,  many  of  these  cells 
appear  to  be  broken ;  but  when  the  bones  are  articulated,  they  are  closed  in  in 
every  part.  The  upper  surface  of  each  lateral  mass  presents  a  number  of  apparently 
half- broken  cellular  spaces ;  these,  however,  are  completely  closed  in  when  articu- 
lated with  the  edges  of  the  ethmoidal  fissure  of  the  frontal  bone.  Crossing  this 
surface  are  two  grooves  on  each  side,  converted  into  canals  by  articulation  with 
the  frontal ;  they  are  the  anterior  and  posterior  ethmoidal  foramina,  and  open 
on  the  inner  wall  of  the  orbit.  The  posterior  surface  also  presents  large  irregular 
cellular  cavities,  which  are  closed  in  by  articulation  with  the  sphenoidal  turbi- 
nated bones,  and  orbital  process  of  the  palate.  The  cells  at  the  anterior  surface 
are  completed  by  the  lachrymal  bone  and  nasal  process  of  the  superior  maxillary, 
and  those  below  also  by  the  superior  maxillary.  The  outer  surface  of  each  lateral 
mass  is  formed  of  a  thin  smooth  square  plate. of  bone,  called  the  os  planum;  it 
forms  part  of  the  inner  wall  of  the  orbit,  and  articulates  above  with  the  orbital 
plate  of  the  frontal ;  below,  with  the  superior  maxillary  and  orbital  process  of  the 
palate ;  in  front,  with  the  lachrymal ;  and  behind,  with  the  sphenoid. 

From  the  inferior  part  of  each  lateral  mass,  immediately  beneath  the  os  planum, 
there  projects  downwards  and  backwards  an  irregular  lamina  of  bone,  called 
the  unciform  process,  from  its  hook-like  form ;  it  serves  to  close  in  the  upper  part 

of  the  orifice  of  the  antrum,  and  arti- 

Fig.  40.— Ethmoid  Bone.     Inner  Surface  of  Right        culates  with  the  ethmoidal  process  of 
Lateral  Mass  (enlarged).  ,1       •    n     •  v  •      .    j  -i 

the  interior  turbinated  bone. 

The  inner  surface  of  each  lateral 
mass  forms  part  of  the  outer  wall  of 
the  nasal  fossa  of  the  corresponding 
side.  It  is  formed  of  a  thin  lamella 
of  bone,  which  descends  from  the 
under  surface  of  the  cribriform  plate, 
and  terminates  below  in  a  free  convo- 
luted margin,  the  middle  turbinated 
bone.  The  whole  of  this  surface  is 
rough,  and  marked  above  by  numerous 
grooves  which  run  nearly  vertically 
downwards  from  the  cribriform  plate ; 
they  lodge  branches  of  the  olfactory  nerve,  which  are  distributed  on  the  mucous 
membrane  covering  the  bone.  The  back  part  of  this  surface  is  subdivided  by  a 
narrow  oblique  fissure,  the  superior  meatus  of  the  nose,  bounded  above  by  a  thin 
curved  plate  of  bone — the  superior  turbinated  bone.  By  means  of  an  orifice  at 
the  upper  part  of  this  fissure,  the  posterior  ethmoidal  cells  open  into  the  nose. 
Below  and  in  front  of  the  superior  meatus  is  seen  the  convex  surface  of  another 
thin  convoluted  plate  of  bone— the  middle  turbinated  bone.  It  extends  along  the 
whole  length  of  the  inner  surface  of  each  lateral  mass;  its  lowermargin  is  free 
and  thick,  and  its  concavity,  directed  outwards,  assists  in  forming  the  middle 
meatus.  It  is  by  means  of  a  large  orifice  at  the  upper  and  front  part  of  the 
middle  meatus,  that  the  anterior  ethmoid  cells,  and  through  them  the  frontal  sinuses, 
by  means  of  a  funnel-shaped  canal,  the  infundibulum,  communicate  with  the  nose. 
The  cellular  cavities  of  each  lateral  mass,  thus  walled  in  by  the  os  planum  on 
the  outer  side,  and  by  its  articulation  with  the  other  bones  already  mentioned,  are 


THE   FONTANELLES. 


t9 


divided  by  a  thin  transverse  bony  partition  into  two  sets,  which  do  not  commu- 
nicate with  each  other;  they  are  termed  the  anterior  and  posterior  "ethmoidal  cells; 
the  former,  the  smallest  but  the  most  numerous,  communicate  with  the  frontal 
sinuses  above,  and  the  middle  meatus  below,  by  means  of  a  long  flexuous  cellular 
canal,  the  infundibulum ;  the  posterior,  the  largest  and  least  numerous,  open  into 
the  superior  meatus,  and  communicate  (occasionally)  with  the  sphenoidal  sinuses. 

Development.  By  three  centres;  one  for  the  perpendicular  lamella,  and  one  for 
each  lateral  mass. 

The  lateral  masses  are  first  developed,  ossific  granules  making  their  first 
appearance  in  the  os  planum  between  the  fourth  and  fifth  months  of  foetal  life, 
and  afterwards  in  the  spongy  bones.  At  birth,  the  bone  consists  of  the  two 
lateral  masses,  which  are  small  and  ill-developed;  but  when  the  perpendicular 
and  horizontal  plates  begin  to  ossify,  as  they  do  about  the  first  year  after  birth, 
the  lateral  masses  become  joined  to  the  cribriform  plate.  The  formation  and 
increase  in  the  ethmoidal  cells,  which  complete  the  formation  of  the  bone,  take 
place  about  the  fifth  or  sixth  year. 

Articulations.  "With  fifteen  bones;  the  sphenoid,  two  sphenoidal  turbinated,  the 
frontal,  and  eleven  of  the  face — two  nasal,  two  superior  maxillary,  two  lachrymal, 
two  palate,  two  inferior  turbinated,  and  vomer. 

Development  of  the  Ckanium. 

The  development  of  the  cranium  takes  place  at  a  very  early  period,  on  account  of  the  im- 
portance of  the  organ  it  is  intended  to  protect.  In  its  most  rudimentary  state,  it  consists  of  a 
thin  membranous  capsule;  inclosing  the  cerebrum,  and  accurately  moulded  upon  its  surface. 
This  capsule  is  placed  external  to  the  dura  mater,  and  in  close  contact  with  it;  its  walls  are 
continuous  with  the  canal  for  the  spinal  cord,  and  the  chorda  dorsalis,  or  primitive  part  of  the 
vertebral  column,  is  continued  forwards,  from  the 
spine,  along  the  base,  to  its  fore  part,  where  it 
terminates  in  a  tapering  point.  The  next  step 
in  the  process  of  development  is  the  formation 
of  cartilage.  This  is  deposited  in  the  base  of 
the  skull,  in  two  symmetrical  segments,  one  on 
either  side  of  the  median  line ;  these  subsequently 
coalesce,  so  as  to  inclose  the  chorda  dorsalis : 
the  chief  part  of  the  cerebral  capsule  still  re- 
taining its  membranous  form.  Ossification  first 
takes  place  in  the  roof,  and  is  preceded  by  the 
deposition  of  a  membranous  blastema  upon  the 
surface  of  the  cerebral  capsule,  in  which  the  ossi- 
fying process  extends ;  the  primitive  membranous 
capsule  becoming  the  internal  periosteum,  and 
being  ultimately  blended  with  the  dura  mater. 
Although  the  bones  of  the  vertex  of  the  skull 
appear  before  those  at  the  base,  and  make  con- 
siderable progress  in  their  growth,  at  birth  ossifi- 
cation is  more  advanced  in  the  base,  this  portion 
of  the  skull  forming  a  solid  immovable  ground- 
work. 


Fie.  41.- 


-Skull  at  Birth,  showing  the  Anterior 
and  Posterior  Fontanelles. 


The  Fontanelles  (figs.  41  and  42). 

Before  birth,  the  bones  at  the  vertex  and  side 
of  the  skull  are  separated  from  each  other  by 
membranous  intervals,  in  which  bone  is  deficient. 
These  intervals,  at  certain  parts,  are  of  consider- 
able size,  and  are  termed  the  fontanelles,  so 
called  from  the  pulsations  of  the  brain,  which 
resemble  the  rising  of  water  at  a  fountain  head. 
The  fontanelles  are  four  in  number,  and  corre- 
spond to  the  junction  of  the  four  angles  of  the 
parietal  with  the  contiguous  bones.  The  ante- 
rior fontanelle  is  the  largest,  and  corresponds  to 
the  junction  of  the  sagittal  and  coronal  sutures; 
the  posterior  fontanelle,  of  smaller  size,  is  situ- 
ated at  the  junction  of  the  sagittal  and  lambdoid 
sutures  ;  the  two  remaining  ones  are  situated  at 


Fig.  42.— The  Lateral  Fontanelles. 


80  OSTEOLOGY. 

the  inferior  angles  of  the  parietal  bone.  The  latter  are  closed  soon  after  birth  ;  the  two  at  the 
superior  angles  remain  open  longer,  the  posterior  one  being  closed  in  a  few  months  after  birth, 
the  anterior  one  remaining  open  until  the  first  or  second  year.  These  spaces  are  gradually  tilled 
in  by  an  extension  of  the  ossifying  process,  or  by  the  development  of  a  Wormian  bone.  Fine 
specimens  of  large  "Wormian  bones  closing  in  the  anterior  and  posterior  fontanelles,  and  replacing 
the  anterior  inferior  angle  of  the  parietal  bones,  exist  in  the  St.  George's  Hospital  Museum. 
Sometimes,  the  anterior  fontanelle  remains  open  beyond  two  years,  and  is  occasionally  persistent 
throughout  life. 

Supernumerary  or  Wormian  Bones. 

When  ossification  of  any  of  the  tabular  bones  of  the  skull  proves  abortive,  the  membranous 
interval  left  unclosed  is  usually  tilled  in  by  a  supernumerary  piece  of  bone,  which  is  developed 
from  a  separate  centre,  and  gradually  extends  until  it  fills  in  the  vacant  space.  These  supernu- 
merary pieces  are  called  Wormian  bones ;'  they  are  called  also,  from  their  form,  ossa  triquetra, 
and  present  much  variation  in  situation,  number,  and  size. 

They  occasionally  occupy  the  situation  of  the  fontanelles.  Bertin,  Cruveilhier,  and  Cuvier 
have  each  noticed  the  presence  of  one  in  the  anterior  fontanelle.  There  are  two  specimens  in  the 
Museum  of  St.  George's  Hospital,  which  present  Wormian  bones  in  this  situation.  In  one,  the 
skull  of  a  child,  the  supernumerary  piece  is  of  considerable  size,  and  of  a  quadrangular  form. 

They  are  occasionally  found  in  the  posterior  fontanelle,  appearing  to  replace  the  superior  angle 
of  the  occipital  bone.  Not  unfrequently,  there  is  one  replacing  the  extremity  of  the  great  wing 
of  the  sphenoid,  or  the  anterior  inferior  angle  of  the  parietal  bone,  in  the  fontanelle  there  situated. 

They  have  been  found  in  the  different  sutures  on  the  vertex  and  side  of  the  skull,  and  in  some 
of  those  at  the  base.  They  are  most  frequent  in  the  lambdoid.  Ward  mentions  an  instance  'in 
which  one  half  of  the  lambdoid  suture  was  formed  by  large  AVormian  bones  disposed  in  a  double 
row,  and  jutting  deeply  into  each  other;'  and  refers  to  similar  specimens  described  by  Dumontier 
and  Bourgery. 

A  deficiency  in  the  ossification  of  the  flat  bones  would  appear  in  some  cases  to  be  symmetrical 
on  the  two  sides  of  the  skull;  for  it  is  not  uncommon  to  find  these  supernumerary  bones  corre- 
sponding in  form,  size,  and  situation  on  each  side.  Thus,  in  several  instances,  I  have  seen  a  pair 
of  large  Wormian  bones  symmetrically  placed  in  the  lambdoid  suture ;  in  another  specimen,  a 
pair  in  the  coronal  suture,  with  a  supernumerary  bone  in  the  spheno-parietal  suture  of  both  sides. 

The  size  of  these  supernumerary  pieces  varies,  in  some  cases  not  being  larger  than  a  pin's  head, 
and  confined  to  the  outer  table ;  in  other  cases  so  large,  that  one  pair  of  these  bones  formed  the 
whole  of  that  portion  of  the  occipital  bone  above  the  superior  curved  lines,  as  described  by 
Beclard  and  Ward.  Their  number  is  generally  limited  to  two  or  three  ;  but  more  than  a  hundred 
have  been  found  in  the  skull  of  an  adult  hydrocephalic  skeleton.  In  their  development,  struc- 
ture, and  mode  of  articulation,  they  resemble  the  other  cranial  bones. 

Congenital  Fissures  and  Gaps. 

Mr.  Humphry  has  called  attention  to  the  existence  of  congenital  fissures,  not  unfrequently 
found  in  the  cranial  bones,  as  the  result  of  incomplete  ossification.  These  fissures  have  been 
noticed  in  the  frontal  and  parietal  bones,  and  the  squamous  portion  of  the  temporal;  they  extend 
from  the  margin  towards  the  middle  of  the  bone,  and  are  of  great  interest  in  a  medico-legal  point 
of  view,  as  they  are  liable  to  be  mistaken  for  fractures.  An  arrest  of  the  ossifying  process  may 
also  give  rise  to  the  deficiencies  or  gaps  occasionally  found  in  the  cranial  bones.  Such  deficien- 
cies are  said  to  occur  most  frequently  when  ossification  is  imperfect,  and  to  be  situated  near  the 
natural  apertures  for  vessels.  Mr.  Humphry  describes  such  deficiencies  to  exist  in  a  calvarium, 
in  the  Cambridge  Museum,  where  a  gap  sufficiently  large  to  admit  the  end  of  the  finger  is  seen 
on  either  side  of  the  sagittal  suture,  in  the  place  of  the  parietal  foramen.  There  is  a  specimen 
precisely  similar  to  this  in  the  Museum  of  St.  George's  Hospital ;  and  another,  in  which  a  small 
circular  gap  exists  in  the  parietal  bone  of  a  young  child,  just  above  the  parietal  eminence. 
Similar  deficiencies  are  not  unfrequently  met  with  in  hydrocephalic  skulls ;  being  most  frequent, 
according  to  Mr.  Humphry,  in  the  frontal  bones,  and  in  the  parietal  bones,  on  either  side  of  the 
sagittal  suture. 

BONES  OF  THE  FACE. 

The  Facial  Bones  are  fourteen  in  number,  viz., 

Two  Nasal,  Two  Palate, 

Two  Superior  Maxillary,  Two  Inferior  Turbinated, 

Two  Lachrymal,  Vomer, 

Two  Malar,  Inferior  Maxillary. 

'  Wormius,  a  physician  in  Copenhagen,  is  said  to  have  given  the  first  detailed  description  of 
these  bones. 


SUPERIOR   MAXILLARY   BONE. 


81 


Fig.  43.— Right  Nasal  Bone. 


Frontal  B, 


4th 


Fig.  44. — Right  Nasal  Bone. 


<Wt/th 

frontal  Sfjnn&. 
crest 


— Opposite  bone. 


Outer  Surface,. 


Inn 


with 
Rrpertdicalar 

.Plate  of  Ethmoid; 


groove  for  nasal  nc  rvc 
Surface 


Nasal  Bones. 

The  Nasal  Bones  are  two  small  oblong  bones,  varying  in  size  and  form  in  different 
individuals ;  they  are  placed  side  by  side  at  the  middle  and  upper  part  of  the  face, 
forming,  by  their  junction,  the  "bridge"  of  the  nose.     Each  bone  presents  for 

examination    two   sur- 
faces, and  four  borders. 

The    outer    surface    is 

concave     from     above 

downwards,        convex 

from  side  to  side ;  it  is 

covered  by  the   Com- 
pressor   naris    muscle, 

marked   by  numerous 

small  arterial  furrows, 

and    perforated    about 

its  centre  by  a  foramen, 

sometimes   double,  for 

the   transmission   of  a 

small  vein.    Sometimes 

this  foramen  is  absent 
on  one  or  both  sides,  and  occasionally  the  foramen  caecum  opens  on  this  surface. 
The  inner  surface  is  concave  from  side  to  side,  convex  from  above  downwards ;  in 
which  direction  it  is  traversed  by  a  longitudinal  groove,  sometimes  a  canal,  for 
the  passage  of  a  branch  of  the  nasal  nerve.  The  superior  border  is  narrow,  thick, 
and  serrated  for  articulation  with  the  nasal  notch,  of  the  frontal  bone.  The  inferior 
border  is  broad,  thin,  sharp,  directed  obliquely  downwards,  outwards,  and  back- 
wards, and  serves  for  the  attachment  of  the  lateral  cartilage  of  the  nose.  This 
border  presents  about  its  centre  a  notch,  which  transmits  the  branch  of  the  nasal 
nerve  above  referred  to ;  and  is  prolonged  at  its  inner  extremity  into  a  sharp 
spine,  which,  when  articulated  with  the  opposite  bone,  forms  the  nasal  angle. 
The  external  border  is  serrated,  bevelled  at  the  expense  of  the  internal  surface 
above,  and  of  the  external  below,  to  articulate  with  the  nasal  process  of  the  superior 
maxillary.  The  internal  border,  thicker  above  than  below,  articulates  with  its 
fellow  of  the  opposite  side,  and  is  prolonged  behind  into  a  vertical  crest,  which 
forms  part  of  the  septum  of  the  nose ;  this  crest  articulates  with  the  nasal  spine 
of  the  frontal  above,  and  the  perpendicular  plate  of  the  ethmoid  below. 

Development.  By  one  centre  for  each  bone,  whicli  appears  about  the  same  period 
as  in  the  vertebrae. 

Articulations.     With  four  bones :  two  of  the  cranium,  the  frontal  and  ethmoid ; 
and  two  of  the  face,  the  opposite  nasal  and  the  superior  maxillary. 
No  muscles  are  directly  attached  to  this  bone. 


Superior  Maxillary  Bone. 

The  Superior  Maxillary  Bone  is  one  of  the  most  important  bones  of  the  face  in 
a  surgical  point  of  view,  on  account  of  the  number  of  diseases  to  which  some  of 
its  parts  are  liable.  Its  minute  examination  becomes,  therefore,  a  matter  of 
considerable  interest.  It  is  the  largest  bone  of  the  face,  excepting  the  lower  jaw ; 
and  forms,  by  its  union  with  its  fellow  of  the  opposite  side,  the  whole  of  the  upper 
jaw.  Each  bone  assists  in  the  formation  of  three  cavities,  the  roof  of  the  mouth, 
the  floor  and  outer  wall  of  the  nose,  and  the  floor  of  the  orbit ;  enters  into  the 
formation  of  two  fossae,  the  zygomatic,  and  spheno-maxillary ;  and  two  fissures, 
the  spheno-maxillary,  and  pterygo-maxillary.  Each  bone  presents  for  examina- 
tion a  body,  and  four  processes,  malar,  nasal,  alveolar,  and  palatine. 

The  body  is  somewhat  quadrilateral,  and  is  hollowed  out  in  its  interior  to  form 
a  large  cavity,  the  antrum  of  Highmore.  It  presents  for  examination  four 
6 


82 


OSTEOLOGY. 


surfaces,  an  external  or  facial,  a  posterior  or  zygomatic,  a  superior  or  orbital, 
and  an  internal. 

The  external  or  facial  surface  (fig.  45)  is  directed  forwards  and  outwards.  In 
the  median  line  of  the  bone,  just  above  the  incisor  teeth,  is  a  depression,  the 
incisive  or  myrtiform  fossa,  which  gives1  origin  to  the  Depressor  alse  nasi.  Above 
and  a  little  external  to  it,  the  Compressor  naris  arises.  More  external,  is  another 
depression,  the  canine  fossa,  larger  and  deeper  than  the  incisive  fossa,  from  which 
it  is  separated  by  a  vertical  ridge,  the  canine  eminence,  corresponding  to  the 
socket  of  the  canine  tooth.  The  canine  fossa  gives  origin  to  the  Levator  anguli 
oris.  Above  the  canine  fossa  is  the  infra-orbital  foramen,  the  termination  of  the 
infra-orbital  canal ;  it  transmits  the  infra-orbital  nerve  and  artery.  Above  the 
infra-orbital  foramen  is  the  margin  of  the  orbit,  which  affords  partial  attachment 
to  the  Levator  labii  superioris  proprius. 

The  posterior  or  zygomatic  surface  is  convex,  directed  backwards  and  outwards, 
and  forms  part  of  the  zygomatic  fossa.  It  presents  about  its  centre  several  aper- 
tures leading  to  canals  in  the  substance  of  the  bone ;  they  are  termed  the  posterior 
dental  canals,  and  transmit  the  posterior  dental  vessels  and  nerves.     At  the  lower 

Fig.  45. — Left  Superior  Maxillary  Bone,     Outer  Surface. 
Outer       Surface . 


Incisive  fossa 


Posterior  Dental  Cunab 


xtlla.ru  Tulerositu. 


■Bicuspids 


part  of  this  surface  is  a  rounded  eminence,  the  maxillary  tuberosity,  especially 
prominent  after  the  growth  of  the  wisdom-tooth,  rough  on  its  inner  side  for 
articulation  with  the  tuberosity  of  the  palate  bone.  Immediately  above  the  rough 
surface  is  a  groove,  which,  running  obliquely  down  on  the  inner  surface  of  the 
bone,  is  converted  into  a  canal  by  articulation  with  the  palate  bone,  forming  the 
posterior  palatine  canal. 

The  superior  or  orbital  surface  is  thin,  smooth,  triangular,  and  forms  part  of 
the  floor  of  the  orbit.  It  is  bounded  internally  by  an  irregular  margin  which 
articulates,  in  front,  with  the  lachrymal ;  in  the  middle,  with  the  os  planum  of 
the  ethmoid ;  behind,  with  the  orbital  process  of  the  palate  bone ;  externally,  by 
a  smooth  rounded  edge  which  enters  into  the  formation  of  the  spheno-maxillary 
fissure,  and  which  sometimes  articulates  at  its  anterior  extremity  with  the  orbital 
plate  of  the  sphenoid ;  and  in  front,  by  part  of  the  circumference  of  the  orbit, 


SUPERIOR   MAXILLARY   BONE. 


83 


which  is  continuous,  on  the  inner  side,  with  the  nasal,  on  the  outer  side,  with  the 
malar  process.  Along  the  middle  line  of  the  orbital  surface  is  a  deep  groove,  the 
infra-orbital,  for  the  passage  of  the  infra-orbital  nerve  and  artery.  This  groove 
commences  at  the  middle  of  the  outer  border  of  this  surface,  and,  passing  forwards, 
terminates  in  a  canal  which  subdivides  into  two  branches ;  one  of  the  canals,  the 
infra-orbital,  opens  just  below  the  margin  of  the  orbit ;  the  other,  which  is  smaller, 
runs  in  the  substance  of  the  anterior  wall  of  the  antrum ;  it  is  called  the  anterior 
dental  canal,  transmitting  the  anterior  dental  vessels  and  nerves  to  the  front  teeth 
of  the  upper  jaw.  At  the  inner  and  fore  part  of  the  orbital  surface,  just  external 
to  the  lachrymal  canal,  is  a  minute  depression,  which  gives  origin  to  the  Inferior 
oblique  muscle  of  the  eye. 

The  internal  surface  (fig.  46)  is  unequally  divided  into  two  parts  by  a  horizontal 
projection  of  bone,  the  palate  process;  that  portion  above  the  palate  process  forms 
part  of  the  outer  wall  of  the  nose;  the  portion  below  it  forms  part  of  the  cavity 
of  the  mouth.  The  superior  division  of  this  surface  presents  a  large  irregular 
shaped  opening  leading  into  the  antrum  of  Highmore.     At  the  upper  border  of 

Fig.  46. — Left  Superior  Maxillary  Bone.    Inner  Surface. 


$°r,'r  partially  closinj  Orfae  of  Antrum 
murk/d    in    ourJiitt, 


■Ethmoid  — 
Inferior  Turbinated- 
JPaLue 


Ant.  JVa*aZ  Spin* 


JS-rletle 
pans  id  through 
Ant.  palat.  Canal 


this  aperture  are  a  number  of  broken  cellular  cavities,  which,  in  the  articulated 
skull,  are  closed  in  by  the  ethmoid  and  lachrymal  bones.  Below  the  aperture  is  a 
smooth  concavity  which  forms  part  of  the  inferior  meatus  of  the  nose,  traversed 
by  a  fissure,  the  maxillary  fissure,  which  runs  from  the  lower  part  of  the  orifice  of 
the  antrum  obliquely  downwards  and  forwards,  and  receives  the  maxillary  process 
of  the  palate  bone.  Behind  it  is  a  rough  surface  which  articulates  with  the  per- 
pendicular plate  of  the  palate  bone,  traversed  by  a  groove  which,  commencing  near 
the  middle  of  the  posterior  border,  runs  obliquely  downwards  and  forwards,  and 
forms,  when  completed  by  its  articulation  with  the  palate  bone,  the  posterior  palatine 
canal.  In  front  of  the  opening  in  the  antrum  is  a  deep  groove,  converted  into  a 
canal  by  the  lachrymal  and  inferior  turbinated  bones,  and  lodging  the  nasal  duct. 
More  anteriorly  is  a  well-marked  rough  ridge,  the  inferior  turbinated  crest,  for 
articulation  with  the  inferior  turbinated  bone.  The  concavity  above  this  ridge 
forms  part  of  the  middle  meatus  of  the  nose ;  whilst  that#  below  it  forms  part  of 
the  inferior  meatus.     The  inferior  division  of  this  surface  is  concave,  rough  and 


U  OSTEOLOGY. 

uneven,  and  perforated  by  numerous  small  foramina  for  the  passage  of  nutrient 
vessels. 

The  Antrum  of  Highmore,  or  Maxillary  Sinus,  is  a  large  triangular-shaped 
cavity,  hollowed  out  of  the  body  of  the  maxillary  bone ;  its  apex,  directed  out- 
wards, is  formed  by  the  malar  process ;  its  base,  by  the  outer  wall  of  the  nose. 
Its  walls  are  everywhere  exceedingly  thin,  its  roof  being  formed  by  the  orbital 
plate ;  its  floor  by  the  alveolar  process,  bounded  in  front  by  the  facial  surface,  and 
behind  by  the  zygomatic.  Its  inner  wall,  or  base,  presents,  in  the  disarticulated 
bone,  a  large  irregular  aperture,  which  communicates  with  the  nasal  fossae.  The 
margins  of  this  aperture  are  thin  and  ragged,  and  the  aperture  itself  is  much  con- 
tracted by  its  articulation  with  the  ethmoid  above,  the  inferior  turbinated  below, 
and  the  palate  bone  behind.  In  the  articulated  skull,  this  cavity  communicates 
with  the  middle  meatus  of  the  nose,  generally  by  two  small  apertures  left  between 
the  above-mentioned  bones.  In  the  recent  state,  usually  only  one  small  opening 
exists,  near  the  upper  part'  of  the  cavity,  sufficiently  large  to  admit  the  end  of  a 
probe,  the  other  being  closed  by  the  lining  membrane  of  the  sinus. 

Crossing  the  cavity  of  the  antrum  are  often  seen  several  projecting  laminae  of 
bone,  similar  to  those  seen  in  the  sinuses  of  the  cranium;  and  on  its  posterior  wall 
are  the  posterior  dental  canals,  transmitting  the  posterior  dental  vessels  and  nerves 
to  the  teeth.  Projecting  into  the  floor  are  several  conical  processes,  corresponding 
to  the  roots  of  the  first  and  second  molar  teeth ;  in  some  cases,  the  floor  is  per- 
forated by  the  teeth  in  this  situation.  It  is  from  the  extreme  thinness  of  the  walls 
of  this  cavity,  that  we  are  enabled  to  explain  how  a  tumor,  growing  from  the 
antrum,  encroaches  upon  the  adjacent  parts,  pushing  up  the  floor  of  the  orbit,  and 
displacing  the  eyeball,  projecting  inward  into  the  nose,  protruding  forwards  on  to 
the  cheek,  and  making  its  way  backwards  into  the  zygomatic  fossa,  and  down- 
wards into  the  mouth. 

The  Malar  Process  is  a  rough  triangular  eminence,  situated  at  the  angle  of 
separation  of  the  facial  from  the  zygomatic  surface.  In  front,  it  is  concave, 
forming  part  of  the  facial  surface ;  behind,  it  is  also  concave,  and  forms  part  of  the 
temporal  fossa ;  above,  it  is  rough  and  serrated  for  articulation  with  the  malar 
bone ;  whilst,  below,  a  prominent  ridge  marks  the  division  between  the  facial  and 
zygomatic  surfaces. 

The  Nasal  Process  is  a  thick  triangular  plate  of  bone,  which  projects  upwards, 
inwards,  and  backwards,  by  the  side  of  the  nose,  forming  part  of  its  lateral 
boundary.  Its  external  surface  is  concave,  smooth,  perforated  by  numerous  fora- 
mina, and  gives  attachment  to  the  Levator  labii  superioris  alaeque  nasi,  the 
Orbicularis  palpebrarum,  and  Tendo  oculi.  Its  internal  surface  forms  part  of  the 
inner  wall  of  the  nose ;  it  articulates  above  with  the  frontal,  and  presents  a  rough 
uneven  surface,  which  articulates  with  the  ethmoid  bone,  closing  in  the  anterior 
ethmoid  cells ;  below  this  is  a  transverse  ridge,  the  superior  turbinated  crest,  for 
articulation  with  the  middle  turbinated  bone  of  the  ethmoid,  bounded  below  by  a 
smooth  concavity,  which  forms  part  of  the  middle  meatus ;  below  this  is  the  inferior 
turbinated  crest,  already  described,  for  articulation  with  the  inferior  turbinated 
bone ;  and  still  more  inferiorly,  the  concavity  which  forms  part  of  the  inferior 
meatus.  The  anterior  border  of  the  nasal  process  is  thin,  directed  obliquely 
downwards  and  forwards,  and  presents  a  serrated  edge  for  articulation  with  the  nasal 
bone :  its  posterior  border  is  thick,  and  hollowed  into  a  groove  for  the  nasal  duct. 
Of  the  two  margins  of  this  groove,  the  inner  one  articulates  with  the  lachrymal 
bone,  the  outer  one  forms  part  of  the  circumference  of  the  orbit.  Just  where 
the  latter  joins  the  orbital  surface  is  a  small  tubercle,  the  lachrymal  tubercle; 
this  serves  as  a  guide  to  the  surgeon  in  the  performance  of  the  operation  for 
fistula  lacrymalis.  The  lachrymal  groove  in  the  articulated  skull  is  converted 
into  a  canal  by  the  lachrymal  bone,  and  lachrymal  process  of  the  inferior  tur- 
binated; it  is  directed  downwards,  and  a  little  backwards  and  outwards,  is  about 
the  diameter  of  a  goose-quill,  slightly  narrower  in  the  middle  than  at  either 
extremity,  and  lodges  the  nasal  duct. 


SUPERIOR   MAXILLARY  BONE. 


85 


The  Alveolar  Process  is  the  thickest  and  most  spongy  part  of  the  bone,  broader 
behind  than  in  front,  and  excavated  into  deep  cavities  for  the  reception  of  the 
teeth.  These  cavities  are  eight  in  number,  and  vary  in  size  and  depth  according 
to  the  teeth  they  contain :  those  for  the  canine  teeth  being  the  deepest ;  those  for 
the  molars  being  widest,  and  subdivided  into  minor  cavities ;  those  for  the  incisors 
being  single,  but  deep  and  narrow. 

The  Palate  Process,  thick  and  strong,  projects  horizontally  inwards  from  the 
inner  surface  of  the  bone.  It  is  much  thicker  in  front  than  behind,  and  forms  a 
considerable  part  of  the  floor  of  the  nares,  and  the  roof  of  the  mouth.  Its  upper 
surface  is  concave  from  side  to  side,  smooth,  and  forms  part  of  the  floor  of  the 
nose.  In  front  is  seen  the  upper  orifice  of  the  anterior  palatine  (incisor)  canal, 
which  leads  into  a  fossa  formed  by  the  junction  of  the  two  superior  maxillary 
bones,  and  is  situated  immediately  behind  the  incisor  teeth.  It  transmits  the  ante- 
rior palatine  vessels,  the  naso-palatine  nerves  passing  through  the  intermaxillary 
suture.  The  inferior  surface,  also  concave,  is  rough  and  uneven,  and  forms  part 
of  the  roof  of  the  mouth.  This  surface  is  perforated  by  numerous  foramina  for 
the  passage  of  nutritious  vessels,  channelled  at  the  back  part  of  its  alveolar  border 
by  a  longitudinal  groove,  sometimes  a  canal,  for  the  transmission  of  the  posterior 
palatine  vessels,  and  a  large  nerve,  and  presents  little  depressions  for  the  lodgment 
of  the  palatine  glands.  This  surface  presents  anteriorly  the  lower  orifice  of  the 
anterior  palatine  fossa.  In  some  bones,  a  delicate  linear  suture  may  be  seen 
extending  from  the  anterior  palatine  fossa  to  the  interval  between  the  lateral 
incisor  and  the  canine  teeth.  This  marks  out  the  intermaxillary  bone,  which  in 
some  animals  exists  permanently  as  a  separate  piece.  It  includes  the  whole  thick- 
•ness  of  the  alveolus,  the  corresponding  part  of  the  floor  of  the  nose,  and  the 
anterior  nasal  spine,  and  contains  the  sockets  of  the  incisor  teeth.  The  outer 
border  of  the  palate  process  is 

firmly  united  with  the  rest  of  the       FiS-  47.— Development  of  Superior  Maxillary  Bone.     By 

bone.  The  inner  border  is  thicker  Four  Centres' 

in  front  than  behind,  raised  above 
into  a  ridge,  which,  with  the  cor- 
responding ridge  in  the  opposite 
bone,  forms  a  groove  for  the  re- 
ception of  the  vomer.  The  an- 
terior margin  is  bounded  by  the 
thin  concave  border  of  the  open- 
ing of  the  nose,  prolonged  for- 
wards internally  into  a  sharp 
process,  forming,  with  a  similar 
process  of  the  opposite  bone,  the 
anterior  nasal  spine.  The  pos- 
terior border  is  serrated  for 
articulation  with  the  horizontal 
plate  of  the  palate  bone. 

Development.  This  bone  is 
formed  at  such  an  early  period, 
and  ossification  proceeds  in  it 
with  such  rapidity,  that  it  has 
been  found  impracticable  hither- 
to to  determine  with  accuracy 
its  number  of  centres.  It  ap- 
pears, however,  probable  that  it  has  four  centres  of  development,  viz.,  one  for  the 
nasal  and  facial  portions,  one  for  the  orbital  and  malar,  one  for  the  incisive,  and 
one  for  the  palatal  portion,  including  the  entire  palate  except  the  incisive  segment. 
The  incisive  portion  is  indicated  in  young  bones  by  a  fissure,  which  marks  off  a 
small  segment  of  the  palate,  including  the  two  incisor  teeth.  In  some  animals,  this 
remains  permanently  as  a  separate  piece,  constituting  the  intermaxillary  bone :  and 


J  for  Natal    fy 
Facial   port?} 


J  for  Orbital  Rr 
Malar  port".' 


Anterior  Surface. 


at 

Birth 


1    fur  In 


port1! 


1   for  Palatal  jiorlVf 


86  OSTEOLOGY. 

in  the  human  subject,  where  the  jaw  is  malformed,  as  in  cleft  palate,  this  segment 
may  be  separated  from  the  maxillary  bone  by  a  deep  fissure  extending  backwards 
between  the  two  into  the  palate.  If  the  fissure  be  on  both  sides,  both  segments  are 
quite  isolated  from  the  maxillary  bones,  and  hang  from  the  end  of  the  vomer,  not 
unfrequently  being  much  displaced,  and  often  accompanied  by  congenital  fissure  of 
die  upper  lip,  either  on  one  or  both  sides  of  the  median  line.  The  maxillary  sinus 
appears  at  an  earlier  period  than  any  of  the  other  sinuses,  its  development  com- 
mencing about  the  fourth  month  of  fcetal  life. 

Articulations.  With  nine  bones :  two  of  the  cranium — the  frontal  and  ethmoid, 
and  seven  of  the  face,  viz.,  the  nasal,  malar,  lachrymal,  inferior  turbinated,  palate, 
vomer,  and  its  fellow  of  the  opposite  side.  Sometimes  it  articulates  with  the 
orbital  plate  of  the  sphenoid. 

Attachment  of  Muscles.  Orbicularis  palpebrarum,  Obliquus  inferior  oculi,  Leva- 
tor labii  superioris  aloeque  nasi,  Levator  labii  superioris  proprius,  Levator  anguli 
oris,  Compressor  naris,  Depressor  alas  nasi,  Masseter,  Buccinator. 

The  Lachrymal  Bones. 

The  Lachrymal  Bones  are  the  smallest  and  most  fragile  bones  of  the  face,  situated 
at  the  front  part  of  the  inner  wall  of  the  orbit,  and  resemble  somewhat  in  form, 
thinness,  and  size,  a  finger-nail ;  hence  they  are  termed 
Fig.  48.— Left  Lachrymal     the  ossa  unguis.     Each  bone  presents  for  examination  two 
Bone.    External  Surface,      surfaces  and  four  borders.    The  external  or  orbital  surface 
v;a  Frontal  (fig-  48)  is  divided  by  a  vertical  ridge  into  two  parts.    The 

portion  of  bone  in  front  of  this  ridge  presents  a  smooth,- 
concave,  longitudinal  groove,  the  free  margin  of  which 
unites  with  the  nasal  process  of  the  superior  maxillary  bone, 
completing  the  lachrymal  groove.  The  upper  part  of  this 
groove  lodges  the  lachrymal  sac ;  the  lower  part  assists  in 
the  formation  of  the  lachrymal  canal,  and  lodges  the  nasal 
duct.  The  portion  of  bone  behind  the  ridge  is  smooth, 
slightly  concave,  and  forms  part  of  the  inner  wall  of  the 
orbit.  The  ridge,  and  part  of  the  orbital  surface  imme- 
itfe*-**^  diately  behind  it,  afford  attachment  to  the  Tensor  tarsi: 

(Sliyfaly  inlarrjcd  \  the  ridge  terminates  below  in  a  small  hook-like  process, 
which  articulates  with  the  lachrymal  tubercle  of  the  supe- 
rior maxillary  bone,  and  completes  the  upper  orifice  of 
the  lachrymal  canal.  It  sometimes  exists  as  a  separate  piece,  which  is  then 
called  the  lesser  lachrymal  bone.  The  internal  or  nasal  surface  presents  a  depressed 
furrow,  corresponding  to  the  ridge  on  its  outer  surface.  The  surface  of  bone  in 
front  of  this  forms  part  of  the  middle  meatus ;  and  that  behind  it  articulates 
with  the  ethmoid  bone,  filling  in  the  anterior  ethmoidal  cells.  Of  the  four  borders, 
the  anterior  is  the  longest,  and  articulates  with  the  nasal  process  of  the  superior 
maxillary  bone.  The  posterior,  thin  and  uneven,  articulates  with  the  os  planum 
of  the  ethmoid.  The  superior,  the  shortest  and  thickest,  articulates  with  the 
internal  angular  process  of  the  frontal  bone.  The  inferior  is  divided  by  the  lower 
edge  of  the  vertical  crest  into  two  parts,  the  posterior  part  articulating  with  the 
orbital  plate  of  the  superior  maxillary  bone ;  the  anterior  portion  being  pro- 
longed downwards  into  a  pointed  process,  which  articulates  with  the  lachrymal 
process  of  the  inferior  turbinated  bone,  assisting  in  the  formation  of  the  lachrymal 
canal. 

.Development.  By  a  single  centre,  which  makes  its  appearance  soon  after  ossi- 
fication of  the  vertebrae  has  commenced. 

Articulations.  With  four  bones :  two  of  the  cranium,  the  frontal  and  ethmoid, 
and  two  of  the  face,  the  superior  maxillary  and  the  inferior  turbinated. 
Attachment  of  Muscles.  The  Tensor  tarsi. 


MALAR  BONE. 


87 


Bn.sde*  passed  through 
T£'mpo70-Mala.r  (iintds 


The  Malar  Bones. 

The  Malar  Bones  are  two  small  quadrangular  bones,  situated  at  the  upper  and 
outer  part  of  the  face,  forming  the  prominence  of  the  cheek,  part  of  the  outer  wall 
and  floor  of  the  orbit,  and  part  of  the  temporal  and  zygomatic  fossae.  Each  bone 
presents  for  examination  an  external  and  an  internal  surface ;  four  processes,  the 
frontal,  orbital,  maxillary,  and  zygomatic ;  and  four  borders.  The  external  surface 
(fig.  49)  is  smooth,  convex,  perforated  near  its  centre  by  one  or  two  small 
apertures,  the  malar  foramina,  for  the  passage  of  nerves  and  vessels,  covered 
by  the  Orbicularis  palpebrarum 

muscle,  and   afibrds   attachment  Fig.  49.— Left  Malar  Bone.     Outer  Surface. 

to  the  Zygomaticus  major  and 
Zygomaticus  minor  muscles. 

The  internal  surface  (fig.  50), 
directed  backwards  and  inwards, 
is  concave,  presenting  internally 
a  rough  triangular  surface,  for 
articulation  with  the  superior 
maxillary  bone ;  and  externally, 
a  smooth  concave  surface,  which 
forms  the  anterior  boundary  of 
the  temporal  fossa  above,  wider 
below,  where  it  forms  part  of 
the  zygomatic  fossa.  This  sur- 
face presents,  a  little  above  its 
centre,  the  aperture  of  one  or  two 
malar  canals,  and  affords  attach- 
ment to  part  of  two  muscles,  the 
Temporal  above,  and  the  Masse- 
ter  below.  Of  the  four  processes, 
the  frontal  is  thick  and  serrated, 
and  articulates  with  the  external 
angular  process  of  the  frontal 
bone.  The  orbital  process  is  a 
thick  and  strong  plate,  which 
projects  backwards  from  the 
orbital  margin  of  the  bone.  Its 
upper  surface,  smooth  and  con- 
cave, forms,  by  its  junction  with 
the  great  ala  of  the  sphenoid, 
the  outer  wall  of  the  orbit.  Its 
under  surface,  smooth  and  con- 
vex, forms  part  of  the  temporal 
fossa.  Its  anterior  margin  is 
smooth  and  rounded,  forming 
part  of  the  circumference  of  the 
orbit.  Its  superior  margin,  rough, 
and  directed  horizontally,  arti- 
culates with  the  frontal  bone 
behind  the  external  angular  pro- 
cess. Its  posterior  margin  is  rough  and  serrated,  for  articulation  with  the  sphenoid : 
internally  it  .is  also  serrated  for  articulation  with  the  orbital  surface  of  the  superior 
maxillary.  At  the  angle  of  junction  of  the  sphenoidal  and  maxillary  portions,  a 
short  rounded  non-articular  margin  is  sometimes  seen ;  this  forms  the  anterior 


Fig.  50. — Left  Malar  Bone.     Inner  Surface. 


88  OSTEOLOGY. 

boundary  of  the  spheno-maxillary  fissure:  occasionally,  no  such  non-articulai 
margin  exists,  the  fissure  being  completed  by  the  direct  junction  of  the  maxillary 
and  sphenoid  bones,  or  by  the  interposition  of  a  small  Wormian  bone  in  the 
angular  interval  between  them.  On  the  upper  surface  of  the  orbital  process  are 
seen  the  orifices  of  one  or  two  temporo-malar  canals ;  one  of  these  usually  opens 
on  the  posterior  surface,  the  other,  occasionally  two,  on  the  facial  surface :  they 
transmit  filaments  (temporo-malar)  of  the  orbital  branch  of  the  superior  maxillary 
nerve.  The  maxillary  process  is  a  rough  triangular  surface,  which  articulates  with 
the  superior  maxillary  bone.  The  zygomatic  process,  long,  narrow,  and  serrated, 
articulates  with  the  zygomatic  process  of  the  temporal  bone.  Of  the  four  borders, 
the  superior  or  orbital  is  smooth,  arched,  and  forms  a  considerable  part  of  the 
circumference  of  the  orbit.  The  inferior  or  zygomatic  is  continuous  with  the 
lower  border  of  the  zygomatic  arch,  affording  attachment  by  its  rough  edge  to  the 
Masseter  muscle.  The  anterior  or  maxillary  border  is  rough,  and  bevelled  at  the 
expense  of  its  inner  table,  to  articulate  with  the  superior  maxillary  bone ;  affording 
attachment  by  its  outer  margin  to  the  Levator  labii  superioris  proprius,  just  at  its 
point  of  junction  with  the  superior  maxillary.  The  posterior  or  temporal  border, 
curved  like  an  italic/,  is  continuous  above  with  the  commencement  of  the  temporal 
ridge ;  below,  with  the  upper  border  of  the  zygomatic  arch ;  it  affords  attachment 
to  the  temporal  fascia. 

Development.  By  a  single  centre  of  ossification,  which  appears  at  about  the 
same  period  when  ossification  of  the  vertebrae  commences. 

Articulations.  With  four  bones  ;  three  of  the  cranium,  the  frontal,  sphenoid,  and 
temporal ;  and  one  of  the  face,  the  superior  maxillary. 

Attachment  of  Muscles.  Levator  labii  superioris  proprius,  Zygomaticus  major 
and  Zygomaticus  minor,  Masseter,  and  Temporal. 

The  Palate  Bones. 

The  Palate  Bones  are  situated  at  the  back  part  of  the  nasal  fossa3 ;  they  are  two 
in  number,  one  on  each  side,  wedged  in  between  the  superior  maxillary  and  the 
pterygoid  process  of  the  sphenoid.  Each  bone  assists  in  the  formation  of  three 
cavities,  the  floor  and  outer  wall  of  the  nose,  the  roof  of  the  mouth,  and  the  floor 
of  the  orbit ;  and  enters  into  the  formation  of  three  fossae,  the  zygomatic,  spheno- 
maxillary, and  pterygoid.  In  form,  the  palate  bone  somewhat  resembles  the  letter 
L,  and  may  be  divided  into  an  inferior  or  horizontal  plate,  and  a  superior  or 
vertical  plate. 

The  Horizontal  Plate  is  thick,  of  a  quadrilateral  form,  and  presents  two  surfaces 
and  four  borders.  The  superior  surface,  concave  from  side  to  side,  forms  the  back 
part  of  the  floor  of  the  nares.  The  inferior  surface,  slightly  concave  and  rough, 
forms  the  back  part  of  the  hard  palate.  At  its  posterior  part  may  be  seen  a 
transverse  ridge,  more  or  less  marked,  for  the  attachment  of  the  aponeurosis  of  the 
Tensor  palati  muscle.  At  the  outer  extremity  of  this  ridge  is  a  deep  groove,  con- 
verted into  a  canal  by  its  articulation  with  the  tuberosity  of  the  superior  maxil- 
lary bone,  and  forming  the  posterior  palatine  canal.  Near  this  groove,  the  orifices 
of  one  or  two  small  canals,  accessory  posterior  palatine,  may  frequently  be  seen. 
The  anterior  border  is  serrated,  bevelled  at  the  expense  of  its  inferior  surface,  and 
articulates  with  the  palate  process  of  the  superior  maxillary  bone.  The  posterior 
border  is  concave,  free,  and  serves  for  the  attachment  of  the  soft  palate.  Its 
inner  extremity  is  sharp  and  pointed,  and,  when  united  with  the  opposite  bone, 
forms  a  projecting  process,  the  posterior  nasal  spine,  for  the  attachment  of  the 
Azygos  uvulae.  The  external  border  is  united  with  the  lower  part  of  the  perpen- 
dicular plate  almost  at  right  angles.  The  internal  border,  the  thickest,  is  serrated 
for  articulation  with  its  fellow  of  the  opposite  side ;  the  superior  edge  is  raised 
into  a  ridge,  which,  united  with  the  opposite  bone,  forms  a  crest  in  which  the 
vomer  is  received. 


PALATE   BOXE. 


89 


The  Vertical  Plate  (fig.  51)  is  thin,  of  an  oblong  form,  and  directed  upwards 
and  a  little  inwards.     It 

Fig.  51. — Left  Palate  Bone.     Internal  View  (enlarged). 


Sup 
fijihttio.  J'tdvtint,}\ 


McuriHary 
J'rocets 


HORIZONTAL      PLATE 


presents  two  surfaces,  an 
external  and  an  internal, 
and  four  borders. 

The  internal  surface  pre- 
sents at  its  lower  part  a 
broad  shallow  depression, 
which  forms  part  of  the 
inferior  meatus  of  the  nose. 
Immediately  above  this  is 
a  well-marked  horizontal 
ridge,  the  inferior  turbi- 
nated crest,  for  articula- 
tion with  the  inferior  tur- 
binated bone;  above  this, 
a  second  broad  shallow 
depression,  which  forms 
part  of  the  middle  meatus, 
surmounted  above  by  a 
horizontal  ridge,  less  pro- 
minent than  the  inferior, 
the  superior  turbinated 
crest,  for  articulation  with 
the  middle  turbinated  bone.  Above  the  superior  turbinated  crest  is  a  narrow 
horizontal  groove,  which  forms  part  of  the  superior  meatus. 

The  external  surface  is  rough  and  irregular  throughout  the  greater  part  of  its 
extent,  for  articulation  with  the  inner  surface  of  the  superior  maxillary  bone,  its 
upper  and  back  part  being  smooth  where  it  enters  into  the  formation  of  the 
zygomatic  fossa ;  it  is  also  smooth  in  front,  where  it  covers  the  orifice  of  the 
antrum.  Towards  the  back  part  of  this  surface  is  a  deep  groove,  converted  into  a 
canal,  the  posterior  palatine,  by  its  articulation  with  the  superior  maxillary  bone. 
It  transmits  the  posterior  palatine  vessels  and  a  large  nerve.  The  anterior  border 
is  thin,  irregular,  and  presents  opposite  the  inferior  turbinated  crest  a  pointed 
projecting  lamina,  the  maxillary  process,  which  is  directed  forwards,  and  closes 
in  the  lower  and  back  part  of  the  opening  of  the  antrum,  being  received  into  a 
fissure  that  exists  at  the  inferior  part  of  this  aperture.  The  posterior  border 
(fig.  52)  presents  a  deep  groove,  the  edges  of  which  are  serrated  for  articulation 
with  the  pterygoid  process  of  the  sphenoid.  At  the  lower  part  of  this  border  is 
seen  a  pyramidal  process  of  bone,  the  pterygoid  process  or  tuberosity  of  the  palate, 
which  is  received  into  the  angular  interval  between  the  two  pterygoid  plates  of 
the  sphenoid  at  their  inferior  extremity.  This  process  presents  at  its  back  part 
three  grooves,  a  median  and  two  lateral  ones.  The  former  is  smooth,  and  forms 
part  of  the  pterygoid  fossa,  affording  attachment  to  the  Internal  pterygoid  muscle ; 
whilst  the  lateral  grooves  are  rough  and  uneven,  for  articulation  with  the  anterior 
border  of  each  pterygoid  plate.  The  base  of  this  process,  continuous  with  the 
horizontal  portion  of  the  bone,  presents  the  apertures  of  the  accessory  descending 
palatine  canals ;  whilst  its  outer  surface  is  rough,  for  articulation  with  the  inner 
surface  of  the  body  of  the  superior  maxillary  bone.  The  superior  border  of  the 
vertical  plate  presents  two  well-marked  processes,  separated  by  an  intervening 
notch  or  foramen.  The  anterior,  or  larger,  is  called  the  orbital  process;  the 
posterior,  the  sphenoidal. 

The  Orbital  Process,  directed  upwards  and  outwards,  is  placed  on  a  higher 
level  than  the  sphenoidal.  It  presents  five  surfaces,  which  inclose  a  hollow  cellu- 
lar cavity,  and  is  connected  to  the  perpendicular  plate  by  a  narrow  constricted 
neck.  Of  these  five  surfaces,  three  are  articular,  two  non-articular  or  free  sur- 
faces.    The  three  articular  are  the  anterior  or  maxillary  surface,  which  is  directed 


90 


OSTEOLOGY. 


forwards,  outwards,  and  downwards,  is  of  an  oblong  form,  and  rough  for  articulation 
with  the  superior  maxillary  bone.  The  posterior  or  sphenoidal  surface  is  directed 
backwards,  upwards,  and  inwards.     It  ordinarily  presents  a  small  half-cellular 

cavity  which  communicates  with 
Fig.  52. — Left  Palate  Bone.     Posterior  View  (enlarged) 


the    sphenoidal    sinus, 
margins   of    which    are 


/Ht/u/l'nt   £<V*. 


tShlicTWidal  firoct&s. 

~A.rticutur  kort. 

..    ,       .       Xxt.Su,rt 
on.  arlicula>r jwrt.  m 


To,r. 


JVfc 


r°*iiu 


and  the 
serrated 
for-  articulation  with  the  vertical 
part  of  the  sphenoidal  turbinated 
bone.  The  internal  or  ethmoidal 
surface  is  directed  inwards,  up- 
wards and  forwards,  and  articu- 
lates with  the  lateral  mass  of  the 
ethmoid  bone.  In  some  cases, 
the  cellular  cavity  above-men- 
tioned opens  on  this  surface  of 
the  bone;  it  then  communicates 
with  the  posterior  ethmoidal 
cells.  More  rarely  it  opens  on 
both  surfaces,  and  then  commu- 
nicates with  the  posterior  eth- 
moidal cells,  and  the  sphenoidal 
sinus.  The  non-articular  or  free 
surfaces  are  the  superior  or  or- 
bital, directed  upwards  and  out- 
wards, of  triangular  form,  concave, 
smooth,  articulating  with  tne  superior  maxillary  bone,  and  forming  the  back 
part  of  the  floor  of  the  orbit.  The  external  or  zygomatic  surface,  directed  out- 
wards, backwards  and  downwards,  is  of  an  oblong  form,  smooth,  and  forms  part 
of  the  zygomatic  fossa.  This  surface  is  separated  from  the  orbit  by  a  smooth 
rounded  border,  which  enters  into  the  formation  of  the  spheno-maxillary  fissure. 
The  Sphenoidal  Process  of  the  palate  bone  is  a  thin  compressed  plate,  much 
smaller  than  the  orbital,  and  directed  upwards  and  inwards.  It  presents  three 
surfaces  and  two  borders.  The  superior  surface,  the  smallest  of  the  three,  arti- 
culates with  the  horizontal  part  of  the  sphenoidal  turbinated  bone ;  it  presents  a 
groove  which  contributes  to  the  formation  of  the  pterygo-palatine  canal.  The 
internal  surface  is  concave,  and  forms  part  of  the  outer  wall  of  the  nasal  fossa. 
The  external  surface  is  divided  into  an  articular,  and  a  non-articular  portion ;  the 
former  is  rough  for  articulation  with  the  inner  surface  of  the  pterygoid  process 
of  the  sphenoid;  the  latter  is  smooth,  and  forms  part  of  the  zygomatic  fossa. 
The  anterior  border  forms  the  posterior  boundary  of  the  spheno-palatine  foramen. 
The  posterior  border,  serrated  at  the  expense  of  the  outer  table,  articulates  with 
the  inner  surface  of  the  pterygoid  process. 

The  orbital  and  sphenoidal  processes  are  separated  from  one  another  by  a  deep 
notch,  which  is  converted  into  a  foramen,  the  spheno-palatine,  by  articulation  with 
the  sphenoidal  turbinated  bone.  Sometimes  the  two  processes  are  united  above, 
and  form  between  them  a  complete  foramen,  or  the  notch  is  crossed  by  one  or 
more  spicula  of  bone,  so  as  to  form  two  or  more  foramina.  In  the  articulated 
skull,  this  foramen  opens  into  the  back  part  of  the  outer  wall  of  the  superior 
meatus,  and  transmits  the  spheno-palatine  vessels  and  nerves. 

Development.  From  a  single  centre,  which  makes  its  appearance  at  the  angle  of 
junction  of  the  two  plates  of  the  bone.  From  this  point  ossification  spreads,  in- 
wards, to  the  horizontal  plate ;  downwards,  into  the  tuberosity ;  and  upwards,  into 
the  vertical  plate.  In  the  foetus,  the  horizontal  plate  is  much  longer  than  the 
vertical ;  and  even  after  it  is  fully  ossified,  the  whole  bone  is  remarkable  for  its 
shortness. 

Articulations.  "With  seven  bones:  the  sphenoid,  ethmoid,  superior  maxillary, 
inferior  turbinated,  vomer,  opposite  palate,  and  sphenoidal  turbinated. 


INFERIOR   TURBINATED   BONE. 


9J 


Attachment  of  Muscles.  The  Tensor  palati,  Azygos  uvulae,  Internal  and  External 
pterygoid. 


The  Inferior  Turbinated  Bones. 

The  Inferior  Turbinated  Bones  are  situated  one  on  each  side  of  the  outer  wall  of 
the  nasal  fossse.  Each  bone  consists  of  a  layer  of  thin  spongy  bone,  curled 
upon  itself  like  a  scroll,  hence  its  name  "turbinated;"  and  extends  horizontally 
across  the  outer  wall  of  the  nasal  fossa,  immediately  below  the  orifice  of  the 
antrum.     Each  bone  presents  two  surfaces,  two  borders,  and  two  extremities. 

The  internal  surface  (fig.  53)  is  convex,  perforated  by  numerous  apertures,  and 
traversed    by    longitudinal    grooves 


Fig.  53. — Right  Inferior  Turbinated  Bone. 
Surface. 


Inner 


Fig. 


54. — Right  Inferior  Turbinated  Bone. 
Outer  Surface. 


and  canals  for  the  lodgment  of  arte- 
ries and  veins.  In  the  recent  state  it 
is  covered  by  the  lining  membrane  of 
the  nose.  The  external  surface  is  con- 
cave (fig.  54),  and  forms  part  of  the 
inferior  meatus.  Its  upper  border  is 
thin,  irregular,  and  connected  to  vari- 
ous bones  along  the  outer  wall  of  the 
nose.  .  It  may  be  divided  into  three 
portions;  of  these,  the  anterior  arti- 
culates with  the  inferior  turbinated 
crest  of  the  superior  maxillary  bone; 

the  posterior  with  the  inferior  turbinated  crest  of  the  palate  bone ;  the  middle 
portion  of  the  superior  border  presents  three  well-marked  processes,  which  vary 
much  in  their  size  and  form.  Of  these  the 
anterior  and  smallest  is  situated  at  the 
junction  of  the  anterior  fourth  with  the 
posterior  three-fourths  of  the  bone;  it  is 
small  and  pointed,  and  is  called  the  lachry- 
mal process,  for  it  articulates  with  the  ante- 
rior inferior  angle  of  the  lachrymal  bone, 
and  by  its  margins  with  the  groove  on 
the  back  of  the  nasal  process  of  the  supe- 
rior maxillary,  and  thus  assists  in  forming 
the  lachrymal  canal.  At  the  junction  of 
the  two  middle  fourths  of  the  bone,  but  en- 
croaching on  the  latter,  a  broad  thin  plate,  the  ethmoidal  process,  ascends  to  join 
the  unciform  process  of  the  ethmoid ;  from  the  lower  border  of  this  process,  a  thin 
lamina  of  bone  curves  downwards  and  outwards,  hooking  over  the  lower  edge  of 
the  orifice  of  the  antrum,  which  it  narrows  below ;  it  is  called  the  maxillary  pro- 
cess, and  fixes  the  bone  firmly  on  to  the  outer  wall  of  the  nasal  fossa.  The  infe- 
rior border  is  free,  thick  and  cellular  in  structure,  more  especially  in  the  centre 
of  the  bone.  Both  extremities  are  more  or  less  narrow  and  pointed.  If  the  bone 
is  held  so  that  its  outer  concave  surface  is  directed  backwards  (i.  e.,  towards  the 
holder),  and  its  superior  border,  from  which  the  lachrymal  and  ethmoidal  pro- 
cesses project,  upwards,  the  lachrymal  process  will  be  directed  to  the  side  to  which 
the  bone  belongs. 

Development.  By  a  single  centre  which  makes  its  appearance  about  the  middle 
of  foetal  life. 

Articulations.  "With  four  bones:  one  of  the  cranium,  the  ethmoid;  and  three  of 
the  face,  the  superior  maxillary,  lachrymal  and  palate. 

No  muscles  are  attached  to  this  bone. 


92 


OSTEOLOGY. 


•"^A.  Sup  -M«* 


&.  ^ 


The  Vomer. 

The  Vomer  is  a  single  bone,  situated  vertically  at  the  back  part  of  the  nasal 
fossae,  forming  part  of  the  septum  of  the  nose.  It  is  thin,  somewhat  like  a 
ploughshare  in  form ;  but  it  varies  in  different  individuals,  being  frequently  bent 

to  one  or  the  other  side;  it 
Fig.  55.— Vomer.  presents  for  examination  two 

surfaces  and  four  borders. 
The  lateral  surfaces  are  smooth, 
marked  with  small  furrows  for 
the  lodgment  of  bloodvessels, 
and  by  a  groove  on  each  side, 
sometimes  a  canal,  the  naso- 
palatine, which  runs  obliquely 
downwards  and  forwards  to 
the  intermaxillary  suture  be- 
tween the  two  anterior  palatine 
canals;  it  transmits  the  naso- 
palatine nerve.  The  superior 
border,  the  thickest,  presents 
a  deep  groove,  bounded  on 
each  side  by  a  horizontal  pro- 
jecting ala  of  bone ;  the  groove 
receives  the  rostrum  of  the  sphenoid,  whilst  the  alas  are  overlapped  and  retained 
by  laminae  (the  vaginal  processes)  which  project  from  the  under  surface  of  the 
body  of  the  sphenoid  at  the  base  of  the  pterygoid  processes.  At  the  front  of  the 
groove  a  fissure  is  left  for  the  transmission  of  bloodvessels  to  the  substance  of  the 
bone.  The  inferior  border,  the  longest,  is  broad  and  uneven  in  front,  where  it 
articulates  with  the  two  superior  maxillary  bones ;  thin  and  sharp  behind  where 
it  joins  with  the  palate  bones.  The  upper  half  of  the  anterior  border  usually 
consists  of  two  laminae  of  bone,  between  which  is  received  the  perpendicular 
plate  of  the  ethmoid,  the  lower  half  consisting  of  a  single  rough  edge,  also  occa- 
sionally channelled,  which  is  united  to  the  triangular  cartilage  of  the  nose.  The 
posterior  border  is  free,  concave,  and  separates  the  nasal  fossae  behind.  It  is 
thick  and  bifid  above,  thin  below. 

Development.  The  vomer  at  an  early  period  consists  of  two  laminae  separated 
by  a  very  considerable  interval,  and  inclosing  between  them  a  plate  of  cartilage 
which  is  prolonged  forwards  to  form  the  remainder  of  the  septum.  Ossification 
commences  in  it  at  about  the  same  period  as  in  the  vertebrae,  the  coalescence  of  the 
laminae  taking  place  from  behind  forwards,  but  is  not  complete  until  after  puberty. 

Articulations.  With  six  bones:  two  of  the  cranium,  the  sphenoid  and  ethmoid; 
and  four  of  the  face,  the  two  superior  maxillary  and  the  two  palate  bones ;  and  with 
the  cartilage  of  the  septum. 

The  vomer  has  no  muscles  attached  to  it. 


The  Inferior  Maxillary  Bone. 

The  Inferior  Maxillary  Bone,  the  largest  and  strongest  bone  of  the  face,  serves 
for  the  reception  of  the  inferior  teeth.  It  consists  of  a  curved  horizontal  portion, 
the  body,  and  of  two  perpendicular  portions,  the  rami,  which  join  the  former 
nearly  at  right  angles  behind. 

The  Horizontal  portion  or  body  (fig.  56),  is  convex  in  its  general  outline,  and 
curved  somewhat  like  a  horseshoe.  It  presents  for  examination  two  surfaces 
and  two  borders.  The  external  surface  is  convex  from  side  to  side,  concave 
from  above  downwards.  In  the  median  line  is  a  vertical  ridge,  the  symphysis  ;  it 
extends  from  the  upper  to  the  lower  border  of  the  bone,  and  indicates  the  point 
of  junction  of  the  two  pieces  of  which  the  bone  is  composed  at  an  early  period  of 
life.  The  lower  part  of  the  ridge  terminates  in  a  prominent  triangular  eminence, 
the  mental  process.     On  either  side  of  the  symphysis,  just  below  the  roots  of  the 


o 


INFERIOR   MAXILLARY  BONE. 


93 


incisor  teeth,  is  a  depression,  the  incisive  fossa,  for  the  attachment  of  the  Levator 
menti ;  and,  still  more  externally,  a  foramen,  the  mental  foramen,  for  the  passage 
of  the  mental  nerve  and  artery.  This  foramen  is  placed  just  below  the  root  of 
the  second  bicuspid  tooth.  Running  outwards  from  the  base  of  the  mental  process 
on  each  side,  is  a  well-marked  ridge,  the  external  oblique  line.  This  ridge  is  at 
first  nearly  horizontal,  but  afterwards  inclines  upwards  and  backwards,  and  is 
continuous  with  the  anterior  border  of  the  ramus ;  it  affords  attachment  to  the 
Depressor  labii  inferioris  and  Depressor  anguli  oris;  below  these  the  Platysma 
myoides  is  inserted.  The  external  oblique  line,  and  the  internal  oblique  or 
mylo-hyoidean  line,  to  be  hereafter  described,  divide  the  body  of  the  bone  into 
a  superior  or  alveolar,  and  an  inferior  or  basilar  portion. 

Fig.  56. — Inferior  Maxillary  Bone.     Outer  Surface.     Side  View. 


,<<<*> 


Men  ial 
/iroeesa 


The  internal  surface  (fig.  57)  is  concave  from  side  to  side,  convex  from  above 
downwards.  In  the  middle  line  is  an  indistinct  linear  depression,  corresponding 
to  the  symphysis  externally;  on  either  side  of  this  depression,  just  below  its 
centre,  are  four  prominent  tubercles,  placed  in  pairs,  two  above  and  two  below ; 
they  are  called  the  genial  tubercles,  and  afford  attachment,  the  upper  pair  to  the 
Genio-hyoglossi  muscles,  the  lower  pair  to  the  Genio-hyoidei  muscles.  Sometimes 
the  tubercles  on  each  side  are  blended  into  one,  or  they  all  unite  into  an  irregular 
eminence  of  bone,  or  nothing  but  an  irregularity  may  be  seen  on  the  surface  of 
the  bone  at  this  part.  On  either  side  of  the  genial  tubercles  is  an  oval  depression, 
the  sublingual  fossa,  for  lodging  the  sublingual  gland ;  and  beneath  the  fossa  a 
rough  depression  on  each  side,  which  gives  attachment  to  the  anterior  belly  of  the 
Digastric  muscle.  At  the  back  part  of  the  sublingual  fossa,  the  internal  oblique 
or  mylo-hyoidean  line  commences ;  it  is  at  first  faintly  marked,  but  becomes  more 
distinct  as  it  passes  upwards  and  outwards,  and  is  especially  prominent  opposite 
the  last  two  molar  teeth ;  it  divides  the  lateral  surface  of  the  bone  into  two  por- 
tions, and  affords  attachment  throughout  its  whole  extent  to  the  Mylo-hyoid 
muscle,  the  Superior  constrictor  being  attached  above  its  posterior  extremity, 
nearer  the  alveolar  margin.  The  portion  of  bone  above  this  ridge  is  smooth,  and 
covered  by  the  mucous  membrane  of  the  mouth ;  whilst  that  below  it  presents 
an  oblong  depression,  the  submaxillary  fossa,  wider  behind  than  in  front,  for  the 
lodgment  of  the  submaxillary  gland.  The  superior  or  alveolar  border  is  wider, 
and  its  margins  thicker,  behind  than  in  front.  It  is  hollowed  into  numerous 
cavities,  for  the  reception  of  the  teeth;  these  are  sixteen  in  number,  and  vary  in 
depth  and  size  according  to  the  teeth  which  they  contain.  The  inferior  border  is 
rounded,  longer  than  the  superior,  and  thicker  in  front  than  behind ;  it  presents 


94 


OSTEOLOGY. 


a  shallow  groove,  just  where  the  body  joins  the  ramus,  over  which  the  facial 
artery  turns. 

The  Perpendicular  Portions  or  Rami  are  of  a  quadrilateral  form.  Each 
presents  for  examination  two  surfaces,  four  borders,  and  two  processes.  The 
external  surface  is  flat,  marked  with  ridges,  and  gives  attachment  throughout 
nearly  the  whole  of  its  extent  to  the  Masseter  muscle.  The  internal  surface  pre- 
sents about  its  centre  the  oblique  aperture  of  the  inferior  dental  canal,  for  the 
passage  of  the  inferior  dental  vessels  and  nerve.  The  margin  of  this  opening 
is  irregular ;  it  presents  in  front  a  prominent  ridge,  surmounted  by  a  sharp  spine, 
which  gives  attachment  to  the  internal  lateral  ligament  of  the  lower  jaw ;  and  at 
its  lower  and  back  part  a  notch  leading  to  a  groove,  the  mylo-hyoidean,  which 
runs  obliquely  downwards  to  the  back  part  of  the  submaxillary  fossa,  and  lodges 
the  mylo-hyoid  vessels  and  nerve ;  behind  the  groove  is  a  rough  surface,  for  the 
insertion  of  the  Internal  pterygoid  muscle.  The  inferior  dental  canal  descends 
obliquely  downwards  and  forwards  in  the  substance  of  the  ramus,  and  then  hori- 
zontally forwards  in  the  body ;  it  is  here  placed  under  the  alveoli,  with  which  it 
communicates  by  small  openings.  On  arriving  at  the  incisor  teeth,  it  turns  back 
to  communicate  with  the  mental  foramen,  giving  off  two  small  canals,  which  run 


Fig.  57. — Inferior  Maxillary  Bone.     Inner  Surface.     Side  View. 


>^^ 


CENIO-HYO-CLOSSUS 
CEN10-HY0IDCU5 


Mylo-hyoid  Ridge 


Bod 


forward,  to  be  lost  in  the  cancellous  tissue  of  the  bone  beneath  the  incisor  teeth. 
This  canal,  in  the  posterior  two-thirds  of  the  bone,  runs  nearest  the  internal  sur- 
face of  the  jaw ;  and  in  the  anterior  third,  nearer  its  external  surface.  Its  walls 
are  composed  of  compact  tissue  at  either  extremity,  cancellous  in  the  centre.  It 
contains  the  inferior  dental  vessels  and  nerve,  from  which  branches  are  distributed 
to  the  teeth  through  small  apertures  at  the  bases  of  the  alveoli.  The  upper  border 
of  the  ramus  is  thin,  and  presents  two  processes,  separated  by  a  deep  concavitv, 
the  sigmoid  notch.  Of  these  processes,  the  anterior  is  the  coronoid,  the  posterior 
the  condyloid. 

The  Coronoid  Process  is  a  thin,  flattened,  triangular  eminence  of  bone,  which 
varies  in  shape  and  size  in  different  subjects,  and  serves  essentially  for  the  attach- 
ment of  the  Temporal  muscle.  Its  external  surface  is  smooth,  and  affords 
attachment  to  the  Masseter  and  Temporal  muscles.  Its  internal  surface  gives 
attachment  to  the  Temporal  muscle,  and  presents  the  commencement  of  a  longi- 
tudinal ridge,  which  is  continued  to  the  posterior  part  of  the  alveolar  process.  On 
the  outer  side  of  this  ridge  is  a  deep  groove,  continued  below  on  the  outer  side  of 


INFERIOR   MAXILLARY   BONE.  9S 

the  alveolar  process ;  this  ridge  and  part  of  the  groove  afford  attachment,  above, 
to  the  Temporal ;  below,  to  the  Buccinator  muscle. 

The  Condyloid  Process,  shorter  but  thicker  than  the  coronoid,  consists  of  two 
portions :  the  condyle,  and  the  constricted  portion  which  supports  the  condyle,  the 
neck.  The  condyle  is  of  an  oblong  form,  its  long  axis  being  transverse,  and  set 
obliquely  on  the  neck  in  such  a  manner  that  its  outer  end  is  a  little  more  forward 
and  a  little  higher  than  its  inner.  It  is  convex  from  before  backwards,  and  from 
side  to  side,  the  articular  surface  extending  further  on  the  posterior  than  on  the 
anterior  surface.  The  neck  of  the  condyle  is  flattened  from  before  backwards, 
and  strengthened  by  ridges  which  descend  from  the  fore  part  and  sides  of  the 
condyle.  Its  lateral  margins  are  narrow,  and  present  externally  a  tubercle  for 
the  external  lateral  ligament.  Its  posterior  surface  is  convex;  its  anterior  is 
hollowed  out  on  its  inner  side  by  a  depression,  the  pterygoid  fossa,  for  the  attach- 
ment of  the  External  pterygoid  muscle.  The  lower  border  of  the  ramus  is  thick, 
straight,  and  continuous  with  the  body  of  the  bone.  At  its  junction  with  the 
posterior  border  is  the  angle  of  the  jaw,  which  is  either  inverted  or  everted,  and 
marked  by  rough  oblique  ridges  on  each  side  for  the  attachment  of  the  Masseter 
externally,  and  the  Internal  pterygoid  internally;  and,  between  them,  is  the 
attachment  of  the  stylo-maxillary  ligament.  The  anterior  border  is  thin  above, 
thicker  below,  and  continuous  with  the  external  oblique  line.  The  posterior 
border  is  thick,  smooth,  rounded,  and  covered  by  the  parotid  gland. 

The  Sigmoid  Notch,  separating  the  two  processes,  is  a  deep  semilunar  depression, 
crossed  by  the  masseteric  artery  and  nerve. 

Development.  This  bone  is  formed  at  such  an  early  period  of  life,  before,  indeed, 
any  other  bone,  excepting  the  clavicle,  that  it  has  been  found  impossible  at  present 
to  determine  its  earliest  condition.  It  appears  probable,  however,  that  it  is  devel- 
oped by  two  centres,  one  for  each  lateral  half,  the  two  segments  meeting  at  the 
symphysis,  where  they  become  united.  Additional  centres  have  also  been 
described  for  the  coronoid  process,  the  condyle,  the  angle,  and  the  thin  plate  of 
bone  which  forms  the  inner  side  of  the  alveolus. 

Changes  produced  in  the  Lower  Jaw  by  Age. 

The  changes  which  the  Lower  Jaw  undergoes  after  birth,  relate — 1.  To  the  alterations  effected 
in  the  body  of  the  bone  by  the  first  and  second  dentitions,  the  loss  of  the  teeth  in  the  aged,  and 
the  subsequent  absorption  of  the  alveoli ;  2.  To  the  size  and  situation  of  the  dental  canal ;  and, 
3.  To  the  angle  at  which  the  ramus  joins  with  the  body. 

At  birth  (fig.  58),  the  bone  consists  of  two  lateral  halves,  united  by  fibro-cartilaginous  tissue, 
in  which  one  or  two  osseous  nuclei  are  generally  found.  The  body  is  a  mere  shell  of  bone,  con- 
taining the  sockets  of  the  two  incisor,  the  canine,  and  the  first  molar  teeth,  imperfectly  partitioned 
from  one  another.  The  dental  canal  is  of  large  size,  and  runs  near  the  lower  border  of  the  bone, 
the  mental  foramen  opening  beneath  the  socket  of  the  first  molar.  The  angle  is  obtuse,  from  the 
jaws  not  being  as  yet  separated  by  the  eruption  of  the  teeth. 

After  birth  (fig.  59),  the  two  segments  of  the  bone  become  joined  at  the  symphysis,  from  below 
upwards,  in  the  first  year ;  but  a  trace  of  separation  may  be  visible  in  the  beginning  of  the  second 
year,  near  the  alveolar  margin.  The  body  becomes  elongated  in  its  whole  length,  but  more  espe- 
cially behind  the  mental  foramen,  to  provide  space  for  the  three  additional  teeth  developed  in  this 
part.  The  depth  of  the  body  becomes  greater,  owing  to  increased  growth  of  the  alveolar  part, 
to  afford  room  for  the  fangs  of  the  teeth,  and  by  thickening  of  the  snbdental  portion  which  enables 
the  jaw  to  withstand  the  powerful  action  of  the  masticatory  muscles ;  but  the  alveolar  portion  is 
the  deeper  of  the  two,  and,  consequently,  the  chief  part  of  the  body  lies  above  the  oblique  line. 
The  dental  canal,  after  the  second  dentition,  is  situated  just  above  the  level  of  the  mylo-hyoid 
ridge  ;  and  the  mental  foramen  occupies  the  position  usual  to  it  in  the  adult.  The  angle  becomes 
less  obtuse,  owing  to  the  separation  of  the  jaws  by  the  teeth. 

In  the  adult  (fig.  60),  the  alveolar  and  basilar  portions  of  the  body  are  usually  of  equal  depth. 
The  mental  foramen  opens  midway  between  the  upper  and  lower  border  of  the  bone,  and  the 
dental  canal  runs  nearly  parallel  with  the  mylo-hyoid  line.  The  ramus  is  almost  vertical  in 
direction,  and  joins  the  body  nearly  at  right  angles. 

In  old  age  (fig.  61),  the  bone  becomes  greatly  reduced  in  size;  for,  with  the  loss  of  the  teeth, 
the  alveolar  process  is  absorbed,  and  the  basilar  part  of  the  bone  alone  remains ;  consequently, 
the  chief  part  of  the  bone  is  beloiv  the  oblique  line.  The  dental  canal,  with  the  mental  foramen 
opening  from  it,  is  close  to  the  alveolar  border.  The  rami  are  oblique  in  direction,  and  the  angle 
obtuse. 


8£ 


OSTEOLOGY. 


Side  "View  of  the  Lower  Jaw  at  different  Periods  of  Life. 

Fig.  58.— At  Birth. 


Fig.  59.— At  Puberty. 


Fig.  60.— In  the  Adult. 


Fig.  61.— In  Old  Age. 


SUTURES   OF   THE   SKULL.  97 

Articulations.  With  the  glenoid  fossae  of  the  two  temporal  bones. 

Attachment  of  Muscles.  By  its  external  surface,  commencing  at  the  symphysis 
and  proceeding  backwards :  Levator  menti,  Depressor  labii  inferioris,  Depressor 
anguli  oris,  Platysma  myoides,  Buccinator,  Masseter.  By  its  internal  surface,  com- 
mencing at  the  same  point;  Genio-hyo-glossus,  Genio-hyoideus,  Mylo-hyoideus, 
Digastricus,  Superior  constrictor,  Temporal,  Internal  pterygoid,  External  pterygoid. 

THE    SUTURES. 

The  bones  of  the  cranium  and  face  are  connected  to  each  other  by  means  of 
sutures.  The  dentations  by  which  they  are  joined  are  confined  to  the  external 
table,  the  edges  of  the  internal  table  lying  merely  in  apposition  with  the  contiguous 
bone.  The  Cranial  Sutures  may  be  divided  into  three  sets:  1.  Those  at  the  ver- 
tex of  the  skull.     2.  Those  at  the  side  of  the  skull.     3.  Those  at  the  base. 

The  sutures  at  the  vertex  of  the  skull  are  three,  the  sagittal,  coronal,  and  lamb- 
doid. 

The  Sagittal  Suture  (interparietal)  is  formed  by  the  junction  of  the  two  parietal 
bones,  and  extends  from  the  middle  of  the  frontal  bone,  backwards  to  the  superior 
angle  of  the  occipital.  In  childhood,  and  occasionally  in  the  adult,  when  the  two 
halves  of  the  frontal  bone  are  not  united,  it  is  continued  forwards  to  the  root  of  the 
nose.  This  suture  sometimes  presents,  near  its  posterior  extremity,  the  parietal 
foramen  on  each  side ;  and  in  front,  where  it  joins  the  coronal  suture,  a  space  is 
occasionally  left,  which  incloses  a  large  Wormian  bone. 

The  Coronal  Suture  (fronto-parietaT)  extends  transversely  across  the  vertex 
of  the  skull,  and  connects  the  frontal  with  the  parietal  bones.  It  commences  at 
the  extremity  of  the  great  wing  of  the  sphenoid  on  one  side,  and  terminates  at  the 
same  point  on  the  opposite  side.  The  dentations  of  this  suture  are  more  marked 
at  the  sides  than  at  the  summit,  and  are  so  constructed  that  the  frontal  rests  on  the 
parietal  above,  whilst  laterally  the  frontal  supports  the  parietal. 

The  Lambdoid  Suture  (occipitoparietal),  so  called  from  its  resemblance  to  the 
Greek  letter  a,  connects  the  occipital  with  the  parietal  bones.  It  commences  on 
each  side  at  the  mastoid  portion  of  the  temporal  bone,  and  inclines  upwards  to  the 
end  of  the  sagittal  suture.  The  dentations  of  this  suture  are  very  deep  and  dis- 
tinct, and  are  often  interrupted  by  several  small  Wormian  bones. 

The  sutures  at  the  side  of  the  skull  are  also  three  in  number:  the  spheno-parietal, 
squamo-parietal,  and  masto-parietal.  They  are  subdivisions  of  a  single  suture, 
formed  between  the  lower  border  of  the  parietal,  and  the  temporal  and  sphenoid 
bones,  and  which  extends  from  the  lower  end  of  the  lambdoid  suture  behind,  to 
the  lower  end  of  the  coronal  suture  in  front. 

The  Spheno-parietal  is  very  short ;  it  is  formed  by  the  tip  of  the  great  wing  of 
the  sphenoid,  which  overlaps  the  anterior  inferior  angle  of  the  parietal  bone. 

The  Squamo-parietal,  or  squamous  suture,  is  arched.  It  is  formed  by  the 
squamous  portion  of  the  temporal  bone  overlapping  the  middle  division  of  the 
lower  border  of  the  parietal. 

The  Masto-parietal  is  a  short  suture,  deeply  dentated,  formed  by  the  posterior 
inferior  angle  of  the  parietal,  and  the  superior  border  of  the  mastoid  portion  of  the 
temporal. 

The  sutures  of  the  base  of  the  skull  are,  the  basilar  in  the  centre,  and,  on  each 
side,  the  petro-occipital  and  masto-occipital,  the  petro-sphenoidal  and  the  squamo- 
sphenoidal. 

The  Basilar  Suture  is  formed  by  the  junction  of  the  basilar  surface  of  the 
occipital  bone  with  the  posterior  surface  of  the  body  of  the  sphenoid.  At  an  early 
period  of  life,  a  thin  plate  of  cartilage  exists  between  these  bones;  but  in  the  adult 
they  become  inseparably  united.  Between  the  outer  extremity  of  the  basilar  suture, 
and  the  termination  of  the  lambdoid,  an  irregular  suture  exists  which  is  subdivided 
into  two  portions.  The  inner  portion,  formed  by  the  union  of  the  petrous  part  of 
the  temporal  with  the  occipital  bone,  is  termed  the  petro-occipital.  The  outer 
7 


98  OSTEOLOGY. 

portion,  formed  by  the  junction  of  the  mastoid  part  of  the  temporal  with  the  occi- 
pital, is  called  the  masto-occipital.  Between  the  bones  forming  the  petro-occipital 
suture,  a  thin  plate  of  cartilage  exists  ;  in  the  masto-occipital  is  occasionally  found 
the  opening  of  the  mastoid  foramen.  Between  the  outer  extremity'of  the  basilar 
suture  and  the  spheno-parietal  an  irregular  suture  may  be  seen,  formed  by  the  union 
of  the  sphenoid  with  the  temporal  bone.  The  inner  and  smaller  portion  of  this 
suture  is  termed  the  petro-sphenoidal ;  it  is  formed  between  the  petrous  portion  of 
the  temporal  and  the  great  wing  of  the  sphenoid :  the  outer  portion,  of  greater 
length,  and  arched,  is  formed  between  the  squamous  portion  of  the  temporal  and 
the  great  wing  of  the  sphenoid :  it  is  called  the  squamo-sphenoidal. 

The  cranial  bones  are  connected  with  those  of  the  face,  and  the  facial  bones  with 
each  other,  by  numerous  sutures,  which,  though  distinctly  marked,  have  received 
no  special  names.  The  only  remaining  suture  deserving  especial  consideration  is 
the  transverse.  This  extends  across  the  upper  part  of  the  face,  and  is  formed  by 
the  junction  of  the  frontal  with  the  facial  bones ;  it  extends  from  the  external 
angular  process  of  one  side,  to  the  same  point  on  the  opposite  side,  and  connects 
the  frontal  with  the  malar,  the  sphenoid,  the  ethmoid,  the  lachrymal,  the  superior 
maxillary,  and  the  nasal  bones  on  each  side. 

The  sutures  remain  separate  for  a  considerable  period  after  the  complete  forma- 
tion of  the  skull.  It  is  probable,  that  they  serve  the  purpose  of  permitting  the 
growth  of  the  bones  at  their  margins ;  while  their  peculiar  formation,  and  the 
interposition  of  the  sutural  ligament  between  the  bones  forming  them,  prevents 
the  dispersion  of  blows  or  jars  received  upon  the  skull.  Mr.  Humphry  remarks, 
"that,  as  a  general  rule,  the  sutures  are  first  obliterated  at  the  parts  in  which  the 
ossification  of  the  skull  was  last  completed,  viz.,  in  the  neighborhood  of  the 
fontanelles ;  and  the  cranial  bones  seem  in  this  respect  to  observe  a  similar  law  to 
that  which  regulates  the  union  of  the  epiphyses  to  the  shafts  of  the  long  bones." 

The  Skull. 

The  Skull,  formed  by  the  union  of  the  several  cranial  and  facial  bones  already 
described,  when  considered  as  a  whole,  is  divisible  into  five  regions ;  a  superior 
region  or  vertex,  an  inferior  region  or  base,  two  lateral  regions,  and  an  anterior 
region,  the  face. 

Veetex  of  the  Skull. 

The  Superior  Region  or  Vertex  presents  two  surfaces,  an  external,  and  an  internal. 

The  External  Surface  is  bounded,  in  front,  by  the  nasal  eminences,  and  super- 
ciliary ridges ;  behind,  by  the  occipital  protuberance  and  superior  curved  -lines  of 
the  occipital  bone ;  laterally,  by  an  imaginary  line  extending  from  the  outer  end  of 
the  superior  curved  line,  along  the  temporal  ridge,  to  the  external  angular  process 
of  the  frontal.  This  surface  includes  the  vertical  portion  of  the  frontal,  the  greater 
part  of  the  parietal,  and  the  superior  third  of  the  occipital  bone ;  it  is  smooth, 
convex,  of  an  elongated  oval  form,  crossed  transversely  by  the  coronal  suture,  and 
from  before  backwards  by  the  sagittal,  which  terminates  behind  in  the  lambdoid. 
From  before  backwards  may  be  seen  the  frontal  eminences  and  remains  of  the 
suture  connecting  the  two  lateral  halves  of  the  frontal  bone ;  on  each  side  of  the 
sagittal  suture  are  the  parietal  foramen  and  parietal  eminence,  and  still  more  pos- 
teriorly the  smooth  convex  surface  of  the  occipital  bone. 

The  Internal  Surface  is  concave,  presenting  eminences  and  depressions  for  the 
convolutions  of  the  cerebrum,  and  numerous  furrows  for  the  lodgment  of  branches 
of  the  meningeal  arteries.  Along  the  middle  line  of  this  surface  is  a  longitudinal 
groove,  narrow  in  front,  where  it  terminates  in  the  frontal  crest :  broader  behind ; 
it  lodges  the  superior  longitudinal  sinus,  and  its  margins  afford  attachment  to  the 
falx  cerebri.  On  either  side  of  it  are  several  depressions  for  the  Pacchionian 
bodies,  and  at  its  back  part,  the  internal  openings  of  the  parietal  foramina.  This 
surface  is  crossed,  in  front,  by  the  coronal  suture ;  from  before  backwards,  by  the 
sagittal ;  behind,  by  the  lambdoid. 


BASE    OP   THE    SKULL. 


99 


Base  of  the  Skull. 

The  Inferior  Region  or  Base  of  the  skull  presents  two  surfaces,  an  internal  or 
cerebral,  and  an  external  or  basilar. 


Fig.  62.— Base  of  the  Skull.     Inner  or  Cerebral  Surface. 


Groove  for  Super.  "Lmoititd.  Sinus 

Qroovtt  for  Avter.  Meiiiiitjfal A 

Foramen  t'otruiti 

Crista  GtiMi 

Slit  for  Vttml  nervtk. 

Qrooi't  Jnr  Tfvtxnlj  nerve. 
Anterior  Ethmoidal  For. 

Orifioee  far  Olfactory  verve 
Posterior  Etlimaidal  Fort 


.Ethmoidal  Spine  - 


Olfactory  Croats 

Optic    Foravun 
Optic  Oroovt- 
Olivary  pre, 
Anterior  Clinoid  proa 

Middle  Clinoid  proc 

Foste  rio  r  Clinoid  proa 

Groove  for  6'$  nerve 

Tor"  laeerum  medium. 

Orifice  of  Carotid,  Canal 

Depression  for  Casserian  Ganglion 


Meatus  Auditor.  Tntemris 

Slit  for  Vara  -Ma  Wr 

Sup.  Petrosal  groove 

For.  laeerum  poster itu 


Anterior  Condyloid  For 
Aqueduct.  Veetibuli 
Posterior  Condyloid  For. 


Mastoid  Foe 
Lost.  Meningeal  Grooves. 


100  OSTEOLOGY. 

The  Internal  or  Cerebral  Surface  (fig.  62)  presents  three  fossae  on  each  side, 
called  the  anterior,  middle  and  posterior  fossae  of  the  cranium. 

The  Anterior  Fossa  is  formed  by  the  orbital  plate  of  the  frontal,  the  cribriform 
plate  of  the  ethmoid,  the  ethmoidal  process  and  lesser  wing  of  the  sphenoid.  It 
is  the  most  elevated  of  the  three  fossae,  convex  externally  where  it  corresponds  to 
the  roof  of  the  orbit,  concave  in  the  median  line  in  the  situation  of  the  cribriform 
plate  of  the  ethmoid.  It  is  traversed  by  three  sutures,  the  ethmoido-frontal, 
ethmo-sphenoidal,  and  fronto-sphenoidal ;  and  lodges  the  anterior  lobe  of  the  cere- 
brum. It  presents,  in  the  median  line,  from  before  backwards,  the  commencement 
of  the  groove  for  the  superior  longitudinal  sinus,  and  crest  for  the  attachment  of 
the  falx  cerebri;  the  foramen  caecum,  this  aperture  being  formed  by  the  frontal  and 
crista  galli  of  the  ethmoid,  and,  if  pervious,  transmitting  a  small  vein  from  the  nose 
to  the  superior  longitudinal  sinus.  Behind  the  foramen  caecum  is  the  crista  galli, 
the  posterior  margin  of  which  affords  attachment  to  the  falx  cerebri.  On  either 
side  of  the  crista  galli  is  the  olfactory  groove,  which  supports  the  bulb  of  the 
olfactory  nerve,  perforated  by  three  rows  of  orifices  which  give  passage  to  its 
filaments;  and  in  front  by  a  slit-like  opening,  which  transmits  the  nasal  branch 
of  the  ophthalmic  nerve.  On  the  outer  side  of  each  olfactory  groove  are  the 
internal  openings  of  the  anterior  and  posterior  ethmoidal  foramina;  the  former, 
situated  about  the  middle  of  its  outer  margin,  transmits  the  nasal  nerve,  which 
runs  in  a  groove  along  its  surface  to  the  slit-like  opening  above  mentioned;  whilst 
the  latter,  the  posterior  ethmoidal  foramen,  opens  at  the  back  part  of  the  margin 
under  cover  of  a  projecting  lamina  of  the  sphenoid ;  it  transmits  the  posterior 
ethmoidal  artery  and  vein  to  the  posterior  ethmoidal  cells.  Further  back  in  the 
middle  line  is  the  ethmoidal  spine,  bounded  behind  by  an  elevated  ridge,  sepa- 
rating a  longitudinal  groove  on  each  side  which  supports  the  olfactory  nerve. 
The  anterior  fossa  presents  laterally  eminences  and  depressions  for  the  convolu- 
tions of  the  brain,  and  grooves  for  the  lodgment  of  the  anterior  meningeal  arteries. 

The  Middle  Fossa,  somewhat  deeper  than  the  preceding,  is  narrow  in  the  middle, 
and  becomes  wider  as  it  expands  laterally.  It  is  bounded  in  front  by  the  posterior 
margin  of  the  lesser  wing  of  the  sphenoid,  the  anterior  clinoid  process,  and  the 
anterior  margin  of  the  optic  groove;  behind,  by  the  petrous  portion  of  the  tem- 
poral, and  basilar  suture;  externally,  by  the  squamous  portion  of  the  temporal, 
and  anterior  inferior  angle  of  the  parietal  bone ;  and  is  separated  from  its  fellow  by 
the  sella  Turcica.  It  is  traversed  by  four  sutures,  the  squamous,  sphenoparietal, 
spheno-temporal,  and  petro-sphenoidal. 

In  the  middle  line,  from  before  backwards,  is  the  optic  groove,  which  supports 
the  optic  commissure,  terminating  on  each  side  in  the  optic  foramen,  for  the 
passage  of  the  optic  nerve  and  ophthalmic  artery ;  behind  the  optic  groove  is 
the  olivary  process,  and  laterally  the  anterior  clinoid  processes,  which  afford 
attachment  to  the  folds  of  the  dura  mater,  which  form  the  cavernous  sinuses. 
Separating  the  middle  fossae  is  the  sella  Turcica,  a  deep  depression,  which  lodges 
the  pituitary  gland,  bounded  in  front  by  a  small  eminence  on  either  side,  the 
middle  clinoid  process,  and  behind  by  a  broad  square  plate  of  bone,  surmounted 
at  each  superior  angle  by  a  tubercle,  the  posterior  clinoid  process;  beneath  the 
latter  process  is  a  groove,  for  the  lodgment  of  the  sixth  nerve.  On  each  side  of  the 
sella  Turcica  is  the  cavernous  groove;  it  is  broad,  shallow,  and  curved  somewhat 
like  the  Italic  letter/:  it  commences  behind  at  the  foramen  lacerum  medium,  and 
terminates  on  the  inner  side  of  the  anterior  clinoid  process.  This  groove  lodges 
the  cavernous  sinus,  the  internal  carotid  artery,  and  the  orbital  nerves.  The  sides 
of  the  middle  fossa  are  of  considerable  depth;  they  present  eminences  and  depres- 
sions for  the  middle  lobes  of  the  brain,  and  grooves  for  lodging  the  branches  of 
the  middle  meningeal  artery ;  the  latter  commence  on  the  outer  side  of  the  fora- 
men spinosum,  and  consist  of  two  large  branches,  an  anterior  and  a  posterior ;  the 
former  passing  upwards  and  forwards  to  the  anterior  inferior  angle  of  the  parietal 
bone,  the  latter  passing  upwards  and  backwards.  The  following  foramina  may 
also  be  seen  from  before  backwards.     Most  anteriorly  is  the  foramen  lacerum 


BASE   OF   THE    SKULL.  101 

anterius,  or  sphenoidal  fissure,  formed  above  by  the  lesser  wing  of  the  sphenoid ; 
below,  by  the  greater  wing ;  internally,  by  the  body  of  the  sphenoid ;  and  com- 
pleted externally  by  the  orbital  plate  of  the  frontal  bone.  It  transmits  the  third, 
fourth,  the  three  branches  of  the  ophthalmic  division  of  the  fifth,  the  sixth  nerve, 
and  the  ophthalmic  vein.  Behind  the  inner  extremity  of  the  sphenoidal  fissure 
is  the  foramen  rotundum,  for  the  passage  of  the  second  division  of  the  fifth  or 
superior  maxillary  nerve ;  still  more  posteriorly  is  seen  a  small  orifice,  the  foramen 
Vesalii;  this  opening  is  situated  between  the  foramen  rotundum  and  foramen  ovale, 
a  little  internal  to  both ;  it  varies  in  size  in  different  individuals,  and  transmits  a  small 
vein.  It  opens  below  in  the  pterygoid  fossa,  just  at  the  outer  side  of  the  scaphoid 
depression.  Behind  and  external  to  the  latter  opening  is  the  foramen  ovale,  which 
transmits  the  third  division  of  the  fifth  or  inferior  maxillary  nerve,  the  small 
meningeal  artery,  and  the  small  petrosal  nerve.  On  the  outer  side  of  the  foramen 
ovale  is  the  foramen  spinosum,  for  the  passage  of  the  middle  meningeal  artery ; 
and  on  the  inner  side  of  the  foramen  ovale,  the  foramen  lacerum  medium.  The 
lower  part  of  this  aperture  is  filled  up  with  cartilage  in  the  recent  state.  On  the 
anterior  surface  of  the  petrous  portion  of  the  temporal  bone  is  seen,  from  without 
inwards,  the  eminence  caused  by  the  projection  of  the  superior  semicircular  canal, 
and  the  groove  leading  to  the  hiatus  Fallopii,  for  the  transmission  of  the  petrosal 
branch  of  the  Vidian  nerve;  beneath  it,  the  smaller  groove,  for  the  passage  of  the 
smaller  petrosal  nerve ;  and  near  the  apex  of  the  bone,  the  depression  for  the 
Casserian  ganglion,  and  the  orifice  of  the  carotid  canal,  for  the  passage  of  the 
internal  carotid  artery  and  carotid  plexus  of  nerves. 

The  Posterior  Fossa,  deeply  concave,  is  the  largest  of  the  three,  and  situated  on 
a  lower  level  than  either  of  the  preceding.  It  is  formed  by  the  occipital,  the 
petrous  and  mastoid  portions  of  the  temporal,  and  the  posterior  inferior  angle  of 
the  parietal  bone ;  is  crossed  by  three  sutures,  the  petro-occipital,  masto-occipital, 
and  masto-parietal ;  and  lodges  the  cerebellum,  pons  Varolii,  and  medulla  oblon- 
gata. It  is  separated  from  the  middle  fossa  in  the  median  line  by  the  basilar 
suture,  and  on  each  side  by  the  superior  border  of  the  petrous  portion  of  the 
temporal  bone.  This  serves  for  the  attachment  of  the  tentorium  cerebelli,  is 
grooved  externally  for  the  superior  petrosal  sinus,  and  at  its  inner  extremity  pre- 
sents a  notch,  upon  which  rests  the  fifth  nerve.  Its  circumference  is  bounded 
posteriorly  by  the  grooves  for  the  lateral  sinuses.  In  the  centre  of  this  fossa  is 
the  foramen  magnum,  bounded  on  either  side  by  a  rough  tubercle,  which  gives 
attachment  to  the  odontoid  ligaments;  and  a  little  above  these  are  seen  the 
internal  openings  of  the  anterior  condyloid  foramina.  In  front  of  the  foramen 
magnum  is  the  basilar  process,  grooved  for  the  support  of  the  medulla  oblongata 
and  pons  Varolii,  and  articulating  on  each  side  with  the  petrous  portion  of  the  tem- 
poral bone,  forming  the  petro-occipital  suture,  the  anterior  half  of  which  is  grooved 
for  the  inferior  petrosal  sinus,  the  posterior  half  being  encroached  upon  by  the 
foramen  lacerum  posterius  or  jugular  foramen.  This  foramen  is  partially  subdi- 
vided into  two  parts ;  the  posterior  and  larger  division  transmits  the  internal  jugu- 
lar vein,  the  anterior  the  eighth  pair  of  nerves.  Above  the  jugular  foramen  is  the 
internal  auditory  foramen,  for  the  auditory  and  facial  nerves  and  auditory  artery; 
behind  and  external  to  this  is  the  slit-like  opening  leading  into  the  aquaeductus 
vestibuli;  whilst  between  the  two  latter,  and  near  the  superior  border  of  the 
petrous  portion,  is  a  small  triangular  depression,  which  lodges  a  process  of 
the  dura  mater,  and  occasionally  transmits  a  small  vein  into  the  substance  of  the 
bone.  Behind  the  foramen  magnum  are  the  inferior  occipital  fossae,  which  lodge 
the  lateral  lobes  of  the  cerebellum,  separated  from  one  another  by  the  internal 
occipital  crest,  which  serves  for  the  attachment  of  the  falx  cerebelli,  and  lodges 
the  occipital  sinuses.  These  fossae  are  surmounted,  above,  by  the  deep  transverse 
grooves  for  the  lodgment  of  the  lateral  sinuses.  These  channels,  in  their  passage 
outwards,  groove  the  occipital  bone,  the  posterior  inferior  angle  of  the  parietal,  the 
mastoid  portion  of  the  temporal,  and  the  occipital  just  behind  the  jugular  foramen, 
at  the  back  part  of  which  they  terminate.     Where  this  sinus  grooves  the  mastoid 


102  OSTEOLOGY. 

part  of  the  temporal  bone,  the  orifice  of  the  mastoid  foramen  may  be  seen ;  and, 
just  previous  to  its  termination,  it  has  opening  into  it  the  posterior  condyloid 
foramen. 

The  External  Surface  of  the  base  of  the  skull  (fig.  63)  is  extremely  irregular. 
It  is  bounded  in  front  by  the  incisor  teeth  in  the  upper  jaws ;  behind,  by  the 
superior  curved  lines  of  the  occipital  bone ;  and  laterally,  by  the  alveolar  arch,  the 
lower  border  of  the  malar  bone,  the  zygoma,  and  an  imaginary  line,  extending 
from  the  zygoma  to  the  mastoid  process  and  extremity  of  the  superior  curved  line 
of  the  occiput.  It  is  formed  by  the  palate  processes  of  the  two  superior  maxillary 
and  palate  bones,  the  vomer,  the  pterygoid,  under  surface  of  the  great  wing, 
spinous  process  and  part  of  the  body  of  the  sphenoid,  the  under  surface  of  the 
squamous,  mastoid,  and  petrous '  portions  of  the  temporal,  and  occipital  bones. 
The  anterior  part  of  the  base  of  the  skull  is  raised  above  the  level  of  the  rest  of 
this  surface  (when  the  skull  is  turned  over  for  the  purpose  of  examination), 
surrounded  by  the  alveolar  process,  which  is  thicker  behind  than  in  front,  and 
excavated  by  sixteen  depressions  for  lodging  the  teeth  of  the  upper  jaw ;  they 
vary  in  depth  and  size  according  to  the  teeth  they  contain.  Immediately  behind 
the  incisor  teeth  is  the  anterior  palatine  fossa.  At  the  bottom  of  this  fossa  may 
usually  be  seen  four  apertures,  two  placed  laterally,  which  open  above,  one  in  the 
floor  of  each  nostril,  and  transmit  the  anterior  palatine  vessels,  and  two  in 
the  median  line  of  the  intermaxillary  suture,  one  in  front  of  the  other,  the  most 
anterior  one  transmitting  the  left,  and  the  posterior  one  (the  larger)  the  right 
naso-palatine  nerve.  These  two  latter  canals  are  sometimes  wanting,  or  they  may 
join  to  form  a  single  one,  or  one  of  them  may  open  into  one  of  the  lateral  canals 
above  referred  to.  The  palatine  vault  is  concave,  uneven,  perforated  by  numerous 
foramina,  marked  by  depressions  for  the  palatal  glands,  and  crossed  by  a  crucial 
suture,  which  indicates  the  point  of  junction  of  the  four  bones  of  which  it  is  com- 
posed. One  or  two  small  foramina,  seen  in  the  alveolar  margin  behind  the  incisor 
teeth,  occasionally  seen  in  the  adult,  almost  constant  in  young  subjects,  are  called  the 
incisive  foramina ;  they  transmit  nerves  and  vessels  to  the  incisor  teeth.  At  each 
posterior  angle  of  the  bard  palate  is  the  posterior  palatine  foramen,  for  the  trans- 
mission of  the  posterior  palatine  vessels  and  anterior  palatine  nerve,  and  running 
forwards  and  inwards  from  it  a  groove,  which  lodges  the  same  vessels  and  nerve. 
Behind  the  posterior  palatine  foramen  is  the  tuberosity  of  the  palate  bone,  per- 
forated by  one  or  more  accessory  posterior  palatine  canals,  and  marked  by  the 
commencement  of  a  ridge,  which  runs  transversely  inwards,  and  serves  for  the 
attachment  of  the  tendinous  expansion  of  the  Tensor  palati.  muscle.  Projecting 
backwards  from  the  centre  of  the  posterior  border  of  the  hard  palate  is  the  pos- 
terior nasal  spine,  for  the  attachment  of  the  Azygos  uvulae.  Behind  and  above 
the  hard  palate  is  the  posterior  aperture  of  the  nares,  divided  into  two  parts  by 
the  vomer,  bounded  above  by  the  body  of  the  sphenoid,  below  by  the  horizontal 
plate  of  the  palate  bone,  and  laterally  by  the  pterygoid  processes  of  the  sphenoid. 
Each  aperture  measures  about  an  inch  in  the  vertical,  and  half  an  inch  in  the 
transverse  direction.  At  the  base  of  the  vomer  may  be  seen  the  expanded  aloe 
of  this  bone,  receiving  between  them  the  rostrum  of  the  sphenoid.  Near  the 
lateral  margins  of  the  vomer,  at  the  root  of  the  pterygoid  processes,  are  the 
pterygo-palatine  canals.  The  pterygoid  process,  which  bounds  the  posterior 
nares  on  each  side,  presents  near  its  base  the  pterygoid  or  Vidian  canal,  for  the 
Vidian  nerve  and  artery.  Each  process  consists  of  two  plates,  which  bifurcate 
at  the  extremity  to  receive  the  tuberosity  of  the  palate  bone,  and  are  separated 
behind  by  the  pterygoid  fossa,  which  lodges  the  Internal  pterygoid  muscle.  The 
internal  plate  is  long  and  narrow,  presenting  on  the  outer  side  of  its  base  the 
scaphoid  fossa,  for  the  origin  of  the  Tensor  palati  muscle,  and  at  its  extremity 
the  hamular  process,  around  which  the  tendon  of  this  muscle  turns.  The  external 
pterygoid  plate  is  broad,  forms  the  inner  boundary  of  the  zygomatic  fossa,  and 
affords  attachment  to  the  External  pterygoid  muscle. 


BASE   OF   THE    SKULL. 


103 


Behind  the  nasal  fossa)  in  the  middle  line  is  the  basilar  surface  of  the  occipital 
bone,  presenting  in  its  centre  the  pharyngeal  spine  for  the  attachment  of  the 

Fig.  63.— Base  of  the  Skull.     External  Surface. 


Ant.  pala/tim  fossa 

'mnsmits  left  Naso-palat.  n. 
Transmit*  A<nz.  palat  vess. 
Transmits   riyht  Na so pala t.n. 


deces  sary  palatine 
Foram-i  na . 

■Pflft.NastU  Spin*. 

AilOOt     UVULA 

Ila  inula  r  jj  rot: 

SpJienoid.proc.  of  Palate-. 
1'ttrijtjo-ualatt  ii€  C. 


-T.ENSOR    TVMPANI. 

PJtxiry7Ufca.lSpinr.firr  8UP.  CONSTRICT. 

Sif  tfEittttuAuin  tti*  k  CamtlferTentrrTyrm, 

lajatof    TrmpxMi. 
Ctiiuil  Jot  Jacobs on  i  n. 
Aqueduct.  CtfchUa. 
""*  For.  lore  rii-  mpusterai  s. 
Ca.na.lft/rJlrnoUty  it. 
.Xu.riculo.r  fissiiig 


104  OSTEOLOGY. 

Superior  constrictor  muscle  of  the  pharynx,  with  depressions  on  each  side  for  the 
insertion  of  the  Rectus  anticus  major  and  minor.  At  the  base  of  the  external 
pterygoid  plate  is  the  foramen  ovale ;  behind  this,  the  foramen  spinosum,  and  the 
prominent  spinous  process  of  the  sphenoid,  which  gives  attachment  to  the  internal 
lateral  ligament  of  the  lower  jaw  and  the  Laxator  tympani  muscle.  External  to 
the  spinous  process  is  the  glenoid  fossa,  divided  into  two  parts  by  the  Glaserian 
fissure,  the  anterior  portion  being  concave,  smooth,  bounded  in  front  by  the  emi- 
nentia  articularis,  and  serving  for  the  articulation  of  the  condyle  of  the  lower  jaw; 
the  posterior  portion  rough,  bounded  behind  by  the  vaginal  process,  and  serving 
for  the  reception  of  part  of  the  parotid  gland.  Emerging  from  between  the  lamina? 
of  the  vaginal  process  is  the  styloid  process ;  and  at  the  base  of  this  process  is  the 
stylo-mastoid  foramen,  for  the  exit  of  the  facial  nerve,  and  entrance  of  the  stylo- 
mastoid artery.  External  to  the  stylo-mastoid  foramen  is  the  auricular  fissure  for 
the  auricular  branch  of  the  pneumogastric,  bounded  behind  by  the  mastoid  process. 
Upon  the  inner  side  of  the  mastoid  process  is  a  deep  groove,  the  digastric  fossa; 
and  a  little  more  internally,  the  occipital  groove,  for  the  occipital  artery.  At  the 
base  of  the  internal  pterygoid  plate  is  a  large  and  somewhat  triangular  aperture, 
the  foramen  lacerum  medium,  bounded  in  front  by  the  great  wing  of  the  sphenoid, 
behind  by  the  apex  of  the  petrous  portion  of  the  temporal  bone,  and  internally 
by  the  body  of  the  sphenoid  and  basilar  process  of  the  occipital  bone;  it  presents 
in  front  the  posterior  orifice  of  the  Vidian  canal;  behind,  the  aperture  of  the 
carotid  canal.  The  basilar  surface  of  this  opening  is  filled  up  in  the  recent  state 
by  a  fibro-cartilaginous  substance ;  across  its  upper  or  cerebral  aspect  pass  the 
internal  carotid  artery  and  Vidian  nerve.  External  to  this  aperture,  the  petro- 
sphenoidal  suture  is  observed,  at  the  outer  termination  of  which  is  seen  the  orifice 
of  the  canal  for  the  Eustachian  tube,  and  that  for  the  Tensor  tympani  muscle. 
Behind  this  suture  is  seen  the  under  surface  of  the  petrous  portion  of  the  tem- 
poral bone,  presenting  from  within  outwards  the  quadrilateral  rough  surface, 
part  of  which  affords  attachment  to  the  Levator  palati  and  Tensor  tympani  . 
muscles;  external  to  this  surface  are  the  orifices  of  the  carotid  canal  and  the 
aquaeductus  cochlea?,  the  former  transmitting  the  internal  carotid  artery  and  the 
ascending  branches  of  the  superior  cervical  ganglion  of  the  sympathetic,  the  latter 
serving  for  the  passage  of  a  small  artery  and  vein  to  the  cochlea.  Behind  the 
carotid  canal  is  a  large  aperture,  the  jugular  fossa,  formed  in  front  by  the  petrous 
portion  of  the  temporal,  and  behind  by  the  occipital;  it  is  general^  larger  on  the 
right  than  on  the  left  side;  and  towards  its  cerebral  aspect  is  divided  into  two  parts 
by  a  ridge  of  bone,  which  projects  usually  from  the  temporal,  the  anterior  or  smaller 
portion  transmitting  the  three  divisions  of  the  eighth  pair  of  nerves ;  the  posterior 
transmitting  the  internal  jugular  vein  and  the  ascending  meningeal  vessels,  from 
the  occipital  and  ascending  pharyngeal  arteries.  On  the  ridge  of  bone  dividing 
the  carotid  canal  from  the  jugular  fossa,  is  the  small  foramen  for  the  transmission 
of  the  tympanic  nerve;  and  on  the  outer  wall  of  the  jugular  foramen,  near  the 
root  of  the  styloid  process,  is  the  small  aperture  for  the  transmission  of  Arnold's 
nerve.  Behind  the  basilar  surface  of  the  occipital  bone  is  the  foramen  magnum, 
bounded  on  each  side  by  the  condyles,  rough  internally  for  the  attachment  of  the 
alar  ligaments,  and  presenting  externally  a  rough  surface,  the  jugular  process, 
which  serves  for  the  attachment  of  the  Rectus  lateralis.  On  either  side  of  each 
condyle  anteriorly  is  the  anterior  condyloid  fossa,  perforated  by  the  anterior  con- 
dyloid foramen,  for  the  passage  of  the  hypoglossal  nerve.  Behind  each  condyle 
are  the  posterior  condyloid  fossae,  perforated  on  one  or  both  sides  by  the  posterior 
condyloid  foramina,  for  the  transmission  of  a  vein  to  the  lateral  sinus.  Behind 
the  foramen  magnum  is  the  external  occipital  crest,  terminating  above  at  the 
external  occipital  protuberance,  whilst  on  each  side  are  seen  the  superior  and 
inferior  curved  lines;  these,  as  well  as  the  surfaces  of  the  bone  between  them, 
being  rough  for  the  attachment  of  numerous  muscles. 


LATERAL  REGION  OF  THE  SKULL. 


105 


Lateral  Region  of  the  Skull. 

The  Lateral  Region  of  the  Skull  is  somewhat  of  a  triangular  form,  its  oase  being 
formed  by  a  line  extending  from  the  external  angular  process  of  the  frontal  bone 
along  the  temporal  ridge  backwards  to  the  outer  extremity  of  the  superior  curved 
line  of  the  occiput :  and  the  sides  being  formed  by  two  lines,  the  one  drawn 
downwards  and  backwards  from  the  external  angular  process  of  the  frontal  bone 
to  the  angle  of  the  lower  jaw,  the  other  from  the  angle  of  the  jaw  upwards  and 
backwards  to  the  extremity  of  the  superior  curved  line.  This  region  is  divisible 
into  three  portions,  temporal,  mastoid,  and  zygomatic. 


G4.— Side  View  of  the  Skull. 


Frenlal 


'artelal 


The  Temporal  Fossae. 

The  Temporal  fossa  is  bounded  above  and  behind  by  the  temporal  ridge,  which 
extends  from  the  external  angular  process  of  the  frontal  upwards  and  backwards 
across  the  frontal  and  parietal  bones,  curving  downwards  behind  to  terminate  at 
the  root  of  the  zygomatic  process.  In  front,  it  is  bounded  by  the  frontal,  malar, 
and  great  wing  of  the  sphenoid :  externally,  by  the  zygomatic  arch,  formed 
conjointly  by  the  malar  and  temporal  bones;  below,  it  is  separated  from  the 
zygomatic  fossa  by  the  pterygoid  ridge,  seen  on  the  outer  surface  of  the  great 
wing  of  the  sphenoid.  This  fossa  is  formed  by  five  bones,  part  of  the  frontal, 
great  wing  of  the  sphenoid,  parietal,  squamous  portion  of  the  temporal,  and  malar 
bones,  and  is  traversed  by  five  sutures,  the  transverse  facial,  coronal,  spheno 
parietal,  squamo-parietal,  and  squamo-sphenoidal.  It  is  deeply  concave  in  front, 
convex  behind,  traversed  by  grooves  for  lodging  branches  of  the  deep  temporal 
arteries,  and  filled  by  the  Temporal  muscle. 


106  OSTEOLOGY. 

The  Mastoid  Portion  is  bounded  in  front  by  the  anterior  root  of  the  zygoma ; 
above,  by  a  line  which  runs  from  the  posterior  root  of  the  zygoma  to  the  end  of 
the  masto-parietal  suture ;  -behind  and  below,  by  the  masto-occipital  suture.  It 
is  formed  by  the  mastoid  and  part  of  the  squamous  portion  of  the  temporal  bone ; 
its  surface  is  convex  and  rough  for  the  attachment  of  muscles,  and  presents,  from 
behind  forwards,  the  mastoid  foramen,  the  mastoid  process,  the  external  auditory 
meatus,  surrounded  by  the  auditory  process,  and,  most  anteriorly,  the  glenoid 
fossa,  bounded  in  front  by  the  eminentia  articularis,  behind  by  the  vaginal  process. 

The  Zygomatic  Fossae. 

The  Zygomatic  fossa  is  an  irregular-shaped  cavity,  situated  below,  and  on  the 
inner  side  of  the  zygoma ;  bounded,  in  front,  by  the  tuberosity  of  the  superior 
maxillary  bone  and  the  ridge  which  descends  from  its  malar  process";  behind, 
by  the  posterior  border  of  the  pterygoid  process ;  above,  by  the  pterygoid  ridge 
on  the  outer  surface  of  the  great  wing  of  the  sphenoid  and  squamous  portion  of 
the  temporal ;  below,  by  the  alveolar  border  of  the  superior  maxilla ;  internally, 
by  the  external  pterygoid  plate ;  and  externally,  by  the  zygomatic  arch  and 
ramus  of  the  jaw.  It  contains  the  lower  part  of  the  Temporal,  the  External  and 
Internal  pterygoid  muscles,  the  internal  maxillary  artery,  the  inferior  maxillary 
nerve,  and  their  branches.  At  its  upper  and  inner  part  may  be  observed  two 
fissures,  the  spheno-maxillary  and  pterygo-maxillary. 

The  Spheno-maxillary  fissure,  horizontal  in  direction,  opens  into  the  outer  and 
back  part  of  the  orbit.  It  is  formed  above  by  the  lower  border  of  the  orbital 
surface  of  the  great  wing  of  the  sphenoid ;  below,  by  the  external  border  of  the 
orbital  surface  of  the  superior  maxillary  and  a  small  part  of  the  palate  bone ; 
externally,  by  a  small  part  of  the  malar  bone ;  internally,  it  joins  at  right  angles 
with  the  pterygo-maxillary  fissure.  This  fissure  opens  a  communication  from  the 
orbit  into  three  fossa?,  the  temporal,  zygomatic,  and  spheno-maxillary;  it  transmits 
the  superior  maxillary  nerve,  infra-orbital  artery,  and  ascending  branches  from 
Meckel's  ganglion. 

The  Pterygo-maxillary  fissure  is  vertical,  and  descends  at  right  angles  from 
the  inner  extremity  of  the  preceding ;  it  is  an  elongated  interval,  formed  by  the 
divergence  of  the  superior  maxillary  bone  from  the  pterygoid  process  of  the 
sphenoid.  It  serves  to  connect  the  spheno-maxillary  fossa  with  the  zygomatic, 
and  transmits  branches  of  the  internal  maxillary  artery. 

The  Spheno-Maxillaey  Fossa. 

The  Spheno-maxillary  fossa  is  a  small  triangular  space  situated  at  the  angle  of 
junction  of  the  spheno-maxillary  and  pterygo-maxillary  fissures,  and  placed 
beneath  the  apex  of  the  orbit.  It  is  formed  above  by  the  under  surface  of  the 
body  of  the  sphenoid;  in  front,  by  the  superior  maxillary  bone;  behind,  by  the 
pterygoid  process  of  the  sphenoid ;  internally,  by  the  vertical  plate  of  the  palate. 
This  fossa  has  three  fissures  terminating  in  it,  the  sphenoidal,  spheno-maxillary, 
and  pterygo-maxillary ;  it  communicates  with  three  fossa?,  the  orbital,  nasal,  and 
zygomatic,  and  with  the  cavity  of  the  cranium,  and  has  opening  into  it  five  fora- 
mina. Of  these  there  are  three  on  the  posterior  wall,  the  foramen  rotundum 
above,  the  Vidian  below  and  internal,  and,  still  more  inferior  and  internal,  the 
pterygo-palatine.  On  the  inner  wall  is  the  spheno-palatine  foramen  by  which  it 
communicates  with  the  nasal  fossa,  and  below,  the  superior  orifice  of  the  posterior 
palatine  canal,  besides  occasionally  the  orifices  of  two  or  three  accessory  posterior 
palatine  canals. 

Anterior  Eegion  of  the  Skull. 

The  Anterior  Eegion  of  the  Skull,  which  forms  the  face,  is  of  an  oval  form, 
presents  an  irregular  surface,  and  is  excavated  for  the  reception  of  the  two  prin- 
cipal organs  of  sense,  the  eye  and  the  nose.     It  is  bounded  above  by  the  nasal 


ANTERIOR  REGION  OF  THE  SKULL. 


101 


eminences  and  margins  of  the  orbit ;  below,  by  the  prominence  of  the  chin ;  on 
each  side,  by  the  malar  bone  and  anterior  margin  of  the  ramus  of  the  jaw.  In 
the  median  line  are  seen  from  above  downwards,  the  nasal  eminences,  which 
indicate  the  situation  of  the  frontal  sinuses ;  diverging'  outwards  from  the  nasal 
eminences  are  the  superciliary  ridges  which  support  the  eyebrows.  Beneath  the 
nasal  eminences  are  the  arch  of  the  nose,  formed  by  the  nasal  bones,  and  the  nasal 
processes  of  the  superior  maxillary.  The  nasal  arch  is  convex  from  side  to  side, 
concave  from  above  downwards,  presenting  in  the  median  line  the  inter-nasal 
suture,  formed  between  the  nasal  bones,  laterally  the  naso-maxillary  suture, 
formed  between  the  nasal  bone  and  the  nasal  process  of  the  superior  maxillary 
bones,  both  these  sutures  terminating  above  in  that  part  of  the  transverse  suture 

Fig.  65. — Anterior  Region  of  the  Skull. 
1&0K'**?*       hone 


TIN  DO    OCULI 


JLnten-or 
JVarea 


Ant.  Nasal  Spin* 
Jncis-ivc,  fossa 


Orcove  far  TtLtstal  a  Y 


which  connects  the  nasal  bones  and  nasal  processes  of  the  superior  maxillary 
with  the  frontal.  Below  the  nose  is  seen  the  heart-shaped  opening  of  the  ante- 
rior nares,  the  narrow  end  upwards,  and  broad  below ;  it  presents  laterally  the 
thin  sharp  margins  which  serve  for  the  attachment  of  the  lateral  cartilages  of 
the  nose,  and  in  the  middle  line  below,  a  prominent  process,  the  anterior  nasal 
spine,  bounded  by  two  deep  notches.  Below  this  is  the  intermaxillary  suture, 
and  on  each  side  of  it  the  incisive  fossa.  Beneath  this  fossa  is  the  alveolar- pro- 
cess of  the  upper  and  lower  jaw,  containing  the  incisor  teeth,  and,  at  the-  lower 
part  of  the  median  line,  the  symphysis  of  the  chin,  the  mental  eminence,,  ami  the 
incisive  fossa  of  the  lower  jaw. 

Proceeding  from  above  downwards,  on  each  side,  is  the  supra-orbital  ridge. 


103  OSTEOLOGY. 

terminating  externally  in  the  external  angular  process  at  its  junction  with  the 
malar,  and  internally  in  the  internal  angular  process ;  towards  the  inner  third  of 
this  ridge  is  the  supra-orbital  notch  or  foramen,  for  the  passage  of  the  supra- 
orbital vessels  and  nerve,  and  at  its  inner  side  a  slight  depression  for  the  attach- 
ment of  the  cartilaginous  pulley  of  the  Superior  oblique  muscle.  Beneath  the 
supra-orbital  ridge  is  the  opening  of  the  orbit,  bounded  externally  by  the  orbital 
ridge  of  the  malar  bone ;  below,  by  the  orbital  ridge  formed  by  the  malar,  supe- 
rior maxillary,  and  lachrymal  bones ;  internally,  by  the  nasal  process  of  the  supe- 
rior maxillary,  and  the  internal  angular  process  of  the  frontal  bone.  On  the  outer 
side  of  the  orbit,  is  the  quadrilateral  anterior  surface  of  the  malar  bone,  perforated 
by  one  or  two  small  malar  foramina.  Below  the  inferior  margin  of  the  orbit  is 
the  infra-orbital  foramen,  the  termination  of  the  infra-orbital  canal,  and,  beneath 
this,  the  canine  fossa,  which  gives  attachment  to  the  Levator  anguli  oris ;  bounded 
below  by  the  alveolar  processes,  containing  the  teeth  of  the  upper  and  lower  jaw. 
Beneath  the  alveolar  arch  of  the  lower  jaw  are  the  mental  foramen  for  the  passage 
of  the  mental  nerve  and  artery,  the  external  oblique  line,  and  at  the  lower  border  of 
the  bone,  at  the  point  of  junction  of  the  body  with  the  ramus,  a  shallow  groove 
for  the  passage  of  the  facial  artery. 

The  Orbits. 

The  Orbits  (fig.  65)  are  two  quadrilateral  hollow  cones,  situated  at  the  upper 
and  anterior  part  of  the  face,  their  bases  being  directed  forwards  and  outwards, 
and  their  apices  backwards  and  inwards.  Each  orbit  is  formed  of  seven  bones, 
the  frontal,  sphenoid,  ethmoid,  superior  maxillary,  malar,  lachrymal,  and  palate ; 
but  three  of  these,  the  frontal,  ethmoid,  and  sphenoid,  enter  into  the  formation  of 
both  orbits,  so  that  the  two  cavities  are  formed  of  eleven  bones  only.  Each  cavity 
presents  for  examination,  a  roof,  a  floor,  an  inner  and  an  outer  wall,  a  circumfer- 
ence or  base,  and  an  apex.  The  Roof  is  concave,  directed  downwards  and  for- 
wards, and  formed  in  front  by  the  orbital  plate  of  the  frontal ;  behind,  by  the 
lesser  wing  of  the  sphenoid.  This  surface  presents  internally  the  depression  for 
the  nbro-cartilaginous  pulley  of  the  Superior  oblique  muscle ;  externally,  the 
depression  for  the  lachrymal  gland,  and  posteriorly,  the  suture  connecting  the 
frontal  and  lesser  wing  of  the  sphenoid. 

The  Floor  is  nearly  flat,  and  of  less  extent  than  the  roof;  it  is  formed  chiefly 
by  the  orbital  process  of  the  superior  maxillary;  in  front,  to  a  small  extent,  by 
the  orbital  process  of  the  malar,  and  behind,  by  the  orbital  surface  of  the  palate. 
This  surface  presents  at  its  anterior  and  internal  part,  just  external  to  the  lachry- 
mal canal,  a  depression  for  the  attachment  of  the  Inferior  oblique  muscle ;  exter- 
nally, the  suture  between  the  malar  and  superior  maxillary  bones ;  near  its  middle, 
the  infra-orbital  groove ;  and  posteriorly,  the  suture  between  the  maxillary  and 
palate  bones. 

The  Inner  Wall  is  flattened,  and  formed  from  before  backwards  by  the  nasal 
process  of  the  superior  maxillary,  the  lachrymal,  os  planum  of  the  ethmoid,  and 
a  small  part  of  the  body  of  the  sphenoid.  This  surface  presents  the  lachrymal 
groove,  and  crest  of  the  lachrj^mal  bone,  and  the  sutures  connecting  the  ethmoid, 
in  front,  with  the  lachrymal,  behind,  with  the  sphenoid. 

The  Outer  Wall  is  formed  in  front  by  the  orbital  process  of  the  malar  bone ; 
behind,  by  the  orbital  plate  of  the  sphenoid.  On  it  are  seen  the  orifices  of  one 
or  two  malar  canals,  and  the  suture  connecting  the  sphenoid  and  malar  bones. 

Angles.  The  superior  external  angle  is  formed  by  the  junction  of  the  upper  and 
outer  walls ;  it  presents,  from  before  backwards,  the  suture  connecting  the  frontal 
with  the  malar  in  front,  and  with  the  orbital  plate  of  the  sphenoid  behind ;  quite 
posteriorly  is  the  foramen  lacerum  anterius,  or  sphenoidal  fissure,  which  transmits 
the  third,  fourth,  ophthalmic  division  of  the  fifth  and  sixth  nerves,  and  the 
ophthalmic  vein.  The  superior  internal  angle  is  formed  by  the  junction  of  the 
upper  and  inner  wall,  and  presents  the  suture  connecting  the  frontal  with  the 
hcoxymal  in  front,  and  with  the  ethmoid  behind.     This  suture  is  perforated  by 


NASAL   F0SSJ3.  109 

two  foramina,  the  anterior  and  posterior  ethmoidal,  the  former  transmitting 
the  anterior  ethmoidal  artery  and  nasal  nerve,  the  latter  the  posterior  ethmoidal 
artery  and  vein.  The  inferior  external  angle,  formed  by  the  junction  of  the  outer 
wall  and  floor,  presents  the  spheno-maxillary  fissure,  which  transmits  the  infra- 
orbital vessels  and  nerve,  and  the  ascending  branches  from  the  spheno-palatine 
ganglion.  The  inferior  internal  angle  is  formed  by  the  union  of  the  lachrymal  bone 
and  os  planum  of  the  ethmoid,  with  the  superior  maxillary  and  palate  bones.  The 
circumference  or  base  of  the  orbit,  quadrilateral  in  form,  is  bounded  above  by  the 
supra-orbital  arch ;  below,  by  the  anterior  border  of  the  orbital  plate  of  the  malar, 
superior  maxillary,  and  lachrymal  bones;  externally,  by  the  external  angular 
process  of  the  frontal  and  the  malar  bone ;  internally,  by  the  internal  angular 
process  of  the  frontal,  and  the  nasal  process  of  the  superior  maxillary.  The 
circumference  is  marked  by  three  sutures,  the  fronto- maxillary  internally,  the 
fronto-malar  externally,  and  the  malo-maxillary  below;  it  contributes  to  the 
formation  of  the  lachrymal  groove,  and  presents,  above,  the  supra-orbital  notch 
or  foramen,  for  the  passage  of  the  supra-orbital  artery,  veins,  and  nerve.  The 
apex,  situated  at  the  back  of  the  orbit,  corresponds  to  the  optic  foramen,  a  short 
circular  canal,  which  transmits  the  optic  nerve  and  ophthalmic  artery.  It  will 
thus  be  seen  that  there  are  nine  openings  communicating  with  each  orbit,  viz., 
the  optic,  foramen  lacerum  anterius,  spheno-maxillary  fissure,  supra-orbital  fora- 
men, infra-orbital  canal,  anterior  and  posterior  ethmoidal  foramina,  malar  foramina, 
and  lachrymal  canal. 

The  Nasal  Fossae. 

The  Nasal  Fossse  are  two  large  irregular  cavities,  situated  in  the  middle  line  of 
the  face,  extending  from  the  base  of  the  cranium  to  the  roof  of  the  mouth,  and 
separated  from  each  other  by  a  thin  vertical  septum.  They  communicate  by  two 
large  apertures,  the  anterior  nares,  with  the  front  of  the  face ;  and  with  the  pharynx 
behind  by  the  two  posterior  nares.  These  fossae  are  much  narrower  above  than 
below,  and  in  the  middle  than  at  the  anterior  or  posterior  openings :  their  depth, 
which  is  considerable,  is  much  greater  in  the  middle  than  at  either  extremity. 
Each  nasal  fossa  communicates  with  four  sinuses,  the  frontal  above,  the  sphenoidal 
behind,  and  the  maxillary  and  ethmoidal  on  either  side.  Each  fossa  also  commu- 
nicates with  four  cavities:  with  the  orbit  by  the  lachrymal  canal,  with  the  mouth 
by  the  anterior  palatine  canal,  with  the  cranium  by  the  olfactory  foramina,  and 
with  the  spheno-maxillary  fossa  by  the  spheno-palatine  foramen ;  and  they  occa- 
sionally communicate  with  each  other  by  an  aperture  in  the  septum.  The  bones 
entering  into  their  formation  are  fourteen  in  number :  three  of  the  cranium,  the 
frontal,  sphenoid,  and  ethmoid,  and  all  the  bones  of  the  face  excepting  the  malar  and 
lower  jaw.    Each  cavity  is  bounded  by  a  roof,  a  floor,  an  inner  and  an  outer  wall. 

The  upper  wall  or  roof  (fig.  66)  is  long,  narrow,  and  concave  from  before  back- 
wards ;  it  is  formed  in  front  by  the  nasal  bones  and  nasal  spine  of  the  frontal, 
which  are  directed  downwards  and  forwards ;  in  the  middle,  by  the  cribriform 
lamella  of  the  ethmoid,  which  is  horizontal ;  and  behind,  by  the  under  surface  of 
the  body  of  the  sphenoid,  and  sphenoidal  turbinated  bones,  which  are  directed 
downwards  and  backwards.  This  surface  presents,  from  before  backwards,  the 
internal  aspect  of  the  nasal  bones ;  on  their  outer  side,  the  suture  formed  between 
the  nasal,  with  the  nasal  process  of  the  superior  maxillary ;  on  their  inner  side, 
the  elevated  crest  which  receives  the  nasal  spine  of  the  frontal,  and  the  perpendicular 
plate  of  the  ethmoid,  and  articulates  with  Its  fellow  of  the  opposite  side ;  whilst  the 
surface  of  the  bones  is  perforated  by  a  few  small  vascular  apertures,  and  presents 
the  longitudinal  groove  for  the  nasal  nerve :  further  back  is  the  transverse  suture, 
connecting  the  frontal  with  the  nasal  in  front,  and  the  ethmoid  behind,  the  olfactory 
foramina  on  the  under  surface  of  the  cribriform  plate,  and  the  suture  between  it 
and  the  sphenoid  behind :  quite  posteriorly  are  seen  the  sphenoidal  turbinated 
bones,  the  orifices  of  the  sphenoidal  sinuses,  and  the  articulation  of  the  ulae  of  the 
vomer  with  the  under  surface  of  the  body  of  the  sphenoid. 


110 


OSTEOLOGY. 


The  floor  is  flattened  from  before  backwards,  concave  from  side  to  side,  and  wider 
in  the  middle  than  at  either  extremity.  It  is  formed  in  front  by  the  palate  process 
of  the  superior  maxillary ;  behind,  by  the  palate  process  of  the  palate  bone.  This 
surface  presents,  from  before  backwards,  the  anterior  nasal  spine ;  behind  this, 
the  upper  orifice  of  the  anterior  palatine  canal ;  internally,  the  elevated  crest 
which  articulates  with  the  vomer;  and  behind,  the  suture  between  the  palate  and 
superior  maxillary  bones,  and  the  posterior  nasal  spine. 

Fig.  66.— Roof,  Floor,  and  Outer  Wall  of  Nasal  Fossa*. 

Eaof  i  .  .      . 

Xasal  jJoiu.  \  aA      //      Peobe  f*—*  thmujt* 

Xv  /  {-^^v  n-^Naso-lachrymal  Canal 

'.rial  fyimof  Frenital  Bon*      ^v  \\^m^\) 

,„,     ,Vti       i       ^\        \.     /  flllMY           Brittle  passed 'through 
Orruontuimu  rfMthmd  ^  \      Uilll      §A Injurdvbalam . 


Outer  Wall 

-^fnsal  Roc.  of  Suffix 
Lachrymal 
f'.tlinaiid. 

Vticijcnmrroc  cf  ditto 

Inf trior  Turbinated 
Palate 

Superior  Meatus 
Middle  Meatus 
.jcrior  Meatus 


Tloor 

Ant.Na.scil  SjJin£ 
Pa  late  1'roc.  of  Sup-  Max.  ■ 

Palate  Proc.  of  Palate- 

Post. Nasal  Spine 
Ant.  Palatine  Canal 


The  inner  wall  or  septum  (fig.  67)  is  a  thin  vertical  partition,  which  separates 
the  nasal  fossje  from  one  another ;  it  is  occasionally  perforated  so  that  the  fossae 
communicate,  and  it  is  frequently  deflected  considerably  to  one  side.  It  is  formed, 
in  front,  by  the  crest  of  the  nasal  bones  and  nasal  spine  of  the  frontal ;  in  the 
middle,  by  the  perpendicular  lamella  of  the  ethmoid ;  behind,  by  the  vomer  and 
rostrum  of  the  sphenoid;  below,  by  the  crest  of  the  superior  maxillary  and  palate 
bones.  It  presents,  in  front,  a  large  triangular  notch,  which  receives  the  triangular 
cartilage  of  the  nose :  above,  the  lower  orifices  of  the  olfactory  canals ;  and  behind, 
the  guttural  edge  of  the  vomer.  Its  surface  is  marked  by  numerous  vascular  and 
nervous  canals,  and  traversed  by  sutures  connecting  the  bones  of  which  it  is 
formed. 

The  outer  wall  is  formed,  in  front,  by  the  nasal  process  of  the  superior  maxillary 
and  lachrymal  bones ;  in  the  middle,  by  the  ethmoid  and  inner  surface  of  the 
superior  maxillary  and  inferior  turbinated  bones ;  behind,  by  the  vertical  plate  of 
the  palate  bone.  This  surface  presents  three  irregular  longitudinal  passages  or 
meatuses,  formed  between  three  horizontal  plates  of  bone  that  spring  from  it;  they 
are  termed  the  superior,  middle,  and  inferior  meatuses  of  the  nose.  The  superior 
meatus,  the  smallest  of  the  three,  is  situated  at  the  upper  and  back  part  of  each 
nasal  fossa,  occupying  the  posterior  third  of  the  outer  wall.  It  is  situated  between 
the  superior  and  middle  turbinated  bones,  and  has  opening  into  it  two  foramina, 
the  spheno-palatine  at  the  back  part  of  its  outer  wall,  the  posterior  ethmoidal  cells 


OS    HTOIDES. 


Ill 


at  the  front  part  of  the  upper  wall.  The  opening  of  the  sphenoidal  sinuses  is 
usually  at  the  upper  and  back  part  of  the  nasal  fossae,  immediately  behind  the 
superior  turbinated  bone.  The  middle  meatus  is  situated  between  the  middle  and 
inferior  turbinated  bones,  and  occupies  the  posterior  two-thirds  of  the  outer  wall 
of  the  nasal  fossa.  It  presents  two  apertures.  In  front  is  the  orifice  of  the  infun- 
dibulum,  by  which  the  middle  meatus  communicates  with  the  anterior  ethmoidal 
cells,  and  through  these  with  the  frontal  sinuses.     At  the  centre  of  the  outer  wall 

Fig.  t'7. — Inner  Wall  of  Nasal  Fossae,  or  Septum  of  Nose. 


Crest  of  battel   Ion,. 
Masai  Spin*  <•{ Frontal  ft. 


Space  for  Triangular 
Cartilage  of  Septum 


Crest   of  Palate  Bone 
Crest  of  Stip.AIaocill.E,,* 


is  the  orifice  of  the  antrum,  which  varies  somewhat  as  to  its  exact  position  in 
different  skulls.  The  inferior  meatus,  the  largest  of  the  three,  is  the  space  between 
the  inferior  turbinated  bone  and  the  floor  of  the  nasal  fossa.  It  extends  along  the 
entire  length  of  the  outer  wallof  the  nose,  is  broader  in  front  than  behind,  and 
presents  anteriorly  the  lower  orifice  of  the  lachrymal  canal. 

Os  Hyoides. 

The  Hyoid  bone  is  named  from  its  resemblance  to  the  Greek  Upsilon ;  it  is  also 
called  the  lingual  bone,  from  supporting  the  tongue,  and  giving  attachment  to  its 
numerous  muscles.     It  is  a  bony  arch,  shaped 
like  a  horseshoe,  and  consisting  of  five  seg- 
ments, a  central  portion  or  body,  two  greater 
cornua,  and  two  lesser  cornua. 

The  Body  forms  the  central  part  of  the 
bone,  is  of  a  quadrilateral  form,  its  anterior 
surface  (fig.  68),  convex,  directed  forwards 
and  upwards,  is  divided  into  two  parts  by 
a  vertical  ridge,  which  descends  along  the 
median  line,  and  is  crossed  at  right  angles  by 
a  horizontal  ridge,  so  that  this  surface  is 
divided  into  four  muscular  depressions.  At 
the  point  of  meeting  of  these  two  lines  is  a 


Fig.  68. — Hyoid  Bone.    Anterior  Surface. 


112  OSTEOLOGY. 

prominent  elevation,  the  tubercle.  The  portion  above  the  horizontal  ridge  is 
directed  upwards,  and  is  sometimes  described  as  the  superior  border.  The  anterior 
surface  gives  attachment  to  the  Genio-hyoid  in  the  greater  part  of  its  extent ; 
above,  to  the  Genio-hyo-glossus ;  below,  to  the  Mylo-hyoid,  Stylo-hyoid,  and 
aponeurosis  of  the  Digastric ;  and  between  these  to  part  of  the  Hyo-glossus.  The 
posterior  surface  is  smooth,  concave,  directed  backwards  and  downwards,  and 
separated  from  the  epiglottis  by  the  thyro-hyoid  membrane,  and  by  a  quantity 
of  loose  areolar  tissue.  The  superior  border  is  rounded,  and  gives  attachment  to 
the  thyro-hyoid  membrane,  and  part  of  the  Genio-hyo-glossi  muscles.  The 
inferior  border  gives  attachment,  in  front,  to  the  Sterno-hyoid ;  behind,  to  part 
of  the  Thyro-hyoid,  and  to  the  Omo-hyoid  at  its  junction  with  the  great  cornu. 
The  lateral  surfaces  are  small  oval,  convex  facets,  covered  with  cartilage  for 
articulation  with  the  greater  cornua. 

The  Greater  Cornua  project  backwards  from  the  lateral  surfaces  of  the  body; 
they  are  flattened  from  above  downwards,  diminish  in  size  from  before  backwards, 
and  terminate  posteriorly  in  a  tubercle  for  the  attachment  of  the  thyro-hyoid 
ligament.  Their  outer  surface  gives  attachment  to  the  Hyo-glossus;  their  upper 
border,  to  the  Middle  constrictor  of  the  pharynx ;  their  lower  border,  to  part  of 
the  Thyro-hyoid  muscle. 

The  Lesser  Cornua  are  two  small  conical-shaped  eminences,  attached  by  their 
bases  to  the  angles  of  junction  between  the  body  and  greater  cornua,  and  giving 
attachment  by  their  apices  to  the  stylo-hyoid  ligaments.  In  youth,  the  cornua  are 
connected  to  the  body  by  cartilaginous  surfaces,  and  held  together  by  ligaments ; 
in  middle  life,  the  body  and  greater  cornua  usually  become  joined ;  and  in  old 
age,  all  the  segments  are  united  together,  forming  a  single  bone. 

Development.  By  five  centres ;  one  for  the  body,  and  one  for  each  cornu. 
Ossification  commences  in  the  body  and  greater  cornua  towards  the  end  of  foetal 
life,  those  of  the  cornua  first  appearing.  Ossification  of  the  lesser  cornua  com- 
mences some  months  after  birth. 

Attachment  of  Muscles.  Sterno-hyoid,  Thyro-hyoid,  Omo-hyoid,  aponeurosis 
of  the  Digastricus,  Stylo-hyoid,  Mylo-hyoid,  Genio-hyoid,  Genio-hyo-glossus, 
Hyo-glossus,  Middle  constrictor  of  the  pharynx,  and  occasionally  a  few  fibres  of 
the  Lingualis.  It  also  gives  attachment  to  the  thyro-hyoidean  membrane,  and 
the  stylo-hyoid,  thyro-hyoid,  and  hyo-epiglottic  ligaments. 

THE   THOEAX. 

The  Thorax  or  Chest  is  an  osseo-cartilaginous  cage,  intended  to  contain  and 
protect  the  principal  organs  of  respiration  and  circulation.  It  is  the  largest  of 
the  three  cavities  connected  with  the  spine,  and  is  formed  by  the  sternum  and 
costal  cartilages  in  front,  the  twelve  ribs  on  each  side,  and  the  bodies  of  the  dorsal 
vertebras  behind. 

The  Sternum. 

The  Sternum  (figs.  69  and  70)  is  a  flat  narrow  bone,  situated  in  the  median  line 
of  the  front  of  the  chest,  and  consisting,  in  the  adult,  of  three  portions.  Its  form 
resembles  an  ancient  sword :  the  upper  piece,  representing  the  handle,  is  termed 
the  manubrium;  the  middle  and  largest  piece,  which  represents  the  chief  part  of  the 
blade,  is  termed  the  gladiolus;  and  the  inferior  piece,  like  the  point  of  the  sword, 
is  termed  the  ensiform  or  xiphoid  appendix.  In  its  natural  position,  its  direction 
is  oblique  from  above,  downwards,  and  forwards.  It  is  flattened  in  front,  concave 
behind,  broad  above,  becoming  narrowed  at  the  point  where  the  first  and  second 
pieces  are  connected ;  after  which  it  again  widens  a  little,  and  is  pointed  at  its 
extremity.  Its  average  length  in  the  adult  is  six  inches,  being  rather  longer  in 
the  male  than  in  the  female. 

The  First  Piece  of  the  sternum,  the  Manubrium,  is  of  a  somewhat  triangular 
form,  broad  and  thick  above,  narrow  below  at  its  junction  with  the  middle  piece. 
Its  anterior  surface,  convex  from  side  to  side,  concave  from  above  downwards,  is 
rrnooth,  and  affords  attachment  on  each  side  to  the  Pectoralis  major  and  sternal 


STERNUM. 


l\B 


Fig.  G9. — Sternum  and  Costal  Cartilages.     Anterior  Surface. 

S7IRNO-CLEI00.  MASTOID 

suacuwius      -  ^  <*' 


Fig.  70. — Posterior  Surface  of  Sternum. 


Hi  OSTEOLOGY. 

origin  of  the  Sterno-cleido-mastoid  muscles.  In  well-marked  bones,  ridges  limiting 
the  attachment  of  these  muscles  are  very  distinct.  Its  posterior  surface,  concave 
and  smooth,  affords  attachment  on  each  side  to  the  Stemo-hyoid  and  Sterno-thyroid 
muscles.  The  superior  border,  the  thickest,  presents  at  its  centre  the  interclavicular 
notch;  and,  on  each  side,  an  oval  articular  surface,  directed  upwards,  backwards, 
and  outwards,  for  articulation  with  the  sternal  end  of  the  clavicle.  The  inferior 
border  presents  an  oval  rough  surface,  covered  in  the  recent  state  with  a  thin  layer 
of  cartilage,  for  articulation  with  the  second  portion  of  the  bone.  The  lateral 
borders  are  marked  above  by  an  articular  depression  for  the  first  costal  cartilage, 
and  below  by  a  small  facet,  which,  with  a  similar  facet  on  the  upper  angle  of  the 
middle  portion  of  the  bone,  forms  a  notch  for  the  reception  of  the  costal  cartilage 
of  the  second  rib.  These  articular  surfaces  are  separated  by  a  narrow  curved 
edge  which  slopes  from  above  downwards  and  inwards. 

The  Second  Piece  of  the  sternum,  the  gladiolus,  considerably  longer,  narrower, 
and  thinner  than  the  superior,  is  broader  below  than  above.  Its  anterior  surface 
is  nearly  flat,  directed  upwards  and  forwards,  and  marked  by  three  transverse  lines 
which  cross  the  bone  opposite  the  third,  fourth,  and  fifth  articular  depressions. 
These  lines  indicate  the  point  of  union  of  the  four  separate  pieces  of  which  this 
part  of  the  bone  consists  at  an  early  period  of  life.  At  the  junction  of  the  third 
and  fourth  pieces  is  occasionally  seen  an  orifice,  the  sternal  foramen ;  it  varies  in 
size  and  form  in  different  individuals,  and  pierces  the  bone  from  before  backwards. 
This  surface  affords  attachment  on  each  side  to  the  sternal  origin  of  the  Pectoralis 
major.  The  posterior  surface,  slightly  concave,  is  also  marked  by  three  transverse 
lines,  but  they  are  less  distinct  than  those  in  front;  this  surface  affords  attachment 
below,  on  each  side,  to  the  Triangularis  sterni  muscle,"  and  occasionally  presents 
the  posterior  opening  of  the  sternal  foramen.  The  superior  border  presents  an 
oval  surface  for  articulation  with  the  manubrium.  The  inferior  border  is  narrow, 
and  articulates'  with  the  ensiform  appendix.  Each  lateral  border  presents  at  each 
superior  angle  a  small  facet,  which,  with  a  similar  facet  on  the  manubrium,  forms 
a  cavity  for  the  cartilage  of  the  second  rib ;  the  four  succeeding  angular  depressions 
receive  the  cartilages  of  the  third,  fourth,  fifth,  and  sixth  ribs,  whilst  each  inferior 
angle  presents  a  small  facet,  which,  with  a  corresponding  one  on  the  ensiform 
appendix,  forms  a  notch  for  the  cartilage  of  the  seventh  rib.  These  articular 
depressions  are  separated  by  a  series  of  curved  interarticular  intervals,  which 
diminish  in  length  from  above  downwards,  and  correspond  to  the  intercostal  spaces. 
The  costal  cartilage  of  each  true  rib,  excepting  the  first,  is  thus  seen  to  articulate 
with  the  sternum  at  the  line  of  junction  of  two  of  its  primitive  component 
segments.  This  is  well  seen  in  many  of  the  lower  animals,  where  the  separate 
parts  of  the  bone  remain  ununited  longer  than  in  man.  In  this  respect  a  striking 
analogy  exists  between  the  mode  of  connection  of  the  ribs  with  the  vertebral 
column,  and  the  connection  of  their  cartilages  with  the  sternal  column. 

The  Third  Piece  of  the  sternum,  the  ensiform  or  xiphoid  appendix,  is  the 
smallest  of  the  three;  it  is  thin  and  elongated  in  form,  cartilaginous  in  structure 
in  youth,  but  more  or  less  ossified  at  its  upper  part  in  the  adult.  Its  anterior 
surface  affords  attachment  to  the  costo-xiphoid  ligaments.  Its  posterior  surface, 
to  some  of  the  fibres  of  the  Diaphragm  and  Triangularis  sterni  muscles.  Its 
lateral  borders,  to  the  aponeurosis  of  the  abdominal  muscles.  Above,  it  is  con- 
tinuous with  the  lower  end  of  the  gladiolus ;  below,  by  its  pointed  extremity,  it 
gives  attachment  to  the  linea  alba,  and  at  each  superior  angle  presents  a  facet  for 
the  lower  half  of  the  cartilage  of  the  seventh  rib.  This  portion  of  the  sternum  is 
very  various  in  appearance,  being  sometimes  pointed,  broad  and  thin,  sometimes 
bifid,  or  perforated  by  a  round  hole,  occasionally  curved,  or  deflected  considerably 
to  one  or  the  other  side. 

Structure.  This  bone  is  composed  of  delicate  cancellated  texture,  covered  by 
a  thin  layer  of  compact  tissue,  which  is  thickest  in  the  manubrium,  between  the 
articular  facets  for  the  clavicles. 

Development.     The  sternum,  including  the  ensiform  appendix,  is  developed  by 


six  centres; — one  for  the 
first  piece  or  manubrium, 
four  for  the  second  piece 
or  gladiolus,  and  one  for 
the  eusiform  appendix. 
The  sternum  is  entirely 
cartilaginous  up  to  the  mid- 
dle of  foetal  life,  and  when 
ossification  takes  place,  the 
ossiiic  granules  are  depo- 
sited in  the  middle  of  the 
intervals  between  the  ar- 
ticular depressions  for  the 
costal  cartilages,  in  the  fol- 
lowing order  (fig.  71):  in 
the  first  piece,  between  the 
fifth  and  sixth  months; 
in  the  second  and  third, 
between  the  sixth  and  se- 
venth months ;  in  the  fourth 
piece,  at  the  ninth  month ; 
in  the  fifth,  within  the  first 
year,  or  between  the  first 
and  second  years  after 
birth ;  and  in  the  ensiform 
appendix,  between  the  se- 
cond and  the  seventeenth 
or  eighteenth  years,  by  a 
single  centre  which  makes 
its  appearance  at  the  upper 
part,  and  proceeds  gra- 
dually downwards.  To 
these  may  be  added  the 
occasional  existence,  as 
described  by  Breschet,  of 
two  small  episternal  cen- 
tres, which  make  their  ap- 
pearance one  on  each  side 
of  the  interclavicular  notch. 
These  are  regarded  by  him 
as  the  anterior  rudiments 
of  a  rib,  of  which  the  pos- 
terior rudiment  is  the  ante- 
rior lamina  of  the  trans- 
verse process  of  the  seventh 
cervical  vertebra.  It  occa- 
sionally happens  that  some 
of  the  segments  are  form- 
ed from  more  than  one 
centre,  the  number  and  posi- 
tion of  which  vary  (fig.  73). 
Thus  the  first  piece  may 
have  two,  three,  or  even 
six  centres.  "When  two  are 
present,  they  are  generally 
situated  one  above  the 
other,  the  upper  one  being 


STERNUM.  115 

Fig.  71. — Development  of  Sternum,  by  Six  Centres. 


1  fori* piece  fs-ti  mo  fc.'.il 
cr  K&Ttubritvm 


Time 

"J 
Ajrpearctnce 


U for  2V* piece 

or 
GlcvUolu,* 


6 -J  mo. 


if.   gthmr. 
5.  //-V'A 

7uM 


) for Era i 'form  1      .      «    j 
J Cartilage    )z~   ,8"  * 


Fi£ 


^  rarely  anile , 
|    except  in  old  age 

\         3S-/rO. 

I  20-25 fh  year 

J   soon  after  pu.hertij 

partly  car/iiag  incus  in 
advanxd  life 

Fi<rs.  73  and  74.     Peculiarities. 


for  1??j)tcee  2,  or  wore  rent  rat 


number  of 
C  enti'es 


2?-  pcece,  usually  one 

%rd 

/*$   !   2 placed  latera.Uij 


And  in 

Mode  of 
Union- 


Arrest  of  Devclopmert 
of  lateral  pieces   producing 

Sternal  fissure  & 

Sternal  fora  me  n 


116 


OSTEOLOGY. 


Fig- 


75.— A  Central  Rib  of  Ri< 
►Side.     Inner  Surface. 


lit 


the  larger ;  the  second  piece  has  seldom  more  than  one ;  the  third,  fourth,  and  fifth 
pieces  are  often  formed  from  two  centres  placed  laterally,  the  irregular  union  of 

which  will  serve  to  explain  the  occasional 
occurrence  of  the  sternal  foramen  (fig.  74), 
or  of  the  vertical  fissure  which  some- 
times intersects  this  part  of  the  bone. 
Union  of  the  various  centres  commences 
from  below,  and  proceeds  upwards,  taking 
place  in  the  following  order  (fig.  72). 
The  fifth  piece  is  joined  to  the  fourth 
soon  after  puberty ;  the  fourth  to  the  third, 
between  the  twentieth  and  twenty-fifth 
years;  the  third  to  the  second,  between 
the  thirty-fifth  and  fortieth  years;  the 
second  is  rarely  joined  to  the  first  except 
in  very  advanced  age. 

Articulations.  With  the  clavicles,  and 
seven  costal  cartilages  on  each  side. 

Attachment  of  Muscles.  The  Pectora- 
lis  major,  Sterno-cleido-mastoid,  Sterno- 
hyoid, Sterno-thyroid,  Triangularis  sterni, 
aponeurosis  of  the  Obliquus  externus, 
Obliquus  interims,  and  Transversalis 
muscles,  Eectus  and  Diaphragm. 

The  Ribs. 

The  Ribs  are  elastic  arches  of  bone, 
which  form  the  chief  part  of  the  thoracic 
walls.  They  are  twelve  in  number  on  each 
side;  but  this  number  may  be  increased 
by  the  development  of  a  cervical  or  lumbar 
rib,  or  may  be  diminished  to  eleven.  The 
first  seven  are  connected  behind  with  the 
spine,  and  in  front  with  the  sternum 
through  the  intervention  of  the  costal 
cartilages;  they  are  called  vertebro- 
sternal or  true  ribs.  The  remaining  five 
are  false  ribs ;  of  these  the  first  three, 
being  connected  behind  with  the  spine, 
and  in  front  with  the  costal  cartilages, 
are  called  the  vertebro-costal  ribs:  the 
last  two  are  connected  with  the  vertebras 
only,  being  free  at  their  anterior  ex- 
tremities; they  are  termed  vertebral  or 
floating  ribs.  The  ribs  vary  in  their  di- 
rection, the  upper  ones  being  placed  nearly 
at  right  angles  with  the  spine ;  the  lower 
ones  are  placed  obliquely,  so  that  the 
anterior  extremity  is  lower  than  the 
posterior.  The  extent  of  obliquity  reaches 
its  maximum  at  the  ninth  rib,  gradually 
decreasing  from  that  point  towards  the 
twelfth.  The  ribs  are  situated  one  be- 
neath the  other  in  such  a  manner  that 
spaces  are  left  between  them ;  these  are 
called  intercostal  spaces.  Their  length 
corresponds   to   the   length   of  the    ribs; 


ribs.  m 

their  breadth  is  more  considerable  in  front  than  behind,  and  between  the  upper 
than  between  the  lower  ribs.  The  ribs  increase  in  length  from  the  first  to  the 
seventh,  when  they  again  diminish  to  the  twelfth.  In  breadth  they  decrease  from 
above  downwards ;  in  each  rib  the  greatest  breadth  is  at  the  sternal  extremity. 

Common  characters  of  the  Ribs  (fig.  75).  Take  a  rib  from  the  middle  of  the 
series  in  order  to  study  its  common  characters.  Each  rib  presents  two  extremities, 
a  posterior  or  vertebral,  an  anterior  or  sternal,  and  an  intervening  portion,  the 
body  or  shaft.  The  posterior  or  vertebral  extremity  presents  for  examination  a  head, 
neck,  and  tuberosity. 

The  head  (fig.  76)  is  marked  by  a  kidney-shaped  articular  surface,  divided  by 
a  horizontal  ridge  into  two  facets  for  articulation  with  the  costal  cavity  formed 
by  the  junction  of  the  bodies  of  two  contiguous  dorsal  vertebras ;  the  upper  facet 
is  small,  the  inferior  one  of  large  size ;  the  ridge  separating  them  serves  for  the 
attachment  of  the  interarticular  ligament. 

Fig.  76. — Vertebral  Extremity  of  a  Rib.     External  Surface. 

fcr  Ant.T  Coifo-trmaLla*  pr pt)st?  fat+tnawUK 

Tactl  for  hod.ii  of  tiyj>er  Dor»al  Vr/rtcbra. 

Ridtjt  f.rr  Title r-artictdar  L!yt~ 

facet  for  body  of  loutr  Dorsal  Viert' 

far  traiuv.  vroc.  of  lomti 


The  neck  is  that  flattened  portion  of  the  rib  which  extends  outwards  from  the 
head ;  it  is  about  an  inch  long  and  rests  upon  the  transverse  process  of  the  lower 
of  the  two  vertebrae  with  which  the  head  articulates.  Its  anterior  surface  is  flat 
and  smooth,  its  posterior  rough,  for  the  attachment  of  the  middle  costo-transverse 
ligament,  and  perforated  by  numerous  foramina,  the  direction  of  which  is  less 
constant  than  those  found  on  the  inner  surface  of  the  shaft.  Of  its  two  borders, 
the  superior  presents  a  rough  crest  for  the  attachment  of  the  anterior  costo- 
transverse ligament ;  its  inferior  border  is  rounded.  On  the  posterior  surface  of 
the  neck,  just  where  it  joins  the  shaft,  and  nearer  the  lower  than  the  upper  border, 
is  an  eminence — the  tuberosity ;  it  consists  of  an  articular  and  a  non-articular 
portion.  The  articular  portion,  the  most  internal  and  inferior  of  the  two,  presents 
a  small  oval  surface,  for  articulation  with  the  extremity  of  the  transverse  process 
of  the  lower  of  the  two  vertebrae  to  which  the  head  is  connected.  The  non-arti- 
cular portion  is  a  rough  elevation,  which  affords  attachment  to  the  posterior  costo- 
transverse ligament.  The  tubercle  is  much  more  prominent  in  the  upper  than  in 
the  lower  ribs. 

The  shaft  is  thin  and  flat,  so  as  to  present  two  surfaces,  an  external  and  an 
internal;  and  two  borders,  a  superior  and  an  inferior.  The  external  surface  is 
convex,  smooth,  and  marked,  at  its  back  part,  a  little  in  front  of  the  tuberosity, 
by  a  prominent  line,  directed  obliquely  from  above,  downwards  and  outwards ; 
this  gives  attachment  to  a  tendon  of  the  Sacro-lumbalis  muscle,  and  is  called  the 
angle.  At  this  point,  the  rib  is  bent  in  two  directions.  If  the  rib  is  laid  upon  its 
lower  border,  it  will  be  seen,  that  the  anterior  portion  of  the  shaft,  as  far  as  the 
angle,  rests  upon  this  margin,  while  the  vertebral  end  of  the  bone,  beyond  the 
angle,  is  bent  inwards,  and  at  the  same  time  tilted  upwards.  The  interval  between 
the  angle  and  the  tuberosity  increases  gradually  from  the  second  to  the  tenth  rib. 
The  portion  of  bone  between  these  two  parts  is  rounded,  rough,  and  irregular,  and 
serves  for  the  attachment  of  the  Longissimus  dorsi.  The  portion  of  bone  between 
the  angle  and  sternal  extremity  is  also  slightly  twisted  upon  its  own  axis,  the 
external  surface  looking  downwards  behind  the  angle,  a  little  upwards  in  front 
of  it.  This  surface  presents,  towards  its  sternal  extremity,  an  oblique  line,  the 
anterior  angle.     The  internal  surface  is  concave,  smooth,  directed  a  little  upwards 


118  OSTEOLOGY. 

behind  the  angle ;  a  little  downwards  in  front  of  it.  This  surface  is  marked  by  a 
ridge  ay  Inch,  commences  at  the  lower  extremity  of  the  head;  it  is  strongly  marked 
as  far  as  the  inner  side  of  the  angle,  and  gradually  becomes  lost  at  the  junction  of 
the  anterior  with  the  middle  third  of  the  bone.  The  interval  between  it  and  the 
inferior  border  is  deeply  grooved,  to  lodge  the  intercostal  vessels  and  nerve.  At 
the  back  part  of  the  bone,  this  groove  belongs  to  the  inferior  border ;  but  just  in 
front  of  the  angle,  where  it  is  deepest  and  broadest,  it  corresponds  to  the  internal 
surface.  The  superior  edge  of  the  groove  is  rounded ;  it  serves  for  the  attachment 
of  the  Internal  intercostal  muscle.  The  inferior  edge  corresponds  to  the  lower 
margin  of  the  rib,  and  gives  attachment  to  the  External  intercostal.  Within  the 
groove  are  seen  the  orifices  of  numerous  small  foramina,  which  traverse  the  wall 
•of  the  shaft  obliquely  from  before  backwards.  The  superior  border,  thick  and 
rounded,  is  marked  by  an  external  and  an  internal  lip,  more  distinct  behind  than 
in  front ;  they  serve  for  the  attachment  of  the  External  and  Internal  intercostal 
muscles.  The  inferior  border,  thin  and  sharp,  has  attached  the  External  intercostal 
muscle.  The  anterior  or  sternal  extremity  is  flattened,  and  presents  a  porous,  oval, 
concave  depression,  into  which  the  costal  cartilage  is  received. 

Structure.   The  ribs  consist  of  cancellous  tissue,  inclosed  in  a  thin  compact  layer. 

Development.  Each  rib,  with  the  exception  of  the  last  two,  is  developed  by 
three  centres,  one  for  the  shaft,  one  for  the  head,  and  one  for  the  tubercle.  The 
last  two  have  only  two  centres,  that  for  the  tubercle  being  wanting.  Ossification 
commences  in  the  body  of  the  ribs  at  a  very  early  period,  before  its  appearance 
in  the  vertebras.  The  epiphysis  of  the  head,  which  is  of  a  slightly  angular  shape, 
and  that  for  the  tubercle,  of  a  lenticular  form,  make  their  appearance  between  the 
sixteenth  and  twentieth  years,  and  are  not  united  to  the  rest  of  the  bone  until 
about  the  twenty-fifth  year. 

Attachment  of  Muscles.  The  Intercostals,  Scalenus  anticus,  Scalenus  medius, 
Scalenus  posticus,  Pectoralis  minor,  Serratus  magnus,  Obliquus  externus,  Trans- 
versalis,  Quaclratus  lumborum,  Diaphragm,  Latissimus  dorsi,  Serratus  posticus 
superior,  Serratus  posticus  inferior,  Sacro-lumbalis,  Musculus  accessorius  ad  sacro- 
lumbalem,  Longissimus  dorsi,  Cervicalis  ascendens,  Levatores  costarum. 

Peculiar  Eibs. 

The  ribs  which  require  especial  consideration  are  five  in  number,  viz.,  the  first, 
second,  tenth,  eleventh,  and  twelfth. 

The  first  rib  (fig.  77)  is  one  of  the  shortest  and  the  most  curved  of  all  the  ribs ; 
it  is  broad,  flat,  and  placed  horizontally  at  the  upper  part  of  the  thorax,  its  surfaces 
looking  upwards  and  downwards,  and  its  borders  inwards  .and  outwards.  The 
head  is  of  small  size,  rounded,  and  presents  only  a  single  articular  facet  for  arti- 
culation with  the  body  of  the  first  dorsal  vertebra.  The  neck  is  narrow  and 
rounded.  The  tuberosity,  thick  and  prominent,  rests  on  the  outer  border.  There 
is  no  angle,  and  the  shaft  is  not  twisted  on  its  axis.  The  upper  surface  of  the  shaft 
is  marked  by  two  shallow  depressions,  separated  from  one  another  by  a  ridge, 
which  becomes  more  prominent  towards  the  internal  border,  where  it  terminates 
in  a  tubercle;  this  tubercle  and  ridge  serve  for  the  attachment  of  the  Scalenus 
anticus  muscle,  the  groove  in  front  of  it  transmitting  the  subclavian  vein ;  that 
behind  it,  the  subclavian  artery.  Between  the  groove  for  the  subclavian  artery 
and  the  tuberosity,  is  a  depression  for  the  attachment  of  the  Scalenus  medius 
muscle.  The  under  surface  is  smooth,  and  destitute  of  the  groove  observed  on  the 
other  ribs.  The  outer  border  is  convex,  thick,  and  rounded.  The  inner,  concave, 
thin,  and  sharp,  and  marked  about  its  centre  by  the  tubercle  before  mentioned. 
The  anterior  extremity  is  larger  and  thicker  than  in  any  of  the  other  ribs. 

The  second  rib  (fig.  78)  is  much  longer  than  the  first,  but  bears  a  very  consider- 
able resemblance  to  it  in  the  direction  of  its  curvature.  The  non-articular  portion 
of  the  tuberosity  is  occasionally  only  slightly  marked.  The  angle  is  slight,  and 
situated  close  to  the  tuberosity,  and  the  shaft  is  not  twisted,  so  that  both  ends 


RIBS. 


119 


touch  any  plane  surface  upon  which  it  may  be  laid.  The  shaft  is  not  horizontal, 
like  that  of  the  first  rib ;  its  outer  surface,  which  is  convex,  looking  upwards  and 
a  little  outwards.  It  presents,  near  the  middle,  a  rough  eminence  for  the  attach- 
ment of  part  of  the  first,  and  the  second  serration  of  the  Serratus  magnus.  The 
inner  surface,  smooth  and  concave,  is  directed  downwards  and  a  little  inwards;  it 
presents  a  short  groove  towards  its  posterior  part. 

The  tenth  rib  (fig.  79)  has  only  a  single  articular  facet  on  its  head. 

Peculiar  Ribs. 


Fig.  77.    , 


Fig.  78 


^t  dost  to  tube/roti 


iluwf 


K^S 


Fig.  79. 
SinqU  urtir.ula/r  facet  - 


Fig.  80. 
Single   artie.  fwmt  — 


Fig.  81. 
iSingU    turtle.  fa,c 


The  eleventh  and  twelfth  ribs  (figs.  80  and  81)  have  each  a  single  articular  facet 
on  the  head,  which  is  of  rather  large  size ;  they  have  no  neck  or  tuberosity .  and 
are  pointed  at  the  extremity.  The  eleventh  has  a  slight  angle  and  a  shallow 
groove  on  the  lower  border.  The  twelfth  has  neither,  and  is  much  shorter  than 
the  eleventh. 


120  OSTEOLOGY. 


The  Costal  Caetilages. 


The  Costal  Cartilages  (fig.  69)  are  white  elastic  structures,  which  serve  to  pro- 
long the  ribs  forward  to  the  front  of  the  chest,  and  contribute  very  materially  to 
the  elasticity  of  this  cavity.  The  first  seven  are  connected  with  the  sternum,  the 
next  three  with  the  lower  border  of  the  cartilage  of  the  preceding  rib.  The 
cartilages  of  the  last  two  ribs,  which  have  pointed  extremities,  float  freely  in  the 
walls  of  the  abdomen.  Like  the  ribs,  the  costal  cartilages  vary  in  their  length, 
breadth,  and  direction.  They  increase  in  length  from  the  first  to  the  seventh,  then 
gradually  diminish  to  the  last.  They  diminish  in  breadth,  as  well  as  the  intervals 
between  them,  from  the  first  to  the  last.  They  are  broad  at  their  attachment  to 
the  ribs,  and  taper  towards  their  sternal  extremities,  excepting  the  first  two,  which 
are  of  the  same  breadth  throughout,  and  the  sixth,  seventh,  and  eighth,  which  are 
enlarged  where  their  margins  are  in  contact.  In  direction  they  also  vary ;  the 
first  descends  a  little,  the  second  is  horizontal,  the  third  ascends  slightly,  whilst  all 
the  rest  follow  the  course  of  the  ribs  for  a  short  extent,  and  then  ascend  to  the 
sternum  or  preceding  cartilage.  Each  costal  cartilage  presents  two  surfaces,  two 
borders,  and  two  extremities.  The  anterior  surface  is  convex,  and  looks  forwards 
and  upwards ;  that  of  the  first  gives  attachment  to  the  costo-clavicular  ligament ; 
that  of  the  first,  second,  third,  fourth,  fifth,  and  sixth,  at  their  sternal  ends,  to  the 
Pectoralis  major.  The  others  are  covered,  and  give  partial  attachment  to  some 
of  the  great  flat  muscles  of  the  abdomen.  The  posterior  surface  is  concave,  and 
directed  backwards  and  downwards,  the  six  or  seven  inferior  ones  affording 
attachment  to  the  Transversalis  and  Diaphragm  muscles.  Of  the  two  borders, 
the  superior  is  concave,  the  inferior  convex ;  they  afford  attachment  to  the  Inter- 
costal muscles,  the  upper  border  of  the  sixth  giving  attachment  to  the  Pectoralis 
major  muscle.  The  contiguous  borders  of  the  sixth,  seventh,  and  eighth,  and 
sometimes  the  ninth  and  tenth  costal  cartilages,  present  smooth  oblong  surfaces  at 
the  points  where  they  articulate.  Of  the  two  extremities,  the  outer  one  is  con- 
tinuous with  the  osseous  tissue  of  the  rib  to  which  it  belongs.  The  inner  extremity 
of  the  first  is  continuous  with  the  sternum ;  the  six  succeeding  ones  have  rounded 
extremities,  which  are  received  into  shallow  concavities  on  the  lateral  margins  of 
the  sternum.  The  inner  extremities  of  the  eighth,  ninth,  and  tenth  costal  carti- 
lages are  pointed,  and  lie  in  contact  with  the  cartilage  above.  Those  of  the 
eleventh  and  twelfth  are  free,  and  pointed. 

The  costal  cartilages  are  most  elastic  in  youth,  those  of  the  false  ribs  being 
more  so  than  the  true.  In  old  age,  they  become  of  a  deep  yellow  color.  Under 
certain  diseased  conditions,  they  are  prone  to  ossify.  Mr.  Humphry's  observa- 
tions on  this  subject  have  led  him  to  regard  the  ossification  of  the  costal  cartilages 
as  a  sign  of  disease  rather  than  of  age.  "  The  ossification  takes  place  in  the  first 
cartilage  sooner  than  in  the  others ;  and  in  men  more  frequently,  and  at  an  earlier 
period  of  life,  than  in  women." 

Attachment  of  Muscles.  The  Subclavius,  Sterno-thyroid,  Pectoralis  major, 
Internal  oblique,  Transversalis,  Pectus,  Diaphragm,  Triangularis  sterni,  Internal 
and  External  intercostals. 


OF    TEE    EXTEEMITIES. 

The  Extremities  or  limbs  are  those  long-jointed  appendages  of  the  body,  which 
are  connected  to  the  trunk  by  one  end,  being  free  in  the  rest  of  their  extent. 
They  are  four  in  number :  an  upper  or  thoracic  pair,  connected  with  the  thorax 
through  the  intervention  of  the  shoulder,  and  subservient  mainly  to  tact  and  pre- 
hension ;  and  a  lower  pair,  connected  with  the  pelvis,  intended  for  support  and 
locomotion.  Both  pairs  of  limbs  are  constructed  after  one  common  type,  so  that 
they  present  numerous  analogies ;  while,  at  the  same  time,  certain  differences  are 
observed  in  each,  dependent  on  the  peculiar  offices  they  severally  perform. 


CLAVICLE.  121 


OF    THE    UPPER    EXTREMITY. 

The  upper  extremity  consists  of  the  arm,  the  forearm,  and  the  hand.  Its  con- 
tinuity with  the  trunk  is  established  by  means  of  the  shoulder,  which  is  homo- 
logous with  the  innominate  or  haunch  bone  in  the  lower  limb. 


OF    THE    SHOULDER. 

The  shoulder  is  placed  upon  the  upper  part  and  side  of  the  chest,  connecting 
the  upper  extremity  to  the  trunk  ;  it  consists  of  two  bones,  the  clavicle,  and  the 
scapula. 

The  Clavicle. 

The  Clavicle  (clavis,  a  key)  or  collar-bone  forms  the  anterior  portion  of  the 
shoulder.  It  is  a  long  bone,  curved  somewhat  like  the  Italic  letter/,  and  placed 
nearly  horizontally  at  the  upper  and  anterior  part  of  the  thorax,  immediately 
above  the  first  rib.  It  articulates  internally  with  the  upper  border  of  the  sternum, 
and  with  the  acromion  process  of  the  scapula  by  its  outer  extremity ;  serving  to 
sustain  the  upper  extremity  in  the  various  positions  which  it  assumes,  whilst,  at 
the  same  time,  it  allows  it  great  latitude  of  motion.  The  horizontal  plane  of  the 
clavicle  is  nearly  straight ;  but  in  the  vertical  plane  it  presents  a  double  curvature, 
the  convexity  being,  in  front,  at  the  sternal  end;  and,  behind,  at  the  scapular  end. 
Its  outer  third  is  flattened  from  above  downwards,  and  extends,  in  the  natural 
position  of  the  bone,  from  the  coracoid  process  to  the  acromion.  Its  inner  two- 
thirds  are  of  a  cylindrical  form,  and  extend  from  the  sternum  to  the  coracoid 
process  of  the  scapula. 

External  or  Flattened  Portion.  The  outer  third  is  flattened  from  above  down- 
wards, so  as  to  present  two  surfaces,  an  upper,  and  a  lower ;  and  two  borders,  an 
anterior,  and  a  posterior. 

The  upper  surface  is  flattened,  rough,  marked  in  front,  for  the  attachment  of 
the  Deltoid ;  behind,  for  the  Trapezius ;  between  these  two  impressions,  externally, 
a  small  portion  of  the  bone  is  subcutaneous.  The  under  surface  is  flattened.  At 
its  posterior  border,  at  the  junction  of  the  prismatic  with  the  flattened  portion,  is 
a  rough  eminence,  the  conoid  tubercle ;  this,  in  the  natural  position  of  the  bone, 
surmounts  the  coracoid  process  of  the  scapula,  and  gives  attachment  to  the  conoid 
ligament.  From  this  tubercle,  an  oblique  line,  occasionally  a  depression,  passes 
forwards  and  outwards  to  near  the  outer  end  of  the  anterior  border ;  it  is  called 
the  oblique  line,  and  affords  attachment  to  the  trapezoid  ligament.  The  anterior 
border'is  concave,  thin,  and  rough;  it  limits  the  attachment  of  the  Deltoid,  and 
occasionally  presents,  near  'the  centre,  a  tubercle,  the  deltoid  tubercle,  which  is 
sometimes  distinct  in  the  living  subject.  The  posterior  border  is  convex,  rough, 
broader  than  the  anterior,  and  gives  attachment  to  the  Trapezius. 

Internal  or  Cylindrical  Portion.  The  cylindrical  portion  forms  the  inner  two- 
thirds  of  the  bone.  It  is  curved,  so  as  to  be  convex  in  front,  concave  behind,  and 
is  marked  by  three  borders  separating  three  surfaces. 

The  anterior  border  is  continuous  with  the  anterior  margin  of  the  flat  portion. 
At  its  commencement  it  is  smooth,  and  corresponds  to  the  unoccupied  interval 
between  the  attachment  of  the  Pectoralis  major  and  Deltoid  muscles ;  about  the 
centre  of  the  clavicle  it  divides  to  inclose  an  elliptical  space  for  the  attachment 
of  the  clavicular  portion  of  the  Pectoralis  major.  This  space  extends  inwards  as 
far  as  the  anterior  margin  of  the  sternal  extremity. 

The  superior  border  is  continuous  with  the  posterior  margin  of  the  flat  portion, 
and  separates  the  anterior  from  the  posterior  surface.  At  its  commencement  it  is 
smooth  and  rounded,  becomes  rough  towards  the  inner  third  for  the  attachment 
of  the  Sterno-cleido-mastoid  muscle,  and  terminates  at  the  upper  angle  of  the 
eternal  extremity. 


122 


OSTEOLOGY. 


The  .posterior  or  subclavian  border  separates  the  posterior  from  the  inferior 
surface,  and  extends  from  the  conoid  tubercle  to  the  rhomboid  depression.  It 
forms  the  posterior  boundary  of  the  groove  for  the  Subclavius  muscle,  and  gives 
attachment  to  the  fascia  which  incloses  it. 

The  anterior  surface  is  included  between  the  superior  and  anterior  borders.  It 
is  directed  forwards  and  a  little  upwards  at  the  sternal  end,  outwards  and  still 
more  upwards  at  the  acromial  extremity,  where  it  becomes  continuous  with  the 
upper  surface  of  the  flat  portion.  Externally,  it  is  smooth,  convex,  nearly  sub- 
cutaneous, being  covered  only  by  the  Platysma ;  but,  corresponding  to  the  inner 
half  of  the  bone,  it  is  divided  by  a  more  or  less  prominent  line  into  two  parts :  an 
anterior  portion,  elliptical  in  form,  rough,  and  slightly  convex,  for  the  attachment 
of  the  Pectoralis  major;  and  an  upper  part,  which  is  rough  behind,  for  the 
attachment  of  the  Sterno-cleido-mastoid.  Between  the  two  muscular  impressions 
is  a  small  subcutaneous  interval. 


Fi«r.  82. — Left  Clavicle.     Anterior  Surface. 


StcTTitilJSxrt^ 


Acromial  HxtJ/ 


Fig.  83. — Left  Clavicle.     Inferior  Surface. 


The  posterior  or  cervical  surface  is  smooth,  flat,  directed  vertically,  and  looks 
backwards  towards  the  root  of  the  neck.  It  is  limited,  above,  by  the  superior 
border;  below,  by  the  subclavian  border;  internally,  by  the  margin  of  the  sternal 
extremity;  externally,  it  is  continuous  with  the  posterior  border  of  the  flat  portion. 
It  is  concave  from  within  outwards,  and  is  in  relation,  by  its  lower  part,  with  the 
suprascapular  vessels.  It  gives  attachment,  near  the  sternal  extremity,  to  part  of 
the  Sterno-hyoid  muscle ;  and  presents,  at  or  near  the  middle,  a  foramen,  directed 
obliqiiely  outwards,  which  transmits  the  chief  nutrient  artery  of  the  bone.  Some- 
times, there  are  two  foramina  on  the  posterior  surface ;  or  one  on  the  posterior, 
the  other  on  the  inferior  surface. 

The  inferior  or  subclavian  surface  is  bounded,  in  front,  by  the  anterior  border  ; 
behind,  by  the  subclavian  border.  It  is  narrow  internally,  but  gradually  increases 
in  width  externally,  and  is  continuous  with  the  under  surface  of  the  flat  portion. 
Commencing  at  the  sternal  extremity  may  be  seen  a  small  facet  for  articulation 
with  the  cartilage  of  the  first  rib.  This  is  continuous  with  the  articular  surface 
at  the  sternal  end  of  the  bone.  External  to  this  is  a  broad  rough  impression,  the 
rhomboid,  rather  more  than  an  inch  in  length,  for  the  attachment  of  the  costo- 
clavicular or  rhomboid  ligament.  The  remaining  part  of  this  surface  is  occupied 
by  a  longitudinal  groove,  the  subclavian  groove,  broad  and  smooth  externally, 


SCAPULA.  123 

narrow  and  more  uneven  internally;  it  gives  attachment  to  the  Subclavius  muscle, 
ami,  by  its  anterior  margin,  to  the  strong  aponeurosis  which  incloses  it.  Not 
untivquently  this  groove  is  subdivided  into  two  parts,  by  a  longitudinal  line, 
which  gives  attachment  to  the  intermuscular  septum  of  the  Subclavius  muscle. 

The  internal  or  sternal  end  of  the  clavicle  is  triangular  in  form,  directed  inwards, 
and  a  little  downwards  and  forwards ;  and  presents  an  articular  facet,  concave 
from  before  backwards,  convex  from  above  downwards,  which  articulates  with 
the  sternum  through  the  intervention  of  an  interarticular  fibro-cartilage ;  the 
circumference  of  the  articular  surface  is  rough,  for  the  attachment  of  numerous 
ligaments.  This  surface  is  continuous  with  the  costal  facet  on  the  inner  end  of 
the  inferior  or  subclavian  surface,  which  articulates  with  the  cartilage  of  the 
first  rib. 

The  outer  or  acromial  extremity,  directed  outwards  and  forwards,  presents  a 
small,  flattened,  oval  facet,  directed  obliquely  downwards  and  inwards,  for  articu- 
lation with  the  acromion  process  of  the  scapula.  The  direction  of  this  surface 
serves  to  explain  the  greater  frequency  of  dislocation  of  this  bone  upon,  and  not 
beneath,  the  acromion  process.  The  circumference  of  the  articular  facet  is  rough, 
especially  above,  for  the  attachment  of  the  acromio-clavicular  ligaments. 

Peculiarities  of  the  Bone  in  the  Sexes  and  in  Individuals.  In  the  female,  the  cla- 
vicle is  generally  less  curved,  smoother,  and  more  slender  than  in  the  male.  In 
those  persons  who  perform  considerable  manual  labor,  which  brings  into  constant 
action  the  muscles  connected  with  this  bone,  it  requires  considerable  bulk,  becomes 
shorter,  and  more  curved,  its  ridges  for  muscular  attachment  become  prominently 
marked,  and  its  sternal  end  of  a  prismatic  or  quadrangular  form.  The  right 
clavicle  is  generally  heavier,  thicker,  and  rougher,  and  ofte*n  shorter,  than  the  left. 

Structure.  The  shaft,  as  well  as  the  extremities,  consists  of  cancellous  tissue, 
invested  in  a  compact  layer  much  thicker  in  the  centre  than  at  either  end.  The 
clavicle  is  highly  elastic,  by  reason  of  its  curves.  From  the  experiments  of  Mr. 
"Ward,  it  has  been  shown  that  it  possesses  sufficient  longitudinal  elastic  force  to 
raise  its  own  weight  nearly  two  feet  on  a  level  surface ;  and  sufficient  transverse 
elastic  force,  opposite  the  centre  of  its  anterior  convexity,  to  raise  its  own  weight 
about  a  foot.  This  extent  of  elastic  power  must  serve  to  moderate  very  consi- 
derably the  effect  of  concussions  received  upon  the  point  of  the  shoulder. 

Development.  By  two  centres :  one  for  the  shaft,  and  one  for  the  sternal  extremity. 
The  centre  for  the  shaft  appears  very  early,  before  any  other  bone ;  the  centre 
for  the  sternal  end  makes  its  appearance  about  the  eighteenth  or  twentieth  year, 
and  unites  with  the  rest  of  the  bone  a  few  years  after. 

Articulations.  With  the  sternum,  scapula,  and  cartilage  of  the  first  rib. 

Attachment  of  Muscles.  The  Sterno-cleido-mastoid,  Trapezius,  Pectoralis  major, 
Deltoid,  Subclavius,  and  Sterno-hyoid. 

The  Scapula. 

The  Scapula  forms  the  back  part  of  the  shoulder.  It  is  a  large  flat  bone,  tri- 
angular in  shape,  situated  at  the  posterior  aspect  and  side  of  the  thorax,  between 
the  first  and  eighth  ribs,  its  posterior  border  or  base  being  about  an  inch  from, 
and  nearly  parallel  with,  the  spinous  processes  of  the  vertebras.  It  presents  for 
examination  two  surfaces,  three  borders,  and  three  angles. 

The  anterior  surface  or  venter  (fig.  84)  presents  a  broad  concavity,  the  sub- 
scapular fossa.  It  is  marked,  in  the  posterior  two-thirds,  by  several  oblique  ridges, 
which  pass  from  behind  obliquely  forwards  and  upwards,  the  anterior  third  being 
smooth.  The  oblique  ridges,  above-mentioned,  give  attachment  to  the  tendinous 
intersections;  and  the  surfaces  between  them,  to  the  fleshy  fibres  of  the  Subscapu- 
lars muscle.  The  anterior  third  of  the  fossa,  which  is  smooth,  is  covered  by, 
but  does  not  afford  attachment  to,  the  fibres  of  this  muscle.  This  surface  is  sepa- 
rated from  the  posterior  border  by  a  smooth  triangular  margin  at  the  superior 
and  inferior  angles,  and  in  the  interval  between  these,  by  a  narrow  edge  which  is 


124 


OSTEOLOGY. 


often  deficient.  This  inargin.il  surface  affords  attachment  throughout  its  entire 
extent  to  the  Serratus  magnus  muscle.  The  subscapular  fossa  presents  a  trans- 
verse depression  at  its  upper  part,  called  the  subscapular  angle;  it  is  in  this  situa- 
tion that  the  fossa  is  deepest ;  and  consequently  the  thickest  part  of  the  Sub- 
scapularis  muscle  lies  in  a  line  parallel  with  the  glenoid  cavity,  and  must  conse- 
quently operate  most  effectively  on  the  humerus  which  is  contained  in  it. 

The  posterior  surface  or  dorsum  (fig.  85)  is  arched  from  above  downwards, 
alternately  convex  and  concave  from  side  to  side.     It  is  subdivided  unequally 


Fig.  84. — Left  Scapula.     Anterior  Surface  or  Venter. 


into  two  parts  by  the  spine ;  that  portion  above  the  spine  is  caned  the  supra- 
spinous fossa,  and  that  below  it,  the  infra-spinous  fossa. 

The  supraspinous  fossa,  the  smaller  of  the  two,  is  concave,  smooth,  and 
broader  at  the  vertebral  than  at  the  humeral  extremity.  It  affords  attachment  by 
its  inner  two-thirds  to  the  Supra-spinatus  muscle. 

The  infra-spinous  fossa  is  much  larger  than  the  preceding :  towards  its  ver- 
tebral margin  a  shallow  concavity  is  seen  at  its  upper  part ;  its  centre  presents  a 


SCAPULA. 


125 


prominent  convexity,  -whilst  towards  the  axillary  border  is  a  deep  groove,  which 
runs  from  the  upper  towards  the  lower  part.  The  inner  three-fourths  of  this 
surface  afford  attachment  to  the  Infra-spinatus  muscle ;  the  outer  fourth  is  only 
covered  by  it,  without  giving  origin  to  its  fibres.  This  surface  is  separated  from 
the  axillary  border  by  an  elevated  ridge,  which  runs  from  the  lower  part  of  the 
glenoid  cavity,  downwards  and  backwards  to  the  posterior  border,  about  an  inch 


«<»** 


Fig.  85. — Left  Scapula.     Posterior  Surface  or  Dorsum. 
Cora  co  j  Qf 


above  the  inferior  angle.  This  ridge  serves  for  the  attachment  of  a  strong  apon- 
eurosis, which  separates  the  Infra-spinatus  from  the  two  Teres  muscles.  The 
surface  of  bone  between  this  line  and  the  axillary  border  is  narrow  for  the  upper 
two-thirds  of  its  extent,  and  traversed  near  its  centre  by  a  groove  for  the  passage 
of  the  dorsalis  scapuhe  vessels;  it  affords  attachment  to  the  Teres  minor.  Its 
lower  third  presents  a  broader,  somewhat  triangular  surface,  which  gives  origin 
to  the  Teres  major,  and  over  which  glides  the  Latissimus  dorsi ;  sometimes  the 
latter  muscle  takes  its  origin  by  a  few  fibres  from  this  part.    The  broad  and  narrow 


126  -  OSTEOLOGY. 

portions  of  bone  above  alluded  to  are  separated  by  an  oblique  line,  which  runs 
from  the  axillary  border,  downwards  and  backwards ;  to  it  is  attached  the  aponeu- 
rosis separating  the  two  Teres  muscles  from  each  other. 

The  Spine  is  a  prominent  plate  of  bone,  which  crosses  obliquely  the  inner 
four-fifths  of  the  dorsum  of  the  scapula  at  its  upper  part,  and  separates  the 
supra-spinous  from  the  infra-spin  ous  fossa :  it  commences  at  the  vertebral  border 
by  a  smooth  triangular  surface,  over  which  the  Trapezius  glides,  separated  by  a 
bursa ;  and,  gradually  becoming  more  elevated  as  it  passes  forwards,  terminates  in  the 
acromion  process  which  overhangs  the  shoulder-joint.  The  spine  is  triangular  and 
flattened  from  above  downwards,  its  apex  corresponding  to  the  posterior  border ;  its 
base,  which  is  directed  outwards,  to  the  neck  of  the  scapula.  It  presents  two 
surfaces  and  three  borders.  Its  superior  surface  is  concave,  assists  in  forming  the 
supra-spinous  fossa,  and  affords  attachment  to  part  of  the  Supra-spinatus  muscle. 
Its  inferior  surface  forms  part  of  the  infra-spinous  fossa,  gives  origin  to  part  of  the 
lnfra-spinatus  muscle,  and  presents  near  its  centre  the  orifice  of  a  nutritious  canal. 
Of  the  three  borders,  the  anterior  is  attached  to  the  dorsum  of  the  bone ;  the 
posterior,  or  crest  of  the  spine,  is  broad,  and  presents  two  lips,  and  an  intervening 
rough  interval.  To  the  superior  lip  is  attached  the  Trapezius,  to  the  extent  shown 
in  the  figure.  A  very  rough  prominence  is  generally  seen  occupying  that  portion 
of  the  spine  which  receives  the  insertion  of  the  middle  and  inferior  fibres  of  this 
muscle.  To  the  inferior  lip,  throughout  its  whole  length,  is  attached  the  Deltoid. 
The  interval  between  the  lips  is  also  partly  covered  by  the  fibres  of  these  muscles. 
The  external  border,  the  shortest  of  the  three,  is  slightly  concave,  its  edges  thick 
and  round,  continuous  above  with  the  under  surface  of  the  acromion  process ; 
below,  with  the  neck  of  the  scapula.  The  narrow  portion  of  bone  external  to  this 
border  serves  to  connect  the  supra-spinous  and  infra-spinous  fossae. 

The  Acromion  process,  so  called  from  forming  the  summit  of  the  shoulder 
(axpov,  a  summit ;  t3,aos,  the  shoulder),  is  a  large,  and  somewhat  triangular  process, 
flattened  from  behind  forwards,  directed  at  first  a  little  outwards,  and  then  curving 
forwards  and  upwards,  so  as  to  overhang  the  glenoid  cavity.  Its  upper  surface 
directed  upwards,  backwards  and  outwards,  is  convex,  rough,  and  gives  attachment 
to  some  fibres  of  the  Deltoid.  Its  under  surface  is  smooth  and  concave.  Its 
outer  border,  which  is  thick  and  irregular,  affords  attachment  to  the  Deltoid 
muscle.  Its  inner  margin,  shorter  than  the  outer,  is  concave,  gives  attachment 
to  a  portion  of  the  Trapezius  muscle,  and  presents  about  its  centre  a  small  oval 
surface,  for  articulation  with  the  scapular  end  of  the  clavicle.  Its  apex,  which 
corresponds  to  the  point  of  meeting  of  these  two  borders  in  front,  is  thin,  and  has 
attached  to  it  the  coraco-acromial  ligament. 

,Of  the  three  borders  or  costaa  of  the  scapula,  the  superior  is  the  shortest  and 
thinnest ;  it  is  concave,  terminating  at  its  inner  extremity  at  the  superior  angle, 
at  its  outer  extremity  at  the  coracoid  process.  At  its  outer  part  is  a  deep 
semicircular  notch,  the  supra-scapular,  formed  partly  by  the  base  of  the  coracoid 
process.  This  notch  is  converted  into  a  foramen  by  the  transverse  ligament,  and 
serves  for  the  passage  of  the  supra-scapular  nerve.  The  adjacent  margin  of 
the  superior  border  affords  attachment  to  the  Omo-hyoid  muscle.  The  external 
or  axillary  border  is  the  thickest  of  the  three.  It  commences  above  at  the  lower 
margin  of  the  glenoid  cavity,  and  inclines  obliquely  downwards  and  backwards  to 
the  inferior  angle.  Immediately  below  the  glenoid  cavity  is  a  rough  depression 
about  an  inch  in  length,  which  affords  attachment  to  the  long  head  of  the  Triceps 
muscle ;  to  this  succeeds  a  longitudinal  groove,  which  extends  as  far  as  its  lower 
third,  and  affords  origin  to  part  of  the  Subscapularis  muscle.  The  inferior  third 
of  this  border,  which  is  thin  and  sharp,  serves  for  the  attachment  of  a  few  fibres 
of  the  Teres  major  behind,  and  of  the  Subscapularis  in  front.  The  internal  or 
vertebral  border,  also  named  the  base,  is  the  longest  of  the  three,  and  extends 
from  the  superior  to  the  inferior  angle  of  the  bone.  It  is  arched,  intermediate  in 
thickness  between  the  superior  and  the  external  borders,  and  that  portion  of  it 
above  the  spine  is  bent  considerably  outwards,  so  as  to  form  an  obtuse  angle  with 


SCAPULA.  127 

the  lower  part.  The  vertebral  border  presents  an  anterior  lip,  a  posterior  lip,  and 
an  intermediate  space.  The  anterior  lip  affords  attachment  to  the  Serratus  mag- 
mis  ;  the  posterior  lip,  to  the  Supra-spinatus  above  the  spine,  the  Infra-spinatus 
below ;  the  interval  between  the  two  lips,  to  the  Levator  anguli  scapulas  above 
the  triangular  surface  at  the  commencement  of  the  spine ;  the  Ehomboideus  minor, 
to  the  edge  of  that  surface;  the  Ehomboideus  major  being  attached  by  means  of 
a  fibrous  arch,  connected  above  to  the  lower  part  of  the  triangular  surface  at  the 
base  of  the  spine,  and  below  to  the  lower  part  of  the  posterior  border. 

Of  the  three  angles,  the  superior,  formed  by  the  junction  of  the  superior  and 
internal  borders,  is  thin,  smooth,  rounded,  somewhat  inclined  outwards,  and  gives 
attachment  to  a  few  fibres  of  the  Levator  anguli  scapulas  muscle.  The  inferior 
angle,  thick  and  rough,  is  formed  by  the  union  of  the  vertebral  and  axillary 
borders,  its  outer  surface  affording  attachment  to  the  Teres  major,  and  occasionally 
a  few  fibres  of  the  Latissimus  dorsi.  The  anterior  angle  is  the  thickest  part  of 
the  bone,  and  forms  what  is  called  the  head  of  the  scapula.  The  head  presents 
a  shallow,  pyriform,  articular  surface,  the  glenoid  cavity  (y^vrj,  a  superficial 
cavity;  nSo?,  like);  its  longest  diameter  is  from  above  downwards,  and  its 
direction  outwards  and  forwards.  It  is  broader  below  than  above ;  at  its  apex  is 
attached  the  long  tendon  of  the  Biceps  muscle.  It  is  covered  with  cartilage  in 
the  recent  state;  and  its  margins,  slightly  raised,  give  attachment  to  a  fibro- 
cartilaginous structure,  the  glenoid  ligament,  by  which  its  cavity  is  deepened. 
The  neck  of  the  scapula  is  the  slightly  depressed  surface  which  surrounds  the 
head ;  it  is  more  distinct  on  the  posterior  than  on  the  anterior  surface,  and  below 
than  above.  In  the  latter  situation  it  has,  arising  from  it,  a  thick  prominence, 
the  coracoid  process. 

The  Coracoid  process,  so  called  from  its  fancied  resemblance  to  a  crow's  beak 
(xopat,  a  crow  ;  «8os,  resemblance),  is  a  thick  curved  process  of  bone,  which  arises  by 
a  broad  base  from  the  upper  part  of  the  neck  of  the  scapula ;  it  ascends  at  first 
upwards  and  inwards ;  then,  becoming  smaller,  it  changes  its  direction  and  passes 
forwards  and  outwards.  The  ascending  portion,  flattened  from  before  backwards, 
presents  in  front  a  smooth  concave  surface,  over  which  passes  the  Subscapularis 
muscle.  The  horizontal  portion  is  flattened  from  above  downwards ;  its  upper 
surface  is  convex  and  irregular ;  its  under  surface  is  smooth ;  its  anterior  border 
is  rough,  and  gives  attachment  to  the  Pectoralis  minor ;  its  posterior  border  is  also 
rough  for  the  coraco-acromial  ligament,  while  the  apex  is  embraced  by  the  con- 
joined tendon  of  origin  of  the  short  head  of  the  Biceps  and  Coraco-brachialis 
muscles.  At  the  inner  side  of  the  root  of  the  coracoid  process  is  a  rough  depres- 
sion for  the  attachment  of  the  conoid  ligament,  and,  running  from  it  obliquely 
forwards  and  outwards  on  the  upper  surface  of  the  horizontal  portion,  an  elevated 
ridge  for  the  attachment  of  the  trapezoid  ligament. 

Structure.  In  the  head,  processes,  and  all  the  thickened  parts  of  the  bone,  it 
is  cellular  in  structure,  of  a  dense  compact  tissue  in  the  rest  of  its  extent.  The 
centre  and  upper  part  of  the  dorsum,  but  especially  the  former,  is  usually  so  thin 
as  to  be  semi-transparent ;  occasionally  the  bone  is  found  wanting  in  this  situation, 
and  the  adjacent  muscles  come  into  contact. 

Development  (fig.  86).  By  seven  centres ;  one  for  the  body,  two  for  the  coracoid 
process,  two  for  the  acromion,  one  for  the  posterior  border,  and  one  for  the  inferior 
angle. 

Ossification  of  the  body  of  the  scapula  commences  about  the  second  month  of 
fcetal  life,  by  the  formation  of  an  irregular  quadrilateral  plate  of  bone,  imme- 
diately behind  the  glenoid  cavity.  This  plate  extends  itself  so  as  to  form  the 
chief  part  of  the  bone,  the  spine  growing  up  from  its  posterior  surface  about  the 
third  month.  At  birth  the  chief  part  of  the  scapula  is  osseous,  the  coracoid  and 
acromion  processes,  the  posterior  border,  and  inferior  angle,  being  cartilaginous. 
About  the  first  year  after  birth,  ossification  takes  place  in  the  middle  of  the 
coracoid  process ;  which  usually  becomes  joined  with  the  rest  of  the  bone  at  the 
time  when  the  other  centres  make  their  appearance.     Between  the  fifteenth  und 


128 


OSTEOLOGY. 


seventeenth  years,  ossification  of  the  remaining  centres  takes  place  in  quick  suc- 
cession, and  in  the  following  order :  first,  near  the  base  of  the  acromion,  and  in  the 
upper  part  of  the  coracoid  process,  the  latter  appearing  in  the  form  of  a  broad 
scale ;  secondly,  in  the  inferior  angle  and  contiguous  part  of  the  posterior  border ; 
thirdly,  near  the  extremity  of  the  acromion;  fourthly,  in  the  posterior  border. 
The  acromion  process,  besides  being  formed  of  two  separate  nuclei,  has  its  base 
formed  by  an  extension  into  it  of  the  centre  of  ossification  which  belongs  to  the 
spine,  the  extent  of  which  varies  in-  different  cases.  The  two  separate  nuclei 
unite,  and  then  join  with  the  extension  carried  in  from  the  spine.  These  various 
epiphyses  become  joined  to  the  bone  between  the  ages  of  twenty-two  and  twenty- 
five  years.  Sometimes  failure  of  union  between  the  acromion  process  and  spine 
occurs,  the  junction  being  effected  by  fibrous  tissue,  or  by  an  imperfect  articulation; 


Fig.  86. — Plan  of  the  Development  of  the  Scapula.     By  Seven  Centres. 


2  for  fc 


Kferio* 


in  some  cases  of  supposed  fracture  of  .the  acromion  with  ligamentous  union,  it  is 
probable  the  detached  segment  was  never  united  to  the  rest  of  the  bone. 

Articulations.    With  the  humerus  and  clavicle. 

Attachment  of  Muscles.  To  the  anterior  surface,  the  Subscapularis ;  posterior 
surface,  Supra- spinatus,  Infra-spinatus ;  spine,  Trapezius,  Deltoid;  superior  border, 
Omo-hyoid ;  vertebral  border,  Serratus  magnus,  Levator  anguli  scapulas,  Ehom- 
boideus  minor  and  major ;  axillary  border,  Triceps,  Teres  minor,  Teres  major ; 
glenoid  cavity,  long  head  of  the  Biceps ;  coracoid  process,  short  head  of  Biceps, 
Coraco-brach'ialis,  Pectoralis  minor ;  and  to  the  inferior  angle,  occasionally  a  few 
fibres  of  the  Latissimus  dorsi. 


HUMERUS.  12? 


The  Humerus. 


The  Humerus  (fig.  87)  is  the  longest  and  largest  bone  of  the  upper  extremity ; 
it  presents  for  examination  a  shaft  and  two  extremities. 

The  Upper  Extremity  is  the  largest  part  of  the  bone ;  it  presents  a  rounded 
head,  a  constriction  around  the  base  of  the  head,  the  neck,  and  two  other  emi- 
nences, the  greater  and  ]esser  tuberosities. 

The  head,  nearly  hemispherical  in  form,  is  directed  upwards,  inwards,  and  a 
little  backwards ;  its  surface  is  smooth,  coated  with  cartilage  in  the  recent  state, 
and  articulates  with  the  glenoid  cavity  of  the  scapula.  The  circumference  of  its 
articular  surface  is  slightly  constricted,  and  is  termed  the  anatomical  neck,  in 
contradistinction  to  the  constriction  which  exists  below  the  tuberosities,  and  is 
called  the  surgical  neck,  from  its  often  being  the  seat  of  fracture.  It  should  be 
remembered,  however,  that  fracture  of  the  anatomical  neck  does  sometimes, 
though  rarely,  occur. 

The  anatomical  neck  is  obliquely  directed,  forming  an  obtuse  angle  with  the 
shaft.  It  is  more  distinctly  marked  in  the  lower  half  of  its  circumference  than  in 
the  upper  half,  where  it  presents  a  narrow  groove,  separating  the  head  from  the 
tuberosities.  Its  circumference  affords  attachment  to  the  capsular  ligament,  and 
is  perforated  by  numerous  vascular  foramina. 

The  greater  tuberosity  is  situated  on  the  outer  side  of  the  head  and  lesser 
tuberosity.  Its  upper  surface  is  rounded  and  marked  by  three  flat  facets,  separated 
by  two  slight  ridges ;  the  most  anterior  facet  gives  attachment  to  the  tendon  of 
the  Supra-spinatus ;  the  middle  one,  to  the  Infra-spinatus ;  the  posterior  one,  to 
the  Teres  minor.  The  outer  surface  of  the  great  tuberosity  is  convex,  rough, 
and  continuous  with  the  outer  side  of  the  shaft. 

The  lesser  tuberosity  is  more  prominent,  although  smaller  than  the  greater ;  it 
is  situated  in  front  of  the  head,  and  is  directed  inwards  and  forwards.  Its  summit 
presents  a  prominent  facet  for  the  insertion  of  the  tendon  of  the  Subscapularis 
muscle.  The  tuberosities  are  separated  from  one  another  by  a  deep  groove,  the 
bicipital  groove,  so  called  from  its  lodging  the  long  tendon  of  the  Biceps  muscle. 
It  commences  above  between  the  two  tuberosities,  passes  obliquely  downwards 
and  a  little  inwards,  and  terminates  at  the  junction  of  the  upper  with  the  middle 
third  of  the  bone.  It  is  deep  and  narrow  at  its  commencement,  and  becomes 
shallow  and  a  little  broader  as  it  descends.  In  the  recent  state  it  is  covered  with 
a  thin  layer  of  cartilage,  lined  by  a  prolongation  of  the  synovial  membrane  of  the 
shoulder-joint,  and  receives  part  of  the  tendon  of  insertion  of  the  Latissimus  dorsi 
about  its  centre. 

The  Shaft  of  the  humerus  is  almost  cylindrical  in  the  upper  half  of  its  extent ; 
prismatic  and  flattened  below,  it  presents  three  borders  and  three  surfaces  for 
examination. 

The  anterior  border  runs  from  the  front  of  the  great  tuberosity  above,  to  the 
coronoid  depression  below,  separating  the  internal  from  the  external  surface.  Its 
upper  part  is  very  prominent  and  rough;  forms  the  outer  lip  of  the  bicipital 
groove,  and  serves  for  the  attachment  of  the  tendon  of  the  Pectoralis  major. 
About  its  centre  is  seen  the  rough  deltoid  impression ;  below,  it  is  smooth  and 
rounded,  affording  attachment  to  the  Brachialis  anticus. 

The  external  border  runs  from  the  back  part  of  the  greater  tuberosity  to 
the  external  condyle,  and  separates  the  external  from  the  posterior  surface.  It  is 
rounded  and  indistinctly  marked  in  its  upper  half,  serving  for  the  attachment  of 
the  external  head  of  the  Triceps  muscle ;  its  centre  is  traversed  by  a  broad  but 
shallow  oblique  depression,  the  musculo-spiral  groove.;  its  lower  part  is  marked 
by  a  prominent  rough  margin,  a  little  curved  from  behind  forwards,  which 
presents  an  anterior  lip  for  the  attachment  of  the  Supinator  longus,  above  the 
Extensor  carpi  radialis  longior  below;  a  posterior  lip  for  the  Triceps,  and  an 
interstice  for  the  attachment  of  the  external  intermuscular  aponeurosis. 


L30 


OSTEOLOGY. 


Fig.  87. — Left  Humerus.     Anterior  View. 


Surgical  Neck 


Common  Origin 

WFjA 

rLEXOft   CARPI    RADIALI8          WT^m 
fAi.MAR18       LONCUS                                 * 
FLEXOR     nr.lTORUM      SUBLIMIS 
,,           UHH      ULNARI* 

fflfTroch 

8UPINATOB     RADII     lONCUf 


EXTEN30R    OARPI     RADIALI3 
LQNCIQB 


.t>    Comrn-on  Amm 

of 

y    .V  EXTENSOR.  CARP.  BAD.  SREV 

j&  „    DICITOHUM  COMMUNIS 

.,     MINIMI    DICITI 

„     CARPI  UlNARIS 

iUPikUTQR  SREVIS 


HUMERUS.  131 

The  internal  border  extends  from  the  lesser  tuberosity  to  the  internal  condyle. 
Its  upper  third  is  marked  by  a  prominent  ridge,  forming  the  inner  lip  of  the 
bicipital  groove,  and  gives  attachment  from  above  downwards  to  the  tendons  of 
the  Latissimus  dorsi,  Teres  major,  and  part  of  the  origin  of  the  inner  head  of  the 
Triceps.  About  its  centre  is  a  rough  ridge  for  the  attachment  of  the  Coraco- 
brachialis,  and  just  below  this  is  seen  the  entrance  of  the  nutritious  canal  directed 
downwards.  Sometimes  there  is  a  second  canal  higher  up,  which  takes  a  similar 
direction.  Its  inferior  third  is  raised  into  a  slight  ridge,  which  becomes  very 
prominent  below;  it  presents  an  anterior  lip  for  the  attachment  of  the  Brachialis 
anticus,  a  posterior  lip  for  the  internal  head  of  the  Triceps,  and  an  intermediate 
space  for  the  internal  intermuscular  aponeurosis. 

The  external  surface  is  directed  outwards  above,  where  it  is  smooth,  rounded, 
and  covered  by  the  Deltoid  muscle ;  forwards  below,  where  it  is  slightly  concave 
from  above  downwards,  and  gives  origin  to  part  of  the  Brachialis  anticus  muscle. 
About  the  middle  of  this  surface,  is  seen  a  rough  triangular  impression  for  the 
insertion  of  the  Deltoid  muscle,  and  below  it  the  musculo-spiral  groove,  directed 
obliquely  from  behind,  forwards  and  downwards ;  it  transmits  the  musculo-spiral 
nerve  and  superior  profunda  artery. 

The  internal  surface,  less  extensive  than  the  external,  is  directed  forwards 
above,  forwards  and  inwards  below ;  at  its  upper  part  it  is  narrow,  and  forms  the 
bicipital  groove.  The  middle  part  of  this  surface  is  slightly  rough  for  the 
attachment  of  the  Coraco-brachialis ;  its  lower  part  is  smooth,  concave,  and  gives 
attachment  to  the  Brachialis  anticus  muscle.1 

The  "posterior  surface  (fig.  88)  appears  somewhat  twisted,  so  that  its  upper  part 
is  directed  a  little  inwards,  its  lower  part  backwards,  and  a  little  outwards. 
Nearly  the  whole  of  this  surface  is  covered  by  the  external  and  internal  heads  of 
the  Triceps,  the  former  being  attached  to  its  upper  and  outer  part,  the  latter  to 
its  inner  and  back  part,  their  origin  being  separated  by  the  musculo-spiral  groove. 

The  Lower  Extremity  is  flattened  from  before  backwards,  and  curved  slightly 
forwards :  it  terminates  below  in  a  broad  articular  surface,  which  is  divided  into 
two  parts  by  a  slight  ridge.  On  either  side  of  the  articular  surface  are  the  ex- 
ternal and  internal  condyles.  The  articular  surface  extends  a  little  lower  than 
the  condyles,  and  is  curved  slightly  forwards,  so  as  to  occupy  the  more  anterior 
part  of  the  bone ;  its  greatest  breadth  is  in  the  transverse  diameter,  and  it  is 
obliquely  directed,  so  that  its  inner  extremity  occupies  a  lower  level  than  the 
outer.  The  outer  portion  of  the  articular  surface  presents  a  smooth  rounded 
eminence,  which  has  received  the  name  of  the  lesser  or  radial  head  of  the  humerus ; 
it  articulates  with  the  cup-shaped  depression  on  the  head  of  the  radius,  is  limited 
to  the  front  and  lower  part  of  the  bone,  not  extending  as  far  back  as  the  other 
portion  of  the  articular  surface.  On  the  inner  side  of  this  eminence  is  a  shallow 
groove,  in  which  is  received  the  inner  margin  of  the  head  of  the  radius.  The 
inner  or  trochlear  portion  of  the  articular  surface  presents  a  deep  depression 
between  two  well-marked  borders.  This  surface  is  convex  from  before  back- 
wards, concave  from  side  to  side,  and  occupies  the  anterior  lower  and  posterior  parts 
of  the  bone.     The  external  border,  less  prominent  than  the  internal,  corresponds 

1  A  small  hook-shaped  process  of  bone,  varying  from  T'ff  to  $  of  an  inch  in  length,  is  not 
unfrequently  found  projecting  from  the  inner  surface  of  the  shaft  of  the  humerus  two  inches 
above  the  internal  condyle.  It  is  curved  downwards,  forwards,  and  inwards,  and  its  pointed 
extremity  is  connected  to  the  internal  border  just  above  the  inner  condyle,  by  a  ligament  or 
fibrous  band;  completing  an  arch,  through  which  the  median  nerve  and  brachial  artery  pass, 
when  these  structures  deviate  from  their  usual  course.  Sometimes  the  nerve  alone  is  transmitted 
through  it,  or  the  nerve  may  be  accompanied  by  the  ulnar  interosseous  artery,  in  cases  of  high 
division  of  the  brachial.  A  well-marked  groove  is  usually  found  behind  the  process,  in  which 
the  nerve  and  artery  are  lodged.  This  space  is  analogous  to  the  supra-condyloid  foramen  in 
many  animals,  and  probably  serves  in  them  to  protect  the  nerve  and  artery  from  compression 
during  the  contraction  of  the  muscles  in  this  region.  A  detailed  account  of  this  process  is  given 
by  Dr.  Struthers,  in  his  "  Anatomical  and  Physiological  Observations,"  p.  202. 


132 


OSTEOLOGY. 


Fie;.  88. — Left  Humerus.     Posterior  Surface. 


1 9 


e 


f* 


[Jrochi 


to  tlie  interval  between  the  radius  and 
ulna.  The  internal  border  is  thicker, 
more  prominent,  and  consequently  of 
greater  length  than  the  external.  The 
grooved  portion  of  the  articular  surface  fits 
accurately  within  the  greater  sigmoid  ca- 
vity of  the  ulna ;  it  is  broader  and  deeper 
on  the  posterior  than  on  the  anterior  aspect 
of  the  bone,  and  is  directed  obliquely  from 
behind  forwards,  and  from  without  in- 
wards. Above  the  back  part  of  the 
trochlear  surface,  is  a  deep  triangular  de- 
pression, the  olecranon  depression  in  which 
is  received  the  summit  of  the  olecranon 
process  in  extension  of  the  forearm.  Above 
the  front  part  of  the  trochlear  surface,  is 
seen  a  small  depression,  the  coronoid  de- 
pression ;  it  receives  the  coronoid  process 
of  the  ulna  during  flexion  of  the  fore- 
arm. These  fossae  are  separated  from  one 
another  by  a  thin  transparent  laminae  of 
bone,  which  is  sometimes  perforated;  their 
margins  afford  attachment  to  the  anterior 
and  posterior  ligaments  of  the  elbow -joint, 
and  they  are  lined  in  the  recent  state  by 
the  synovial  membrane  of  this  articula- 
tion. Above  the  front  part  of  the  radial 
tuberosity,  is  seen  a  slight  depression 
which  receives  the  anterior  border  of  the 
head  of  the  radius  when  the  forearm  is 
strongly  flexed.  The  external  condyle 
is  a  small  tubercular  eminence,  less  pro- 
minent than  the  internal,  curved  a  little 
forwards,  and  giving  attachment  to  the 
external  lateral  ligament  of  the  elbow- 
joint,  and  to  a  tendon  common  to  the 
origin  of  some  of  the  extensor  and  supi- 
nator muscles.  The  internal  condyle, 
larger  and  more  prominent  than  the  ex- 
ternal, is  directed  a  little  backwards,  and 
gives  attachment  to  the  internal  lateral 
ligament,  and  to  a  tendon  common  to  the 
origin  of  some  of  the  flexor  muscles  of 
the  forearm.  These  eminences  are  di- 
rectly continuous  above  with  the  external 
and  internal  borders.  The  greater  pro- 
minence of  the  inner  one  renders  it  more 
liable  to  fracture. 

Structure.  The  extremities  consist  of 
cancellous  tissue,  covered  with  a  thin 
compact  layer ;  the  shaft  is  composed  of 
a  cylinder  of  compact  tissue,  thicker  at 
the  centre  than  at  the  extremities,  and 
hollowed  out  by  a  large  medullary  canal, 
which  extends  along  its  whole  length. 

Development,  By  seven  centres  (fig. 
89):  one  for  the  shaft,  one  for  the  head, 


HUMERUS. 


133 


Fig.  89. — Plan  of  the  Development  of  the 
Humerus.     By  7  Centres. 


Epiphyses  ef  Head fcj    A* 
Tuberosities  blrml at\<*j 
S.Uranil  unite  \ 
*>i'L&  SAaft  at  2U  4*y '. J 


one  for  the  greater  tuberosity,  one  for  the  radial  portion  of  the  articular  surface, 
one  for  the  trochlear  portion,  and  one  for  each  condyle.  The  centre  for  the  shaft 
appears  very  early,  soon  after  ossification  has  commenced  in  the  clavicle,  and 
soon  extends  towards  the  extremities.  At  birth,  it  is  ossified  nearly  in  its  whole 
length,  the  extremities  remaining  cartilaginous.  Between  the  first  and  second 
years,  ossification  commences  in  the  head  of  the  bone,  and  between  the  second 
and  third  years  the  centre  for  the  tuberosities  makes  its  appearance  usually  by  a 
single  ossific  point,  but  sometimes,  according  to  Beclard,  by  one  for  each  tube- 
rosity, that  for  the  lesser  being  small,  and  not  appearing  until  after  the  fourth 
year.  By  the  fifth  year,  the  centres  for  the  head  and  tuberosities  have  enlarged 
and  become  joined,  so  as  to  form  a  single  large  epiphysis. 

The  lower  end  of  the  humerus  is  devel- 
oped in  the  following  manner :  At  the  end 
of  the  second  year,  ossification  commences 
in  the  radial  portion  of  the  articular  sur- 
face, and  from  this  point  extends  inwards, 
so  as  to  form  the  chief  part  of  the  articular 
end  of  the  bone,  the  centre  for  the  inner 
part  of  the  articular  surface  not  appearing 
until  about  the  age  of  twelve.  Ossification 
commences  in  the  internal  condyle  about 
the  fifth  year,  and  in  the  external  one  not 
until  between  the  thirteenth  or  fourteenth 
year.  About  the  sixteenth  or  seventeenth 
year,  the  outer  condyle  and  both  portions 
of  the  articulating  surface,  having  already 
joined,  unite  with  the  shaft ;  at  eighteen 
years,  the  inner  condyle  becomes  joined, 
whilst  the  upper  epiphysis,  although  the 
first  formed,  is  not  united  until  about  the 
twentieth  year. 

Articulations.  "With  the  glenoid  cavity 
of  the  scapula,  and  with  the  ulna  and  radius. 

Attachment  of  Muscles.  To  the  greater 
tuberosity,  the  Supra-spinatus,  Infraspina- 
tus, and  Teres  minor ;  to  the  lesser  tube- 
rosity, the  Subscapularis ;  to  the  anterior 
bicipital  ridge,  the  Pectoralis  major;  to  the 
posterior  bicipital  ridge  and  groove,  the 
Latissimus  dorsi  and  Teres  major ;  to  the 
shaft,  the  Deltoid,  Coraco-brachialis,  Bra- 
chialis  anticus,  external  and  internal  heads 

of  the  Triceps ;  to  the  internal  condyle,  the  Pronator  radii  teres,  and  common 
tendon  of  the  Flexor  carpi  radialis,  Palmaris  longus,  Flexor  digitorum  sublimis, 
and  Flexor  carpi  ulnaris ;  to  the  external  condyloid  ridge,  the  Supinator  longus, 
and  Extensor  carpi  radialis  longior ;  to  the  external  condyle,  the  common  tendon 
of  the  Extensor  carpi  radialis  brevior,  Extensor  communis  digitorum,  Extensor 
minimi  digiti,  and  Extensor  carpi  ulnaris,  the  Anconeus,  and  Supinator  brevis. 


TTnites  with. 
Shaftat 


18* 


'*'   )A 


THE  FOREARM. 

The  Forearm  is  that  portion  of  the  upper  extremity,  situated  between  the  elbow 
and  wrist.     It  is  composed  of  two  bones,  the  Ulna,  and  the  Radius. 

The  Ulna. 

The  Ulna  (figs.  90  and  91),  so  called  from  its  forming  the  elbow  {iumfo  is  a  long 
bone,  prismatic  in  form,  placed  at  the  inner  6ide  of  the  forearm,  parallel  with  the 


134 


OSTEOLOGY. 


Fig.  90. — Bones  of  the  Left  Forearm.     Anterior  Surface. 
ULNA 
i    *    T  <* 

ME  „,-,/■'« 

RADIUS 


fJXKOR    DICITORUM 
SUBLIMIS 


PRONATOR 
RAOII.  TERES 


accairicrn/iZ  origi 

tf  FLEXOR     IONCUS    POLL1CIS 


RadiuZ  Oriain 

FLEXOR    DICITORUM 
SUBLIMIS 


Styloid  Process       ^ 


SUPINATOR  LONCU» 

Grooix  for  ext.  ossis 
METACARPI  FOLLIC/5 
GrceivfinEKT.  PR1MI 
ERNOOII  POLLICIS 


/Styloid  J.'rJcess 


ULNA.  135 

radius,  being  the  largest  and  longest  of  the  two.  Its  upper  extremity,  of  great 
thickness  and  strength,  forms  a  large  part  of  the  articulation  of  the  elbow-joint ; 
it  diminishes  in  size  from  above  downwards,  its  lower  extremity  being  very 
small,  and  excluded  from  the  wrist-joint  by  the  interposition  of  an  interarticular 
fibro-cartilage.     It  is  divisible  into  a  shaft,  and  two  extremities. 

The  Upper  Extremity,  the  strongest  part  of  the  bone,  presents  for  examination 
two  large  curved  processes,  the  Olecranon  process,  and  the  Coronoid  process ;  and 
two  concave  articular  cavities,  the  greater  and  lesser  Sigmoid  cavities. 

The  Olecranon  Process  (<Z\(vrj,  elbow;  x\>dvov,  head)  is  a  large,  thick,  curved 
eminence,  situated  at  the  upper  and  back  part  of  the  ulna.  It  rises  somewhat 
higher  than  the  coronoid,  is  curved  forwards  at  the  summit  so  as  to  present  a  pro- 
minent tip,  its  base  being  contracted  where  it  joins  the  shaft.  This  is  the 
narrowest  part  of  the  upper  end  of  the  ulna,  and,  consequently,  the  most  usual 
seat  of  fracture.  Its  posterior  surface,  directed  backwards,  is  of  a  triangular  form, 
smooth,  subcutaneous,  and  covered  by  a  bursa.  Its  upper  surface,  directed 
upwards,  is  of  a  quadrilateral  form,  marked  behind  by  a  rough  impression  for 
the  attachment  of  the  Triceps  muscle ;  and,  in  front,  near  the  margin,  by  a  slight 
transverse  groove  for  the  attachment  of  part  of  the  posterior  ligament  of  the 
elbow-joint.  Its  anterior  surface  is  smooth,  concave,  covered  with  cartilage  in 
the  recent  state,  and  forms  the  upper  and  back  part  of  the  great  sigmoid  cavity. 
The  lateral  borders  present  a  continuation  of  the  same  groove  that  was  seen  on 
the  margin  of  the  superior  surface ;  they  serve  for  the  attachment  of  ligaments, 
viz.,  the  back  part  of  the  interior  lateral  ligament  internally ;  the  posterior  liga- 
ment externally.  The  olecranon  process,  in  its  structure  as  well  as  in  its  position 
and  use,  resembles  the  Patella  in  the  lower  limb ;  and,  like  it,  sometimes  exists 
as  a  separate  piece,  not  united  to  the  rest  of  the  bone.1 

The  Coronoid  Process  (xopAvt],  a  crow's  beak;  n'So$,  form)  is  a  rough  triangular 
eminence  of  bone  which  projects  horizontally  forwards  from  the  upper  and  front 
part  of  the  ulna,  forming  the  lower  part  of  the  great  sigmoid  cavity.  Its  base  is 
continuous  with  the  shaft,  and  of  considerable  strength,  so  much  so,  that  fracture 
of  it  is  an  accident  of  rare  occurrence.  Its  apex  is  pointed,  slightly  curved  upwards, 
and  received  into  the  coronoid  depression  of  the  humerus  in  flexion  of  the  forearm. 
Its  upper  surface  is  smooth,  concave,  and  forms  the  lower  part  of  the  great  sigmoid 
cavity.  The  under  surface  is  concave,  and  marked  internally  by  a  rough  impression 
for  the  insertion  of  the  Brachialis  anticus.  At  the  junction  of  this  surface  with 
the  shaft  is  a  rough  eminence,  the  tubercle  of  the  ulna,  for  the  attachment  of  the 
oblique  ligament.  Its  outer  surface  presents  a  narrow,  oblong,  articular  depression, 
the  lesser  sigmoid  cavity.  The  inner  surface,  by  its  prominent  free  margin,  serves 
for  the  attachment  of  part  of  the  internal  lateral  ligament.  At  the  front  part  of 
this  surface  is  a  small  rounded  eminence  for  the  attachment  of  one  head  of  the 
Flexor  digitorum  sublimis.  Behind  the  eminence,  a  depression  for  part  of  the  origin 
of  the  Flexor  profundus  digitorum ;  and,  descending  from  the  eminence,  a  ridge, 
which  gives  attachment  to  one  head  of  the  Pronator  radii  teres. 

The  Greater  Sigmoid  Cavity  (olyna,  fJSoj,  form),  so  called  from  its  resemblance 
to  the  Greek  letter  x,  is  a  semilunar  depression  of  large  size,  situated  between  the 
olecranon  and  coronoid  processes,  and  serving  for  .articulation  with  the  trochlear 
surface  of  the  humerus.  About  the  middle  of  either  lateral  border  of  this  cavity 
is  a  notch  which  contracts  it  somewhat,  and  serves  to  indicate  the  junction  of  the 
two  processes  of  which  it  is  formed.  The  cavity  is  concave  from  above  downwards, 
and  divided  into  two  lateral  parts  by  a  smooth  elevated  ridge,  which  runs  from 
the  summit  of  the  olecranon  to  the  tip  of  the  coronoid  process.  Of  these  two 
portions,  the  internal  is  the  largest ;  it  is  slightly  concave  transversely,  the  external 
portion  being  nearly  plane  from  side  to  side. 

1  Professor  Owen  regards  the  olecranon  to  be  homologous  not  with  the  patella,  but  with  an 
extension  of  the  upper  end  of  the  fibula  above  the  knee-joint,  which  is  met  with  in  the  Ornitho- 
rynchus,  Echidna,  and  some  other  animals.  (Owen,  "  On  the  Nature  of  Limbs.") 


136  OSTEOLOGY. 

The  Lesser  Sigmoid  Cavity  is  a  narrow,  oblong,  articular  depression,  placed  on 
the  outer  side  of  the  coronoid  process,  and  serving  for  articulation  with  the  head 
of  the  radius.  It  is  concave  from  before  backwards ;  and  its  extremities,  which 
are  prominent,  serve  for  the  attachment  of  the  orbicular  ligament. 

The  Shaft  is  prismatic  in  form  at  its  upper  part,  and  curved  from  behind  for- 
wards, and  from  within  outwards,  so  as  to  be  convex  behind  and  externally ;  its 
central  part  is  quite  straight ;  its  lower  part  rounded,  smooth,  and  bent  a  little 
outwards ;  it  tapers  gradually  from  above  downwards,  and  presents  for  examina- 
tion three  borders,  and  three  surfaces. 

The  anterior  border  commences  above  at  the  prominent  inner  angle  of  the  coro- 
noid process,  and  terminates  below  in  front  of  the  styloid  process.  It  is  well 
marked  above,  smooth  and  rounded  in  the  middle  of  its  extent,  and  affords 
attachment  to  the  Flexor  profundus  digitorum :  sharp  and  prominent  in  its  lower 
fourth  for  the  attachment  of  the  Pronator  quadratus.  It  separates  the  anterior 
from  the  internal  surface. 

The  posterior  border  commences  above  at  the  apex  of  the  triangular  surface  at 
the  back  part  of  the  olecranon,  and  terminates  below  at  the  back  part  of  the  styloid 
process ;  it  is  well  marked  in  the  upper  three-fourths,  and  gives  attachment  to  an 
aponeurosis  common  to  the  Flexor  carpi  ulnaris,  the  Extensor  carpi  ulnaris,  and 
the  Flexor  profundus  digitorum  muscles ;  its  lower  fourth  is  smooth  and  rounded. 
This  border  separates  the  internal  from  the  posterior  surface. 

The  external  border  commences  above  by  two  lines,  which  converge  one  from 
each  extremity  of  the  lesser  sigmoid  cavity,  inclosing  between  them  a  triangular 
space  for  the  attachment  of  part  of  the  Supinator  brevis,  and  terminates  below  at 
the  middle  of  the  head  of  the  ulna.  Its  two  middle  fourths  are  very  prominent, 
and  serve  for  the  attachment  of  the  interosseous  membrane ;  its  lower  fourth  is 
smooth  and  rounded.   This  border  separates  the  anterior  from  the  posterior  surface. 

The  anterior  surface,  much  broader  above  than  below,  is  concave  in  the  upper 
three-fourths  of  its  extent,  and  affords  attachment  to  the  Flexor  profundus  digi- 
torum; its  lower  fourth,  also  concave,  to  the  Pronator  quadratus.  The  lower 
fourth  is  separated  from  the  remaining  portion  of  the  bone  by  a  prominent  ridge, 
directed  obliquely  from  above  downwards  and  inwards ;  this  ridge  marks  the 
extent  of  attachment  of  the  Pronator  above.  At  the  junction  of  the  upper  with 
the  middle  third  of  the  bone,  is  the  nutritious  canal,  directed  obliquely  upwards 
and  inwards. 

The  posterior  surface,  directed  backwards  and  outwards,  is  broad  and  concave 
above,  somewhat  narrower  and  convex  in  the  middle  of  its  course,  narrow,  smooth, 
and  rounded  below.  It  presents  above,  an  oblique  ridge,  which  runs  from  the 
posterior  extremity  of  the  lesser  sigmoid  cavity,  downwards  to  the  posterior 
border ;  the  triangular  surface  above  this  ridge  receives  the  insertion  of  the  An- 
coneus muscle,  whilst  the  ridge  itself  affords  attachment  to  the  Supinator  brevis. 
The  surface  of  bone  below  this  is  subdivided  by  a  longitudinal  ridge  into  two 
parts ;  the  internal  part  is  smooth,  concave,  and  gives  origin  to,  occasionally  is 
merely  covered  by,  the  Extensor  carpi  ulnaris.  The  external  portion,  wider  and 
rougher,  gives  attachment  from  above  downwards  to  part  of  the  Supinator  brevis, 
the  Extensor  ossis  metacarpi  pollicis,  the  Extensor  secundi  internodii  pollicis,  and 
the  Extensor  indicis  muscles. 

The  internal  surface  is  broad  and  concave  above,  narrow  and  convex  below. 
It  gives  attachment  by  its  upper  three-fourths  to  the  Flexor  profundus  digitorum 
muscle ;  its  lower  fourth  is  subcutaneous. 

The  Lower  Extremity  of  the  ulna  is  of  small  size,  and  excluded  from  the  articu- 
lation of  the  wrist-joint.  It  presents  for  examination  two  eminences ;  the  outer 
and  larger  is  a  rounded  articular  eminence,  termed  the  head  of  the  ulna.  The 
inner,  narrower  and  more  projecting,  is  a  non-  articular  eminence,  the  styloid 
process.  The  head  presents  an  articular  facet,  part  of  which,  of  an  oval  form,  is 
directed  downwards,  and  plays  on  the  surface  of  the  triangular  fibro-cartilage, 
which  separates  this  bone  from  the  wrist-joint ;  the  remaining  portion,  directed 


ULNA. 


137 


Fig.  91. — Bones  of  the  Left  Forearm.     Posterior  Surface. 

ULNA 


RADIUS 


for  £XT.  CARFI    RAD.LONC. 

EXT.  CARD    RAD.BKEVIOR 
EXT.    StCUNDI    INTERNOOII   POLLIC1* 


LfXOR    TJiaiTOnUM 
SUSLIMIS 


firr    CXT.  CARPI      ULNAR. 

['  EXT.  INDICII 
ft/'ri    tvr.   DICITORUM    COMMUNIS 
[  »~T.  MINIMI     DIGIT! 


138 


OSTEOLOGY, 


Fi 


92. — Plan  of  the  Development  of  the  Ulna. 
By  3  Centres. 


Olec  ran&n 
Agpca  rs  at  10^^-f^^^JointS'Jiafc  ac  /(>.'?  y* 


outwards,  is  narrow,  convex,  and  received  into  the  sigmoid  cavity  of  the  radius. 
The  styloid  process  projects  from  the  inner  and  back  part  of  the  bone,  and  descends 
a  little  lower  than  the  head,  terminating  in  a  rounded  summit,  which  affords 
attachment  to  the  internal  lateral  ligament  of  the  wrist.  The  head  is  separated 
from  the  styloid  process  by  a  depression  for  the  attachment  of  the  triangular 
interarticular  fibro-cartilage ;  and  behind,  by  a  shallow  groove  for  the  passage 
of  the  tendon  of  the  Extensor  carpi  ulnaris. 

Structure.     Similar  to  that  of  the  other  long  bones. 

Development.    By  three  centres:  one  for  the  shaft,  one  for  the  inferior  extremity, 
and  one  for  the  olecranon  (fig.  92).     Ossification  commences  near  the  middle  of 

the  shaft  about  the  fifth  week,  and  soon 
extends  through  the  greater  part  of  the 
bone.  At  birth,  the  ends  are  cartilaginous. 
About  the  fourth  year,  a  separate  osseous 
nucleus  appears  in  the  middle  of  the  head, 
which  soon  extends  into  the  styloid  pro- 
cess. About  the  tenth  year,  ossific  matter 
appears  in  the  olecranon  near  its  extremity, 
the  chief  part  of  this  process  being  formed 
from  an  extension  of  the  shaft  of  the  bone 
into  it.  At  about  the  sixteenth  year,  the 
upper  epiphysis  becomes  joined,  and  at 
about  the  twentieth  year  the  lower  one. 

Articulations.  With  the  humerus  and 
radius. 

Attachment  of  Muscles.  To  the  olecra- 
non :  the  Triceps,  Anconeus,  and  one  head 
of  the  Flexor  carpi  ulnaris.  To  the  coro- 
noid  process;  the  Brachialis  anticus,  Pro- 
nator radii  teres,  Flexor  sublimis  digito- 
rum,  and  Flexor  profundus  digitorum.  To 
the  shaft:  the  Flexor  profundus  digitorum, 
Pronator  quadratus,  Flexor  carpi  ulnaris, 
Extensor  carpi  ulnaris,  Anconeus,  Supi- 
nator brevis,  Extensor  ossis  metacarpi 
pollicis,  Extensor  secundi  internodii  polli- 
cis,  and  Extensor  indicis. 


Appear?  at  4  3f#  {j3fS-J»itU  Slmft  at  ZOtl  ■;* 


°^Har 


«**' 


The  Eadius. 

The  Radius,  so  called  from  its  fancied  resemblance  to  the  spoke  of  a  wheel,  is 
situated  on  the  outer  side  of  the  forearm,  lying  parallel  with  the  ulna,  which 
exceeds  it  in  length  and  size.  Its  upper  end  is  small,  and  forms  only  a  small  part 
of  the  elbow-joint;  but  its  lower  end  is  large,  and  forms  the  chief  part  of  the 
wrist.  It  is  one  of  the  long  bones,  having  a  prismatic  form,  slightly  curved 
longitudinally,  and  presenting  for  examination  a  shaft  and  two  extremities. 

The  Upper  Extremity  presents  a  head,  neck,  and  tuberosity.  The' head  is  of 
a  cylindrical  form,  depressed  on  its  upper  surface  into  a  shallow  cup,  which 
articulates  with  the  radial  or  lesser  head  of  the  humerus  in  flexion  of  the  .joint. 
Around  the  circumference  of  the  head  is  a  smooth  articular  surface,  coated  with 
cartilage  in  the  recent  state,  broad  internally  where  it  rotates  within  the  lesser 
sigmoid  cavity  of  the  ulna,  narrow  in  the  rest  of  its  circumference,  to  play  in  the 
orbicular  ligament.  The  head  is  supported  on  a  round,  smooth,  and  constricted 
portion  of  bone,  called  the  neck,  which  presents,  behind,  a  slight  ridge,  for  the 
attachment  of  part  of  the  Supinator  brevis.  Beneath  the  neck,  at  the  inner  and 
front  aspect  of  the  bone,  is  a  rough  eminence,  the  tuberosity.  Its  surface  is 
divided  into  two  parts  by  a  vertical  line ;   a  posterior  rough  portion,  for  the 


RADIUS.  139 

insertion  of  the  tendon  of  the  Biceps  muscle,  and  an  anterior  smooth  portion,  on 
which  a  bursa  is  interposed  between  the  tendon  and  the  bone. 

The  Shaft  of  the  bone  is  prismoid  in  form,  narrower  above  than  below,  and 
slightly  curved,  so  as  to  be  convex  outwards.  It  presents  three  surfaces,  separated 
by  three  borders. 

The  anterior  border  extends  from  the  lower  part  of  the  tifberosity  above,  to  the 
anterior  part  of  the  base  of  the  styloid  process  below.  It  separates  the  anterior 
from  the  external  surface.  Its  upper  third  is  very  prominent ;  and,  from  its 
oblique  direction,  downwards  and  outwards,  has  received  the  name  of  the  oblique 
line  of  the  radius.  It  gives  attachment,  externally,  to  the  Supinator  brevis; 
internally,  to  the  Flexor  longus  pollicis,  and  between  these  to  the  Flexor  digito- 
rum  sublimis.  The  middle  third  of  the  anterior  border  is  indistinct  and  rounded. 
Its  lower  fourth  is  sharp,  prominent,  affords  attachment  to  the  Pronator  quadra- 
tus,  and  terminates  in  a  small  tubercle,  into  which  is  inserted  the  tendon  of  the 
Supinator  longus. 

The  posterior  border  commences  above,  at  the  back  part  of  the  neck  of  the 
radius,  and  terminates  below,  at  the  posterior  part  of  the  base  of  the  styloid  pro- 
cess ;  it  separates  the  posterior  from  the  external  surface.  It  is  indistinct  above 
and  below,  but  well  marked  in  the  middle  third  of  the  bone. 

The  internal  or  interosseous  border  commences  above,  at  the  back  part  of  the 
tuberosity,  where  it  is  rounded  and  indistinct,  becomes  sharp  and  prominent  as  it 
descends,  and  at  its  lower  part  bifurcates  into  two  ridges,  which  descend  to  the 
anterior  and  posterior  margins  of  the  sigmoid  cavity.  This  border  separates  the 
anterior  from  the  posterior  surface,  and  has  the  interosseous  membrane  attached 
to  it  throughout  the  greater  part  of  its  extent. 

The  anterior  surface  is  narrow  and  concave  for  its  upper  two-thirds,  and  gives 
attachment  to  the  Flexor  longus  pollicis  muscle ;  below,  it  is  broad  and  flat,  and 
gives  attachment  to  the  Pronator  quadratus.  At  the  junction  of  the  upper  and 
middle  thirds  of  this  surface  is  the  nutritious  foramen,  which  is  directed  obliquely 
upwards. 

The  posterior  surface  is  rounded,  convex,  and  smooth  in  the  upper  third  of  its 
extent,  and  covered  by  the  Supinator  brevis  muscle.  Its  middle  third  is  broad, 
slightly  concave,  and  gives  attachment  to  the  Extensor  ossis  metacarpi  pollicis 
above,  the  Extensor  primi  internodii  pollicis  below.  Its  lower  third  is  broad, 
convex,  and  covered  by  the  tendons  of  the  muscles  which  subsequently  run  in 
the  grooves  on  the  lower  end  of  the  bone. 

The  external  surface  is  rounded  and  convex  throughout  its  entire  extent.  Its 
upper  third  gives  attachment  to  the  Supinator  brevis  muscle.  About  its  centre 
is  seen  a  rough  ridge,  for  the  insertion  of  the  Pronator  radii  teres  muscle.  Its 
lower  part  is  narrow,  and  covered  by  the  tendons  of  the  Extensor  ossis  metacarpi 
pollicis  and  Extensor  primi  internodii  pollicis  muscles. 

The  Lower  extremity  of  the  radius  is  large,  of  quadrilateral  form,  and  provided 
with  two  articular  surfaces,  one  at  the  extremity  for  articulation  with  the  carpus, 
and  one  at  the  inner  side  of  the  bone  for  articulation  with  the  ulna.  The  carpal 
articular  surface  is  of  triangular  form,  concave,  smooth,  and  divided  by  a  slight 
antero-posterior  ridge  into  two  parts.  Of  these,  the  external  is  large,  of  a  trian- 
gular form,  and  articulates  with  the  scaphoid  bone;  the  inner,  smaller  and 
quadrilateral,  articulates  with  the  semilunar.  The  articular  surface  for  the  ulna 
is  called  the  sigmoid  cavity  of  the  radius;  it  is  narrow,  concave,  smooth,  and 
articulates  with  the  head  of  the  ulna.  The  circumference  of  this  end  of  the  bone 
presents  three  surfaces,  an  anterior,  external,  and  posterior. 

The  anterior  surface,  rough  and  irregular,  affords  attachment  to  the  anterior 
ligament  of  the  wrist-joint.  The  external  surface  is  prolonged  obliquely  down- 
wards into  a  strong  conical  projection,  the  styloid  process,  which  gives  attachment 
by  its  base  to  the  tendon  of  the  Supinator  longus,  and  by  its  apex  to  the  external 
lateral  ligament  of  the  wrist-joint.  The  outer  surface  of  this  process  is  marked 
by  two  grooves,  which  run  obliquely  downwards  and  forwards,  and  are  separated 


140 


OSTEOLOGY. 


Fig.  93. — Plan  of  the  Development  of  the  Radius. 
By  3  Centres. 


Aj>Dta.rs  at  Jt*y-- 


JTeatf 


)-:lfruttll  it-ith  Shaft  aba 

puberty 


from  one  another  by  an  elevated  ridge.  The  most  anterior  one  gives  passage  to 
the  tendon  of  the  Extensor  ossis  metacarpi  pollicis,  the  posterior  one  to  the  tendon 
of  the  Extensor  primi  internodii  pollicis.  The  posterior  surface  is  convex,  affords 
attachment  to  the  posterior  ligament  of  the  wrist,  and  is  marked  by  three  grooves. 
The  most  external  is  broad,  but  shallow,  and  subdivided  into  two  by  a  slightly 
elevated  ridge.  The  external  groove  transmits  the  tendon  of  the  Extensor  carpi 
radialis  longior,  the  inner  one  the  tendon  of  the  Extensor  carpi  radialis  brevior, 
Near  the  centre  of  the  bone  is  a  deep,  but  narrow,  groove,  directed  obliquely  from 
above  downwards  and  outwards;  it  transmits  the  tendon  of  the  Extensor  secundi 
internodii  pollicis.  Internally  is  a  broad  groove,  for  the  passage  of  the  tendons  of 
the  Extensor  communis  digitorum,  and  Extensor  indicis ;  the  tendon  of  the  Extensor 
minimi  digiti  passing  through  the  groove  at  its  point  of  articulation  with  the  ulna. 
Structure.  Similar  to  that  of  the  other  long  bones. 

Development  (fig.  93).  By  three  centres:  one  for  the  shaft,  and  one  for  each 

extremity.  That  for  the  shaft  makes 
its  appearance  near  the  centre  of  the 
bone,  soon  after  the  development  of 
the  humerus  commences.  At  birth, 
the  shaft  is  ossified ;  but  the  ends  of 
the  bone  are  cartilaginous.  About  the 
end  of  the  second  year,  ossification 
commences  in  the  lower  epiphysis; 
and  about  the  fifth  year,  in  the  upper 
one.  At  the  age  of  puberty,  the  up- 
per epiphysis  becomes  joined  to  the 
shaft;  the  lower  epiphysis  becoming 
united  about  the  twentieth  year. 

Articulations.  With  four  bones;  the 
humerus,  ulna,  scaphoid,  and  semi- 
lunar. 

Attachment  of  Muscles.  To  the  tu- 
berosity, the  Biceps ;  to  the  oblique 
ridge,  the  Supinator  brevis,  Flexor 
digitorum  sublimis,  and  Flexor  longus 
pollicis ;  to  the  shaft — its  anterior  sur- 
face, the  Flexor  longus  pollicis  and 
Pronator  quadratus ;  its  posterior  sur- 
face, the  Extensor  ossis  metacarpi 
pollicis,  and  Extensor  primi  internodii 
pollicis;  its  outer  surface,  the  Pro- 
nator radii  teres;  and  to  the  styloid 
process,  the  Supinator  longus. 


feaw 


Appears  at  Zv^-yH 


\  "Unites  with.  SAa  ft  al.t 


.fcxtrcmi 


THE   HAND. 

The  Hand  is  subdivided  into  three  segments,  the  Carpus  or  wrist,  the  Meta- 
carpus or  palm,  and  the  Phalanges  or  fingers. 

Carpus. 

The  bones  of  the  Carpus,  eight  in  number,  are  arranged  in -two  rows.  Those 
of  the  upper  row,  enumerated  from  the  radial  to  the  ulnar  side,  are  the  scaphoid, 
semilunar,  cuneiform,  and  pisiform ;  those  of  the  lower  row,  enumerated  in  the 
same  order,  are  the  trapezium,  trapezoid,  magnum,  and  unciform. 

Common  Characters  of  the  Carpal  Bones. 

Each  bone  (excepting  the  pisiform)  presents  six  surfaces.  Of  these,  the  ante- 
rior or  palmar,  and  the  posterior  or  dorsal,  are  rough,  for  ligamentous  attachment, 


CARPUS.  141 

the  dorsal  surface  being  generally  the  broadest  of  the  two.  The  superior  and 
inferior  are  articular,  the  superior  generally  convex,  the  inferior  concave ;  and 
the  internal  and  external  are  also  articular  when  in  contact  with  contiguous 
bones,  otherwise  rough  and  tubercular.  Their  structure  in  all  is  similar,  con- 
sisting within  of  cancellous  tissue  inclosed  in  a  layer  of  compact  bone.  Each 
bone  is  also  developed  from  a  single  centre  of  ossification. 

Bones  of  the  Upper  Row.    (Figs.  94  and  95.) 

The  Scaphoid  is  the  largest  bone  of  the  first  row.  It  has  received  its  name 
from  its  fancied  resemblance  to  a  boat,  being  broad  at  one  end,  and  narrowed  like 
a  prow  at  the  opposite.  It  is  situated  at  the  upper  and  outer  part  of  the  carpus, 
its  direction  being  from  above  downwards,  outwards,  and  forwards.  Its  superior 
surface  is  convex,  smooth,  of  triangular  shape,  and  articulates  with  the  lower  end 
of  the  radius.  Its  inferior  surface,  directed  downwards,  outwards,  and  backwards, 
is  smooth,  convex,  and  triangular,  and  divided  by  a  slight  ridge  into  two  parts, 
the  external  of  which  articulates  with  the  trapezium,  the  inner  with  the  trapezoid. 
Its  posterior  or  dorsal  surface  presents  a  narrow,  rough  groove,  which  runs  the 
entire  breadth  of  the  bone,  and  serves  for  the  attachment  of  ligaments.  The 
anterior  or  palmar  surface  is  concave  above,  and  elevated  at  its  lower  and  outer 
part  into  a  prominent  rounded  tubercle,  which  projects  forwards  from  the  front 
of  the  carpus,  and  gives  attachment  to  the  anterior  annular  ligament  of  the  wrist. 
The  external  surface  is  rough  and  narrow,  and  gives  attachment  to  the  external 
lateral  ligament  of  the  wrist.  The  internal  surface  presents  two  articular  facets : 
of  these  the  superior  or  smaller  one  is  flattened,  of  semilunar  form,  and  articulates 
with  the  semilunar  bone;  the  inferior  or  larger  is  concave,  forming,  with  the 
semilunar  bone,  a  concavity  for  the  head  of  the  os  magnum. 

To  ascertain  to  which  hand  this  bone  belongs,  hold  the  convex  radial  articular 
surface  upwards,  and  the  dorsal  surface  backwards ;  the  prominent  tubercle  will 
be  directed  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  five  bones ;  the  radius  above,  trapezium  and  trapezoid 
below,  os  magnum  and  semilunar  internally. 

The  Semilunar  bone  may  be  distinguished  by  its  deep  concavity  and  crescentic 
outline.  It  is  situated  in  the  centre  of  the  upper  range  of  the  carpus,  between 
the  scaphoid  and  cuneiform.  Its  superior  surface,  convex,  smooth,  and  quadrilateral 
in  form,  articulates  with  the  radius.  Its  inferior  surface  is  deeply  concave,  and 
of  greater  extent  from  before  backwards,  than  transversely ;  it  articulates  with  the 
head  of  the  os  magnum,  and  by  a  long  narrow  facet,  separated  by  a  ridge  from 
the  general  surface,  with  the  unciform  bone.  Its  anterior  or  palmar  and  posterior 
or  dorsal  surfaces  are  rough,  for  the  attachment  of  ligaments,  the  former  being  the 
broader,  and  of  somewhat  rounded  form.  The  external  surface  presents  a  narrow, 
flattened,  semilunar  facet,  for  articulation  with  the  scaphoid.  The  internal  surface 
is  marked  by  a  smooth,  quadrilateral  facet,  for  articulation  with  the  cuneiform. 

To  ascertain  to  which  hand  this  bone  belongs,  hold  it  with  the  dorsal  surface 
upwards,  and  the  convex  articular  surface  backwards ;  the  quadrilateral  articular 
facet  will  then  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  five  bones :  the  radius  above,  os  magnum  and  unciform 
below,  scaphoid  and  cuneiform  on  either  side. 

The  Cuneiform  (VOs  Pyramidal)  may  be  distinguished  by  its  pyramidal  shape, 
and  from  having  an  oval-shaped,  isolated  facet,  for  articulation  with  the  pisiform 
bone.  It  is  situated  at  the  upper  and  inner  side  of  the  carpus.  The  superior 
surface  presents  an  internal,  rough,  non-articular  portion;  and  an  external  or 
articular  portion,  which  is  convex,  smooth,  and  separated  from  the  lower  end  of 
the  ulna  by  the  interarticular  fibro-cartilage  of  the  wrist.  The  inferior  surface, 
directed  outwards,  is  concave,  sinuously  curved,  and  smooth,  for  articulation  with 
the  unciform.  Its  posterior  or  dorsal  surface  is  rough,  for  the  attachment  of  liga- 
ments.    Its  anterior  or  palmar  surface  presents,  at  its  inner  side,  an  oval-shaped 


142 


OSTEOLOGY. 


facet,  for  articulation  with  the  pisiform ;  and.  is  rough  externally,  for  ligamentous 
attachment.  Its  external  surface,  the  base  of  the  pyramid,  is  marked  by  a  flat, 
quadrilateral,  smooth  facet,  for  articulation  with  the  semilunar.  The  internal 
surface,  the  summit  of  the  pyramid,  is  pointed  and  roughened,  for  the  attachment 
of  the  internal  lateral  ligament  of  the  wrist. 


Fig.  94. — Bones  of  the  Left  Hand.     Dorsal  Surface. 


""■"""•iDM 


l,s  snviog 


Metacarpus 


,XT-  MUM, 
mTERMoo„ 


Phalange* 
1U Row 


Z^Row 


Tr?M0Ufi 


CARPUS.  143 

To  ascertain  to  which  hand  this  bone  belongs,  hold  it  so  that  the  base  is 
directed  backwards,  and  the  articular  facet  for  the  pisiform  bone  upwards ;  the 
concave  articular  facet  will  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  three  bones:  the  semilunar  externally,  the  pisiform  in 
front,  the  unciform  below,  and  with  the  triangular  interarticular  fibro-cartilage 
which  separates  it  from  the  lower  end  of  the  ulna. 

The  Pisiform  bone  may  be  known  by  its  small  size,  and  from  its  presenting  a 
single  articular  facet.  It  is  situated  at  the  anterior  and  inner  side  of  the  carpus, 
is  nearly  circular  in  form,  and  presents  on  its  posterior  surface  a  smooth,  oval 
facet,  for  articulation  with  the  cuneiform  bone.  This  facet  approaches  the  supe- 
rior, but  not  the  inferior,  border  of  the  bone!  Its  anterior  or  palmar  surface  is 
rounded  and  rough,  and  gives  attachment  to  the  anterior  annular  ligament.  The 
outer  and  inner  surfaces  are  also  rough,  the  former  being  convex,  the  latter  usually 
concave. 

To  ascertain  to  which  hand  it  belongs,  hold  the  bone  with  its  posterior  or  artic- 
ular facet  downwards,  and  the  non-articular  portion  of  the  same  surface  back- 
wards ;  the  inner  concave  surface  will  then  point  to  the  side  to  which  the  bone 
belongs. 

Articulations.  With  one  bone,  the  cuneiform. 

Attachment  of  Muscles.  To  two :  the  Flexor  carpi  ulnaris,  and  Abductor  minimi 
digiti ;  and  to  the  anterior  annular  ligament. 

Bones  of  the  Lower  Row.    (Figs.  94  and  95.) 

The  Trapezium  is  of  very  irregular  form.  It  may  be  distinguished  by  a  deep 
groove,  for  the  tendon  of  the  Flexor  carpi  radialis  muscle.  It  is  situated  at  the 
external  and  inferior  part  of  the  carpus,  between  the  scaphoid  and  first  meta- 
carpal bone.  The  superior  surface,  concave  and  smooth,  is  directed  upwards  and 
inwards,  and  articulates  with  the  scaphoid.  Its  inferior  surface,  directed  down- 
wards and  outwards,  is  oval,  concave  from  side  to  side,  convex  from  before  back- 
wards, so  as  to  form  a  saddle-shaped  surface,  for  articulation  with  the  base  of  the 
first  metacarpal  bone.  The  anterior  or  palmar  surface  is  narrow  and  rough. 
At  its  upper  part  is  a  deep  groove,  running  from  above  obliquely  downwards  and 
inwards;  it  transmits  the  tendon  of  the  Flexor  carpi  radialis,  and  is  bounded 
externally  by  a  prominent  ridge,  the  oblique  ridge  of  the  trapezium.  This  sur- 
face gives  attachment  to  the  Abductor  pollicis,  Flexor  ossis  metacarpi,  and  Flexor 
brevis  pollicis  muscles;  and  the  anterior  annular  ligament.  The  posterior  or 
dorsal  surface  is  rough,  and  the  external  surface  also  broad  and  rough,  for  the 
attachment  of  ligaments.  The  internal  surface  presents  two  articular  facets ;  the 
upper  one,  large  and  concave,  articulates  with  the  trapezoid;  the  lower  one, 
narrow  and  flattened,  with  the  base  of  the  second  metacarpal  bone. 

To  ascertain  to  which  hand  it  belongs,  hold  the  bone  with  the  grooved  palmar 

surface  upwards,  and  the  external,  broad,  non-articular  surface  backwards;  the 

saddle-shaped  surface  will  then  be  directed  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones :  the  scaphoid  above,  the  trapezoid  and  second 

metacarpal  bones  internally,  the  first  metacarpal  below. 

Attachment  of  Muscles.  Abductor  pollicis,  Flexor  ossis  metacarpi,  part  of  the 
Flexor  brevis  pollicis,  and  the  anterior  annular  ligament. 

The  Trapezoid  is  the  smallest  bone  in  the  second  row.  It  may  be  known  by 
its  wedge-shaped  form ;  its  broad  end  occupying  the  dorsal,  its  narrow  end  the 
palmar  surface  of  the  hand.  Its  superior  surface,  quadrilateral  in  form,  smooth 
and  slightly  concave,  articulates  with  the  scaphoid.  The  inferior  surface  articu- 
lates with  the  upper  end  of  the  second  metacarpal  bone ;  it  is  convex  from  side  to 
side,  concave  from  before  backwards,  and  subdivided,  by  an  elevated  ridge,  into 
two  unequal  lateral  facets.  The  posterior  or  dorsal,  and  anterior  or  palmar 
surfaces  are  rough,  for  the  attachment  of  ligaments ;  the  former  being  the  larger 
of  the   two.     The   external  surface,  convex   and   smooth,   articulates   with   the 


144 


OSTEOLOGY. 


trapezium.     The  internal  surface  is  concave  and  smooth  below,  for  articulation 
with  the  os  magnum ;  rough  above,  for  the  attachment  of  an  interosseous  ligament. 


Fig.  95. — Bones  of  the  Left  Hand.     Palmar  Surface. 


Ccorjms 

FLEXOR.  CARPi    ULNARIS 

FLEXOR    BREVtS    MINIMI     DICIT 

fLEXOR    OSSIS    METACARPI 
MINIMI      DICITl 


h"''      ...» 


MrfMcar/iiLS 


Dp„ofU"ou8 


CARPUS.  145 

To  ascertain  to  which  side  this  bone  belongs,  let  the  broad  dorsal  surface  be 
held  upwards,  and  its  inferior  concavo-convex  surface  forwards;  the  internal 
concave  surface  will  then  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones :  the  scaphoid  above,  second  metacarpal  bone 
below,  trapezium  externally,  os  magnum  internally. 

Attachment  of  Muscks.     Part  of  the  Flexor  brevis  pollicis. 

The  Os  Magnum  is  the  largest  bone  of  the  carpus,  and  occupies  the  centre  of 
the  wrist.  It  presents,  above,  a  rounded  portion  or  head,  which  is  received  into 
the  concavity  formed  by  the  scaphoid  and  semilunar  bones ;  a  constricted  portion 
or  neck;  and,  below,  the  body.  Its  superior  surface  is  rounded,  smooth,  and 
articulates  with  the  semilunar.  Its  inferior  surface  is  divided  by  two  ridges  into 
three  facets,  for  articulation  with  the  second,  third,  and  fourth  metacarpal  bones ; 
that  for  the  third,  the  middle  facet,  being  the  largest  of  the  three.  The  posterior 
or  dorsal  surface  is  broad  and  rough ;  and  the  anterior  or  palmar,  narrow,  rounded, 
but  also  rough,  for  the  attachment  of  ligaments.  The  external  surface  articulates 
with  the  trapezoid  by  a  small  facet  at  its  anterior  inferior  angle,  behind  which  is 
a  rough  depression  for  the  attachment  of  an  interosseous  ligament.  Above  this 
is  a  deep  and  rough  groove,  which  forms  part  of  the  neck,  and  serves  for  the 
attachment  of  ligaments,  bounded  superiorly  by  a  smooth,  convex  surface,  for 
articulation  with  the  scaphoid.  The  internal  surface  articulates  with  the  unciform 
by  a  smooth,  concave,  oblong  facet,  which  occupies  its  posterior  and  superior 
parts ;  rough  in  front,  for  the  attachment  of  an  interosseous  ligament. 

To  ascertain  to  which  hand  this  bone  belongs,  the  rounded  head  should  be  held 
upwards,  and  the  broad  dorsal  surface  forwards ;  the  internal  concave  articular 
surface  will  point  to  its  appropriate  side. 

Articulations.  With  seven  bones :  the  scaphoid  and  semilunar  above ;  the 
second,  third,  and  fourth  metacarpal  below ;  the  trapezoid  on  the  radial  side ;  and 
the  unciform  on  the  ulnar  side. 

Attachment  of  Muscles.    Part  of  the  Flexor  brevis  pollicis. 

The  Unciform  bone  may  be  readily  distinguished  by  its  wedge-shaped  form,  and 
the  hook-like  process  that  projects  from  its  palmar  surface.  It  is  situated  at  the 
inner  and  lower  angle  of  the  carpus,  with  its  base  downwards,  resting  on  the  two 
inner  metacarpal  bones,  and  its  apex  directed  upwards  and  outwards.  Its  superior 
surface,  the  apex  of  the  wedge,  is  narrow,  convex,  smooth,  and  articulates  with 
the  semilunar.  Its  inferior  surface  articulates  with  the  fourth  and  fifth  meta- 
carpal bones,  the  concave  surface  for  each  being  separated  by  a  ridge,  which  runs 
from  before  backwards.  The  posterior  or  dorsal  surface  is  triangular  and  rough, 
for  ligamentous  attachment.  The  anterior  or  palmar  surface  presents,  at  its  lower 
and  inner  side,  a  curved,  hook-like  process  of  bone,  the  unciform  process,  directed 
from  the  palmar  surface  forwards  and  outwards.  It  gives  attachment,  by  its 
apex,  to  the  annular  ligament ;  by  its  inner  surface,  to  the  Flexor  brevis  minimi 
digiti,  and  the  Flexor  ossis  metacarpi  minimi  digiti ;  and  is  grooved  on  its  outer 
side,  for  the  passage  of  the  Flexor  tendons  into  the  palm  of  the  hand.  This  is  one 
of  the  four  eminences  on  the  front  of  the  carpus,  to  which  the  anterior  annular 
ligament  is  attached ;  the  others  being  the  pisiform  internally,  the  oblique  ridge 
of  the  trapezium,  and  the  tuberosity  of  the  scaphoid  externally.  The  internal 
surface  articulates  with  the  cuneiform  by  an  oblong  surface,  cut  obliquely  from 
above  downwards  and  inwards.  Its  external  surface  articulates  with  the  os  mag- 
num by  its  upper  and  posterior  part,  the  remaining  portion  being  rough,  for  the 
attachment  of  ligaments. 

To  ascertain  to  which  hand  it  belongs,  hold  the  apex  of  the  bone  upward^  and 
the  broad  dorsal  surface  backwards  ;  the  concavity  of  the  unciform  process  will 
be  directed  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  five  bones :  the  semilunar  above,  the  fourth  and  fifth  meta- 
carpal below,  the  cuneiform  internally,  the  os  magnum  externally. 

Attachment  of  Muscles.     To  two :    the  Flexor  brevis  minimi  digiti,  and  the 
Flexor  ossis  metacarpi  minimi  digiti ;  and  to  the  anterior  annular  ligament. 
10 


146  OSTEOLOGY. 

The  Metacaepus. 

The  Metacarpal  bones  are  five  in  number :  they  are  long  cylindrical  bones, 
presenting  for  examination  a  shaft,  and  two  extremities. 

Common  Chaeactees  of  the  Metacaepal  Bones. 

The  shaft  is  prismoid  in  form,  and  curved  longitudinally,  so  as  to  be  convex  in 
the  longitudinal  direction  behind,  concave  in  front.  It  presents  three  surfaces : 
two  lateral,  and  one  posterior.  The  lateral  surfaces  are  concave,  for  the  attach- 
ment of  the  Interossei  muscles,  and  separated  from  one  another  by  a  prominent 
line.  The  posterior  or  dorsal  surface  is  triangular,  smooth,  and  flattened  below, 
and  covered,  in  the  recent  state,  by  the  tendons  of  the  extensor  muscles.  In  its 
upper  half,  it  is  divided  by  a  ridge  into  two  narrow  lateral  depressions,  for  the 
attachment  of  the  Dorsal  interossei  muscles.  This  ridge  bifurcates  a  little  above 
the  centre  of  the  bone,  and  its  branches  run  to  the  small  tubercle  on  each  side  of 
the  digital  extremity. 

The  carpal  extremity  or  base  is  of  a  cuboidal  form,  and  broader  behind  thnn  in 
front:  it  articulates,  above,  with  the  carpus;  and,'  on  each  side,  with  the  adjoining 
metacarpal  bones ;  its  dorsal  and  palmar  surfaces  being  rough,  for  the  attachment 
of  tendons  and  ligaments. 

The  digital  extremity  or  head  presents  an  oblong  surface,  flattened  at  each 
side,  for  articulation  with  the  first  phalanx;  it  is  broader  and  extends  farther 
forwards  in  front  than  behind ;  and  is  longer  in  the  antero-posterior  than  in  the 
transverse  diameter.  On  either  side  of  the  head  is  a  deep  depression,  surmounted 
by  a  tubercle,  for  the  attachment  of  the  lateral  ligament  of  the  metacarpophalan- 
geal joint.  The  posterior  surface,  broad  and  flat,  supports  the  Extensor  tendons ; 
and  the  anterior  surface  presents  a  median  groove,  bounded  on  each  side  by  a 
tubercle,  for  the  passage  of  the  Flexor  tendons. 

Peculiae  Metacaepal  Bones. 

The  metacarpal  bone  of  the  thumb  is  shorter  and  wider  than  the  rest,  diverges 
to  a  greater  degree  from  the  carpus,  and  its  palmar  surface  is  directed  inwards 
towards  the  palm.  The  shaft  is  flattened  and  broad  on  its  dorsal  aspect,  and  does 
not  present  the  bifurcated  ridge  peculiar  to  the  other  metacarpal  bones ;  concave 
from  before  backwards  on  its  palmar  surface.  The  carpal  extremity  or  base 
presents  a  concavo-convex  surface,  for  articulation  with  the  trapezium,  and  has  no 
lateral  facets.  The  digital  extremity  is  less  convex  than  that  of  the  other  metacarpal 
bones,  broader  from  side  to  side  than  from  before  backwards,  and  terminates  anteri- 
orly in  a  small  articular  eminence  on  each  side,  over  which  play  two  sesamoid  bones. 

The  metacarpal  bone  of  the  index  finger  is  the  longest,  and  its  base  the  largest  of 
the  other  four.  Its  carpal  extremity  is  prolonged  upwards  and  inwards ;  and  its 
dorsal  and  palmar  surfaces  are  rough,  for  the  attachment  of  tendons  and  ligaments. 
It  presents  four  articular  facets:  one  at  the  end  of  the  bone,  which  has  an  angular 
depression,  for  articulation  with  the  trapezoid ;  on  the  radial  side,  a  flat  quadri- 
lateral facet,  for  articulation  with  the  trapezium ;  its  ulnar  side  being  prolonged 
upwards  and  inwards,  to  articulate,  above,  with  the  os  magnum ;  internally,  with 
the  third  metacarpal  bone. 

The  metacarpal  bone  of  the  middle  finger  is  a  little  smaller  than  the  preceding ; 
it  presents  a  pyramidal  eminence  on  the  radial  side  of  its  base  (dorsal  aspect),  which 
extends  upwards  behind  the  os  magnum.  The  carpal  articular  facet  is  concave  be- 
hind, flat  and  horizontal  in  front,  and  corresponds  to  the  os  magnum.  On  the  radial 
side  is  a  smooth  concave  facet,  for  articulation  with  the  second  metacarpal  bone ;  and 
on  the  ulnar  side  two  small  oval  facets,  for  articulation  with  the  f  jurth  metacarpal. 

The  metacarpal  bone  of  the  ring  finger  is  shorter  and  smaller  than  the  pre- 
ceding, and  its  base  small  and  quadrilateral,  its  carpal  surface  presenting  two 
facets,  for  articulation  with  the  unciform  and  os  magnum.  On  the  radial  side 
are  two  oval  facets,  for  articulation  with  the  third  metacarpal  bone ;  and  on  the 
ulnar  side  a  single  concave  facet,  for  the  fifth  metacarpal. 


METACARPUS  AND  PHALANGES.  147 

The  metacarpal  bone  of  the  little  finger  may  be  distinguished  by  the  concavo- 
convex  form  of  its  carpal  surface,  for  articulation  with  the  unciform,  and  from 
having  only  one  lateral  articular  facet,  which  corresponds  with  the  fourth  meta- 
carpal bone.  On  its  ulnar  side,  is  a  prominent  tubercle  for  the  insertion  of  the 
tendon  of  the  Extensor  carpi  ulnaris.  The  dorsal  surface  of  the  shaft  is  marked 
by  an  oblique  ridge,  which  extends  from  near  the  ulnar  side  of  the  upper  extremity, 
to  the  radial  side  of  the  lower.  The  outer  division  of  this  surface  serves  for  the 
attachment  of  the  fourth  Dorsal  interosseous  muscle ;  the  inner  division  is  smooth, 
and  covered  by  the  Extensor  tendons  of  the  little  finger. 

Articulations.  The  first,  with  the  trapezium ;  the  second,  with  the  trapezium, 
trapezoides,  os  magnum,  and  third  metacarpal  bones ;  the  third,  with  the  os  mag- 
num, and  second  and  fourth  metacarpal  bones ;  the  fourth,  with  the  os  magnum, 
unciform,  and  third  and  fifth  metacarpal  bones ;  and  the  fifth,  with  the  unciform 
and  fourth  metacarpal. 

Attachment  of  Muscles.  To  the  metacarpal  bone  of  the  thumb,  three :  the  Flexor 
ossis  metacarpi  pollicis,  Extensor  ossis  metacarpi  pollicis,  and  first  Dorsal  inter- 
osseous. To  the  second  metacarpal  bone,  five :  the  Flexor  carpi  radialis,  Extensor 
carpi  radialis  longior,  first  and  second  Dorsal  interosseous,  and  first  Palmar  inter- 
osseous. To  the  third,  five :  the  Extensor  carpi  radialis  brevior,  Flexor  brevis 
pollicis,  Adductor  pollicis,  and  second  and  third  Dorsal  interosseous.  To  the 
fourth,  three :  the  third  and  fourth  Dorsal  interosseous  and  second  Palmar.  To 
the  fifth,  four :  the  Extensor  carpi  ulnaris,  Flexor  carpi  ulnaris,  Flexor  ossis 
metacarpi  minimi  digiti,  and  third  Dorsal  interosseous. 

Phalanges. 

The  Phalanges  are  the  bones  of  the  fingers ;  they  are  fourteen  in  number,  three 
for  each  finger  and  two  for  the  thumb.  They  are  long  bones,  and  present  for 
examination  a  shaft,  and  two  extremities.  The  shaft  tapers  from  above  down- 
wards, is  convex  posteriorly,  concave  in  front  from  above  downwards,  flat  from 
side  to  side,  and  marked  laterally  by  rough  ridges,  which  give  attachment  to  the 
fibrous  sheaths  of  the  Flexor  tendons.  The  metacarpal  extremity  or  base,  in  the 
first  row,  presents  an  oval  concave  articular  surface,  broader  from  side  to  side, 
than  from  before  backwards ;  and  the  same  extremity  in  the  other  two  rows,  a 
double  concavity  separated  by  a  longitudinal  median  ridge,  extending  from  before 
backwards.  The  digital  extremities  are  smaller  than  the  others,  and  terminate, 
in  the  first  and  second  row,  in  two  small  lateral  condyles,  separated  by  a  slight 
groove,  the  articular  surface  being  prolonged  farther  forwards  on  the  palmar  than 
on  the  dorsal  surface,  especially  in  the  first  row. 

The  Ungual  phalanges  are  convex  on  their  dorsal,  flat  on  their  palmar  surfaces; 
they  are  recognized  by  their  small  size,  and  from  their  ungual  extremity  presenting, 
on  its  palmar  aspect,  a  roughened  elevated  surface  of  a  horseshoe  form,  which 
serves  to  support  the  sensitive  pulp  of  the  finger. 

Articulations.  The  first  row  with  the  metacarpal  bones,  and  the  second  row  of 
phalanges ;  the  second  row,  with  the  first  and  third ;  the  third,  with  the  second 
row. 

Attachment  of  Muscles.  To  the  base  of  the  first  phalanx  of  the  thumb,  four 
muscles :  the  Extensor  primi  internodii  pollicis,  Flexor  brevis  pollicis,  Abductor 
pollicis,  Adductor  pollicis.  To  the  second  phalanx,  two :  the  Flexor  longus  pollicis, 
and  the  Extensor  secundi  internodii.  To  the  base  of  the  first  phalanx  of  the 
index  finger,  the  first  Dorsal  and  the  first  Palmar  interosseous;  to  that  of  the  middle 
finger,  the  second  and  third  Dorsal  interosseous;  to  the  ring  finger,  the  fourth 
Dorsal  and  the  second  Palmar  interosseous ;  and  to  that  of  the  little  finger,  the 
third  Palmar  interosseous,  the  Flexor  brevis  minimi  digiti,  and  Abductor  minimi 
digiti.  To  the  second  phalanges,  the  Flexor  sublimis  digitorum,  Extensor  com- 
munis digitorum ;  and,  in  addition,  the  Extensor  indicis,  to  the  index  finger ;  the 
Extensor  minimi  digiti,  to  the  little  finger.  To  the  third  phalanges,  the.  Flexor 
profundus  digitorum  and  Extensor  communis  digitorum. 


148 


OSTEOLOGY. 


Development  of  the  Hand. 

The  Carpal  hones  are  each  developed  by  a  single  centre;  at  birth  they  are  all 
cartilaginous.  Ossification  proceeds  in  the  following  order  (fig.  96):  in  the  os 
magnum  and  unciform  an  ossific  point  appears  during  the  first  year,  the  former 
preceding  the  latter ;  in  the  cuneiform,  at  the  third  year ;  in  the  trapezium  and 
semilunar,  at  the  fifth  year,  the  former  preceding  the  latter ;  in  the  scaphoid,  at  the 
sixth  year ;  in  the  trapezoid,  during  the  eighth  year ;  and  in  the  pisiform,  about 
the  twelfth  year. 

Fig.  96. — Plan  of  the  Development  of  the  Hand. 


Carpus 
1  cent  re  jo  reach  bone 
Ml  cartilaginous  at  lirtJt 


Metacarpus 
2  Centres  for  euch  bone 
■Ifor  Shaft 
i  for  Digital  Extremity 

except  1-4 


Phalanges 

2  Centres  for  each  lone 

t  for  Shaft 

1  for  Metacarpal  L'xt*. 


ap/i.fr-O'f'yr 
untie  f8-Z0^'y^ 


The  Metacarpal  bones  are  each  developed  by  two  centres :  one  for  the  shaft,  and 
one  for  the  digital  extremity,  for  the  four  inner  metacarpal  bones ;  one  for  the 
shaft  and  one  for  the  base,  for  the  metacarpal  bone  of  the  thumb,  which,  in  this 
respect,  resembles  the  phalanges.  Ossification  commences  in  the  centre  of  the 
shaft  about  the  sixth  week,  and  gradually  proceeds  to  either  end  of  the  bone ; 
about  the  third  year  the  digital  extremities  of  the  four  inner  metacarpal  bones  and 
the  base  of  the  first  metacarpal,  commence  to  ossify,  and  they  unite  about  the 
twentieth  year. 

The  Phalanges  are  each  developed  by  two  centres :  one  for  the  shaft  and  one 
for  the  base.  Ossification  commences  in  the  shaft,  in  all  three  rows,  at  about  the 
sixth  week,  and  gradually  involves  the  whole  of  the  bone  excepting  the  upper 
extremity.  Ossification  of  the  base  commences  in  the  first  row  between  the  third 
and  fourth  years,  and  a  year  later  in  those  of  the  second  and  third  row.  The  two 
centres  become  united,  in  each  row,  between  the  eighteenth  and  twentieth  years. 


OS    INNOMINATUM.  149 


OF    THE    LOWER    EXTREMITY. 

The  Lower  Extremity  consists  of  three  segments,  the  thigh,  leg,  snadfoot,  which 
correspond  to  the  arm,  forearm,  and  hand  in  the  upper  extremity.  It  is  connected 
to  the  trunk  through  the  os  innominatum  or  haunch,  which  is  homologous  with 
the  shoulder. 

The  Os  Innominatum. 

The  Os  Innominatum  or  nameless  bone,  so  called  from  bearing  no  resemblance 
to  any  known  object,  is  a  large  irregular-shaped  bone,  which,  with  its  fellow  of 
the  opposite  side,  forms  the  sides  and  anterior  wall  of  the  pelvic  cavity.  In 
young  subjects  it  consists  of  three  separate  parts,  which  meet  and  form  the  large 
cup-like  cavity,  situated  near  the  middle  of  the  outer  side  of  the  bone;  and, 
although  in  the  adult  these  have  become  united,  it  is  usual  to  describe  the  bone 
as  divisible  into  three  portions,  the  ilium,  the  ischium,  and  the  pubes. 

The  ilium,  so  called  from  its  supporting  the  flank  (ilia),  is  the  superior  broad 
and  expanded  portion  which  runs  upwards  from  the  upper  and  back  part  of  the 
acetabulum,  and  forms  the  prominence  of  the  hip. 

The  ischium  (lax^,  the  hip)  is  the  inferior  and  strongest  portion  of  the  bone ; 
it  proceeds  downwards  from  the  acetabulum,  expands  into  a  large  tuberosity,  and 
then,  curving  upwards,  forms  with  the  descending  ramus  of  the  pubes  a  large 
aperture,  the  obturator  foramen. 

The  pubes  is  that  portion  which  runs  horizontally  inwards  from  the  inner  side 
of  the  acetabulum  for  about  two  inches,  then  makes  a  sudden  bend,  and  descends 
to  the  same  extent ;  it  forms  the  front  of  the  pelvis,  supports  the  external  organs 
of  generation,  and  has  received  its  name  from  being  covered  with  hair. 

The  Ilium  presents  for  examination  two  surfaces,  an  external  and  an  internal, 
a  crest,  and  two  borders,  an  anterior  and  a  posterior. 

External  Surface  or  Dorsum  of  the  Ilium  (fig.  97).  The  back  part  of  this  sur- 
face is  directed  backwards,  downwards,  and  outwards ;  its  front  part  forwards, 
downwards  and  outwards.  It  is  smooth,  convex  in  front,  deeply  concave  behind; 
bounded  above  by  the  crest,  below  by  the  upper  border  of  the  acetabulum ;  in 
front  and  behind,  by  the  anterior  and  posterior  borders.  This  surface  is  crossed 
in  an  arched  direction  by  three  semicircular  lines,  the  superior,  middle,  and 
inferior  curved  lines.  The  superior  curved  line,  the  shortest  of  the  three,  com- 
mences at  the  crest,  about  two  inches  in  front  of  its  posterior  extremity ;  it  is  at 
first  distinctly  marked,  but  as  it  passes  downwards  and  outwards  to  the  upper 
part  of  the  great  sacro-sciatic  notch,  where  it  terminates,  it  becomes  less  marked, 
and  is  often  altogether  lost.  The  rough  surface  included  between  this  line  and 
the  crest,  affords  attachment  to  part  of  the  Gluteus  maximus  above,  a  few  fibres 
of  the  Pyriformis  below.  The  middle  curved  line,  the  longest  of  the  three,  com- 
mences at  the  crest,  about  an  inch  behind  its  anterior  extremity,  and,  taking  a 
curved  direction  downwards  and  backwards,  terminates  at  the  upper  part  of  the 
great  sacro-sciatic  notch.  The  space  between  the  middle  and  superior  curved 
lines,  and  the  crest,  is  concave,  and  affords  attachment  to  the  Gluteus  medius 
muscle.  Near  the  central  part  of  this  line  may  often  be  observed  the  orifice  of  a 
nutritious  foramen.  The  inferior  curved  line,  the  least  distinct  of  the  three,  com- 
mences in  front  at  the  upper  part  of  the  anterior  inferior  spinous  process,  and 
taking  a  curved  direction  backwards  and  downwards,  terminates  at  the  anterior 
part  of  the  great  sacro-sciatic  notch.  The  surface  of  bone  included  between  the 
middle  and  inferior  curved  lines  is  concave  from  above  downwards,  convex  from 
before  backwards,  and  affords  attachment  to  the  Gluteus  minimus  muscle.  Beneath 
the  inferior  curved  line,  and  corresponding  to  the  upper  part  of  the  acetabulum, 
is  a  smooth  eminence,  sometimes  a  depression,  to  which  is  attached  the  reflected 
tendon  of  the  Rectus  femoris  muscle. 

The  Internal  Surface  (fig.  98)  of  the  ilium  is  bounded  above  by  the  crest, 
below  by  a  prominent  line,  the  linea  ilio-pectinea,  and  before  and  behind  by  the 


150 


OSTEOLOGY. 


anterior  and  posterior  borders.  It  presents  anteriorly  a  large  smooth  concave 
surface  called  the  internal  iliac  fossa  or  venter  of  the  ilium  ;  it  lodges  the  Iliacus 
muscle,  and  presents  at  its  lower  part  the  orifice  of  a  nutritious  canal.  Behind 
the  iliac  fossa  is  a  rough  surface,  divided  into  two  portions,  a  superior  and  an 

Fig.  97. — Right  Os  Innominatum.     External  Surface. 


Anfrriom 

prruir 


Iho-pirtttua  I  Lin*  for 
GimbtT nat't  Lie  T. 


CEMELL.U3  SUPERIOR 

fifint.  of  Sick, 


CEREU.US    IN  TEH  10 


Spine  of  Fulirs 
for  Fat/parti  lic  anient 


.ArujlitfPubts 

cctus  abuomimi* 
ctumioams 


inferior.  The  inferior  or  auricular  portion,  so  called  from  its  resemblance  to  the 
external  ear,  is  coated  with  cartilage  in  the  recent  state,  and  articulates  with  a 
similar  shaped  surface  on  the  side  of  the  sacrum.  The  superior  portion  is  con- 
cave and  rough  for  the  attachment  of  the  posterior  sacro-iliac  ligaments. 

The  crest  of  the  ilium  is  convex  in  its  general  outline  and  sinuously  curved, 
being  bent  inwards  anteriorly,  outwards  posteriorly.  It  is  longer  in  the  female 
than  in  the  male,  very  thick  behind,  and  thinner  at  the  centre  than  at  the 
extremities.  It  terminates  at  either  end  in  a  prominent  eminence,  the  anterior 
superior,  and   posterior  superior   spinous  process.     The  surface  of  the  crest  is 


OS   INNOMINATUM. 


151 


broad,  and  divided  into  an  external  lip,  an  internal  lip,  and  an  intermediate 
space.'  To  the  external  lip  is  attached  the  Tensor  vaginae  femoris,  Obliquus 
externus  abdominis,  and  Latissimus  dorsi,  and  by  its  whole  length  the  fascia 
lata ;  to  the  interspace  between  the  lips,  the  Internal  oblique ;  to  the  internal  lip, 
the  Trans versalis,  Quadratus  lumborum,  and  Erector  spinas. 

Fig.  98. — Right  Os  Innominatum.     Internal  Surface. 


■  MIMUBt'OUIUIA 


The  anterior  border  of  the  ilium  is  concave.  It  presents  two  projections 
separated  by  a  notch.  Of  these,  the  uppermost,  situated  at  the  junction  of  the 
crest  and  anterior  border,  is  called  the  anterior  superior  spinous  process  of  the 
ilium,  the  outer  border  of  which  gives  attachment  to  the  fascia  lata,  and  the  origin 
of  the  Tensor  vaginas  femoris ;  its  inner  border,  to  the  Iliacus  internus ;  whilst  its 
extremity  affords  attachment  to  Poupart's  ligament,  and  the  origin  of  the  Sartorius. 
Beneath  this  eminence  is  a  notch  which  gives  attachment  to  the  Sartorius  muscle, 
and  across  which  passes  the  external  cutaneous  nerve.  Below  the  notch  is  the 
anterior  inferior  spinous  process,  which  terminates  in  the  upper  lip  of  the  aceta- 
bulum ;  it  gives  attachment  to  the  straight  tendon  of  the  Kectus  femoris  muscle. 


152  OSTEOLOGY. 

On  the  inner  side  of  the  anterior  inferior  spinous  process  is  a  broad  shallow  groove, 
over  which  passes  the  Iliacus  muscle.  The  posterior  border  of  the  ilium,  shorter 
than  the  anterior,  also  presents  two  projections  separated  by  a  notch,  the  posterior 
superior,  and  the  posterior  inferior  spinous  processes.  The  former  corresponds 
with  that  portion  of  the  posterior  surface  of  the  ilium  which  serves  for  the 
attachment  of  the  sacro-iliac  ligaments  ;  the-  latter,  to  the  auricular  portion  which 
articulates  with  the  sacrum.  Below  the  posterior  inferior  spinous  process  is  a 
deep  notch,  the  great  sacro-sciatic. 

The  Ischium  forms  the  lower  and  back  part  of  the  os  innominatum.  It  is  divisible 
into  a  thick  and  solid  portion,  the  body ;  and  a  thin  ascending  part,  the  ramus. 

The  body,  somewhat  triangular  in  form,  presents  three  surfaces,  external, 
internal,  and  posterior.  The  external  surface  corresponds  to  that  portion  of  the 
acetabulum  formed  by  the  ischium;  it  is  smooth  and  concave  above,  and  forms  a 
little  more  than  two-fifths  of  that  cavity ;  its  outer  margin  is  bounded  by  a  pro- 
minent rim  or  lip,  to  which  the  cotyloid  fibro- cartilage  is  attached.  Below  the 
acetabulum,  between  it  and  the  tuberosity,  is  a  deep  groove,  along  which  the  tendon 
of  the  Obturator  externus  muscle  runs,  as  it  passes  outwards  to  be  inserted  into 
the  digital  fossa  of  the  femur.  The  internal  surface  is  smooth,  concave,  and  forms 
the  lateral  boundary  of  the  true  pelvic  cavity ;  it  is  broad  above,  and  separated 
from  the  venter  of  the  ilium  by  the  linea  ilio-pectinea ;  narrow  below ;  its  posterior 
border  is  encroached  upon  a  little  below  its  centre,  by  the  spine  of  the  ischium, 
above  and  below  which  are  the  greater  and  lesser  sacro-sciatic  notches ;  in  front  it 
presents  a  sharp  margin,  which  forms  the  outer  boundary  of  the  obturator  foramen. 
This  surface  is  perforated  by  two  or  three  large  vascular  foramina,  and  affords 
attachment  to  part  of  the  Obturator  internus  muscle.  The  posterior  surface  is 
quadrilateral  in  form,  broad  and  smooth  above,  narrow  below  where  it  becomes 
continuous  with  the  tuberosity ;  it  is  limited,  in  front,  by  the  margin  of  the  ace- 
tabulum ;  behind,  by  the  front  part  of  the  great  sacro-sciatic  notch.  This  surface 
supports  the  Pyriformis,  the  two  Gemelli,  and  the  Obturator  internus  muscles,  in 
their  passage  outwards  to  the  great  trochanter.  The  body  of  the  ischium  presents 
three  borders,  posterior,  inferior,  and  internal.  The  posterior  border  presents,  a 
little  below  the  centre,  a  thin  and  pointed  triangular  eminence,  the  spine  of  the 
ischium,  more  or  less  elongated  in  different  subjects.  Its  external  surface  gives 
attachment  to  the  Gemellus  superior ;  its  internal  surface,  to  the  Coccygeus  and 
Levator  ani ;  whilst  to  the  pointed  extremity  is  connected  the  lesser  sacro-sciatic 
ligament.  Above  the  spine  is  a  notch  of  large  size,  the  great  sacro-sciatic,  con- 
verted into  a  foramen  by  the  lesser  sacro-sciatic  ligament ;  it  transmits  the  Pyri- 
formis muscle,  the  gluteal  vessels  and  nerve  passing  out  of  the  pelvis  above  this 
muscle ;  the  sciatic,  and  internal  pudic  vessels  and  nerve,  and  a  small  nerve  to  the 
Obturator  internus  muscle  below  it.  Below  the  spine  is  a  smaller  notch,  the  lesser 
sacro-sciatic ;  it  is  smooth,  coated  with  cartilage  in  the  recent  state,  the  surface  of 
which  presents  numerous  markings  corresponding  to  the  subdivisions  of  the  tendon 
of  the  Obturator  internus  which  winds  over  it.  It  is  converted  into  a  foramen  by 
the  sacro-sciatic  ligaments,  and  transmits  the  tendon  of  the  Obturator  internus, 
the  nerve  which  supplies  this  muscle,  and  the  pudic  vessels  and  nerve.  The 
inferior  border  is  thick  and  broad ;  at  its  point  of  junction  with  the  posterior,  is  a 
large  rough  eminence  upon  which  the  body  rests  in  sitting ;  it  is  called  the  tube- 
rosity of  the  ischium.  The  internal  border  is  thin,  and  forms  the  outer  circum- 
ference of  the  obturator  foramen. 

The  tuberosity,  situated  at  the  junction  of  the  posterior  and  inferior  borders, 
presents  for  examination  an  external  lip,  an  internal  lip,  and  an  intermediate  space. 
The  external  lip  gives  attachment  to  the  Quadratus  femoris,  and  part  of  the  Ad- 
ductor magnus  muscles.  The  inner  lip  is  bounded  by  a  sharp  ridge  for  the  attach- 
ment of  a  falciform  prolongation  of  the  great  sacro-sciatic  ligament ;  presents  a 
groove  on  the  inner  side  of  this  for  the  lodgment  of  the  internal  pudic  vessels 
and  nerve ;  and,  more  anteriorly,  has  attached  the  Transversus  perinei,  Erector 
penis,  and  Compressor  urethra  muscles.     The  intermediate  surface  presents  four 


OS  INNOMINATUM.  153 

distinct  impressions.  Two  of  these,  seen  at  the  front  part  of  the  tuberosity,  are 
rough,  elongated,  and  separated  from  each  other  by  a  prominent  ridge ;  the  outer 
one  gives  attachment  to  the  Adductor  magnus,  the  inner  one  to  the  great  sacro- 
sciatic  ligament.  Two,  situated  at  the  back  part,  are  smooth,  larger  in  size,  and 
separated  by  an  oblique  ridge;  from  the  upper  and  outer  arises  the  Semi-mem- 
branosus  ;  from  the  lower  and  inner,  the  Biceps  and  Semi-tendinosus.  The  upper- 
most part  of  the  tuberosity  gives  attachment  to  the  Gemellus  inferior. 

The  ramus  is  the  thin  flattened  part  of  the  ischium,  which  ascends  from  the 
tuberosity  upwards  and  inwards,  and  joins  the  ramus  of  the  pubes,  their  point  of 
junction  being  indicated  in  the  adult  by  a  rough  eminence.  Its  outer  surface  is 
rough  for  the  attachment  of  the  Obturator  externus  muscle.  Its  inner  surface 
forms  part  of  the  anterior  wall  of  the  pelvis.  Its  inner  border  is  thick,  rough, 
slightly  everted,  forms  part  of  the  outlet  of  the  pelvis,  and  serves  for  the  attach- 
ment of  the  crus  penis.  Its  outer  border  is  thin  and  sharp,  and  forms  part  of  the 
inner  margin  of  the  obturator  foramen. 

The  Pubes  forms  the  anterior  part  of  the  os  innominatum ;  it  is  divisible  into  a 
horizontal  ramus  or  body,  and  a  perpendicular  ramus. 

The  body  or  horizontal  ramus  presents  for  examination  two  extremities,  an  outer 
and  an  inner,  and  four  surfaces.  The  outer  extremity,  the  thickest  part  of  the  bone, 
forms  one-fifth  of  the  cavity  of  the  acetabulum ;  it  presents,  above,  a  rough  emi- 
nence, the  ilio-pectineal,  which  serves  to  indicate  the  point  of  junction  of  the 
ilium  and  pubes.  The  inner  extremity  is  the  symphysis ;  it  is  oval,  covered  by 
eight  or  nine  transverse  ridges,  or  a  series  of  nipple-like  processes  arranged  in 
rows,  separated  by  grooves ;  they  serve  for  the  attachment  of  the  interarticular 
fibro-cartilage,  placed  between  it  and  the  opposite  bone.  The  upper  surface, 
triangular  in  form,  wider  externally  than  internally,  is  bounded  behind  by  a  sharp 
ridge,  the  pectineal  line,  or  linea  ilio-pectinea,  which,  running  outwards,  marks  the 
brim  of  the  true  pelvis.  The  surface  of  bone  in  front  of  the  pubic  portion  of  the 
linea  iliq-pectinea  serves  for  the  attachment  of  the  Pectineus  muscle.  This  ridge 
terminates  internally  at  a  tubercle,  which  projects  forwards,  and  is  called  the  spine 
of  the  pubes.  The  portion  of  bone  included  between  the  spine  and  inner  extre- 
mity of  the  pubes  is  called  the  crest ;  it  serves  for  the  attachment  of  the  Rectus, 
Pyramidalis,  and  conjoined  tendon  of  the  Internal  oblique  and  Transversalis. 
The  point  of  junction  of  the  crest  with  the  symphysis  is  called  the  angle  of  the  p>ubes. 
The  inferior  surface  presents,  externally,  a  broad  and  deep  oblique  groove,  for 
the  passage  of  the  obturator  vessels  and  nerve ;  and,  internally,  a  sharp  margin, 
which  forms  part  of  the  circumference  of  the  obturator  foramen.  Its  external 
surface,  flat  and  compressed,  serves  for  the  attachment  of  muscles.  Its  internal 
surface,  convex  from  above  downwards,  concave  from  side  to  side,  is  smooth  and 
forms  part  of  the  anterior  wall  of  the  pelvis. 

The  descending  ramus  of  the  pubes  passes  outwards  and  downwards,  becoming 
thinner  and  narrower  as  it  descends,  and  joins  with  the  ramus  of  the  ischium.  Its 
external  surface  is  rough,  for  the  attachment  of  muscles.  Its  inner  surface  is 
smooth.  Its  inner  border  is  thick,  rough,  and  everted,  especially  in  females.  In 
the  male,  it  serves  for  the  attachment  of  the  crus  penis.  Its  outer  border  forms 
part  of  the  circumference  of  the  obturator  foramen. 

The  cotyloid  cavity,  or  acetabulum,  is  a  deep,  cup-shaped,  hemispherical  depres- 
sion, formed,  internally,  by  the  pubes;  above,  by  the  ilium;  behind  and  below, 
by  the  ischium ;  a  little  less  than  two-fifths  being  formed  by  the  ilium,  a  little 
more  than  two-fifths  by  the  ischium,  and  the  remaining  fifth  by  the  pubes.  It  is 
bounded  by  a  prominent  uneven  rim,  which  is  thick  and  strong  above,  and  serves 
for  the  attachment  of  a  fibro-cartilaginous  structure,  which  contracts  its  orifice, 
and  deepens  the  surface  for  articulation.  It  presents  on  its  inner  side  a  deep 
notch,  the  cotyloid  notch,  which  transmits  the  nutrient  vessels  into  the  interior  of 
the  joint,  and  is  continuous  with  a  circular  depression  at  the  bottom  of  the  cavity; 
this  depression  is  perforated  by  numerous  apertures,  lodges  a  mass  of  fat,  and  its 
margins  serve  for  the  attachment  of  the  ligamentum  teres.     The  notch  is  con- 


154 


OSTEOLOGY. 


verted,  in  the  natural  state,  into  a  foramen  by  a  dense  ligamentous  band  which 
passes  across  it.  Through  this  foramen,  the  nutrient  vessels  and  nerves  enter  the 
joint. 

The  obturator  or  thyroid  foramen  is  a  large  aperture,  situated  between  the 
ischium  and  pubes.  In  the  male  it  is  large,  of  an  oval  form,  its  longest  diameter 
being  obliquely  from  above  downwards ;  in  the  female,  smaller,  and  more  trian- 
gular. It  is  bounded  by  a  thin  uneven  margin,  to  which  a  strong  membrane  is 
attached;  and  presents,  at  its  upper  and  outer  part,  a  deep  groove,  which  runs 
from  the  pelvis  obliquely  forwards,  inwards,  and  downwards.  This  groove  is 
converted  into  a  foramen  by  the  obturator  membrane,  and  transmits  the  obturator 
vessels  and  nerve. 

Structure.  This  bone  consists  of  much  cancellous  tissue,  especially  where  it  is 
thick,  inclosed  between  two  layers  of  dense  compact  tissue.  In  the  thinner  parts 
of  the  bone,  as  at  the  bottom  of  the  acetabulum,  and  centre  of  the  iliac  fossa,  it 
is  usually  semi-transparent,  and  composed  entirely  of  compact  tissue. 

Development  (fig.  99).  By  eight  centres ;  three  primary — one  for  the  ilium,  ote 


Fig.  99. — Plan  of  the  Development  of  the  Os  Innominatum. 
•n       *   ft        .  I     & -Primary  (/IvuaniJJic/tiun^tc  Pu/hcs  j 

i     5.Stconda,TTt 


The  3  l*rimevry  centre*  finite    fArouyA   ~YShetfi€<l  Jileee  jtilotit  JwZerfy 
T.pijiJiyses   ativear  about  puberty,  $c    unite     about  26!?  year 

for  the  ischium,  and  one  for  the  pubes ;  and  five  secondary — one  for  the  crest  of  the 
ilium  its  whole  length,  one  for  the  anterior  inferior  spinous  process  (said  to  occur 
more  frequently  in  the  male  than  in  the  female),  one  for  the  tuberosity  of  the  ischium, 
one  for  the  symphysis  pubis  (more  frequent  in  the  female  than  the  male),  and  one 
for  the  Y-shaped  piece  at  the  bottom  of  the  acetabulum.  These  various  centres 
appear  in  the  following  order :  First,  in  the  ilium,  at  the  lower  part  of  the  bone, 
immediately  above  the  sciatic  notch,  at  about  the  same  period  that  the  develop- 
ment of  the  vertebra?  commences.  Secondly,  in  the  body  of  the  ischium,  at  about 
the  third  month  of  foetal  life.  Thirdly,  in  the  body  of  the  pubes,  between  the  fourth 
and  fifth  months.  At  birth,  the  three  primary  centres  are  quite  separate ;  the  crest, 
the  bottom  of  the  acetabulum,  and  the  rami  of  the  ischium  and  pubes,  being  still 


PELVIS.  155 

cartilaginous.  At  about  the  sixth  year,  the  rami  of  the  pubes  and  ischium  are 
almost° completely  ossified.  About  the  thirteenth  or  fourteenth  year,  the  three 
divisions  of  the  bone  have  extended  their  growth  into  the  bottom  of  the  acetabu- 
lum, being  separated  from  each  other  by  a  Y-shaped  portion  of  cartilage,  which 
now  presents  traces  of  ossification.  The  ilium  and  ischium  then  become  joined, 
and  lastly  the  pubes,  through  the  intervention  of  the  portion  above-mentioned. 
At  about  the  age  of  puberty,  ossification  takes  place  in  each  of  the  remaining 
portions,  and  they  become  joined  to  the  rest  of  the  bone  about  the  twenty-fifth 
year. 

Articulations.     With  its  fellow  of  the  opposite  side,  the  sacrum  and  femur. 

Attachment  of  Muscles.  Ilium.  To  the  outer  lip  of  the  crest,  the  Tensor 
vaginae  femoris,  Obliquus  externus  abdominis,  and  Latissimus  dorsi;  to  the  internal 
lip,  the  Transversalis,  Quadratus  lumborum,  and  Erector  spinse ;  to  the  interspace 
between  the  lips,  the  Obliquus  internus.  To  the  outer  surface  of  the  ilium,  the 
Gluteus  maximus,  Gluteus  medius,  Gluteus  minimus,  reflected  tendon  of  Rectus, 
portion  of  Pyriformis ;  to  the  internal  surface,  the  Iliacus ;  to  the  anterior  border, 
the  Sartorius  and  straight  tendon  of  the  Eectus.  Ischium.  To  its  outer  surface, 
the  Obturator  externus;  internal  surface,  Obturator  internus  and  Levator  ani. 
To  the  spine,  the  Gemellus  superior,  Levator  ani,  and  Coccygeus.  To  the 
tuberosity,  the  Biceps,  Semi-tendinosus,  Semi-membranosus,  Quadratus  femoris, 
Adductor  magnus,  Gemellus  inferior,  Transversus  perinsei,  Erector  penis.  Pubes, 
the  Obliquus  externus,  Obliquus  internus,  Transversalis,  Rectus,  Pyramidalis, 
Psoas  parvus,  Pectineus,  Adductor  longus,  Adductor  brevis,  Gracilis,  Obtu- 
rator externus  and  internus,  Levator  ani,  Compressor  urethral,  and  occasionally  a 
few  fibres  of  the  Accelerator  urinse. 

The  Pelvis  (figs.  100  and  101). 

The  pelvis,  so  called  from  its  resemblance  to  a  basin  {ni-Kv^),  is  stronger  and 
more  massively  constructed  than  either  of  the  other  osseous  cavities  already  con- 
sidered ;  it  is  a  bony  ring,  interposed  between  the  lower  end  of  the  spine,  which 
it  supports,  and  the  lower  extremities,  upon  which  it  rests.  It  is  composed  of 
four  bones — the  two  ossa  innotninata,  which  bound  it  on  either  side  and  in  front ; 
and  the  sacrum  and  coccyx,  which  complete  it  behind. 

The  pelvis  is  divided  by  a  prominent  line,  the  linea  ilio-pectinea,  into  a  false 
and  true  pelvis. 

The  false  pelvis  is  all  that  expanded  portion  of  the  pelvic  cavity  which  is 
situated  above  the  linea  ilio-pectinea.  It  is  bounded  on  each  side  by  the  ossa  ilii ; 
in  front  it  is  incomplete,  presenting  a  wide  interval  between  the  spinous  processes 
of  the  ilia  on  either  side,  filled  up  in  the  recent  state  by  the  parietes  of  the 
abdomen ;  behind,  in  the  middle  line,  is  a  deep  notch.  This  broad  shallow  cavity 
is  admirably  adapted  to  support  the  intestines,  and  to  transmit  part  of  their  weight 
to  the  anterior  wall  of  the  abdomen. 

The  true  pelvis  is  all  that  part  of  the  pelvic  cavity  which  is  situated  beneath 
the  linea  ilio-pectinea.  It  is  smaller  than  the  false  pelvis,  but  its  walls  are  more 
perfect.  For  convenience  of  description,  it  may  be  divided  into  a  superior  cir- 
cumference or  inlet,  an  inferior  circumference  or  outlet,  and  a  cavity. 

The  superior  circumference  forms  the  margin  or  brim  of  the  pelvis,  the  included 
space  being  called  the  inlet.  It  is  formed  by  the  linea  ilio-pectinea,  completed 
in  front  by  the  spine  and  crest  of  the  pubes,  and  behind  by  the  anterior  margin  of 
the  base  of  the  sacrum  and  sacro- vertebral  angle. 

The  inlet  of  the  pelvis  is  somewhat  heart-shaped,  obtusely  pointed  in  front, 
diverging  on  either  side,  and  encroached  upon  behind  by  the  projection  forwards 
of  the  promontory  of  the  sacrum.  It  has  three  principal  diameters:  antero- 
posterior or  sacro-pubic,  transverse,  and  oblique.  The  antero-posterior  extends 
from  the  sacro- vertebral  angle  to  the  symphysis  pubis ;  its  average  measurement 
is  four  inches.     The  transverse  extends  across  the  greatest  width  of  the  inlet, 


15G 


OSTEOLOGY. 


from  the  middle  of  the  brim  on  one  side,  to  the  same  point  on  the  opposite-  its 
average  measurement  is  five  inches.  The  oblique  extends  from  the  margin  of  the 
pelvis  corresponding  to  the  ilio-pectineal  eminence  on  one  side,  to  the  sacro-iliac 
symphysis  on  the  opposite  side ;  its  average  measurement  is  also  five  inches. 

Fig.  100.— Male  Pelvis  (Adult). 


Fig.  101.— Female  Pelvis  (Adult). 


The  cavity  of  the  true  pelvis  is  bounded  in  front  by  the  symphysis  pubis ; 
behind,  by  the  concavity  of  the  sacrum  and  coccyx,  which  curving  forwards 
above  and  below,  contracts  the  inlet  and  outlet  of  the  canal ;  and  laterally  it  is 
bounded  by  a  broad,  smooth,  quadrangular  plate  of  bone,  corresponding  to  the 
inner  surface  of  the  body  of  the  ischium.  The  cavity  is  shallow  in  front,  meas- 
uring at  the  symphysis  an  inch  and  a  half  in  depth,  three  inches  and  a  half  in 


PELVIS.  157 

the  middle,  and  four  inches  and  a  half  posteriorly.  From  this  description,  it 
will  be  seen  that  the  cavity  of  the  pelvis  is  a  short,  curved  canal,  considerably 
deeper  on  its  posterior  than  on  its  anterior  wall,  and  broader  in  the  middle  than 
at  either  extremity,  from  the  projection  forwards  of  the  sacro-coccygeal  column 
above  and  below.  This  cavity  contains,  in  the  recent  subject,  the  rectum,  bladder, 
and  part  of  the  organs  of  generation.  The  rectum  is  placed  at  the  back  of  the 
pelvis,  and  corresponds  to  the  curve  of  the  sacro-coccygeal  column;  the  bladder 
in  front,  behind  the  symphysis  pubis.  In  the  female,  the  uterus  and  vagina 
occupy  the  interval  between  these  parts. 

The  lower  circumference  of  the  pelvis  is  very  irregular,  and  forms  what  is  called 
the  outlet.  It  is  bounded  by  three  prominent  eminences :  one  posterior,  formed 
by  the  point  of  the  coccyx ;  and  one  on  each  side,  the  tuberosities  of  the  ischia. 
These  eminences  are  separated  by  three  notches ;  one  in  front,  the  pubic  arch, 
formed  by  the  convergence  of  the  rami  of  the  ischia  and  pubes  on  each  side.  The 
other  notches,  one  on  each  side,  are  formed  by  the  sacrum  and  coccyx  behind, 
the  ischium  in  front,  and  the  ilium  above:  they  are  called  the  sacro-sciatic  notches; 
in  the  natural  state  they  are  converted  into  foramina  by  the  lesser  and  greater 
sacro-sciatic  ligaments. 

The  diameters  of  the  outlet  of  the  pelvis  are  two,  antero-posterior  and  trans- 
verse. The  antero-posterior  extends  from  the  tip  of  the  coccyx  to  the  lower  part 
of  the  symphysis  pubis ;  and  the  transverse  from  the  posterior  part  of  one  ischiatic 
tuberosity,  to  the  same  point  on  the  opposite  side :  the  average  measurement  of 
both  is  four  inches.  The  antero-posterior  diameter  varies  with  the  length  of  the 
coccyx,  and  is  capable  of  increase  or  diminution,  on  account  of  the  mobility  of 
this  bone. 

Position  of  the  Pelvis.  In  the  erect  posture,  the  pelvis  is  placed  obliquely  with 
regard  to  the  trunk  of  the  body ;  the  pelvic  surface  of  the  symphysis  pubis  looking 
upwards  and  backwards,  the  concavity  of  the  sacrum  and  coccyx  looking  down- 
wards and  forwards;  the  base  of  the  sacrum,  in  well-formed  female  bodies, 
being  nearly  four  inches  above  the  upper  border  of  the  symphysis  pubis,  and 
the  apex  of  the  coccyx  a  little  more  than  half  an  inch  above  its  lower  border. 
This  obliquity  is  much  greater  in  the  foetus,  and  at  an  early  period  of  life  than 
in  the  adult. 

Axes  of  the  Pelvis  (fig.  102).  The  plane  of  the  inlet  of  the  true  pelvis  will  be 
represented  by  a  line  drawn  from  the  base  of  the  sacrum  to  the  upper  margin  of 
the  symphysis  pubis.    A  line  carried 

at  right  angles  with  this,  at  its  middle,   Fig.  102.— Vertical  Section  of  the  Pelvis,  with  lines 
would  correspond  at  one    extremity  indicating  the  Axes  of  the  Pelvis, 

with  the  umbilicus,  and  at  the  other 
with  the  middle  of  the  coccyx ;  the 
axis  of  the  inlet  is  therefore  directed 
downwards  and  backwards.  The  axis 
of  the  outlet,  produced  upwards,  would 
touch  the  base  of  the  sacrum ;  and  is 
therefore  directed  downwards  and 
forwards.  The  axis  of  the  cavity  is 
curved  like  the  cavity  itself;  this 
curve  corresponds  to  the  concavity 
of  the  sacrum  and  coccyx,  the  ex- 
tremities being  indicated  by  the 
central  points  of  the  inlet  and  outlet. 
A  knowledge  of  the  direction  of  these 
axes  serves  to  explain  the  course  of 
the  foetus  in  its  passage  through  the 
pelvis  during  parturition.  It  is  also 
important  to  the  surgeon  as  indicating  fUne 

the  direction  of  the  force  required  in 


158  OSTEOLOGY. 

the  removal  of  calculi  from  the  bladder,  and  as  determining  the  direction  in 
which  instruments  should  be  used  in  operations  upon  the  pelvic  viscera. 

Differences  between  the  Male  and  Female  Pelvis.  In  the  male,  the  bones  are 
thicker  and  stronger,  and  the  muscular  eminences  and  impressions  on  their  sur- 
faces more  strongly  marked.  The  male  pelvis  is  altogether  more  massive;  its 
cavity  is  deeper  and  narrower,  and  the  obturator  foramina  of  larger  size.  In  the 
female,  the  bones  are  lighter  and  more  expanded,  the  muscular  impressions  on 
their  surfaces  are  only  slightly  marked,  and  the  pelvis  generally  is  less  massive  in 
structure.  The  iliac  fossae  are  broad,  and  the  spines  of  the  ilia  widely  separated ; 
hence  the  great  prominence  of  the  hips.  The  inlet  and  the  outlet  are  larger ;  the 
cavity  is  more  capacious,  and  the  spines  of  \h&  ischia  project  less  into  it.  The 
promontory  is  less  projecting,  the  sacrum  wider  and  less  curved,1  and  the  coccyx 
more  movable.  The  arch  of  the  pubes  is  wider,  and  its  edges  more  everted. 
The. tuberosities  of  the  ischia  and  the  acetabula  are  wider  apart. 

In  the  foetus,  and  for  several  years  after  birth,  the  pelvis  is  small  in  proportion 
to  that  of  the  adult.  The  cavity  is  deep,  and  the  projection  of  the  sacro- vertebral 
angle  less  marked.  The  antero-posterior  and  transverse  diameters  are  nearly 
equal.  About  puberty,  the  pelvis  in  both  sexes  presents  the  general  characters 
of  the  adult  male  pelvis,  but  after  puberty  it  acquires  the  sexual  characters  pecu- 
liar to  it  in  adult  life. 


OF  THE   THIGH. 
The  thigh  is  formed  of  a  single  bone,  the  femur. 

The  Femur. 

The  Femur  is  the  longest,  largest,  and  strongest  bone  in  the  skeleton,  and  almost 
perfectly  cylindrical  in  the  greater  part  of  its  extent.  In  the  erect  posture,  it  is 
not  vertical,  being  separated  from  its  fellow  above  by  a  considerable  interval 
which  corresponds  to  the  entire  breadth  of  the  pelvis,  but  gradually  inclines 
downwards  and  inwards,  so  as  to  approach  its  fellow  towards  its  lower  part,  for 
the  purpose  of  bringing  the  knee-joint  near  the  line  of  gravity  of  the  body.  The 
degree  of  this  inclination  varies  in  different  persons,  and  is  greater  in  the  female 
than  in  the  male,  on  account  of  the  greater  breadth  of  the  pelvis.  The  femur, 
like  other  long  bones,  is  divisible  into  a  shaft,  and  two  extremities. 

The  Upper  Extremity  presents  for  examination  a  head,  a  neck,  and  the  greater 
and  lesser  trochanters. 

The  head,  which  is  globular,  and  forms  rather  more  than  a  hemisphere,  is  di- 
rected upwards,  inwards,  and  a  little  forwards,  the  greater  part  of  its  convexity 
being  above  and  in  front.  Its  surface  is  smooth,  coated  with  cartilage  in  the 
recent  state,  and  presents,  a  little  behind  and  below  its  centre,  an  ovoid  depression, 
for  the  attachment  of  the  ligamentum  teres.  The  neck  is  a  flattened  pyramidal 
process  of  bone,  which  connects  the  head  with  the  shaft.  It  varies  in  length  and 
obliquity  at  various  periods  of  life,  and  under  different  circumstances.  Before 
puberty,  it  is  directed  obliquely,  so  as  to  form  a  gentle  curve  from  the  axis  of  the 
shaft.  In  the  adult  male,  it  forms  an  obtuse  angle  with  the  shaft,  being  directed 
upwards,  inwards,  and  a  little  forwards.  In  the  female,  it  approaches  more  nearly 
a  right  angle.  Occasionally,  in  very  old  subjects,  and  more  especially  in  those 
greatly  debilitated,  its  direction  becomes  horizontal,  so  that  the  head  sinks  below 
the  level  of  the  trochanter,  and  its  length  diminishes  to  such  a  degree,  that  the 
head  becomes  almost  contiguous  with  the  shaft.  The  neck  is  flattened  from  before 
backwards,  contracted  in  the  middle,  and  broader  at  its  outer  extremity,  where  it 

1  It  is  not  unusual  to  find  the  sacrum  in  the  female  presenting  a  considerable  curve  extending 
throughout  its  whole  length. 


FEMUR. 


159 


is  connected  with  the  shaft,  than  at  its 
summit,  where  it  is  attached  to  the  head. 
It  is  much  broader  in  the  vertical  than  in 
the  antero-posterior  diameter,  and  much 
thicker  below  than  above,  on  account  of 
the  greater  amount  of  resistance  required 
in  sustaining  the  weight  of  the  trunk. 
Its  anterior  surface  is  perforated  by  nu- 
merous vascular  foramina.  Its  posterior 
surface  is  smooth,  broader,  and  more  con- 
cave than  the  anterior ;  and  receives  to- 
wards its  outer  side  the  attachment  of 
the  capsular  ligament  of  the  hip.  Its 
superior  border  is  short  and  thick,  bounded 
externally  by  the  great  trochanter,  and 
its  surface  perforated  by  large  foramina. 
Its  inferior  border,  long  and  narrow, 
curves  a  little  backwards,  to  terminate  at 
the  lesser  trochanter. 

The  Trochanters  (rpo^ow,  to  run  or 
roll)  are  prominent  processes  of  bone 
which  afford  greater  leverage  to  the 
muscles  which  rotate  the  thigh  on  its 
axis.  They  are  two  in  number,  the 
greater,  and  the  lesser. 

The  Great  Trochanter  is  a  large 
irregular  quadrilateral  eminence,  situated 
at  the  outer  side  of  the  neck,  at  its  junc- 
tion with  the  upper  part  of  the  shaft. 
It  is  directed  a  little  outwards  and  back- 
wards ;  and,  in  the  adult,  is  about  three 
quarters  of  an  inch  lower  than  the  head. 
It  presents  for  examination  two  surfaces, 
and  four  borders. 

Its  external  surface,  quadrilateral  in 
form,  is  broad,  rough,  convex,  and  marked 
by  a  prominent  diagonal  line,  which  ex- 
tends from  the  posterior  superior  to  the 
anterior  inferior  angle ;  this  line  serves 
for  the  attachment  of  the  tendon  of  the 
Gluteus  medius.  Above  the  line  is  a  tri- 
angular surface,  sometimes  rough  for  part 
of  the  tendon  of  the  same  muscle,  some- 
times smooth  for  the  interposition  of  a 
bursa  between  that  tendon  and  the  bone. 
Below  and  behind  the  diagonal  line  is  a 
smooth  triangular  surface,  over  which  the 
tendon  of  the  Gluteus  maxim  us  muscle 
plays,  a  bursa  being  interposed.  The  in- 
ternal surface  is  of  much  less  extent 
than  the  external,  and  presents  at  its  base 
a  deep  depression,  the  digital  or  trochan- 
teric fossa,  for  the  attachment  of  the  ten- 
don of  the  Obturator  externus  muscle. 

The  superior  border  is  free ;  it  is  thick 
and  irregular,  and  marked  by  impressions 
for   the   attachment   of  the   Pyriformis 


Fig.  103.— Right  Femur.     Anterior  Surface. 


0»TUP»TO«      INTERNUS 

l>VRiron«is 


JJr/irttmlon.  for 
UO.MtMTUH  tcd: 


''/•iVwuliJ 


160  OSTEOLOGY. 

behind,  the  Obturator  interim  s  and  Gemelli  in  front.  The  inferior  border  corre- 
sponds to  the  point  of  junction  of  the  base  of  the  trochanter  with  the  outer  surface 
of  the  shaft ;  it  is  rough,  prominent,  slightly  curved,  and  gives  attachment  to  the 
upper  part  of  the  Vastus  externus  muscle.  The  anterior  border  is  prominent, 
somewhat  irregular,  as  well  as  the  surface  of  bone  immediately  below  it ;  it  affords 
attachment  by  its  outer  part  to  the  Gluteus  minimus.  The  posterior  border  is  very 
prominent,  and  appears  as  a  free  rounded  edge,  which  forms  the  back  part  of  the 
digital  fossa. 

The  Lesser  Trochanter  is  a  conical  eminence,  which  varies  in  size  in  different 
subjects;  it  projects  from  the  lower  and  back  part  of  the  base  of  the  neck.  Its 
base  is  triangular,  and  connected  with  the  adjacent  parts  of  the  bone  by  three 
well-marked  borders :  of  these,  the  superior  is  continuous  with  the  lower  border 
of  the  neck ;  the  posterior,  with  the  posterior  intertrochanteric  line ;  and  the  inferior, 
with  the  middle  bifurcation  of  the  linea  aspera.  Its  summit,  which  is  directed 
inwards  and  backwards,  is  rough,  and  gives  insertion  to  the  tendon  of  the  Psoas 
magnus.  The  Iliacus  is  inserted  into  the  shaft  below  the  lesser  trochanter,  between 
the  Vastus  internus  in  front,  and  the  Pectineus  behind.  A  well-marked  promi- 
nence, of  variable  size,  which  projects  from  the  upper  and  front  part  of  the  neck, 
at  its  junction  with  the  great  trochanter,  is  called  the  tubercle  of  the  femur ;  it  is 
the  point  of  meeting  of  three  muscles,  the  Gluteus  minimus  externally,  the  Vastus 
externus  below,  and  the  tendon  of  the  Obturator  internus  and  Gemelli  above. 
Eunning  obliquely  downwards  and  inwards  from  the  turbercle,  is  the  spiral  line 
of  the  femur,  or  anterior  intertrochanteric  line ;  it  winds  round  the  inner  side  of 
the  shaft,  below  the  lesser  trochanter,  and  terminates  in  the  linea  aspera,  about  two 
inches  below  this  eminence.  Its  upper  half  is  rough,  and  affords  attachment  to 
the  capsular  ligament  of  the  hip -joint;  its  lower  half  is  less  prominent,  and  gives 
attachment  to  the  upper  part  of  the  Vastus  internus.  The  posterior  intertro- 
chanteric line  is  very  prominent,  and  runs  from  the  summit  of  the  great  trochanter 
downwards  and  inwards  to  the  upper  and  back  part  of  the  lesser  trochanter.  Its 
upper  half  forms  the  posterior  border  of  the  great  trochanter.  A  well-marked 
eminence  commences  about  the  middle  of  the  posterior  intertrochanteric  line,  and 
passes  vertically  downwards  for  about  two  inches  along  the  back  part  of  the  shaft ; 
it  is  called  the  linea  quadrati,  and  gives  attachment  to  the  Quadratus  femoris,  and 
a  few  fibres  of  the  Adductor  magnus  muscles. 

The  Shaft,  almost  perfectly  cylindrical  in  form,  is  a  little  broader  above  than  in 
the  centre,  and  somewhat  flattened  from  before  backwards  below.  It  is  slightly 
arched,  so  as  to  be  convex  in  front ;  concave  behind,  where  it  is  strengthened  by 
a  prominent  longitudinal  ridge,  the  linea  aspera.  It  presents  for  examination  three 
borders  separating  three  surfaces.  Of  the  three  borders,  one,  the  linea  aspera,  is 
posterior ;  the  other  two  are  placed  laterally. 

The  linea  aspera  (fig.  104)  is  a  prominent  longitudinal  ridge  or  crest,  presenting 
on  the  middle  third  of  the  bone  an  external  lip,  an  internal  lip,  and  a  rough  inter- 
mediate space.  A  little  above  the  centre  of  the  shaft,  this  crest  divides  into  three 
lines :  the  most  external  one  becomes  very  rough,  and  is  continued  almost  vertically 
upwards  to  the  base  of  the  great  trochanter :  the  middle  one,  the  least  distinct,  is 
continued  to  the  base  of  the  trochanter  minor ;  and  the  internal  one  is  lost  above 
in  the  spiral  line  of  the  femur.  Below,  the  linea  aspera  divides  into  two  bifur- 
cations, which  inclose  between  them  a  triangular  space,  the  popliteal  space,  upon 
which  rests  the  popliteal  artery.  Of  these  two  bifurcations,  the  outer  branch  is 
the  most  prominent,  and  descends  to  the  summit  of  the  outer  condyle.  The  inner 
branch  is  less  marked,  presents  a  broad  and  shallow  groove  for  the  passage  of  the 
femoral  artery,  and  terminates  at  a  small  tubercle  at  the  summit  of  the  internal 
condyle. 

To  the  inner  lip  of  the  linea  aspera,  its  whole  length,  is  attached  the  Vastus 
internus ;  and  to  the  whole  length  of  the  outer  lip,  the  Vastus  externus.  The 
Adductor  magnus  is  also  attached  to  the  whole  length  of  the  linea  aspera,  being 
connected  with  the  outer  lip  above,  and  the  inner  lip  below.     Between  the  Vastus 


FEMUR. 


161 


externus  and  the  Adductor  magnus  are 
attached  two  muscles,  viz.,  the  Gluteus 
maximus  above,  and  the  short  head  of  the 
Biceps  below.  Between  the  Adductor 
magnus  and  the  Vastus  internus,  four 
muscles  are  attached:  the  Iliacus  and 
Pectineus  above,  the  latter  to  the  middle 
division  of  the  upper  bifurcation ;  below 
these,  the  Adductor  brevis  and  Adductor 
longus.  The  linea  aspera  is  perforated  a 
little  below  its  centre  by  the  nutritious 
canal,  which  ip  directed  obliquely  from 
below  upwards. 

The  two  lateral  borders  of  the  femur 
are  only  very  slightly  marked,  the  outer 
one  extending  from  the  anterior  inferior 
angle  of  the  great  trochanter  to  the  an- 
terior extremity  of  the  external  condyle ; 
the  inner  one  passes  from  the  spiral  line, 
at  a  point  opposite  the  trochanter  minor, 
to  the  anterior  extremity  of  the  internal 
condyle.  The  internal  border  marks  this 
limit  of  attachment  of  the  Crureus  muscle 
internally. 

The  anterior  surface  includes  that  por- 
tion of  the  shaft  which  is  situated  between 
the  two  lateral  borders.  It  is  smooth, 
convex,  broader  above  and  below  than  in 
the  centre,  slightly  twisted,  so  that  its 
upper  part  is  directed  forwards  and  a  little 
outwards,  its  lower  part  forwards  and  a 
little  inwards.  The  upper  three-fourths 
of  this  surface  serve  for  the  attachment  of 
the  Crureus ;  the  lower  fourth  is  separated 
from  this  muscle  by  the  intervention  of 
the  synovial  membrane  of  the  knee-joint, 
and  affords  attachment  to  the  Subcrureus 
to  a  small  extent.  The  external  surface 
includes  the  portion  of  bone  between  the 
external  border  and  the  outer  lip  of  the 
linea  aspera ;  it  is  continuous,  above,  with 
the  outer  surface  of  the  great  trochanter; 
below,  with  the  outer  surface  of  the  ex- 
ternal condyle :  to  its  upper  three-fourths 
is  attached  the  outer  portion  of  the  Cru- 
reus muscle.  The  internal  surf  ace  includes 
the  portion  of  bone  between  the  internal 
border  and  the  inner  lip  of  the  linea  as- 
pera; it  is  continuous,  above,  with  the 
lower  border  of  the  neck;  below,  with 
the  inner  side  of  the  internal  condyle :  it 
is  covered  by  the  Vastus  internus  muscle. 

The  Lower  Extremity,  larger  than  the 
upper,  is  of  a  cuboid  form,  flattened  from 
before  backwards,  and  divided  by  an 
interval  presenting  a  smooth  depression 
in  front,  and  a  notch  of  considerable  size 
11 


Fig.  104. — Right  Femur.    Posterior  Surface. 


.  OBTURATOR    EXTERNU* 


5! 


ff 


w 


:.W 


Q 

I-: 


Hi 


i 


.  trtoavt  for  trtulj* 

POPL.U.i 


>•< 


.V1. 


^ 


J* 


162 


OSTEOLOGY. 


behind,  into  two  large  eminences,  the  condyles  (x6vhvxoi}  a  knuckle).  The  interval 
is  called  the  intercondyloid  notch.  The  external  condyle  is  the  most  prominent 
anteriorly,  and  is  the  broadest  both  in  the  antero-posterior  and  transverse  diameters. 
The  internal  condyle  is  the  narrowest,  longest,  and  most  prominent  internally. 
This  difference  in  the  length  of  the  two  condyles  is  only  observed  when  the  bone 
is  perpendicular,  and  depends  upon  the  obliquity  of  the  thigh-bones,  in  conse- 
quence of  their  separation  above  at  the  articulation  with  the  pelvis.  If  the  femur 
is  held  obliquely,  the  surfaces  of  the  two  condyles  will  be  seen  to  be  nearly  hori- 
zontal. The  two  condyles  are  directly  continuous  in  front,  and  form  a  smooth 
trochlear  surface,  the  external  border  of  which  is  more  prominent,  and  ascends 
higher  than  the  internal  one.  This  surface  articulates  with  the  patella.  It  pre- 
sents a  median  groove,  which  extends  downwards  and  backwards  to  the  inter- 
condyloid notch ;  and  two  lateral  convexities,  of  which  the  external  is  the  broader, 
more  prominent,  and  prolonged  farther  upwards  upon  the  front  of  the  outer 
condyle.  The  intercondyloid  notch  lodges  the  crucial  ligaments ;  it  is  bounded 
laterally  by  the  opposed  surfaces  of  the  two  condyles,  and  in  front  by  the  lower 
end  of  the  shaft. 

Outer  Condyle.  The  outer  surface  of  the  external  condyle  presents,  a  little  behind 
its  centre,  an  eminence,  the  outer  tuberosity ;  it  is  less  prominent  than  the  inner 
tuberosity,  and  gives  attachment  to  the  external  lateral  ligament  of  the  knee. 
Immediately  beneath  it  is  a  groove  which  commences  at  a  depression  a  little  behind 
the  centre  of  the  lower  border  of  this  surface :  the  depression  is  for  the  tendon  of 
origin  of  the  Popliteus  muscle ;  the  groove  in  which  this  tendon  is  contained  is 
smooth,  covered  with  cartilage  in  the  recent  state,  and  runs  upwards  and  back- 
wards to  the  posterior  extremity  of  the  condyle.  The  inner  surface  of  the  outer 
condyle  forms  one  of  the  lateral  boundaries  of  the  intercondyloid  notch,  and 
gives  attachment,  by  its  posterior  part,  to  the  anterior  crucial  ligament.  The 
inferior  surface  is  convex,  smooth,  and  broader  than  that  of  the  internal  condyle. 
The  posterior  extremity  is  convex  and  smooth :  just  above  the  articular  surface 
is  a  depression,  for  the  tendon  of  the  outer  head  of  the  Gastrocnemius. 

Inner  Condyle.  The  inner  surface  of  the  inner  condyle  presents  a  convex 
eminence,  the  inner  tuberosity,  rough  for  the  attachment  of  the  internal  lateral 
ligament.  Above  this  tuberosity,  at  the  termination  of  the  inner  bifurcation  of  the 
linea  aspera,  is  a  tubercle,  for  the  insertion  of  the  tendon  of  the  Adductor  magnus ; 
and  behind  and  beneath  the  tubercle  a  depression,  for  the  tendon  of  the  inner  head 
of  the  Gastrocnemius.  The  outer  side  of  the  inner  condyle  forms  one  of  the  lateral 
boundaries  of  the  intercondyloid  notch,  and  gives  attachment,  by  its  anterior  part, 
to  the  posterior  crucial  ligament.  Its  inferior  or  articular  surface  is  convex,  and 
presents  a  less  extensive  surface  than  the  external  condyle. 

Structure.  The  shaft  of  the  femur  is 
a  cylinder  of  compact  tissue  hollowed 
by  a  large  medullary  canal.  The  cylin- 
der is  of  great  thickness  and  density  in 
the  middle  third  of  the  shaft,  wrhere  the 
bone  is  narrowest,  and  the  medullary 
canal  well  formed ;  but  above  and  below 
this,  the  cylinder  gradually  becomes 
thinner,  owing  to  a  separation  of  the 
layers  of  the  bone  into  cancelli,  which 
project  into  the  medullary  canal,  and 
finally  obliterate  it,  so  that  the  upper  and 
lower  ends  of  the  shaft,  and  the  articular 
extremities  more  especially,  consist  of 
cancellated  tissue  invested  by  a  thin 
compact  layer. 

The  arrangement  of  the  cancelli  in  the 
ends  of  the  femur  is  remarkable.     In  the 


Fig.  105. — Diagram  showing  the  Structure  of 
the  Neck  of  the  Femur.     (Ward.) 


FEMUR. 


133 


Fig.  106. — Plan  of  the  Development  of  the  Femur. 
By  5  Centres. 


Appears  at  U$y? 
JVfSiuftMut  m  *y?(£ 


Appears  at vnd «f>y? 
Jci/isS/iaft  aiout  tS.'y1 


Ajipt(trs13-U*  yr- 
Joins Shaft  aiout  1 8*^  y  T 


upper  end  (fig.  105),  they  run  in  parallel  columns  a  a  from  the  summit  of  the  head 
to  the  thick  under  wall  of  the  neck,  while  a  series  of  transverse  fibres  b  b  decus- 
sates the  parallel  columns,  and  connects  them  to  the  thin  upper  wall  of  the  neck. 
Another  series  of  plates  c  c  springs  from  the  whole  interior  of  the  cylinder  above 
the  lesser  trochanter ;  passing  upwards,  they  converge  to  form  a  series  of  arches 
beneath  the  upper  wall  of  the  neck,  near  its  junction  with  the  great  trochanter. 
This  structure  is  admirably  adapted  to  sustain,  with  the  greatest  mechanical 
advantage,  concussion  or  weight  transmitted  from  above,  and  serves  an  important 
office  in  strengthening  a  part  especially  liable  to  fracture. 

In  the  lower  end,  the  cancelli  spring  on  all  sides  from  the  inner  surface  of  the 
cylinder,  and  descend  in  a  perpendicular  direction  to  the  articular  surface,  the 
cancelli  being  strongest,  and  having  a  more  decided  perpendicular  course,  above 
the  condyles. 

Articulations.     With  three  bones :  the  os  innominatum,  tibia,  and  patella. 

Development  (fig.  106).  The 
femur  is  developed  by  jive  centres ; 
one  for  the  shaft,  one  for  each  ex- 
tremity, and  one  for  each  trochanter. 
Of  all  the  long  bones,  it  is  the  first 
to  show  traces  of  ossification:  this 
first  commences  in  the  shaft,  at 
about  the  fifth  week  of  foetal  life, 
the  centres  of  ossification  in  the 
epiphyses  appearing  in  the  follow- 
ing order:  First,  in  the  lower  end 
of  the  bone,  at  the  ninth  month  of 
foetal  life;  from  this  the  condyles 
and  tuberosities  are  formed ;  in  the 
head,  at  the  end  of  the  first  year 
after  birth ;  in  the  great  trochanter, 
during  the  fourth  year ;  and  in  the 
lesser  trochanter,  between  the  thir- 
teenth and  fourteenth.  The  order 
in  which  the  epiphyses  are  joined 
to  the  shaft,  is  the  direct  reverse 
of  their  appearance ;  their  junction 
does  not  commence  until  after 
puberty,  the  lesser  trochanter  being 
first  joined,  then  the  greater,  then 
the  head,  and,  lastly,  the  inferior 
extremity,  the  first  in  which  ossi- 
fication commenced,  which  is  not 
united  until  the  twentieth  year. 

Attachment  of  Muscles.  To  the  great  trochanter:  the  Gluteus  medius,  Gluteus 
minimus,  Pyriformis,  Obturator  internus,  Obturator  externus,  Gemellus  superior, 
Gemellus  inferior,  and  Quadratus  femoris.  To  the  lesser  trochanter :  the  Psoas 
magnus,  and  the  Iliacus  below  it.  To  the  shaft :  its  posterior  surface ;  the  Vastus 
externus,  Gluteus  maximus,  short  head  of  the  Biceps,  Vastus  internus,  Adductor 
magnus,  Pectineus,  Adductor  brevis,  and  Adductor  longus ;  to  its  anterior  surface; 
the  Crureus,  and  Subcrureus.  To  the  condyles:  the  Gastrocnemius,  Plantaris, 
and  Popliteus.  , 


4 


i'PVt 


trs-atQ' 


Joins  SJiaflatZO'tf- 


**•  ExtrertW 


THE    LEG. 

The  Leg  consists  of  three  bones :  the  Patella,  a  larg* 
front  of  the  knee ;  the  Tibia,  and  Fibula. 


sesamoid  bone,  placed  in 


1G4 


OSTEOLOGY. 


Fig.  107.— Right  Patella. 
Anterior  Surface. 


The  Patella.    (Figs.  107  and  108.) 

The  Patella  is  a  small,  flat,  triangular  bone,  situated  at  the  anterior  part  of  the 
knee-joint.  It  resembles  the  sesamoid  bones,  from  being  developed  in  the  tendon 
of  the  Quadriceps  extensor,  and  in  its  structure,  being  composed  throughout  of 
dense  cancellous  tissue;  but  it  is  generally  regarded  as  analogous  to  the  olecranon 
process  of  the  ulna,  which  occasionally  exists  as  a  separate  piece,  connected  to  the 
shaft  of  the  bone  by  a  continuation  of  the  tendon  of  the  Triceps  muscle.1  It 
serves  to  protect  the  front  of  the  joint,  and  increases  the  leverage  of  the  Common 
extensor  by  making  it  act  at  a  greater  angle.  It  presents  an  anterior  and  posterior 
surface,  three  borders,  a  base,  and  an  apex. 

The  anterior  surface  is  convex,  perforated  by  small  apertures,  for  the  passage 
of  nutrient  vessels,  and  marked  by  numerous  rough 
longitudinal  striae.  This  surface  is  covered,  in  the 
recent  state,  by  an  expansion  from  the  tendon  of  the 
Quadriceps  extensor,  separated  from  the  integument 
by  a  bursa,  and  gives  attachment  below  to  the  liga- 
mentum  patellae.  The  posterior  surface  presents  a 
smooth,  oval-shaped,  articular  surface,  covered  with 
cartilage  in  the  recent  state,  and  divided  into  two  facets 
by  a  vertical  ridge,  which  descends  from  the  superior 
towards  the  inferior  angle  of  the  bone.  The  ridge 
corresponds  to  the  groove  on  the  trochlear  surface  of 
the  femur,  and  the  two  facets  to  the  articular  surfaces  of 
the  two  condyles ;  the  outer  facet,  for  articulation  with 
the  outer  condyle,  being  the  broader  and  deeper,  serves 
to  indicate  the  leg  to  which  the  bone  belongs.  Below 
the  articular  surface  is  a  rough,  convex,  non-articular 
depression,  the  lower  half  of  which  gives  attachment  to 
the  ligamentum  patellar ;  the  upper  half  being  separated 
from  the  head  of  the  tibia  by  adipose  tissue. 

Its  superior  and  lateral  borders  give  attachment  to 

the  tendon  of  the  Quadriceps  extensor;  the  superior 

border,  to  that  portion  of  the  tendon  which  is  derived 

from  the  Eectus  and  Crureus  muscles;  and  the  lateral 

borders,  to  the  portion  derived  from  the  external  and 

internal  Vasti  muscles. 

The  base  or  superior  border  is  thick,  directed  upwards,  and  cut  obliquely  at 

the  expense  of  its  outer  surface;  it  receives  the  attachment,  as  already  mentioned, 

of  part  of  the  Quadriceps  extensor  tendon. 

The  apex  is  pointed,  and  gives  attachment  to  the  ligamentum  patellae. 
Structure.     It  consists  of  dense  cancellous  tissue,  covered  by  a  thin  compact 
lamina. 

Development.  By  a  single  centre,  which  makes  its  appearance,  according  to 
Beclard,  about  the  third  year.  In  two  instances,  I  have  seen  this  bone  cartilaginous 
throughout,  at  a  much  later  period  (six  years).  More  rarely,  the  bone  is  developed 
by  two  centres,  placed  side  by  side. 

Articulations.     With  the  two  condyles  of  the  femur. 

Attachment  of  Muscles.  The  Eectus,  Crureus,  Vastus  internus,  and  Vastus 
externus.  These  muscles,  joined  at  their  insertion,  constitute  the  Quadriceps  ex- 
tensor cruris. 


Fig.  108.— Right  Patella. 
Posterior  Surface. 


1  Professor  Owen  states,  that,  "in  certain  bats,  there  is  a  development  of  a  sesamoid 
bone  in  the  biceps  brachii,  which  is  the  true  homotype  of  the  patella  in  the  leg,"  regarding  the 
olecranon  to  be  homologous,  not  with  the  patella,  but  with  an  extension  of  the  upper  end  of 
the  fibula  above  the  knee-joint,  which  is  met  with  in  some  animals.  ('■  On  the  Nature  of  Limbs," 
pp.  19,  24.) 


TIBIA. 


1C5 


The  Tibia. 

The  Tibia  (so  named  from  its 
resemblance  to  a  flute  or  pipe)  is 
situated  at  the  front  and  inner 
side  of  the  leg,  and,  excepting  the 
femur,  is  the  longest  and  largest 
bone  in  the  skeleton.  It  is  pris- 
moid  in  form,  expanded  above, 
where  it  enters  into  formation 
with  the  knee-joint,  more  slightly 
enlarged  below.  In  the  male,  its 
direction  is  vertical,  and  parallel 
with  the  bone  of  the  opposite  side ; 
but  in  the  female  it  has  a  slight 
oblique  direction  downwards  and 
outwards,  to  compensate  for  the 
oblique  direction  of  the  femur 
itiwards.  It  presents  for  exami- 
nation a  shaft  and  two  extremi- 
ties. 

The  Upper  Extremity  or  head 
is  large  and  expanded  on  each 
side  into  two  lateral  eminences, 
the  tuberosities.  Superiorly, 
the  tuberosities  present  two 
smooth  concave  surfaces,  which 
articulate  with  the  condyles  of 
the  femur;  the  internal  articular 
surface  is  longer  than  the  ex- 
ternal, oval  from  before  back- 
wards, to  articulate  with  the 
internal  condyle;  the  external 
one  being  broader,  flatter,  and 
more  circular,  to  articulate  with 
the  external  condyle.  Between 
the  two  articular  surfaces,  and 
nearer  the  posterior  than  the 
anterior  aspect  of  the  bone,  is  an 
eminence,  the  spinous  process  of 
the  tibia,  surmounted  by  a  pro* 
minent  tubercle  on  each  side, 
which  give  attachment  to  the 
extremities  of  the  semilunar 
fibro-cartilages ;  and  in  front  and 
behind  the  spinous  process,  a 
rough  depression  for  the  attach- 
ment of  the  anterior  and  poste- 
rior crucial  ligaments  and  the 
semilunar  cartilages.  Anteriorly 
the  tuberosities  are  continuous 
with  one  another,  presenting  a 
large  and  somewhat  flattened 
triangular  surface,  broad  above, 
and  perforated  by  large  vascular 
foramina;  narrow  below,  where 
it   terminates    in    a  prominent 


Fig.  109. — Bones  of  the  Right  Leg.     Anterior  Surface. 

H  «  a.  tg 


StyTeiif  merer* 


fIBUU 


Jnttrn^l  Mali4clul 


Internal  NnUtatut 


1G6  OSTEOLOGY. 

oblong  elevation  of  large  size,  the  tubercle  of  the  tibia ;  the  lower  half  of  this 
tubercle  is  rough,  for  the  attachment  of  the  ligamentum  patellae  ;  the  upper  half 
is  a  smooth  facet  corresponding,  in  the  recent  state,  with  a  bursa  which  separates 
the  ligament  from  the  bone.  Posteriorly,  the  tuberosities  are  separated  from 
each  other  by  a  shallow  depression,  the  popliteal  notch,  which  gives  attach- 
ment to  the  posterior  crucial  ligament.  The  posterior  surface  of  the  inner 
tuberosity  presents  a  deep  transverse  groove,  for  the  insertion  of  the  tendon  of 
the  Semi-membranosus ;  and  the  posterior  surface  of  the  outer  one,  a  flat  articular 
facet,  nearly  circular  in  form,  directed  downwards,  backwards,  and  outwards,  for 
articulation  with  the  fibula.  The  lateral  surfaces  are  convex  and  rough;  the 
internal  one,  the  most  prominent,  gives  attachment  to  the  internal  lateral 
ligament. 

The  Shaft  of  the  tibia  is  of  a  triangular  prismoid  form,  broad  above,  gradually 
decreasing  in  size  to  the  commencement  of  its  lower  fourth,  its  most  slender  part, 
where  fracture  most  frequently  occurs,  and  then  enlarging  again  towards  its  lower 
extremity.     It  -presents  for  examination  three  surfaces  and  three  borders. 

The  anterior  border,  the  most  prominent  of  the  three,  is  called  the  crest  of  the 
tibia,  or,  in  popular  language,  the  shin ;  it  commences  above  at  the  tubercle,  and 
terminates  below  at  the  anterior  margin  of  the  inner  malleolus.  This  border  is 
very  prominent  in  the  upper  two-thirds  of  its  extent,  smooth  and  rounded  below. 
It  presents  a  very  flexuous  course,  being  curved  outwards  above,  and  inwards 
below ;  it  gives  attachment  to  the  deep  fascia  of  the  leg. 

The  internal  border  is  smooth  and  rounded  above  and  below,  but  more  promi- 
nent in  the  centre ;  it  commences  at  the  back  part  of  the  inner  tuberosity,  and 
terminates  at  the  posterior  border  of  the  internal  malleolus ;  its  upper  third  gives 
attachment  to  the  internal  lateral  ligament  of  the  knee,  and  to  some  fibres  of  the 
Popliteus  muscle ;  its  middle  third,  to  some  fibres  of  the  Soleus  and  Flexor  longus 
digitorum  muscles. 

The  external  border  is  thin  and  prominent,  especially  its  central  part,  and  gives 
attachment  to  the  interosseous  membrane ;  it  commences  above  in  front  of  the 
fibular  articular  facet,  and  bifurcates  below,  to  form  the  boundaries  of  a  triangular 
rough  surface,  for  the  attachment  of  the  interosseous  ligament,  connecting  the 
tibia  and  fibula. 

The  internal  surface  'is  smooth,  convex,  and  broader  above  than  below;  its 
upper  third,  directed  forwards  and  inwards,  is  covered  by  the  aponeurosis  derived 
from  the  tendon  of  the  Sartorius,  and  by  the  tendons  of  the  Gracilis  and  Semi- 
tendinosus,  all  of  which  are  inserted  nearly  as  far  forwards  as  the  anterior 
border ;  in  the  rest  of  its  extent  it  is  subcutaneous. 

The  external  surface  is  narrower  than  the  internal;  its  upper  two-thirds  present 
a  shallow  groove  for  the  attachment  of  the  Tibialis  anticus  muscle ;  its  lower  third 
is  smooth,  convex,  curves  gradually  forwards  to  the  anterior  part  of  the  bone, 
and  is  covered  from  within  outwards  by  the  tendons  of  the  following  muscles : 
Tibialis  anticus,  Extensor  proprius  pollicis,  Extensor  longus  digitorum,  Peroneus 
tertius. 

The  'posterior  surface  (fig.  110)  presents  at  its  upper  part  a  prominent  ridge, 
the  oblique  line  of  the  tibia,  which  extends  from  the  back  part  of  the  articular  facet 
for  the  fibula,  obliquely  downwards,  to  the  internal  border,  at  the  junction  of  its 
upper  and  middle  thirds.  It  marks  the  limit  for  the  insertion  of  the  Popliteus 
muscle,  and  serves  for  the  attachment  of  the  popliteal  fascia,  and  part  of  the 
Soleus,  Flexor  longus  digitorum,  and  Tibialis  posticus  muscles ;  the  triangular 
concave  surface,  above,  and  to  the  inner  side  of,  this  line,  gives  attachment  to 
the  Popliteus  muscle.  The  middle  third  of  the  posterior  surface  is  divided  by  a 
vertical  ridge  into  two  lateral  halves ;  the  ridge  is  well  marked  at  its  commence- 
ment at  the  oblique  line,  but  becomes  gradually  indistinct  below ;  the  inner  and 
broadest  half  gives  attachment  to  the  Flexor  longus  digitorum,  the  outer  and 
narrowest,  to  part  of  the  Tibialis  posticus.  The  remaining  part  of  the  bone  is 
covered  by  the  Tibialis  posticus,  Flexor  longus  digitorum  and  Flexor  longus 


TIBIA. 


167 


pollicis  muscles.  Immediately 
below  the  oblique  line  is  the 
medullary  foramen,  which  is  di- 
rected obliquely  downwards. 

The  Lower  Extremity,  much 
smaller  than  the  upper,  is  some- 
what quadrilateral  in  form,  and 
prolonged  downwards  on  its  in- 
ner side,  into  a  strong  process, 
the  internal  malleolus.  The 
inferior  surface  of  the  bone 
presents  a  quadrilateral  smooth 
surface,  for  articulation  with  the 
astragalus ;  narrow  internally, 
where  it  becomes  continuous  with 
the  articular  surface  of  the  inner 
malleolus,  broader  externally, 
and  traversed  from  before  back- 
wards by  a  slight  elevation,  se- 
parating two  lateral  depressions. 
The  anterior  surface  is  smooth 
and  rounded  above,  and  covered 
by  the  tendons  of  the  Extensor 
muscles  of  the  toes;  its  lower 
margin  presents  a  rough  trans- 
verse depression,  for  the  attach- 
ment of  the  anterior  ligament  of 
the  ankle-joint.  The  posterior 
surface  presents  a  superficial 
groove  directed  obliquely  down- 
wards and  inwards,  continuous 
with  a  similar  groove  on  the  pos- 
terior extremity  of  the  astragalus ; 
it  serves  for  the  passage  of  the 
tendon  of  the  Flexor  longus  polli- 
cis. The  external  surface  presents 
a  triangular  rough  depression, 
the  lower  part  of  which,  in  some 
bones,  is  smooth,  and  covered 
with  cartilage  in  the  recent  state, 
and  articulates  with  the  fibula; 
the  remaining  part  is  rough  for 
the  attachment  of  the  inferior 
interosseous  ligament,  which 
connects  it  with  the  fibula. 
This  surface  is  bounded  by  two 
prominent  ridges,  continuous 
above  with  the  interosseous 
ridge ;  they  afford  attachment 
to  the  anterior  and  posterior 
tibio-fibular  ligaments.  The 
internal  surface  is  prolonged 
downwards  to  form  a  strong  py- 
ramidal-shaped process,  flattened 
from  without  inwards,  the  inner 
malleolus;  its  inner  surface  is 
convex   and   subcutaneous.     Its 


Fig.  110. — Bones  of  the  Eight  Leg.     Posterior  Surface. 


■tfloidji  rticesa 


168 


OSTEOLOGY. 


Fig.  111.— Plau  of  the  Development  of  the  Tibia. 
By  3  Centres. 


Upper  extremity 


Apj>»t{  rx  <il  birth 


Tovns  Shaft  about 
2S  0  yr 


outer  surface,  smooth  and  slightly  concave,  deepens  the  articular  surface  for  the 
astragalus.  Its  anterior  border  is  rough,  for  the  attachment  of  ligamentous  fibres. 
Its  posterior  border  presents  a  broad  and  deep  groove,  directed  obliquely  down- 
wards and  inwards ;  it  is  occasionally  double,  and  transmits  the  tendons  of  the 
Tibialis  posticus  and  Flexor  longus  digitorum  muscles.  Its  summit  is  marked  by 
a  rough  depression  behind,  for  the  attachment  of  the  internal  lateral  ligament  of 
the  ankle-joint. 

Structure.     Like  that  of  the  other  long  bones. 

Development.  By  three  centres  (fig.  Ill):  one  for  the  shaft,  and  one  for  each 
extremity.   Ossification  commences  in  the  centre  of  the  shaft  about  the  same  time 

as  in  the  femur,  the  fifth  week,  and 
gradually  extends  towards  either  ex- 
tremity. The  centre  for  the  upper 
epiphysis  appears  at  birth ;  it  is  flat- 
tened in  form,  and  has  a  thin  tongue- 
shaped  process  in  front,  which  forms 
the  tubercle.  That  for  the  lower 
epiphysis  appears  in  the  second  year. 
The  lower  epiphysis  joins  the  shaft 
at  about  the  twentieth  year,  and  the 
upper  one  about  the  twenty-fifth 
year.  Two  additional  centres  occa- 
sionally exist,  one  for  the  tongue- 
shaped  process  of  the  upper  epiphysis, 
the  tubercle,  and  one  for  the  inner 
malleolus. 

Articulations.     With    three    bones: 
the  femur,  fibula,  and  astragalus. 

Attachment  of  Muscles.  To  the 
inner  tuberosity,  the  Semi-membra- 
nosus.  To  the  outer  tuberosity,  the 
Tibialis  anticus  and  Extensor  longus 
digitorum.  To  the  shaft ;  its  internal 
surface,  the  Sartorius,  Gracilis,  and 
Semi-tendinosus :  to  its  external  sur- 
face, the  Tibialis  anticus :  to  its  pos- 
terior surface,  the  Popliteus,  Soleus, 
Flexor  longus  digitorum,  and  Tibialis  posticus :  to  the  tubercle,  the  ligamentum 
patellae. 

The  Fibula. 

The  Fibula  is  situated  at  the  outer  side  of  the  leg.  It  is  the  smaller  of  the 
two  bones,  and,  in  proportion  to  its  length,  the  most  slender  of  all  the  long  bones ; 
it  is  placed  nearly  parallel  with  the  tibia,  its  upper  extremity  is  small,  placed 
below  the  level  of  the  knee-joint,  and  excluded  from  its  formation ;  but  the 
lower  extremity  inclines  a  little  forwards,  so  as  to  be  on  a  plane  anterior  to  that 
of  the  upper  end,  projects  below  the  tibia,  and  forms  the  outer  ankle.  It  presents 
for  examination  a  shaft  and  two  extremities. 

The  Upper  Extremity  or  Head  is  of  an  irregular  rounded  form,  presenting, 
above,  a  flattened  articular  facet,  directed  upwards  and  inwards,  for  articulation 
with  a  corresponding  facet  on  the  external  tuberosity  of  the  tibia.  On  the  outer 
side  is  a  thick  and  rough  prominence,  continued  behind  into  a  pointed  eminence, 
the  styloid  process,  which  projects  upwards  from  the  posterior  part  of  the  head. 
The  prominence  above  mentioned  gives  attachment  to  the  tendon  of  the  Biceps 
muscle,  and  to  the  long  external  lateral  ligament  of  the  knee,  the  ligament  dividing 
this  tendon  into  two  parts.  The  summit  of  the  styloid  process  gives  attachment 
to  the  short  external  lateral  ligament.     The  remaining  part  of  the  circumference 


Appears  at  2!^«i 

h-uwr  extrewiuJ 


thea* 


FIBULA.  160 

of  the  head  is  rough,  for  the  attachment,  in  front,  of  the  anterior  superior  tibio- 
fibular ligament,  and  the  upper  and  anterior  part  of  the  Peroneus  longus ;  and 
behind,  to  the  posterior  superior  tibio-fibular  ligament,  and  the  upper  fibres  of  the 
outer  head  of  the  Soleus  muscle. 

The  Lower  Extremity  or  external  malleolus  is  of  a  pyramidal  form,  some- 
what flattened  from  without  inwards,  and  is  longer,  and  descends  lower,  than 
the  internal  malleolus.  Its  external  surface  is  convex,  subcutaneous,  and  con- 
tinuous with  a  triangular  surface,  also  subcutaneous,  on  the  outer  side  of  the  shaft. 
The  internal  surface  presents  in  front  a  smooth  triangular  facet,  broader  above 
than  below,  convex  from  above  downwards,  which  articulates  with  a  correspond- 
ing surface  on  the  outer  side  of  the  astragalus.  Behind  and  beneath  the  articular 
surface  is  a  rough  depression,  which  gives  attachment  to  the  posterior  fasciculus  of 
the  external  lateral  ligament  of  the  ankle.  The  anterior  border  is  thick  and  rough, 
and  marked  below  by  a  depression  for  the  attachment  of  the  anterior  fasciculus  of 
the  external  lateral  ligament.  The  posterior  border  is  broad  and  marked  by  a 
shallow  groove,  for  the  passage  of  the  tendons  of  the  Peroneus  longus  and  Peroneus 
brevis  muscles.  Its  summit  is  rounded,  and  gives  attachment  to  the  middle  fasci- 
culus of  the  external  lateral  ligament. 

The  Shaft  presents  three  surfaces,  and  three  borders.  The  anterior  border  com- 
mences above  in  front  of  the  head,  runs  vertically  downwards  to  a  little  below  the 
middle  of  the  bone,  and  then,  curving  a  little  outwards,  bifurcates  below  into  two 
lines,  which  bound  the  triangular  subcutaneous  surface  immediately  above  the 
outer  side  of  the  external  malleolus.  It  gives  attachment  to  an  intermuscular 
septum,  which  separates  the  muscles  on  the  anterior  surface  from  those  on  the 
external. 

The  internal  border  or  interosseous  ridge  is  situated  close  to  the  inner  side  of 
the  preceding ;  it  runs  nearly  parallel  with  it  in  the  upper  third  of  its  extent,  but 
diverges  from  it  so  as  to  include  a  broader  space  in  the  lower  two-thirds.  It 
commences  above  just  beneath  the  head  of  the  bone — sometimes  it  is  quite  indistinct 
for  about  an  inch  below  the  head — and  terminates  below  at  the  apex  of  a  rough 
triangular  surface  immediately  above  the  articular  facet  of  the  external  malleolus. 
It  serves  for  the  attachment  of  the  interosseous  membrane,  and  separates  the 
extensor  muscles  in  front,  from  the  flexor  muscles  behind.  The  portion  of  bone 
included  between  the  anterior  and  interosseous  lines  forms  the  anterior  surface. 

The  posterior  border  is  sharp  and  prominent ;  it  commences  above  at  the  bass 
of  the  styloid  process,  and  terminates  below  in  the  posterior  border  of  the  outer 
malleolus.  It  is  directed  outwards  above,  backwards  in  the  middle  of  its  course, 
backwards  and  a  little  inwards  below,  and  gives  attachment  to  an  aponeurosis 
which  separates  the  muscles  on  the  outer  from  those  on  the  inner  surface  of  the 
shaft.  The  portion  of  bone  included  between  this  line  and  the  interosseous  ridge 
forms  the  internal  surface.  Its  upper  three-fourths  are  subdivided  into  two  parts, 
an  anterior  and  a  posterior,  by  a  very  prominent  ridge,  the  oblique  line  of  the  fibula, 
which  commences  above  at  the  inner  side  of  the  head,  and  terminates  by  being 
continuous  with  the  interosseous  ridge  at  the  lower  fourth  of  the  bone.  It  attaches 
an  aponeurosis  which  separates  the  Tibialis  posticus  from  the  Soleus  above,  and 
the  Flexor  longus  pollicis  below.  This  ridge  sometimes  ceases  just  before  ap- 
proaching the  interosseous  ridge. 

The  anterior  surface  is  the  interval  between  the  anterior  and  interosseous  lines. 
It  is  extremely  narrow  and  fiat  in  the  upper  third  of  its  extent,  broader  and  grooved 
longitudinally  in  its  lower  third ;  it  serves  for  the  attachment  of  three  muscles,  the 
Extensor  longus  digitorum,  Peroneus  tertius,  and  Extensor  longus  pollicis. 

The  external  surface,  much  broader  than  the  preceding,  is  directed  outwards  in 
the  upper  two-thirds  of  its  course,  backwards  in  the  lower  third,  where  it  is  con  • 
tinuous  with  the  posterior  border  of  the  external  malleolus.  This  surface  is  com- 
pletely occupied  by  the  Peroneus  longus  and  Peroneus  brevis  muscles. 

The  internal  surface  is  the  interval  between  the  interosseous  ridge  and  the 
posterior  border,  and  occupies  nearly  two-thirds  of  the  circumference  of  the  bone. 


no 


OSTEOLOGY. 


Fig.  112. — Plan  of  the  Development  of 
the  Fibnla.     By  3  Centres. 


IXtfr 


Vrwtvt  aiou  t25(tijZ 


Its  upper  three-fourths  are  divided  into  an  anterior  and  a  posterior  portion  by  a 
very  prominent  ridge  already  mentioned,  the  oblique  line  of  the  fibula.  The 
anterior  portion  is  directed  inwards,  and  is  grooved  for  the  attachment  of  the 
Tibialis  posticus  muscle.  The  posterior  portion  is  continuous  below  with  the 
rough  triangular  surface  above  the  articular  facet  of  the  outer  malleolus ;  it  is 
directed  backwards  above,  backwards  and  inwards  at  its  middle,  directly  inwards 
below.  Its  upper  fourth  is  rough,  for  the  attachment  of  the  Soleus  muscle :  its 
lower  part  presents  a  triangular  rough  surface,  connected  to  the  tibia  by  a  strong 
interosseous  ligament,  and  between  these  two  points  the  entire  surface  is  covered 
by  the  fibres  of  origin  of  the  Flexor  longus  pollicis  muscle.  At  about  the  middle 
of  this  surface  is  the  nutritious  foramen,  which  is  directed  downwards. 

In  order  to  distinguish  the  side  to  which  the  bone  belongs,  hold  it  with  the 

lower  extremity  downwards,  and  the  broad 
groove  for  the  Peronei  tendons  backwards,  to- 
wards the  holder,  the  triangular  subcutaneous 
surface  will  then  be  directed  to  the  side  to  which 
the  bone  belongs. 

Articulations.  With  two  bones:  the  tibia  and 
astragalus. 

Development.  By  three  centres  (fig.  112): 
one  for  the  shaft,  and  one  for  each  extremity. 
Ossification  commences  in  the  shaft  about  the 
sixth  week  of  foetal  life,  a  little  later  than  in 
the  tibia,  and  extends  gradually  towards  the 
extremities.  At  birth  both  ends  are  cartilaginous. 
Ossification  commences  in  the  lower  end  in  the 
second  year,  and  in  the  upper  one  about  the 
fourth  year.  The  lower  epiphysis,  the  first  in 
which  ossification  commences,  becomes  united 
to  the  shaft  about  the  twentieth  year,  con- 
trary to  the  law  which  appears  to  prevail  with 
regard  to  the  junction  of  the  epiphysis  with  the 
shaft ;  the  upper  one  is  joined  about  the  twenty- 
fifth  year. 

Attachment  of  Muscles.  To  the  head;  the 
Biceps,  Soleus,  and  Peroneus  longus.  To  the 
shaft,  its  anterior  surface ;  the  Extensor  longus 
digitorum,  Peroneus  tertius,  and  Extensor  lon- 
gus pollicis :  to  the  internal  surface ;  the  Soleus, 
Tibialis  posticus,  and  Flexor  longus  pollicis :  to 
the  external  surface ;  the  Peroneus  longus  and  brevis. 


Al'fW  ixat2™<y^L 


-Unit.**  alout2C?!y? 

exit* 


THE    FOOT. 

The  Foot  (figs.  113  and  114)  is  the  terminal  part  of  the  inferior  extremity;  it 
serves  to  support  the  body  in  the  erect  posture,  and  is  an  important  instrument  of 
locomotion.     It  consists  of  three  divisions :  the  Tarsus,  Metatarsus,  and  Phalanges. 

The  Taksus. 

The  bones  of  the  Tarsus  are  seven  in  number ;  viz.,  the  calcaneum  or  os  calcis, 
astragalus,  cuboid,  scaphoid,  internal,  middle,  and  external  cuneiform  bones. 


The  Calcaneum. 

The  Calcaneum  or  Os  Calcis  is  the  largest  and  strongest  of  the  tarsal  bones. 
It  is  irregularly  cuboidal  in  form,  and  situated  at  the  lower  and  back  part  of  the 


TARSUS. 

Fig.  313.— Bones  of  the  Right  Foot.     Dorsal  Surface. 


171 


Groove  for    PFRONEUS    LONCUS 
Groove  far    peroneus    ERE  vis 


PCRONCUS    TtFTiu 
FERONEUS    BRCVIS 


Cnxme  for  ten  Jim  of 

FLEXOR    LONCUS     POLL, CIS 


jTo-TgU* 


Metatarsus 


TnittVTtiett  Utuiifn  <if 

EXT. BREVIS  OICITORUM 


Thalanqes 


EXT.  LONCUS   PBLLICIS 


172  OSTEOLOGY. 

foot,  serving  to  transmit  the  weight  of  the  body  to  the  ground,  and  forming  a 
strong  lever  for  the  muscles  of  the  calf.  It  presents  for  examination  six  surfaces ; 
superior,  inferior,  external,  internal,  anterior,  and  posterior. 

The  superior  surface  is  formed  behind,  of  the  upper  aspect  of  that  part  of  the 
os  calcis  which  projects  backwards  to  form  the  heel.  It  varies  in  length  in 
different  individuals ;  is  convex  from  side  to  side,  concave  from  before  backwards, 
and  corresponds  above  to  a  mass  of  adipose  substance  placed  in  front  of  the  tendo 
Achillis.  In  the  middle  of  this  surface  are  two,  sometimes  three,  articular 
facets,  separated  by  a  broad  shallow  groove,  directed  obliquely  forwards  and 
outwards,  and  rough  for  the  attachment  of  the  interosseous  ligament  connecting 
the  astragalus  and  os  calcis.  Of  these  two  articular  surfaces,  the  external  is  the 
larger,  and  situated  on  the  body  of  the  bone;  it  is  of  an  oblong  form,  wider 
behind  than  in  front,  and  convex  from  before  backwards.  The  interval  articular 
surface  is  supported  on  a  projecting  process  of  bone,  called  the  lesser  process  of  the 
calcaneum  (sustentaculum  tali);  it  is  of  an  oblong  form,  concave  longitudinally, 
and  sometimes  subdivided  into  two,  which  differ  in  size  and  shape.  More  ante- 
riorly is  seen  the  upper  surface  of  the  greater  process,  marked  by  a  rough 
depression  for  the  attachment  of  numerous  ligaments,  and  the  Extensor  brevis 
digitorum  muscle. 

The  inferior  surface  is  narrow,  rough,  uneven,  wider  behind  than  in  front,  and 
convex  from  side  to  side  ;•  it  is  bounded  posteriorly  by  two  tubercles,  separated 
by  a  rough  depression:  the  external,  small,  prominent,  and  rounded,  gives  attach- 
ment to  a  part  of  the  Abductor  minimi  digiti ;  the  internal,  broader  and  larger, 
for  the  support  of  the  heel,  gives  attachment,  by  its  prominent  inner  margin,  to 
the  Abductor  pollicis,  and  in  front  to  the  Flexor  brevis  digitorum  muscles;  the 
depression  between  the  tubercles  attaches  the  Abductor  minimi  digiti,  and  plantar 
fascia.  The  rough  surface  in  front  of  the  tubercles  gives  attachment  to  the  long 
plantar  ligament ;  and  to  a  prominent  tubercle  nearer  the  anterior  part  of  the  bone, 
as  well  as  to  a  transverse  groove  in  front  of  it",  is  attached  the  short  plantar  ligament. 

The  external  surface  is  broad,  flat,  and  almost  subcutaneous;  it  presents  near 
its  centre  a  tubercle,  for  the  attachment  of  the  middle  fasciculus  of  the  external 
lateral  ligament.  Behind  the  tubercle  is  a  broad  smooth  surface,  giving  attach- 
ment, at  its  upper  and  anterior  part,  to  the  external  astragalo-  calcanean  ligament ; 
and  in  front  of  the  tubercle  a  narrow  surface  marked  by  two  oblique  grooves, 
separated  by  an  elevated  ridge:  the  superior  groove  transmits  the  tendon  of  the 
Peroneus  brevis;  the  inferior,  the  tendon  of  the  Peroneus  longus;  the  intervening 
ridge  gives  attachment  to  a  prolongation  from  the  external  annular  ligament. 

The  internal  surface  presents  a  deep  concavity,  directed  obliquely  downwards 
and  forwards,  for  the  transmission  of  the  plantar  vessels  and  nerves  and  Flexor 
tendons  into  the  sole  of  -the  foot;  it  affords  attachment  t->  part  of  the  Flexor 
accessorius  muscle.  This  surface  presents  an  eminence  of  'urne,  the  lesser  process, 
which  projects  horizontally  inwards  from  its  upper  and  1  re  part.  This  process 
is  concave  above,  and  supports  the  anterior  articular  surface  of  the  astragalus ; 
below,  it  is  convex,  and  grooved  for  the  tendon  of  the  Flexor  longus  pollicis. 
Its  free  margin  is  rough,  for  the  attachment  of  ligaments. 

The  anterior  surface,  of  a  somewhat  triangular  form,  is  smooth,  concavo-convex, 
and  articulates  with  the  cuboid.  It  is  surmounted,  on  its  outer  side,  by  a  rough 
prominence,  which  forms  an  important  guide  to  the  surgeon  in  the  performance 
of  Chopart's  operation. 

The  posterior  surface  is  rough,  prominent,  convex,  and  wider  below  than  above. 
Its  lower  part  is  rough,  for  the  attachment  of  the  tendo  Achillis ;  its  upper  part 
smooth,  coated  with  cartilage,  and  corresponds  to  a  bursa  which  separates  this 
tendon  from  the  bone. 

Articulations.    With  two  bones :  the  astragalus  and  cuboid. 

Attachment  of  Muscles.  Part  of  the  Tibialis  posticus,  the  tendo  Achillis,  Plan- 
taris,  Abductor  pollicis,  Abductor  minimi  digiti,  Flexor  brevis  digitorum,  Flexor 
accessorius,  and  Extensor  brevis  digitorum. 


tarsus.  m 


The  Cuboid. 


The  Cuboid  bone  is  placed  on  the  outer  side  of  the  foot,  in  front  of  the  os  calcis, 
and  behind  the  fourth  and  fifth  metatarsal  bones.  It  is  of  a  pyramidal  shape,  its 
base  being  directed  upwards  and  inwards,  its  apex  downwards  and  outwards. 
It  may  be  distinguished  from  the  other  tarsal  bones,  by  the  existence  of  a  deep 
groove  on  its  under  surface,  for  the  tendon  of  the  Peroneus  longus  muscle.  It 
presents  for  examination  six  surfaces ;  three  articular,  and  three  non-articular : 
the  non-articular  surfaces  are  the  superior,  inferior,  and  external. 

The  superior  or  dorsal  surface,  directed  upwards  and  outwards,  is  rough,  for  the 
attachment  of  numerous  ligaments.  The  inferior  or  plantar  surface  presents  in 
front  a  deep  groove,  wrhich  runs  obliquely  from  without,  forwards  and  inwards ; 
it  lodges  the  tendon  of  the  Peroneus  longus,  and  is  bounded  behind  by  a  promi- 
nent ridge,  terminating  externally  in  an  eminence,  the  tuberosity  of  the  cuboid, 
the  surface  of  which  presents  a  convex  facet,  for  articulation  with  the  sesamoid 
bone  of  the  tendon  contained  in  the  groove.  The  ridge  and  surface  of  bone 
behind  it  are  rough,  for  the  attachment  of  the  long  and  short  plantar  ligaments. 
The  external  surface,  the  smallest  and  narrowest  of  the  three,  presents  a  deep 
notch,  formed  by  the  commencement  of  the  peroneal  groove. 

The  articular  surfaces  are  the  posterior,  anterior,  and  internal.  The  posterior 
surface  is  smooth,  triangular,  concavo-convex,  for  articulation  with  the  anterior 
surface  of  the  os  calcis.  The  anterior,  of  smaller  size,  but  also  irregularly  trian- 
gular, is  divided  by  a  vertical  ridge  into  two  facets ;  the  inner  facet,  quadrilateral 
in  form,  articulates  with  the  fourth  metatarsal  bone;  the  outer  one,  larger  and 
more  triangular,  articulates  with  the  fifth  metatarsal.  The  internal  surface  is 
broad,  rough,  irregularly  quadrilateral,  presenting  at  its  middle  and  upper  part  a 
small  oval  facet,  for  articulation  with  the  external  cuneiform  bone ;  and  behind 
tliis.  occasionally,  a  smaller  facet,  for  articulation  with  the  scaphoid ;  it  is  rough 
in  the  rest  of  its  extent,  for  the  attachment  of  strong  interosseous  ligaments. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  so  that  its  under  surface, 
marked  by  the  peroneal  groove,  looks  downwards,  and  the  large  concavo-convex 
articular  surface  backwards,  towards  the  holder ;  the  narrow  non-articular  surface, 
marked  by  the  commencement  of  the  peroneal  groove,  will  point  to  the  side  to 
wiiich  the  bone  belongs. 

Articulations.  With  four  bones :  the  os  calcis,  external  cuneiform,  and  the 
fourth  and  fifth  metatarsal  bones;  occasionally  with  the  scaphoid. 

Attachment  of  Muscles.     Part  of  the  Flexor  brevis  pollicis. 

The  Asteagalus. 

The  Astragalus  (fig.  113),  next  to  the  os  calcis,  is  the  largest  of  the  tarsal  bones. 
It  occupies  the  middle  and  upper  part  of  the  tarsus,  supporting  the  tibia  above, 
articulating  with  the  malleoli  on  either  side,  resting  below  upon  the  os  calcis,  and 
joined  in  front  to  the  scaphoid.  This  bone  may  easily  be  recognized  by  its  large 
rounded  head,  the  broad  articular  facet  on  its  upper  convex  surface,  and  by  the 
two  articular  facets  separated  by  a  deep  groove  on  its  under  concave  surface.  It 
presents  six  surfaces  for  examination. 

The  superior  surface  presents,  behind,  a  broad  smooth  trochlear  surface,  for 
articulation  with  the  tibia ;  it  is  broader  in  front  than  behind,  convex  from  before 
backwards,  slightly  concave  from  side  to  side.  In  front  of  the  trochlea  is  the 
upper  surface  of  the  neck  of  the  astragalus,  rough  for  the  attachment  of  liga- 
ments. The  inferior  surface  presents  two  articular  facets  separated  by  a  deep 
groove.  The  groove  runs  obliquely  forwards  and  outwards,  becoming  gradually 
broader  and  deeper  in  front :  it  corresponds  with  a  similar  groove  upon  the  upper 
surface  of  the  os  calcis,  and  forms,  when  articulated  with  that  bone,  a  canal,  filled 
up  in  the  recent  state  by  the  calcaneo-astragaloid  interosseous  ligament.  Of  the 
two  articular  facets,  the  posterior  is  the  larger,  of  an  oblong  form,  and  deeply 
concave  from  side  to  side :  the  anterior,  although  nearly  of  equal  length,,  is.  nar- 


OSTEOLOGY. 


Fig.  114.— Bones  of  the  Right  Foot.     Plantar  Surface. 


LEXOR  BREVI*  POUICIC 


Taltrcle   of 
ScajJuid 


TIBIALIS  AMICUS 


FLEXOR    L0NCU8 
DIClTORUM 


TARSUS.  175 

rower,  of  an  elongated  oval  form,  convex  longitudinally,  and  often  subdivided 
into  two  by  an  elevated  ridge :  of  these  the  posterior  one  articulates  with  the  lesser 
process  of  the  os  calcis ;  the  anterior  one,  with  the  upper  surface  of  the  calcaneo- 
scaphoid  ligament.  The  internal  surface  presents  at  its  upper  part  a  pear-shaped 
articular  facet  for  the  inner  malleolus,  continuous  above  with  the  trochlear  surface ; 
below  the  articular  surface  is  a  rough  depression,  for  the  attachment  of  the  deep 
portion  of  the  internal  lateral  ligament.  The  external  surface  presents  a  large 
triangular  facet,  concave  from  above  downwards,  for  articulation  with  the  external 
malleolus ;  it  is  continuous  above  with  the  trochlear  surface,  and  in  front  of  it  is 
a  rough  depression  for  the  attachment  of  the  anterior  fasciculus  of  the  external 
lateral  ligament.  The  anterior  surface,  convex  and  rounded,  forms  the  head  of  the 
astragalus ;  it  is  smooth,  of  an  oval  form,  and  directed  obliquely-  inwards  and 
downwards ;  it  is  continuous  below  with  that  part  of  the  anterior  facet  on  the 
under  surface  which  rests  upon  the  calcaneo-scaphoid  ligament.  The  head  is  sur- 
rounded by  a  constricted  portion,  the  neck  of  the,  astragalus.  The  posterior  sur- 
face is  narrow,  and  traversed  by  a  groove,  which  runs  obliquely  downwards  and 
inwards,  and  transmits  the  tendon  of  the  Flexor  longus  pollicis. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  with  the  broad  articular 
surface  upwards,  and  the  rounded  head  forwards ;  the  lateral  triangular  articular 
surface  for  the  external  malleolus  will  then  point  to  the  side  to  which  the  bone 
belongs. 

Articulations.    With  four  bones :  tibia,  fibula,  os  calcis,  and  scaphoid. 

The  Scaphoid. 

The  Scaphoid  or  Navicular  bone,  so  called  from  its  fancied  resemblance  to  a 
boat,  is  situated  at  the  inner  side  of  the  tarsus,  between  the  astragalus  behind  and 
the  three  cuneiform  bones  in  front.  This  bone  may  be  distinguished  by  its  boat- 
like form,  being  concave  behind,  convex  and  subdivided  into  three  facets  in  front. 

The  anterior  surface,  of  an  oblong  form,  is  convex  from  side  to  side,  and  sub- 
divided by  two  ridges  into  three  facets,  for  articulation  with  the  three  cuneiform 
bones.  The  posterior  surface  is  oval,  concave,  broader  externally  than  internally, 
and  articulates  with  the  rounded  head  of  the  astragalus.  The  superior  surface  is 
convex  from  side  to  side,  and  rough  for  the  attachment  of  ligaments;  the 
inferior,  somewhat  concave,  irregular,  and  also  rough  for  the  attachment  of 
ligaments.  The  internal  surface  presents  a  rounded  tubercular  eminence,  the 
tuberosity  of  the  scaphoid,  which  gives  attachment  to  part  of  the  tendon  of  the 
Tibialis  posticus.  The  external  surface  is  broad,  rough,  and  irregular,  for  the 
attachment  of  ligamentous  fibres,  and  occasionally  presents  a  small  facet  for 
articulation  with  the  cuboid  bone. 

To  ascertain  to  which  foot  it  belongs,  hold  the  bone  with  the  concave  articular 
surface  backwards,  and  the  broad  dorsal  surface  upwards ;  the  broad  external 
surface  will  point  to  the  side  to  which  the  bone  belongs. 

Articulations.  With  four  bones :  astragalus  and  three  cuneiform ;  occasionally 
also  with  the  cuboid. 

Attachment  of  Muscles.     Part  of  the  Tibialis  posticus. 

The  Cuneiform  Bones. 

The  Cuneiform  Bones  have  received  their  name  from  their  wedge-like  shape. 
They  form  with  the  cuboid  the  most  anterior  row  of.  the  tarsus,  being  placed 
between  the  scaphoid  behind,  the  three  innermost  metatarsal  bones  in  front,  and 
the  cuboid  externally.  They  are  called  the  first,  second,  and  third,  counting  from 
the  inner  to  the  outer  side  of  the  foot,  and,  from  their  position,  internal,  middle, 
and  external. 

The  Internal  Cuneiform. 

The  Internal  Cuneiform  is  the  largest  of  the  three.  It  is  situated  at  the  inner 
side  of  the  foot,  between  the  scaphoid  behind  and  the  base  of  the  first  metatarsal 


176  OSTEOLOGY. 

in  front.  It  may  be  distinguished  by  its  large  size,  as  compared  with  the  other 
two,  and  from  its  more  irregular  wedge-like  form.  It  presents  for  examination 
six  surfaces. 

The  internal  surface  is  subcutaneous,  and  forms  part  of  the  inner  border  of  the 
foot.  It  is  broad,  quadrilateral,  and  presents  at  its  anterior  inferior  angle  a  smooth 
oval  facet,  over  which  the  tendon  of  the  Tibialis  anticus  muscle  glides ;  rough  in 
the  rest  of  its  extent,  for  the  attachment  of  ligaments.  The  external  surface  is 
concave,  presenting,  along  its  superior  and  posterior  borders,  a  narrow  surface  for 
articulation  with  the  middle  cuneiform  behind,  and  second  metatarsal  bone  in 
front ;  in  the  rest  of  its  extent,  it  is  rough  for  the  attachment  of  ligaments,  and 
prominent  below,  where  it  forms  part  of  the  tuberosity.  The  anterior  surface, 
reniform  in  shape,  articulates  with  the  metatarsal  bone  of  the  great  toe.  The 
posterior  surface  is  triangular,  concave,  and  articulates  with  the  innermost  and 
largest  of  the  three  facets  on  the  anterior  surface  of  the  scaphoid.  The  inferior 
or  plantar  surface  is  rough,  and  presents  a  prominent  tuberosity,  at  its  back  part 
for  the  attachment  of  part  of  the  tendon  of  the  Tibialis  posticus.  It  also  gives 
attachment  in  front  to  part  of  the  tendon  of  the  Tibialis  anticus.  The  superior 
surface  is  the  narrow  pointed  end  of  the  wedge,  which  is  directed  upwards  and 
outwards ;  it  is  rough  for  the  attachment  of  ligaments. 

To  ascertain  to  which  side  it  belongs,  hold  the  bone  so  that  its  superior  narrow 
edge  looks  upwards,  and  the  long  articular  surface  forwards ;  the  external  surface 
marked  by  its  vertical  and  horizontal  articular  facets  will  point  to  the  side  to 
which  it  belongs. 

Articulations.  With  four  bones:  scaphoid,  middle  cuneiform,  and  first  and 
second  metatarsal  bones. 

Attachment  of  Muscles.     The  Tibialis  anticus  and  Tibialis  posticus. 

The  Middle  Cuneifokm. 

The  Middle  Cuneiform,  the  smallest  of  the  three,  is  of  very  regular  wedge- 
like form ;  the  broad  extremity  being  placed  upwards,  the  narrow  end  downwards. 
It  is  situated  between  the  other  two  bones  of  the  same  name,  and  corresponds  to 
the  scaphoid  behind,  and  the  second  metatarsal  in  front. 

The  anterior  surface,  triangular  in  form,  and  narrower  than  the  posterior,  arti- 
culates with  the  base  of  the  second  metatarsal  bone.  The  posterior  surface,  also 
triangular,  articulates  with  the  scaphoid.  The  internal  surface  presents  an  articular 
facet,  running  along  the  superior  and  posterior  borders,  for  articulation  with  the 
internal  cuneiform,  and  is  rough  below  for  the  attachment  of  ligaments.  The 
external  surface  presents  posteriorly  a  smooth  facet  for  articulation  with  the 
external  cuneiform  bone.  The  superior  surface  forms  the  base  of  the  wedge ;  it 
is  quadrilateral,  broader  behind  than  in  front,  and  rough  for  the  attachment  of 
ligaments.  The  inferior  surface,  pointed  and  tubercular,  is  also  rough  for  liga- 
mentous attachment. 

To  ascertain  to  which  foot  the  bone  belongs,  hold  its  superior  or  dorsal  surface 
upwards,  the  broadest  edge  being  towards  the  holder,  and  the  smooth  facet,  limited 
to  the  posterior  border,  will  point  to  the  side  to  which  it  belongs. 

Articulations.  With  four  bones :  scaphoid,  internal  and  external  cuneiform,  and 
second  metatarsal  bone. 

The  External  Cuneiform. 

The  External  Cuneiform,  intermediate  in  size  between  the  two  preceding,  is  of 
a  very  regular  wedge-like  form,  the  broad  extremity  being  placed  upwards,  the 
narrow  end  downwards.  It  occupies  the  centre  of  the  front  row  of  the  tarsus 
between  the  middle  cuneiform  internally,  the  cuboid  externally,  the  scaphoid 
behind,  and  the  third  metatarsal  in  front.     It  has  six  surfaces  for  examination. 

The  anterior  surface,  triangular  in  form,  articulates  with  the  third  metatarsal  bone. 
The  posterior  surface  articulates  with  the  most  external  facet  of  the  scaphoid,  and 
is  rough  below  for  the  attachment  of  ligamentous  fibres.     The  internal  surface 


METATARSAL  BONES.  ITT 

presents  two  articular  facets  separated  by  a  rough  depression ;  the  anterior  one, 
situated  at  the  superior  angle  of  the  bone,  articulates  with  the  outer  side  of  the 
base  of  the  second  metatarsal  bone  ;  the  posterior  one  skirts  the  posterior  border, 
and  articulates  with  the  middle  cuneiform ;  the  rough  depression  between  the  two 
gives  attachment  to  an  interosseous  ligament.  The  external  surface  also  presents 
two  articular  facets,  separated  by  a  rough  non-articular  surface.  The  anterior  facet, 
situated  at  the  superior  angle  of  the  bone,  is  small,  and  articulates  with  the  inner 
side  of  the  base  of  the  fourth  metatarsal ;  the  posterior,  and  larger  one,  articulates 
with  the  cuboid ;  the  rough  non-articular  surface  serves  for  the  attachment  of  an 
interosseous  ligament.  The  three  facets  for  articulation  with  the  three  metatarsal 
bones  are  continuous  with  one  another,  and  covered  by  a  prolongation  of  the  same 
cartilage ;  the  facets  for  articulation  with  the  middle  cuneiform  and  scaphoid  are 
also  continuous,  but  that  for  articulation  with  the  cuboid  is  usually  separate.  The 
superior  or  dorsal  surface,  of  an  oblong  form,  is  rough  for  the  attachment  of  liga- 
ments. The  inferior  or  plantar  surface  is  an  obtuse  rounded  margin,  and  serves  for 
the  attachment  of  part  of  the  tendon  of  the  Tibialis  posticus,  part  of  the  Flexor 
brevis  pollicis,  and  ligaments. 

To  ascertain  to  which  side  it  belongs,  hold  the  bone  with  the  broad  dorsal 
surface  upwards,  the  prolonged  edge  backwards ;  the  separate  articular  facet  for 
the  cuboid  will  point  to  the  proper  side. 

Articulations.  With  six  bones :  the  scaphoid,  middle  cuneiform,  cuboid,  and 
second,  third,  and  fourth  metatarsal  bones. 

Attachment  of  Muscles.     Part  of  Tibialis  posticus,  and  Flexor  brevis  pollicis. 

The  Metatarsal  Bones. 

The  Metatarsal  bones  are  five  in  number ;  they  are  long  bones,  and  subdivided 
into  a  shaft,  and  two  extremities. 

The  Shaft  is  prismoid  in  form,  tapers  gradually  from  the  tarsal  to  the  phalangeal 
extremity,  and  is  slightly  curved  longitudinally,  so  as  to  be  concave  below,  slightly 
convex  above. 

The  Posterior  Extremity  or  Base  is  wedge-shaped,  articulating  by  its  terminal 
surface  with  the  tarsal  bones,  and  by  its  lateral  surfaces  with  the  contiguous  bones  ; 
its  dorsal  and  plantar  surfaces  being  rough,  for  the  attachment  of  ligaments. 

The  Anterior  Extremity  or  Head  presents  a  terminal  rounded  articular  surface, 
oblong  from  above  downwards,  and  extending  further  backwards  below  than  above. 
Its  sides  are  flattened,  and  present  a  depression,  surmounted  by  a  tubercle,  for 
ligamentous  attachment.  Its  under  surface  is  grooved  in  the  middle  line,  for  the 
passage  of  the  Flexor  tendon,  and  marked  on  each  side  by  an  articular  eminence 
continuous  with  the  terminal  articular  surface. 

Peculiar  Metatarsal  Bones. 

The  First  is  remarkable  for  its  great  size,  but  is  the  shortest  of  all  the  meta- 
tarsal bones.  The  shaft  is  strong,  and  of  well-marked  prismoid  form.  The 
posterior  extremity  presents  no  lateral  articular  facets ;  its  terminal  articular  surface 
is  of  large  size,  of  semilunar  form,  and  its  circumference  grooved  for  the  tarso- 
metatarsal ligaments ;  its  inferior  angle  presents  a  rough  oval  prominence,  for  the 
insertion  of  the  tendon  of  the  Peroneus  longus.  The  head  is  of  large  size ;  on  its 
plantar  surface  are  two  grooved  facets,  over  which  glide  sesamoid  bones,  the 
facets  being  separated  by  a  smooth  elevated  ridge. 

The  Second  is  the  longest  and  largest  of  the  remaining  metatarsal  bones ;  being 
prolonged  backwards,  into  the  recess  formed  between  the  three  cuneiform  bones. 
Its  tarsal  extremity  is  broad  above,  narrow  and  rough  below.  It  presents  four 
articular  surfaces:  one  behind,  of  a  triangular  form,  for  articulation  with  the 
middle  cuneiform ;  one  at  the  upper  part  of  its  internal  lateral  surface,  for  articu- 
lation with  the  internal  cuneiform;  and  two  on  its  external  lateral  surface,  a 
superior  and  an  inferior,  separated  by  a  rough  depression.  Each  of  the  latter 
articular  surfaces  is  divided  by  a  vertical  ridge  into  two  parts ;  the  anterior  seg- 
12 


178  OSTEOLOGY. 

merit  of   each  facet   articulates   with  the  third  metatarsal;    the   two  posterior 
sometimes  continuous  with  the  external  cuneiform. 

The  Third  articulates  behind,  by  means  of  a  triangular  smooth  surface,  with  the 
external  cuneiform ;  on  its  inner  side  by  two  facets,  with  the  second  metatarsal ; 
and  on  its  outer  side,  by  a  single  facet,  with  the  fourth  metatarsal.  The  latter 
facet  is  of  circular  form,  and  situated  at  the  upper  angle  of  the  base. 

The  Fourth  is  smaller  in  size  than  the  preceding ;  its  tarsal  extremity  presents 
a.  terminal  quadrilateral  surface,  for  articulation  with  the  cuboid;  a  smooth  facet  on 
the  inner  side,  divided  by  a  ridge  into  an  anterior  portion  for  articulation  with  the 
third  metatarsal,  and  a  posterior  portion  for  articulation  with  the  external  cunei- 
form ;  on  the  outer  side  a  single  facet,  for  articulation  with  the  fifth  metatarsal. 

The  Fifth  is  recognized  by  the  tubercular  eminence  on  the  outer  side  of  its 
base ;  it  articulates  behind,  by  a  triangular  surface  cut  obliquely  from  without 
inwards,  with  the  cuboid ;  and  internally,  with  the  fourth  metatarsal. 

Articulations.  Each  bone  articulates  with  the  tarsal  bones  by  one  extremity, 
and  by  the  other  with  the  first  row  of  phalanges.  The  number  of  tarsal  bones 
with  which  each  metatarsal  articulates  is  one  for  the  first,  three  for  the  second, 
one  for  the  third,  two  for  the  fourth,  and  one  for  the  fifth. 

Attachment  of  Muscles.  To  the  first  metatarsal  bone,  three :  part  of  the  Tibialis 
anticus,  Peroneus  longus,  and  First  dorsal  interosseous.  To  the  second,  three :  the 
Adductor  pollicis,  and  First  and  Second  dorsal  interosseous.  To  the  third,  four : 
the  Adductor  pollicis,  Second  and  Third  dorsal  interosseous,  and  First  plantar. 
To  the  fourth,  four :  the  Adductor  pollicis,  Third  and  Fourth  dorsal,  and  Second 
plantar  interosseous.  To  the  fifth,  five :  the  Peroneus  brevis,  Peroneus  tertius, 
Flexor  brevis  minimi  digiti,  Fourth  dorsal,  interosseous  and  Third  plantar  inter- 
osseous. 

Phalanges. 

The  Phalanges  of  the  foot,  both  in  number  and  general  arrangement,  resemble 
those  in  the  hand ;  there  being  two  in  the  great  toe,  and  three  in  each  of  the 
other  toes. 

The  phalanges  of  the  first  row  resemble  closely  those  of  the  hand.  The  shaft  is 
compressed  from  side  to  side,  convex  above,  concave  below.  The  posterior 
extremity  is  concave ;  and  the  anterior  extremity  presents  a  trochlear  surface,  for 
articulation  with  the  second  phalanges. 

The  phalanges  of  the  second  row  are  remarkably  small  and  short,  but  rather 
broader  than  those  of  the  first  row. 

The  ungual  phalanges,  in  form,  resemble  those  of  the  fingers ;  but  they  are 
smaller,  flattened  from  above  downwards,  presenting  a  broad  base  for  articulation 
with  the  second  row,  and  an  expanded  extremity  for  the  support  of  the  nail  and 
end  of  the  toe. 

Articulations.  The  first  row,  with  the  metatarsal  bones,  and  second  phalanges ; 
the  second  of  the  great  toe,  with  the  first  phalanx,  and  of  the  other  toes,  with  the 
first  and  third  phalanges ;  the  third,  with  the  second  row. 

Attachment  of  Muscles.  To  the  first  phalanges :  Great  toe ;  innermost  tendon  of 
"  Extensor  brevis  digitorum,  Abductor  pollicis,  Adductor  pollicis,  Flexor  brevis 
pollicis,  Transversus  pedis.  Second  toe ;  First  and  Second  dorsal  interosseous. 
Third  toe;  Third  dorsal  and  First  plantar  interosseous.  Fourth  toe;  Fourth 
dorsal  and  Second  plantar  interosseous.  Fifth  toe ;  Flexor  brevis  minimi  digiti, 
Adductor  minimi  digiti,  and  Third  plantar  interosseous. — Second  phalanges: 
Great  toe ;  Extensor  longus  pollicis,  Flexor  longus  pollicis.  Other  toes ;  Flexor 
brevis  digitorum,  one  slip  from  the  Extensor  brevis  digitorum,  and  Extensor 
longus  digitorum. — Third  phalanges ;  two  slips  from  the  common  tendon  of  the 
Extensor  longus  and  Extensor  brevis  digitorum,  and  the  Flexor  longus  digitorum. 

Development  of  the  Foot.    (Fig.  115.) 

The  Tarsal  bones  are  each  developed  by  a  single  centre,  excepting  the  os  calcis, 
which  has  an  epiphysis  for  its  posterior  extremity.     The  centres  make  their 


SESAMOID   BONES. 


H9 


appearance  in  the  following  order :  in  the  os  calcis,  at  the  sixth  month  of  fcetal  life ; 
in  the  astragalus,  about  the  seventh  month ;  in  the  cuboid,  at  the  ninth  month  , 
external  cuneiform,  during  the  first  year ;  internal  cuneiform,  in  the  third  year ; 
middle  cuneiform,  in  the  fourth  year.  The  epiphysis  for  the  posterior  tuberosity 
of  the  os  calcis  appears  at  the  tenth  year,  and  unites  with  the  rest  of  the  bone 
soon  after  puberty. 


Fig.  115. — Plan  of  the  Development  of  the  Foot. 
'  s  is 

Ml 


■Jpp.f /O*  ■•/.? 
unites  after p-ulerty 


Tarsus 

f  Centre  for  e&eJi  ione 
tacept  Os  Calcts 


Metatarsus 

2  Centres  fir  each  ions 
1  for  Shaft 

1  for  Digital  Extremity 
except  1.& 


cent 


Jippcars  6t?  yf 
\  UiiiU/8-Z0#  y.: 

-  App.  7&mi 


Fhalanges 

iCentresfor  each  bo7i0 
tforSliaft 
f fin  Metatarsal  Ext  J 


TfniU  18-20  jf.rf 
App'3?dy. 

App.&&  yx-ggr') 

Unite  /J-tSy-'l 
Agp-  Z-J^-inA—J 


f£^3 


Unite  IT -18  y^^^ftj 

App.  2- A.  mo: 

AyfiJ>$  y? 
Unite  11-18 y.7 

App  J*  »*-IJ>t. 


The  Metatarsal  bones  are  each  developed  by  two  centres:  one  for  the  shaft,  and 
one  for  the  digital  extremity,  in  the  four  outer  metatarsal;  one  for  the  shaft,  and 
one  for  the  base,  in  the  metatarsal  bone  of  the  great  toe.  Ossification  commences 
in  the  centre  of  the  shaft  about  the  seventh  week,  and  extends  towards  either 
extremity,  and  in  the  digital  epiphyses  about  the  third  year ;  they  become  joined 
between  the  eighteenth  and  twentieth  years. 

The  Phalanges  are  developed  by  two  centres  for  each  bone :  one  for  the  shaft, 
and  one  for  the  metatarsal  extremity. 

Sesamoid  Bones. 

These  are  small  rounded  masses,  cartilaginous  in  early  life,  osseous  in  the  adult, 
which  are  developed  in  those  tendons  which  exert  a  certain  amount  of  pressure 
upon  the  parts  over  which  they  glide.  It  is  said  that  they  are  more  commonly 
found  in  the  male  than  in  the  female,  and  in  persons  of  an  active  muscular  habit 


180  OSTEOLOGY. 

than  in  those  that  are  weak  and  debilitated.  They  are  invested  throughout  their 
whole  surface  by  the  fibrous  tissue  of  the  tendon  in  which  they  are  found,  excepting 
upon  that  side  which  lies  in  contact  with  the  part  over  which  they  play,  where 
they  present  a  free  articular  facet.  They  may  be  divided  into  two  kinds ;  those 
which  glide  over  the  articular  surfaces  of  joints,  and  those  which  play  over  the 
cartilaginous  facets  found  on  the  surfaces  of  certain  bones. 

The  sesamoid  bones  of  the  joints  are,  in  the  lower  extremity,  the  patella,  which 
is  developed  in  the  tendon  of  the  Quadriceps  extensor ;  two  small  sesamoid  bones, 
found  opposite  the  metatarso-phalangeal  joint  of  the  great  toe  in  each  foot,  in  the 
tendons  of  the  Flexor  brevis  pollicis,  and  occasionally  one  in  the  metatarso- 
phalangeal joint  of  the  second  toe,  the  little  toe,  and,  still  more  rarely,  in  the 
third  and  fourth  toes. 

In  the  upper  extremity,  there  are  two  on  the  palmar  surface  of  the  metacarpo- 
phalangeal joint  in  the  thumb,  developed  in  the  tendons  of  the  Flexor  brevis 
pollicis.  Occasionally,  one  or  two  opposite  the  metacarpo-phalangeal  articulations 
of  the  fore  and  little  fingers,  and,  still  more  rarely,  one  opposite  the  same  joints 
of  the  third  and  fourth  fingers. 

Those  found  in  tendons  which  glide  over  certain  bones  occupy  the  following 
situations.  One  in  the  tendon  of  the  Peroneus  longus,  where  it  glides  through  the 
groove  in  the  cuboid  bone.  One  appears  late  in  life  in  the  tendon  of  the  Tibialis 
anticus,  opposite  the  smooth  facet  on  the  internal  cuneiform  bone.  One  in  the 
tendon  of  the  Tibialis  posticus,  opposite  the  inner  side  of  the  astragalus.  One  in 
the  outer  head  of  the  Gastrocnemius,  behind  the  outer  condyle  of  the  femur;  and 
one  in  the  Psoas  and  Iliacus,  where  they  glide  over  the  body  of  the  pubes. 
Occasionally  in  the  tendon  of  the  Biceps,  opposite  the  tuberosity  of  the  radius ; 
in  the  tendon  of  the  Gluteus  maximus,  as  it  passes  over  the  great  trochanter; 
and  in  the  tendons  which  wind  round  the  inner  and  outer  malleoli. 


The  author  has  to  acknowledge  valuable  aid  derived  from  the  perusal  of  the  works  of  Cloquet, 
Cruveilhier,  Bourgery,  and  Boyer,  especially  of  the  latter.  Reference  has  also  been  made  to 
the  following:  "Outlines  of  Human  Osteology,"  by  F.  O.  Ward.  "A  Treatise  on  the  Human 
Skeleton,  and  Observations  on  the  Limbs  of  Vertebrate  Animals,"  by  G.  M.  Humphry.  Holden's 
"Human  Osteology."  Henle's  "Handbuch  der  Systematischen  Anatomie  des  Menschen.  Erster 
Band.  Erste  Abtheilung.  Knochenlehre."  " Osteological  Memoirs  (The  Clavicle),"  by  Stru- 
thers.  "On  the  Archetype  and  Homologies  of  the  Vertebrate  Skeleton,"  and  "On  the  Nature 
of  Limbs,"  by  Owen. — Todd  and  Bowman's  "Physiological  Anatomy,"  and  Kolliker's  "Manual 
of  Human  Microscopic  Anatomy,"  contain  the  most  complete  account  of  the  structure  and 
development  of  bone. — The  development  of  the  bones  is  minutely  described  in  "Quain's  Ana- 
tomy," edited  by  Sharpey  and  Ellis.  On  the  chemical  analysis  of  bone,  refer  to  "Lehmann's 
Physiological  Chemistry,"  translated  by  Day,  vol.  iii.  p.  12.  "Simon's  Chemistry,"  translated 
by  Day,  vol.  ii.  p.  396.  A  paper  by  Dr.  Stark,  "On  the  Chemical  Constitution  of  the  Bones  of 
the  Yerteb rated  Animals"  (Edinburgh  Medical  and  Surgical  Journal,  vol.  liii.  p.  308) ;  and  Dr. 
Owen  Rees's  paper  in  the  21st  vol.  of  the  Medico-chirurgical  Transactions. 


The  Articulations. 

The  various  bones  of  which  the  Skeleton  consists  are  connected  together  at 
different  parts  of  their  surfaces,  and  such  connection  is  designated  by  the  name 
of  Joint  or  Articulation.  If  the  joint  is  immovable,  as  between  the  cranial  and 
most  of  the  facial  bones,  the  adjacent  margins  are  applied  in  almost  close 
contact,  a  thin  layer  of  fibrous  membrane,  the  sutural  ligament,  and,  at  the  base 
of  the  skull,  in  certain  situations,  a  thin  layer  of  cartilage,  being  interposed. 
"Where  slight  movement  is  required,  combined  with  great  strength,  the  osseous 
surfaces  are  united  by  tough  and  elastic  fibro-cartilages,  as  in  the  joints  of  the 
spine,  the  sacro-iliac,  and  interpubic  articulations;  but  in  the  movable  joints,  the 
bones  forming  the  articulation  are  generally  expanded  for  greater  convenience  of 
mutual  connection,  covered  by  an  elastic  structure,  called  cartilage,  held  together 
by  strong  bands  or  capsules,  of  fibrous  tissue,  called  ligament,  and  lined  by  a 
membrane,  the  synovial  membrane,  which  secretes  a  fluid  that  lubricates  the 
various  parts  of  which  the  joint  is  formed,  so  that  the  structures  which  enter  into 
the  formation  of  a  joint  are  bone,  cartilage,  fibro-cartilage,  ligament,  and  synovial 
membrane. 

Bone  constitutes  the  fundamental  element  of  all  the  joints.  In  the  long  bones, 
the  extremities  are  the  parts  which  form  the  articulations ;  they  are  generally 
somewhat  enlarged,  consisting  of  spongy  cancellous  tissue,  with  a  thin  coating  of 
compact  substance.  In  the  flat  bones,  the  articulations  usually  take  place  at  the 
edges  ;  and,  in  the  short  bones,  by  various  parts  of  their  surface.  The  layer  of 
compact  bone  which  forms  the  articular  surface,  and  to  which  the  cartilage  is 
attached,  is  called  the  articular  lamella.  It  is  of  a  white  color,  extremely  dense, 
and  varies  in  thickness.  Its  structure  differs  from  ordinary  bone-tissue  in  this 
respect,  that  it  contains  no  Haversian  canals,  and  its  lacunas  are  much  larger  than 
in  ordinary  bone,  and  have  no  canaliculi.  The  vessels  of  the  cancellous  tissue, 
as  they  approach  the  articular  lamella,  turn  back  in  loops,  andkdo  not  perforate 
it;  this  la}''er  is  consequently  more  dense,  and  firmer  than  ordinary  bone,  and 
is  evidently  designed  to  form  a  steady  and  unyielding  support  for  the  articular 
cartilage. 

Cartilage  is  firm,  opaque,  of  a  pearly-white  or  bluish-white  color,  in  some 
varieties  yellow,  highly  elastic,  readily  yielding  to  pressure,  and  recovering  its 
shape  when  the  force  is  removed,  flexible,  and  possessed  of  considerable  cohesive 
power.  In  man,  that  form  of  cartilage  which  constitutes  the  original  framework 
of  the  body,  and  which  in  time  becomes  ossified  throughout  the  greater  part  of  its 
extent,  is  called  temporary  cartilage.  But  there  is  another  form  of  cartilage  em- 
ployed in  the  construction  of  the  body  that  is  not  prone  to  ossify,  viz.,  permanent 
cartilage.  This  is  found — 1.  In  the  joints,  covering  the  ends  of  the  bones 
(articular  cartilage) :  2.  Forming  a  considerable  part  of  the  solid  framework  of 
the  chest  (costal  cartilages) :  3.  Arranged  in  the  form  of  plates  or  lamellas,  of 
greater  or  less  thickness,  which  enter  into  the  formation  of  the  external  ear,  the 
nose,  the  eyelids,  the  Eustachian  tube,  the  larynx,  and  the  windpipe  (reticular 
cartilage).  They  serve  to  maintain  the  shape  of  canals  or  passages,  or  to  form 
tubes  that  require  to  be  kept  permanently  open  without  the  expenditure  of  vital 
force. 

Structure.  Cartilage  consists  either  of  a  parenchyma  of  nucleated  cells,  or  the  cells  are 
imbedded  in  an  intercellular  substance  or  matrix.  The  cells  or  cartilage  corpuscles  are  contained 
in  hollow  cavities  or  lacunae  in  thp  intercellular  substance,  which  appear  to  be  lined  by  a  firm, 
clear,  or  yellowish  layer,  the  cartilage  capsule.     Under  the  influence  of  certain  rea»erns,  the 

181 


182  ARTICULATIONS. 

cartilage  cell  shrinks  up,  and  is  separated  from  its  capsule  by  a  well-marked  interval.  The  car- 
tilage cells  are  usually  round  or  oblong,  sometimes  flattened  or  fusiform.  Each  contains  a  nucleus, 
furnished  occasionally  with  one  or  two  nucleoli.  The  nuclei  vary  from  25,(5n  to  ^'j,,  of  an  inch; 
they  sometimes  contain  fat  globules,  or  appear  converted  into  fat.  The  intercellular  substance 
is  either  homogeneous,  or  finely  granular,  or  fibrous. 

In  temporary  cartilage,  the  intercellular  substance  is  not  abundant ;  but  the  cartilage  cells 
are  numerous,  and  situated  at  nearly  equal  distances  apart.  The  cells  vary  in  shape  and  size, 
the  majority  being  round  or  oval,  and  their  nuclei  are  minutely  granular.  When  ossification 
commences  in  it,  the  cells  become  arranged  in  clusters  or  rows,  the  ends  of  which  are  directed 
towards  the  ossifying  part. 

In  articular  cartilage,  the  intercellular  substance  is  more  abundant  than  in  the  former  variety; 
it  appears  dim,  like  ground  glass,  and  has  a  finely  granular  or  homogeneous  aspect.  The  cells 
are  oval  or  roundish,  from  j^ViT  to  9Hjy  of  an  inch,  the  nuclei  small  and  commonly  vesicular,  and 
parent  cells  are  frequently  seen  inclosing  two  or  more  younger  cells.  On  the  surface  of  the 
cartilage  the  cells  are  numerous,  and  disposed  in  isolated  groups  of  two,  three,  or  four,  the  groups 
being  flattened,  and  lie  with  their  planes  parallel  to  the  surface.  In  the  interior,  and  nearer  the 
bone,  they  are  less  numerous,  and  assume  more  or  less  of  a  linear  direction,  pointing  towards  the 
surface.  This  arrangement  appears  to  be  connected  with  a  corresponding  peculiarity  of  structure 
in  the  matrix,  and  serves  to  explain  the  disposition  which  this  form  of  cartilage  has  to  break  in  a 
direction  perpendicular  to  the  surface,  the  broken  surface  being  to  the  eye  striated  in  the  same 
direction. 

In  the  costal  cartilages,  the  intercellular  substance  is  very  abundant,  finely  mottled,  and,  in 
certain  situations,  presents  a  distinctly  fibrous  structure,  the  fibres  being  fine  and  parallel. 
This  is  most  evident  in  advanced  age.  The  cells,  which  are  collected  into  groups,  are  larger 
than  in  any  other  cartilages  of  the  body,  being  from  ^  to  T£5  of  an  inch  in  diameter.  Many 
contain  two  or  more  clear  transparent  nuclei,  and  some  contain  oil  globules.  Near  the  exterior 
of  the  cartilage  the  cells  are  flattened,  and  lie  parallel  with  the  surface ;  in  the  interior,  the  cells 
have  a  linear  arrangement,  the  separate  rows  being  turned  in  all  directions. 

The  ensiform  cartilage  of  the  sternum,  the  cartilages  of  the  nose,  and  the  cartilages  of  the 
larynx  and  windpipe  (excepting  the  epiglottis  and  cornicula  laryngis)  resemble  the  costal  carti- 
lages in  their  microscopic  characters. 

Reticular  cartilage.  The  epiglottis,  the  cornicula  laryngis,  the  cuneiform  cartilages,  the  carti- 
lage of  the  ear,  of  the  eyelid,  and  of  the  Eustachian  tube,  are  included  in  a  separate  class  under 
the  name  of  "  reticular,"  "  yellow,"  or  "  spongy"  cartilages.  They  are  yellow,  of  a  spongy  texture 
throughout,  more  flexible  than  ordinary  cartilage,  and  not  prone  to  ossify.  This  variety  of 
cartilage  consists  of  an  intercellular  substance,  composed  of  minute  opaque  fibres,  which  inter- 
sect each  other  in  all  directions,  and  are  so  arranged  as  to  inclose  numerous  small  oval  spaces, 
in  which  the  cartilage  corpuscles  are  deposited. 

Articular  cartilage  forms  a  thin  incrustation  upon  the  articular  surfaces  of 
bones,  and  is  admirably  adapted,  by  its  elastic  property,  to  break  the  force  of  con- 
cussions, and,  by^ts  smoothness,  to  afford  perfect  ease  and  freedom  of  movement 
between  the  bones.  Where  it  covers  the  rounded  ends  of  bones,  upon  which  the 
greatest  pressure  is  received,  it  is  thick  at  the  centre,  and  becomes  gradually 
thinner  towards  the  circumference :  an  opposite  arrangement  exists  where  it  lines 
the  corresponding  cavities.  On  the  articular  surfaces  of  the  short  bones,  as  the 
carpus  and  tarsus,  the  cartilage  is  disposed  in  a  layer  of  uniform  thickness  through- 
out. The  attached  surface  of  articular  cartilage  is  closely  adapted,  by  a  rough, 
uneven  surface,  to  the  articular  lamella ;  the  free  surface  is  smooth,  polished,  and 
partially  covered  by  a  perichondrium,  prolonged  from  the  periosteum,  a  short  dis- 
tance over  the  cartilage ;  in  the  foetus,  an  extremely  thin  prolongation  of  synovial 
membrane  may  be  traced  over  the  surface  of  the  cartilage,  according  to  Mr.  Toynbee, 
but,  at  a  later  period  of  life,  this  cannot  be  demonstrated.  Articular  cartilage  in 
the  adult  does  not  contain  bloodvessels;  its  nutrition  being  derived  from  the 
vessels  of  the  synovial  membrane  which  skirt  the  circumference  of  the  cartilage, 
and  from  those  -of  the  adjacent  bone,  which  are,  however,  separated  from  direct 
contact  with  the  cartilage  by  means  of  the  articular  lamella.  Mr.  Toynbee  has 
shown,  that  the  minute  vessels  of  the  cancellous  tissue,  as  they  approach  the 
articular  lamella,  dilate,  and,  forming  arches,  return  into  the  substance  of  the  bone. 
The  vessels  of  the  synovial  membrane  also  advance  forwards  upon  the  circum- 
ference of  the  cartilage  for  a  very  short  distance,  and  then  return  in  loops ;  they 
are  only  found  on  the  parts  not  subjected  to  pressure.  In  the  foetus,  the  vessels 
are  said,  by  Toynbee,  to  advance  for  some  distance  upon  the  surface  of  the  cartilage, 
beneath  the  synovial  membrane ;  but  Kolliker,  from  more  recent  examination, 


STRUCTURE    OF   JOINTS.  183 

doubts  this.  Lymphatic  vessels  and  nerves  have  not,  as  yet,  been  traced  in  its 
substance. 

Fibro-cartilage  is  also  employed,  in  the  construction  of  the  joints,  contributing 
to  their  strength  and  elasticity.  It  consists  of  a  mixture  of  white  fibrous  and 
cartilaginous  tissues  in  various  proportions ;  it  is  to  the  first  of  these  two  consti- 
tuents that  its  flexibility  and  toughness  is  chiefly  owing,  and  to  the  latter  its 
elasticity.  The  fibro-cartilages  admit  of  arrangement  into  four  groups,  inter- 
articular,  connecting,  circumferential,  and  stratiform. 

The  interarticular  fibro-cartilages  or  menisci  are  flattened  fibro-cartilaginous 
plates,  of  a  round,  oval,  or  sickle-like  form,  interposed  between  the  articular  car- 
tilages of  certain  joints.  They  are  free  on  both  surfaces,  thinner  toward  their 
centre  than  at  their  circumference,  and  held,  in  position  by  their  extremities  being 
connected  to  the  surrounding  ligaments.  The  synovial  membrane  of  the  joint  is 
prolonged  over  them  a  short  distance  from  their  attached  margin.  They  are 
found  in  the  temporo-maxillary,  sterno-clavicular,  acromio-clavicular,  wrist  and 
knee-joints.  These  cartilages  are  usually  found  in  those  joints  most  exposed  to 
violent  concussions,  and.  subject  to  frequent  movement.  Their  use  is,  to  maintain 
the  apposition  of  the  opposed  surfaces  in  their  various  motions ;  to  increase  the 
depth  of  the  articular  surface,  and.  give  ease  to  the  gliding  movement ;  to  mode- 
rate the  effects  of  great  pressure,  and  deaden  the  intensity  of  the  shocks  to  which 
they  may  be  submitted. 

The  connecting  fibro-cartilages  are  interposed  between  the  bony  surfaces  of  those 
joints  which  admit  of  only  slight  mobility,  as  between  the  bodies  of  the  vertebrae, 
and  the  symphysis  of  the  pubes ;  they  exist  in  the  form  of  disks,  intimately  adhe- 
rent to  the  opposed  surfaces,  being  composed  of  concentric  rings  of  fibrous  tissue, 
with  cartilaginous  laminae  interposed,  the  former  tissue  predominating  towards  the 
circumference,  the  latter  towards  the  centre. 

The  circumferential  fibro-cartilages  consist  of  a  rim  of  fibro-cartilage,  which 
surrounds  the  margin  of  some  of  the  articular  cavities,  as  the  cotyloid  cavity  of 
the  hip,  and  the  glenoid  cavity  of  the  shoulder ;  they  serve  to  deepen  the  articular 
surface  and  protect  the  edges  of  the  bone. 

The  stratiform  fibro-cartilages  are  those  which  form  a  thin  layer  in  the  osseous 
grooves,  through  which  the  tendons  of  certain  muscles  glide. 

Ligaments  are  found  in  nearly  all  the  movable  articulations ;  they  consist  of 
bands  of  various  forms,  serving  to  connect  together  the  articular  extremities  of 
bones,  and  composed  mainly  of  bundles  of  white  fibrous  tissue  placed  parallel  with, 
or  closely  interlaced  with,  one  another,  and  presenting  a  white,  shining,  silvery 
aspect.  Ligament  is  pliant  and  flexible,  so  as  to  allow  of  the  most  perfect  freedom 
of  movement,  but  strong,  tough,  and  inextensile,  so  as  not  readily  to  yield  under 
the  most  severely  applied  force ;  it  is,  consequently,  admirably  adapted  to  serve 
as  the  connecting  medium  between  the  bones.  Some  ligaments  consist  entirely  of 
yellow  elastic  tissue,  as  the  ligamenta  subflava,  which  connect  together  the  adjacent 
arches  of  the  vertebrae,  and  the  ligamentum  nuchae.  -  * 

Synovial  Membrane  is  a  thin,  delicate  membrane,  arranged  in  the  form  of  a 
short  wide  tube,  attached  by  its  open  ends  to  the  margins  of  the  articular  ex- 
tremities of  the  bones,  and  covering  the  inner  surface  of  the  various  ligaments 
which  connect  the  articulating  surfaces.  It  resembles  the  serous  membranes  in 
structure,  but  differs  from  them  in  the  nature  of  its  secretion,  which  is  thick, 
viscid,  and  glairy,  like  the  white  of  egg,  and  hence  termed  synovia.  The  synovial 
membranes  found  in  the  body  admit  of  subdivision  into  three  kinds,  articular, 
bursal,  and  vaginal. 

The  articular  synovial  membranes  are  found  in  all  the  freely  movable  joints. 
In  the  foetus,  this  membrane  is  said,  by  Toynbee,  to  be  continued  over  the  surface 
of  the  cartilages ;  but  in  the  adult  it  is  wanting,  excepting  at  their  circumference, 
upon  which  it  encroaches  for  a  short  distance :  it  then  invests  the  inner  surface  of 
the  capsular  or  other  ligaments  inclosing  the  joint,  and  is  reflected  over  the 
surface  of  any  tendons  passing  through  its  cavity,  as  the  tendon  of  tha  Popliteus 


184  ARTICULATIONS. 

in  the  knee,  and  the  tendon  of  the  Biceps  in  the  shoulder.  In  most  of  the  joints, 
the  synovial  membrane  is  thrown  into  folds,  which  project  into  the  cavity. 
Some  of  these  folds  contain  large  masses  of  fat.  These  are  especially  distinct  in 
the  hip  and  the  knee.  Others  are  flattened  folds,  subdivided  at  their  margins  into 
fringe-like  processes,  the  vessels  of  which  have  a  convoluted  arrangement.  The 
latter  generally  project  from  the  synovial  membrane  near  the  margin  of  the 
cartilage,  and  lie  flat  upon  its  surface.  They  consist  of  connective  tissue,  covered 
with  epithelium,  and  contain  fat  cells  in  variable  quantity,  and,  more  rarely, 
isolated  cartilage  cells.  They  are  found  in  most  of  the  bursal  and  vaginal,  as 
well  as  in  the  articular  synovial  membranes,  and  were  described,  by  Clopton 
Havers,  as  mucilaginous  glands,  and  as  the  source  of  the  synovial  secretion. 
Under  certain  diseased  conditions,  similar  processes  are  found  covering  the  entire 
surface  of  the  synovial  membrane,  forming  a  mass  of  pedunculated  nbro-fatty 
growths,  which  project  into  the  joint. 

The  bursse  are  found  interposed  between  surfaces  which  move  upon  each  other, 
producing  friction,  as  in  the  gliding  of  a  tendon,  or  of  the  integument  over  pro- 
jecting bony  surfaces.  '  "They  admit  of  subdivision  into  two  kinds,  the  bursse 
mucosse  and  the  synovial  bursse.  The  former  are  large,  simple,  or  irregular 
cavities  in  the  subcutaneous  areolar  tissue,  inclosing  a  clear  viscid  fluid.  They 
are  found  in  various  situations,  as  between  the  integument  and  front  of  the  patella, 
over  the  olecranon,  the  malleoli,  and  other  prominent  parts.  The  synovial  bursse 
are  found  interposed  between  muscles  or  tendons  as  they  play  over  projecting 
bony  surfaces,  as  between  the  Glutei  muscles  and  surface  of  the  great  trochanter. 
They  consist  of  a  thin  wall  of  connective  tissue,  partially  covered  by  epithelium, 
and  contain  a  viscid  fluid.  Where  one  of  these  exists  in  the  neighborhood  of  a 
joint,  it  usually  communicates  with  its  cavity,  as  is  generally  the  case  with  the 
bursa  between  the  tendon  of  the  Psoas  and  Iliacus,  and  the  capsular  ligament  of 
the  hip,  or  the  one  interposed  between  the  under  surface  of  the  Subscapularis  and 
the  neck  of  the  scapula. 

The  vaginal  synovial  membranes  or  synovial  sheaths  serve  to  facilitate  the 
gliding  of  tendons  in  the  osseo-fibrous  canals  through  which  they  pass.  The 
membrane  is  here  arranged  in  the  form  of  a  sheath,  one  layer  of  which  adheres  to 
the  wall  of  the  canal,  and  the  other  is  reflected  upon  the  outer  surface  of  the  con- 
tained tendon ;  the  space  between  the  two  free  surfaces  of  the  membrane  being 
partially  filled  with  synovia.  These  sheaths  are  chiefly  found  surrounding  the 
tendons  of  the  Flexor  and  Extensor  muscles  of  the  fingers  and  toes,  as  they  pass 
through  the  osseo-fibrous  canals  in  the  hand  or  foot. 

Synovia  is  a  transparent,  yellowish- white,  or  slightly  reddish  fluid,  viscid  like 
the  white  of  egg,  having  an  alkaline  reaction,  and  slightly  saline  taste.  It  consists, 
according  to  Frerichs,  in  the  ox,  of  94.85  water,  0.56  mucus  and  epithelium,  0.07 
fat,  3.51  albumen  and  extractive  matter,  and  0.99  salts. 

The  Articulations  are  divided  into  three  classes:  Synarthrosis,  or  immovable 
joints;  Amphiarthrosis,  or  mixed  joints;  and  Diarthrosis,  or  movable  joints. 

1.  Synarthrosis.    Immovable  Articulations. 

Synarthroses  (avv,  with,  apflpoi/,  a  joint)  or  Immovable  Joints  include  all  those 
articulations  in  which  the  surfaces  of  the  bones  are  in  almost  direct  contact,  not 
separated  by  an  intervening  synovial  cavity,  and  immovably  connected  with 
each  other,  as  between  the  bones  of  the  cranium  and  face,  excepting  the  lower 
jaw.  The  varieties  of  synarthrosis  are  three  in  number ;  Sutura,  Schindylesis, 
and  Gomphosis. 

Sutura  (a  seam).  Where  the  articulating  surfaces  are  connected  by  a  series  of 
processes  and  indentations  interlocked  together,  it  is  termed  sutura  vera  ;  of  which 
there  are  three  varieties,  sutura  dentata,  sutura  serrata  and  sutura  limbosa.  The 
surfaces  of  the  bones  are  not  in  direct  contact,  being  separated  by  a  layer  of  mem- 
brane continuous  externally  with  the  pericranium,  internally  with  the  dura  mater. 


SUBDIVISION   INTO   THREE   CLASSES.  185 

The  sutura  dentata  {dens,  a  tooth)  is  so  called  from  the  tooth-like  form  of  the 
projecting  articular  processes,  as  in  the  suture  between  the  parietal  bones.  In 
the  sutura  serrata  (serra,  a  saw),  the  edges  of  the  two  bones  forming  the  articula- 
tion are  serrated  like  the  teeth  of  a  fine  saw,  as  between  the  two  portions  of  the 
frontal  bone.  In  the  sutura  limbosa  {limbus,  a  selvage),  besides  the  dentated  pro- 
cesses, there  is  a  certain  degree  of  bevelling  of  the  articular  surfaces,  so  that  the 
bones  overlap  one  another,  as  in  the  suture  between  the  parietal  and  frontal  bones. 
Where  the  articulation  is  formed  by  roughened  surfaces  placed  in  apposition  with 
one  another,  it  is  termed  the  false  suture,  sutura  nolha,  of  which  there  are  two 
kinds,  the  sutura  squamosa  (squama,  a  scale),  formed  by  the  overlapping  of  two 
contiguous  bones  by  broad  bevelled  margins,  as  in  the  temporo-parietal  or  squa- 
mous suture ;  and  the  sutura  harmonia  (dpuv,  to  adapt),  where  there  is  simple 
apposition  of  two  contiguous  rough  bony  surfaces,  as  in  the  articulation  between 
the  two  superior  maxillary  bones,  or  of  the  horizontal  plates  of  the  palate. 

Schindylesis  (o^cvgvx^atj,  a  fissure)  is  that  form  of  articulation  in  which  a  thin 
plate  of  bone  is  received  into  a  cleft  or  fissure  formed  by  the  separation  of  two 
laminae  of  another,  as  in  the  articulation  of  the  rostrum  of  the  sphenoid,  and 
perpendicular  plate  of  the  ethmoid  with  the  vomer,  or  in  the  reception  of  the  latter 
in  the  fissure  between  the  superior  maxillary  and  palate  bones. 

Gomphosis  (y6(i<pos,  a  nail)  is  an  articulation  formed  by  the  insertion  of  a  conical 
process  into  a  socket,  as  a  nail  is  driven  into  a  board,  and  is  illustrated  in  the 
articulation  of  the  teeth  in  the  alveoli  of  the  maxillary  bones. 

2.  Amphiarthrosis.    Mixed  Articulations. 

Amphiarthrosis  (a^<j>t,  on  all  sides,  apepov,  a  joint)  or  Mixed  Articulation.  In  this 
form  of  articulation,  the  contiguous  osseous  surfaces  are  connected  together  by 
broad  flattened  disks  of  fibro-cartilage,  which  adhere  to  the  ends  of  both  bones,  as 
in  the  articulation  between  the  bodies  of  the  vertebrae,  and  first  two  pieces  of  the 
sternum ;  or  the  articulating  surfaces  are  covered  with  fibro-cartilage,  partially 
lined  by  synovial  membrane,  and  connected  together  by  external  ligaments,  as  in 
the  sacro-iliac  and  pubic  symphyses;  both  these  forms  being  capable  of  limited 
motion  in  every  direction.  The  former  resemble  the  synarthrodial  joints  in  the 
continuity  of  their  surfaces,  and  absence  of  synovial  sac ;  the  latter,  the  diarthro- 
dial.  These  joints  occasionally  become  obliterated  in  old  age :  this  is  frequently 
the  case  in  the  interpubic  articulation,  and  occasionally  in  the  intervertebral  and 
sacro-iliac. 

3.  Diarthrosis.    Movable  Articulations. 

Diarthrosis  (Sta,  through,  apOpov,  a  joint).  This  form  of  articulation  includes  the 
greater  number  of  the  joints  in  the  body,  mobility  being  their  distinguishing 
character.  They  are  formed  by  the  approximation  of  two  contiguous  bony  sur- 
faces, covered  with  cartilage,  connected  by  ligaments,  and  lined  by  synovial 
membrane.  The  varieties  of  joints  in  this  class  have  been  determined  by  the  kind 
of  motion  permitted  in  each,  and  are  four  in  number:  Arthrodia,  Enarthrosis, 
Ginglymus,  Diarthrosis  Rotatorius. 

Arthrodia  is  that  form  of  joint  which  admits  of  a  gliding  movement ;  it  is 
formed  by  the  approximation  of  plane  surfaces,  or  one  slightly  concave,  the  other 
slightly  convex ;  the  amount  of  motion  between  them  being  limited  by  the  liga- 
ments, or  osseous  processes,  surrounding  the  articulation,  as  in  the  articular 
processes  of  the  vertebras,  temporo-maxillary,  sterno-clavicular,  and  acromioclavi- 
cular, inferior  radio-ulnar,  carpal,  carpo-metacarpal,  superior  tibio-fibular,  tarsal, 
and  tarso- metatarsal  articulations. 

Enarthrosis  is  that  form  of  joint  which  is  capable  of  motion  in  all  directions. 
It  is  formed  by  the  reception  of  a  globular  head  into  a  deep  cup-like  cavity  (hence 
the  name  ball  and  socket),  the  parts  being  kept  in  apposition  by  a  capsular  liga- 
ment strengthened  by  accessory  ligamentous  bands.  Examples  of  this  form  of 
articulation  are  found  in  the  hip  and  shoulder. 


186 


ARTICULATIONS. 


Ginglymus  or  Hinge-joint  (y  177X1^6$,  a  hinge).  In  this  form  of  joint,  the  articular 
surfaces  are  moulded  to  each  other  in  such  a  manner  as  to  permit  motion  only  in 
two  directions,  forwards  and  backwards,  the  extent  of  motion  at  the  same  time 
being  considerable.  The  articular  surfaces  are  connected  together  bj  strong 
lateral  ligaments,  which  form  their  chief  bond  of  union.  The  most  perfect  forms 
of  ginglymi  are  the  elbow  and  ankle ;  the  knee  is  less  perfect,  as  it  allows  a  slight 
degree  of  rotation  in  certain  positions  of  the  limb :  there  are  also  the  metatarso- 
phalangeal and  phalangeal  joints  in  the  lower  extremity,  and  the  metacarpo-pha- 
langeal  and  phalangeal  joints  in  the  upper  extremity, 

Diarthrosis  rotatorius  or  Lateral  Ginglymus.  Where  the  movement  is  limited 
to  rotation,  the  joint  is  formed  by  a  pivot-like  process  turning  within  a  ring,  or 
the  ring  on  the  pivot,  the  ring  being  formed  partly  of  bone,  partly  of  ligament. 
In  the  articulation  of  the  odontoid  process  of  the  axis  with  the  atlas,  the  ring  is 
formed  in  front  by  the  anterior  arch  of  the  atlas;  behind,  by  the  transverse  liga- 
ment :  here  the  ring  rotates  round  the  odontoid  process.  In  the  superior  radio  • 
ulnar  articulation,  the  ring  is  formed  partly  by  the  lesser  sigmoid  cavity  of  the 
ulna ;  in  the  rest  of  its  extent,  by  the  orbicular  ligament :  here  the  head  of  the 
radius  rotates  within  the  ring. 

Subjoined,  in  a  tabular  form,  are  the  names,  distinctive  characters,  and  examples 
of  the  different  kinds  of  articulations. 


Synarthrosis  or  Im 
movable  Joint.  Sur- 
faces separated  by 
fibrous  membrane,  no 
intervening  synovial 
cavity,  and  immova- 
bly connected  with 
each  other. 

Example :  bones  of 
the  cranium  and  face, 
except  lower  jaw. 


S.  Dentata,  having 
tooth-like  processes. 
Interparietal      su  • 
ture. 

S.  Serrata,  having 
Sutura         vera  ^serrated    edges,   like 
'(true),  articulation  /the  teeth  of  a  saw. 
by  indented  bor-(     Interfrontal       su- 
ders.  \ture. 

I     S.  Limbosa,  having 
/bevelled        margins, 
I  and     dentated     pro- 
Sutura.     Arti-  \  I  cesses, 

culation  by  pro-  J  \      Fronto-parietal  su- 

cesses  and  i  ndent-  /  ture. 

ations  interlocked 
together. 

S.  Squamosa,  form- 
ed by  thin  bevelled 
margins  overlapping 
each  other. 
Sutura       notha  \     Temporo  -  parietal 
(false),  articulation  /suture. 
\by  rough  surfaces.  \     S.  Harmonia,  form- 
ed by  the  apposition 
of  contiguous  rough 
surfaces. 

Intermaxillary  su- 
ture. 

Schindylesis.  Articulation  formed  by  the  reception  of  a 
thin  plate  of  bone  into  a  fissure  of  another. 

Rostrum  of  sphenoid  with  vomer. 

Gomphosis.  An  articulation  formed  by  the  insertion  of 
a  conical  process  into  a  socket. 

Tooth  in  socket. 


SUBDIVISION   INTO   THREE    CLASSES.  187 

/     1.  Surfaces  connected  by  nbro-cartilage,  not  separated  by 
(  synovial  membrane,  and  having  limited  motion.     Bodies  of 
a  1  mpliiarthrosis,      )  vertebras. 
Mixed  Articulation.)      2.  Surfaces  covered  by  nbro-cartilage;  lined  by  a  partial 
(  synovial  membrane.     Sacro-iliac  and  pubic  symphyses. 

Arthrodia.  Gliding  joint ;  articulation  by  plane  surfaces, 
which  glide  upon  each  other.  As  in  sterno- clavicular  and 
acromio-clavicular  articulations. 

Enarthrosis.  Ball-and-socket  joint ;  capable  of  motion  in 
lall  directions.  Articulation  by  a  globular  head  received  into 
Diarthrosis,  '  a  cup-like  cavity.  As  in  hip  and  shoulder -joints. 
Movable  Joint.  /  Oinglymus.  Hinge  joint ;  motion  limited  to  two  directions, 
forwards  and  backwards.  Articular  surfaces  fitted  together 
/so  as  to  permit  of  movement  in  one  plane.  As  in  the  elbow, 
ankle,  andjaiee. 

Diarthrosis'  rotatorius.  Articulation  by  a  pivot  process 
turning  within  a  ring,  or  ring  around  a  pivot.  As  in  supe- 
Vrior  radio-ulnar  articulation,  and  atlo-axoid  joint. 

The  Kinds  of  Movement  admitted  in  Joints. 

The  movements  admissible  in  joints  may  be  divided  into  four  kinds,  gliding, 
angular  movement,  circumduction,  and  rotation. 

Gliding  movement  is  the  most  simple  kind  of  motion  that  can  take  place  in  a 
joint,  one  surface  gliding  over  another.  It  is  common  to  all  movable  joints ;  but 
in  some,  as  in  the  articulations  of  the  carpus  and  tarsus,  is  the  only  motion  per- 
mitted. This  movement  is  not  confiried  to  plane  surfaces,  but  may  exist  between 
any  two  contiguous  surfaces,  of  whatever  form,  limited  by  the  ligaments  which 
inclose  the  articulation. 

Angular  movement  occurs  only  between  the  long  bones,  and  may  take  place  in 
four  directions,  forwards  or  backwards,  constituting  flexion  and  extension,  or  inwards 
and  outwards,  which  constitutes  abduction  and  adduction.  Flexion  and  extension 
are  confined  to  the  strictly  ginglymoid  or  hinge-joints.  Abduction  and  adduction, 
combined  with  flexion  and  extension,  are  met  with  only  in  the  most  movable 
joints ;  as  in  the  hip,  shoulder,  and  metacarpal  joint  of  the  thumb,  and  partially 
in  the  wrist  and  ankle.  s 

Circumduction  is  that  limited  degree  of  motion  which  takes  place  between  the 
head  of  a  bone  and  its  articular  cavity,  whilst  the  extremity  and  sides  of  a  limb 
are  made  to  circumscribe  a  conical  space,  the  base  of  which  corresponds  with  the 
inferior  extremity  of  the  limb,  the  apex  with  the  articular  cavity ;  and  is  best  seen 
in  the  shoulder  and  hip-joints. 

Botation  is  the  movement  of  a  bone  upon  its  own  axis,  the  bone  retaining  the 
same  relative  situation  with  respect  to  the  adjacent  parts :  as  in  the  articulation 
between  the  atlas  and  axis,  where  the  odontoid  process  serves  as  a  pivot  around 
which  the  atlas  turns ;  or  in  the  rotation  of  the  radius  upon  the  humerus,  and  also 
in  the  hip  and  shoulder. 

The  articulations  may  be  arranged  into  those  of  the  trunk,  those  of  the  upper 
extremity,  and  those  of  the  lower  extremity. 


1 


188  ARTICULATIONS. 


ARTICULATIONS  OF  THE  TRUNK. 

These  may  be  divided  into  the  following  groups,  viz : — 

I.  Of  the  vertebral  column.  V.  Of  the  ribs  with  the  vertebras. 

II.  Of  the  atlas  with  the  axis.  VI.  Of  the  cartilages  of  the  ribs  with 

III.  Of  the  spine  with  the  cranium.  the  sternum,  and  with  each  other 

1.  Of  the  atlas  with  the  occipital  bone.    VII.  Of  the  sternum. 

2.  Of  the  axis  with  the  occipital  bone.    VIII.  Of  the  pelvis  with  the  spine. 

IV.  Of  the  lower  jaw.  IX.  Of  the  pelvis. 

I.  ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN. 

The  different  segments  of  the  spine  are  connected  together  by  ligaments,  which 
admit  of  the  same  arrangement  as  the  vertebrae.  They  may  be  divided  into  five 
sets.  1.  Those  connecting  the  bodies  of  the  vertebras.  2.  Those  connecting  the 
laminae.  3.  Those  connecting  the  articular  processes.  4.  The  ligaments  con- 
necting the  spinous  processes.     5.  Those  of  the  transverse  processes. 

The  articulation  of  the  bodies  of  the  vertebras  with  each  other  forms  a  series  of 
amphiarthrodial  joints ;  whilst  those  between  the  articular  processes  form  a  series 
of  arthrodial  joints. 

1.  The  Ligaments  of  the  Bodies. 

Anterior  Common  Ligament.  Posterior  Common  Ligament. 

Intervertebral  Substance. 

The  Anterior  Common  Ligament  (fig.  116)  is  a  broad  and  strong  band  of  liga- 
mentous fibres,  which  extends  along  the  front  surface  of  the  bodies  of  the  vertebras, 
from  the  axis  to  the  sacrum.  It  is  broader  below  than  above,  and  thicker  in  the 
dorsal  than  in  the  cervical  or  lumbar  regions ;  it  is  also  somewhat  thicker  opposite 
the  front  of  the  body  of  each  vertebra,  than  opposite  the  intervertebral  substance. 
It  is  attached,  above,  to  the  body  of  the  axis  by  a  pointed  process,  which  is  con- 
nected with  the  tendon  of  origin  of  the  Longus  colli  muscle ;  and  extends  down 
as  far  as  the  upper  bone  of  the  sacrum.  It  consists  of  dense  longitudinal  fibres, 
which  are  intimately  adherent  to  the  intervertebral  substance  and  prominent 
margins  of  the  vertebras,  but  less  closely  with  the  middle  of  the  bodies.  In  the 
latter  situation  the  fibres  are  exceedingly  thick,  and  serve  to  fill  up  the  concavities 
on  their  front  surface,  and  to  make  the  anterior  surface  of  the  spine  more  even, 
This  ligament  is  composed  of  several  layers  of  fibres,  which  vary  in  length, 
but  are  closely  interlaced  with  each  other.  The  most  superficial  or  longest  fibres 
extend  between  four  or  five  vertebras.  A  second  subjacent  set  extend  between 
two  or  three  vertebras;  whilst  a  third  set,  the  shortest  and  deepest,  extend  from 
one  vertebra  to  the  next.  At  the  sides  of  the  bodies,  this  ligament  consists  of  a 
few  short  fibres,  which  pass  from  one  vertebra  to  the  next,  separated  from  the 
median  portion  by  large  oval  apertures,  for  the  passage  of  vessels. 

The  Posterior  Common  Ligament  is  situated  within  the  spinal  canal,  and 
extends  along  the  posterior  surface  of  the  bodies  of  the  vertebras,  from  the  body 
of  the  axis  above,  where  it  is  continuous  with  the  occipito-axoid  ligament.,  to  the 
sacrum  below.  It  is  broader  at  the  upper  than  at  the  lower  part  of  the  spine, 
and  thicker  in  the  dorsal  than  in  the  cervical  or  lumbar  regions.  In  the  situation 
of  the  intervertebral  substance  and  contiguous  margins  of  the  vertebras,  where 
the  ligament  is  more  intimately  adherent,  it  is  broad,  and  presents  a  series  of 
dentations  with  intervening  concave  margins ;  but  it  is  narrow  and  thick  over  the 
centre  of  the  bodies,  from  which  it  is  separated  by  the  venae  basis  vertebrae.  This 
ligament  is  composed  of  smooth,  shining,  longitudinal  fibres,  denser  and  more  com- 
pact than  those  of  the  anterior  ligament,  and  composed  of  a  superficial  layer 


OF   THE   SPINE. 


189 


occupying  the  interval  between  three  or  four  vertebrae,  and  of  a  deeper  layer, 
which  extends  between  one  vertebra  and  the  next  adjacent  to  it.  It  is  separated 
from  the  dura  mater  of  the  spinal  cord  by  some  loose  filamentous  tissue,  very 
liable  to  serous  infiltration. 

The  Intervertebral  Substance  (fig.  116)  is  a  lenticular  disk  of  fibro-cartilage, 
interposed  between  the  adjacent  surfaces  of  the  bodies  of  the  vertebrae,  from  the 
axis  to  the  sacrum,  forming  the  chief  bond  of  connection  between  these  bones. 
These  disks  vary  in  shape,  size,  and  thickness,  in  different  parts  of  the  spine.  In 
shape,  they  accurately  correspond  with  the  surfaces  of  the  bodies  between  which 
they  are  placed,  being  oval  in  the  cervical  and  lumbar  regions,  circular  in  the  dorsal. 
Their  size  is  greatest  in  the  lumbar  region.  In  thinness,  they  vary  not  only  in 
the  different  regions  of  the  spine,  but  in  different  parts  of  the  same  region :  thus, 
they  are  uniformly  thick  in  the  lumbar  region ;  thickest,  in  front,  in  the  cervical 
and  lumbar  regions  which  are  convex  forwards ;  and  behind,  to  a  slight  extent 
in  the  dorsal  region.    They  thus  contribute,  in  a  great  measure,  to  the  curvatures 

Fig.  116. — Vertical  Section  of  two  Vertebrae  and  their  Ligaments,  from  the  Lumbar  Region. 


ANTERIOR 

POSTERIOR. 

COMMON 

COMMON 

lltf. 

IICT 

of  the  spine  in  the  neck  and  loins ;  whilst  the  concavity  of  the  dorsal  region  is 
chiefly  due  to  the  shape  of  the  bodies  of  the  vertebrae.  The  intervertebral  disks 
form  about  one-fourth  of  the  spinal  column,  exclusive  of  the  first  two  vertebrae ; 
they  are  not  equally  distributed,  however,  between  the  various  bones ;  the  dorsal 
portion  of  the  spine  having,  in  proportion  to  its  length,  a  much  smaller  quantity 
than  in  the  cervical  and  lumbar  regions,  which  necessarily  gives  to  the  latter  parts 
greater  pliancy  and  freedom  of  movement.  The  intervertebral  disks  are  adherent, 
by  their  surfaces,  to  the  adjacent  parts  of  the  bodies  of  the  vertebrae ;  and  by  their 
circumference  are  closely  connected  in  front  to  the  anterior,  and  behind  to  the 
posterior,  common  ligament ;  whilst,  in  the  dorsal  region,  they  are  connected 
laterally  to  the  heads  of  those  ribs  which  articulate  with  two  vertebrae,  by  means 
of  the  interarticular  ligament.  They,  consequently,  form  part  of  the  articular 
cavities  in  which  the  heads  of  these  bones  are  received. 

The  intervertebral  substance  is  composed,  at  its  circumference,  of  laminae  of 
fibrous  tissue  and  fibro-cartilage ;  and,  at  its  centre,  of  a  soft,  elastic,  pulpy  matter. 
The  laminae  are  arranged  concentrically  one  within  the  other,  with  their  edges 


190  ARTICULATIONS. 

turned  towards  the  corresponding  surfaces  of  the  vertebrae,  and  consist  of  alternate 
plates  of  fibrous  tissue  and  fibro- cartilage.  These  plates  are  not  quite  vertical  in 
their  direction,  those  near  the  circumference  being  curved  outwards  and  closely 
approximated,  whilst  those  nearest  the  centre  curve  in  the  opposite  direction,  and 
are  somewhat  more  widely  separated.  The  fibres  of  which  each  plate  is  composed 
are  directed,  for  the  most  part,  obliquely  from  above  downwards ;  the  fibres  of  an 
adjacent  plate  have  an  exactly  opposite  arrangement,  varying  in  their  direction  in 
every  layer ;  whilst  in  some  few  they  are  horizontal.  This  laminar  arrangement 
belongs  to  about  the  outer  half  of  each  disk,  the  central  part  being  occupied  by  a 
soft,  pulpy,  highly  elastic  substance,  of  a  yellowish  color,  which  rises  up  con- 
siderably above  the  surrounding  level,  when  the  disk  is  divided  horizontally. 
This  substance  presents  no  concentric  arrangement,  and  consists  of  white  fibrous 
tissue,  having  interspersed  cells  of  variable  shape  and  size.  The  pulpy  matter, 
which  is  especially  well  developed  in  the  lumbar  region,  is  separated  from  imme- 
diate contact  with  the  vertebrae,  by  the  interposition  of  thin  plates  of  cartilage. 

2.  Ligaments  connecting  the  Laminae. 
Ligamenta  Subflava. 

The  Ligamenta  Subflava  are  interposed  between  the  laminaa  of  the  vertebrae, 
from  the  axis  to  the  sacrum.  They  are  most  distinct  when  seen  from  the  interior 
of  the  spinal  canal ;  when  viewed  from  the  outer  surface,  they  appear  short,  being 
overlapped  by  the  laminae.  Each  ligament  consists  of  two  lateral  portions,  which 
commence  on  each  side  at  the  root  of  either  articular  process,  and  pass  backwards 
to  the  point  where  the  laminae  converge  to  form  the  spinous  process,  where  their 
margins  are  thickest,  and  separated  by  a  slight  interval,  filled  up  with  areolar 
tissue.  These  ligaments  consist  of  yellow  elastic  tissue,  the  fibres  of  which,  almost 
perpendicular  in  direction,  are  attached  to  the  anterior  surface  of  the  margin  of  the 
lamina  above,  and  to  the  posterior  surface,  as  well  as  to  the  margin,  of  the  lamina 
below.  In  the  cervical  region,  they  are  thin  in  texture,  but  very  broad  and  long ; 
they  become  thicker  in  the  dorsal  region,  and  in  the  lumbar  acquire  very  consi- 
derable thickness.  Their  highly  elastic  property  serves  to  preserve  the  upright 
posture,  and  to  counteract  the  efforts  of  the  flexor  muscles  of  the  spine.  These 
ligaments  do  not  exist  between  the  occiput  and  atlas,  or  between  the  atlas  and  axis, 

3.  Ligaments  connecting  the  Articular  Process. 

Capsular. 

The  Capsular  Ligaments  are  thin  and  loose  ligamentous  sacs,  attached  to  the 
contiguous  margins  of  the  articulating  processes  of  each  vertebra,  through  the 
greater  part  of  their  circumference,  and  completed  internally  by  the  ligamenta 
subflava.  They  are  longer  and  more  loose  in  the  cervical  than  in  the  dorsal  or 
lumbar  regions.  The  capsular  ligaments  are  lined  on  their  inner  surface  by 
synovial  membrane. 

4.  Ligaments  connecting  the  Spinous  Processes. 

Inter-spinous.  Supra-spinous. 

The  Inter-spinous  Ligaments,  thin  and  membranous,  are  interposed  between  the 
spinous  processes  in  the  dorsal  and  lumbar  regions.  Each  ligament  extends  from 
the  root  to  near  the  summit  of  each  spinous  process,  and  connects  together  their 
adjacent  margins.  They  are  narrow  and  elongated  in  the  dorsal  region,  broader, 
quadrilateral  in  form,  and  thicker  in  the  lumbar  region. 

The  Supraspinous  Ligament  is  a  strong  fibrous  cord,  which  connects  together 
the  apices  of  the  spinous  processes  from  the  seventh  cervical  to  the  spine  of  the 
sacrum.  It  is  thicker  and  broader  in  the  lumbar  than  in  the  dorsal  region,  and 
intimately  blended,  in  both  situations,  with  the  neighboring  aponeuroses.     The 


OF   THE   ATLAS   WITH   THE   AXIS.  191 

most  superficial  fibres  of  this  ligament  connect  three  or  four  vertebras;  those 
deeper  seated  pass  between  two  or  three  vertebras ;  whilst  the  deepest  connect  the 
contiguous  extremities  of  neighboring  vertebras. 

5.  Ligaments  connecting  the  Transverse  Processes. 
Inter-transverse. 

The  Inter-transverse  Ligaments  consist  of  a  few  thin  scattered  fibres,  interposed 
between  the  transverse  processes.  They  are  generally  wanting  in  the  cervical 
region;  in  the  dorsal,  they  are  rounded  cords;  in  the  lumbar  region,  thin  and 
membranous. 

Actions.  The  movements  permitted  in  the  spinal  column  are,  Flexion,  Exten- 
sion, Lateral  movement,  Circumduction,  and  Eotation. 

In  Flexion  or  movement  of  the  spine  forwards,  the  anterior  common  ligament 
is  relaxed,  and  the  intervertebral  substances  are  compressed  in  front;  the  posterior 
common  ligament,  the  ligamenta  subflava,  and  the  inter-spinous  and  supra-spinous 
ligaments  are  stretched,  as  well  as  the  posterior  fibres  of  the  intervertebral  disks. 
The  interspaces  between  the  laminae  are  widened,  and  the  inferior  articular  pro- 
cesses glide  upwards,  upon  the  articular  processes  of  the  vertebras  below.  Flexion 
is  the  most  extensive  of  all  the  movements  of  the  spine. 

In  Extension  or  movement  of  the  spine  backwards,  an  exactly  opposite  dispo- 
sition of  the  parts  takes  place.  This  movement  is  not  extensive,  being  limited  by 
the  anterior  common  ligament,  and  by  the  approximation  of  the  spinous  processes. 

Flexion  and  extension  are  most  free  in  the  lower  part  of  the  lumbar,  and  in  the 
cervical  regions ;  extension  in  the  latter  region  being  greater  than  flexion,  the 
reverse  of  which  exists  in  the  lumbar  region.  These  movements  are  least  free  in 
the  middle  and  upper  part  of  the  back. 

In  Lateral  Movement,  the  sides  of  the  intervertebral  disks  are  compressed,  the 
extent  of  motion  being  limited  by  the  resistance  offered  by  the  surrounding  liga- 
ments, and  by  the  approximation  of  the  transverse  processes.  This  movement 
may  take  place  in  any  part  of  the  spine,  but  is  most  free  in  the  neck  and  loins. 

Circumduction  is  very  limited,  and  is  produced  merely  by  a  succession  of  the 
preceding  movements. 

Rotation  is  produced  by  the  twisting  of  the  intervertebral  substances;  this, 
although  only  slight  between  any  two  vertebras,  produces  great  extent  of  move- 
ment, when  it  takes  place  in  the  whole  length  of  the  spine,  the  front  of  the  column 
being  turned  to  one  or  the  other  side.  This  movement  takes  place  only  to  a  slight 
extent  in  the  neck,  but  is  more  free  in  the  lower  part  of  the  dorsal  and  lumbar 
regions. 

It  is  thus  seen,  that  the  cervical  region  enjoys  the  greatest  extent  of  each  variety 
of  movement,  flexion  and  extension  being  very  free ;  lateral  movement  and  rota- 
tion, although  less  extensive  than  the  former,  being  greater  than  in  any  other 
region.  In  the  dorsal  region,  especially  at  its  upper  part,  the  movements  are  most 
limited ;  flexion,  extension,  and  lateral  motion  taking  place  only  to  a  slight  extent. 
In  the  lumbar  region,  all  the  movements  are  very  free. 

II.  ARTICULATION  OF  THE  ATLAS  WITH  THE  AXIS. 

The  articulation  of  the  anterior  arch  of  the  atlas  with  the  odontoid  process  forms 
a  lateral  ginglymoid  joint,  whilst  that  between  the  articulating  processes  of  the 
two  bones  forms  a  double  arthrodia.     The  ligaments  of  this  articulation  are  the 

Two  Anterior  Atlo-axoid.  Transverse. 

Posterior  Atlo-axoid.  Two  Capsular. 

Of  the  Two  Anterior  Atlo-axoid  Ligaments  (fig.  117),  the  most  superficial  is  a 
rounded  cord,  situated  in  the  middle  iine ;  attached,  above,  to  the  tubercle  on  the 
anterior  arch  of  the  atlas ;  below,  to  the  base  of  the  odontoid  process  and  body  of 
the  axis.     The  deeper  ligament  is  a  membranous  layer,  attached,  above,  to  the 


192 


ARTICULATIONS. 


lower  border  of  the  anterior  arch  of  the  atlas ;  below,  to  the  base  of  the  odontoid 
process,  and  body  of  the  axis.  These  ligaments  are  in  relation,  in  front,  with  the 
.Recti  antici  majores. 

Fig.  117. — Occipito-atloid  and  Atlo-axoid  Ligaments.     Anterior  View. 


10 J         CAPSULAR     LICT    It 

J        SYNOVIAL   M  EMORANS 


AXOIO  f      CAPSULAR     LICT    6c 

SYNOVIAL  MEMO  RAN  6 


Fig.  118. — Occipito-atloid  and  Atlo-axoid  Ligaments.     Posterior  View. 


Arch  forjiaasagi  ofVeTuLraZAra 
&,  1t?  Ct-rvical  i 


The  Posterior  Atlo-axoid  Ligament  (fig.  118)  is  a  broad  and  thin  membranous 
Layer,  attached,  above,  to  the  lower  border  of  the  posterior  arch  of  the  atlas ; 


OF   THE   SPINE   WITH   THE   CRANIUM. 


193 


below,  to  the  upper  edge  of  the  lamina  of  the  axis.  This  ligament  supplies  the 
place  of  the  ligamenta  subflava,  and  is  in  relation,  behind,  with  the  Inferior  oblique 
muscles. 

The  Transverse  Ligament  (figs.  119  and  120)  is  a  thick  and  strong  ligamentous 
band,  which  arches  across  the  ring  of  the  atlas,  and  serves  to  retain  the  odontoid 
process  in  firm  connection  with  its  anterior  arch.  This  ligament  is  flattened  from 
before  backwards,  broader  and  thicker  in  the  middle  than  at  either  extremity,  and 
firmly  attached  on  each  side  of  the  atlas  to  a  small  tubercle  on  the  inner  surface  of 
each  of  its  lateral  masses.  As  it  crosses  the  odontoid  process,  a  small  fasciculus 
is  derived  from  its  upper  and  lower  borders ;  the  former  passing  upwards,  to  be 
inserted  into  the  basilar  process  of  the  occipital  bone ;  the  latter  downwards,  to 

Fig.  119. — Articulation  between  Odontoid  Process  and  Atlas. 


be  attached  to  the  root  of  the  odontoid  process :  hence,  this  ligament  has  received 
the  name  of  cruciform.  The  transverse  ligament  divides  the  ring  of  the  atlas  into 
two  unequal  parts :  of  these,  the  posterior  and  larger  serves  for  the  transmission 
of  the  coed  and  its  membranes ;  the  anterior  and  smaller  serving  to  retain  the 
odontoid  process  in  its  position.  The  lower  border  of  the  space  between  the  atlas 
and  transverse  ligament  being  smaller  than  the  upper,  on  account  of  the  transverse 
ligament  embracing  firmly  the  narrow  neck  of  the  odontoid  process,  this  process 
is  retained  in  firm  connection  with  the  atlas  when  all  the  other  ligaments  have 
been  divided. 

The  Capsular  Ligaments  are  two  thin  and  loose  capsules,  connecting  the  articu- 
lar surfaces  of  the  atlas  and  axis,  the  fibres  being  strongest  on  the  anterior  and 
external  part  of  the  articulation. 

There  are  four  Synovial  Membranes  in  this  articulation.  One  lining  the  inner 
surface  of  each  of  the  capsular  ligaments ;  one  between  the  anterior  surface  of  the 
odontoid  process  and  anterior  arch  of  the  atlas ;  and  one  between  the  posterior 
surface  of  the  odontoid  process  and  the  transverse  ligament.  The  latter  often 
communicates  with  those  between  the  condyles  of  the  occipital  bone  and  the 
articular  surfaces  of  the  atlas. 

Actions.  This  joint  is  capable  of  great  mobility,  and  allows  the  rotation  of  the 
atlas,  and,  with  it,  of  the  cranium  upon  the  axis,  the  extent  of  rotation  being 
limited  by  the  odontoid  ligaments. 


III.  ARTICULATION  OF  THE  SPINE  WITH  THE  CRANIUM. 

The  ligaments  connecting  the  spine  with  the  cranium  may  be  divided  into  two 
sets :  1.  Those  connecting  the  occipital  bone  with  the  atlas ;  2.  Those  connecting 
the  occipital  bone  with  the  axis. 
13 


194 


ARTICULATIONS. 


1.  Articulation  of  the  Atlas  with  the  Occipital  Bone. 

This  articulation  is  a  double  arthrodia.     Its  ligaments  are  the 

Two  Anterior  Occipito-atloid. 
Posterior  Occipito-atloid. 
Two  Lateral  Occipito-atloid. 
Two  Capsular. 

Of  the  Two  Anterior  Ligaments  (fig.  117),  the  most  superficial  is  a  strong 
narrow,  rounded  cord,  attached,  above,  to  the  basilar  process  of  the  occiput; 
below,  to  the  tubercle  on  the  anterior  arch  of  the  atlas :  the  deeper  ligament  is  a 
broad  and  thin  membranous  layer,  which  passes  between  the  anterior  margin  of 
the  foramen  magnum  above,  and  the  whole  length  of  the  upper  border  of  the 
anterior  arch  of  the  atlas  below.  This  ligament  is  in  relation,  in  front,  with  the 
Recti  antici  minores ;  behind,  with  the  odontoid  ligaments. 

The  Posterior  Occipito-atloid  Ligament  (fig.  118)  is  a  very  broad  but  thin  mem- 
branous lamina,  intimately  blended  with  the  dura  mater.  It  is  connected,  above, 
to  the  posterior  margin  of  the  foramen  magnum;  below,  to  the  upper  border  of 
the  posterior  arch  of  the  atlas.  This  ligament  is  incomplete  at  each  side,  and 
forms,  with  the  superior  intervertebral  notch,  an  opening  for  the  passage  of  the 
vertebral  artery  and  suboccipital  nerve.  It  is  in  relation,  behind,  with  the  Recti 
postici  minores  and  Obliqui  superiores;  in  front,  with  the  dura  mater  of  the  spinal 
canal,  to  which  it  is  intimately  adherent. 

Fig.  120. — Occipito-axoid  and  Atlo-axoid  Ligaments.    Posterior  View. 


He  Vertical  fierfitn 

&/OOONTCID     LIC:? 


OCCIXTOI    CAPSULAR     LICT     A 

atlOiD  j  Synovial  membrane 


ATLO-f    CAPSULAR     LICT     s, 
MOID  [Synovia  I  membrane 


The  Lateral  Ligaments  are  strong  fibrous  bands,  directed  obliquely  upwards 
and  inwards,  attached,  above,  to  the  jugular  process  of  the  occipital  bone;  below, 
to  the  base  of  the  transverse  process  of  the  atlas. 

The  Capsular  Ligaments  surround  the  condyles  of  the  occipital  bone,  and  con- 
dect  them  with  the  articular  surfaces  of  the  atlas ;  they  consist  of  thin  and  loose 
capsules,  which  inclose  the  synovial  membrane  of  the  articulation.  The  synovial 
membranes  between  the  occipital  bone  and  atlas  communicate  occasionally  with 


TEMPORO-MAXILLARY.  195 

that  between  the  posterior  surface  of  the  odontoid  process  and  transverse  liga- 
ment. 

Actions.  The  movements  permitted  in  this  joint  are  flexion  and  extension, 
which  give  rise  to  the  ordinary  forward  or  backward  nodding  of  the  head,  besides 
slight  lateral  motion  to  one  or  the  other  side.  When  either  of  these  actions  is 
carried  beyond  a  slight  extent,  the  whole  of  the  cervical  portion  of  the  spine 
assists  in  its  production. 

2.  Articulation  of  the  Axis  with  the  Occipital  Bone. 
Occipito-axoid.  Three  Odontoid. 

To  expose  these  ligaments,  the  spinal  canal  should,  be  laid  open  by  removing 
the  posterior  arch  of  the  atlas,  the  laminae  and  spinous  process  of  the  axis,  and  that 
portion  of  the  occipital  bone  behind  the  foramen  magnum,  as  seen  in  fig.  120. 

The  Occipito-axoid  Ligament  (Apparatus  ligamentosus  colli)  is  situated  at  the 
upper  part  of  the  front  surface  of  the  spinal  canal.  It  is  a  broad  and  strong 
ligamentous  band,  which  covers  the  odontoid  process  and  its  ligaments,  and  appears 
to  be  a  prolongation  upwards  of  the  posterior  common  ligament  of  the  spine.  It 
is  attached,  below,  to  the  posterior  surface  of  the  body  of  the  axis,  and  becoming 
expanded  as  it  ascends,  is  inserted  into  the  basilar  groove  of  the  occipital  bone,  in 
front  of  the  foramen  magnum. 

Relations.  By  its  anterior  surface,  it  is  intimately  connected  with  the  transverse 
ligament ;  by  its  posterior  surface  with  the  dura  mater.  By  dividing  this  ligament 
transversely  across,  and  turning  its  ends  aside,  the  transverse  and  odontoid  liga- 
ments are  exposed. 

The  Odontoid  or  Check  Ligaments  are  strong  rounded  fibrous  cords,  which 
arise  one  on  either  side  of  the  apex  of  the  odontoid  process,  and  passing  obliquely 
upwards  and  outwards,  are  inserted  into  the  rough  depressions  on  the  inner  side 
of  the  condyles  of  the  occipital  bone.  In  the  triangular  interval  left  between  these 
ligaments  and  the  margin  of  the  foramen  magnum,  a  third  strong  ligamentous 
band  (ligamentum  suspensorium)  may  be  seen,  which  passes  almost  perpendicularly 
from  the  apex  of  the  odontoid  process  to  the  anterior  margin  of  the  foramen,  being 
intimately  blended  with  the  anterior  occipito-atloid  ligament,  and  upper  fasciculus 
of  the  transverse  ligament  of  the  atlas. 

Actions.  The  odontoid  ligaments  serve  to  limit  the  extent  to  which  rotation 
of  the  cranium  may  be  carried ;  hence  they  have  received  the  name  of  check 
ligaments. 

IY.    TEMPORO-MAXILLARY"  ARTICULATION. 

This  articulation  is  a  double  arthrodia.  The  parts  entering  into  its  formation 
are,  on  each  side,  the  anterior  part  of  the  glenoid  cavity  of  the  temporal  bone  and 
the  eminentia  articularis  above;  with  the  condyle  of  the  lower  jaw  below.  The 
ligaments  are  the  following: — 

External  Lateral.  Stylo-maxillary. 

Internal  Lateral.  Capsular. 

Interarticular  Fibro-cartilage. 

The  External  Lateral  Ligament  (fig.  121)  is  a  short,  thin,  and  narrow  fasciculus, 
attached  above  to  the  outer  surface  of  the  zygoma  and  to  the  rough  tubercle  on 
its  lower  border ;  below,  to  the  outer  surface  and  posterior  border  of  the  neck 
of  the  lower  jaw.  This  ligament  is  broader  above  than  below;  its  fibres  are 
placed  parallel  with  one  another,  and  directed  obliquely  downwards  and  back- 
wards. Externally,  it  is  covered  by  the  parotid  gland  and  by  the  integument. 
Internally,  it  is  in  relation  with  the  interarticular  fibro-cartilage  and  the  synovial 
membranes. 


196 


ARTICULATIONS. 


The  Internal  Lateral  Ligament  (fig.  122)  is  a  long,  thin,  and  loose  "band, 
attached  above  to  the  spinous  process  of  the  sphenoid  bone,  and,  becoming  broader 
as  it  descends,  is  inserted  into  the  inner  margin  of  the  dental  foramen.     Its  outer 

Fig.  121. — Temporo-maxillary  Articulation.     External  View. 

si 


surface  is  in  relation  above  with  the  External  pterygoid  muscle;  lower  down  it  is 
separated  from  the  neck  of  the  condyle  by  the  internal  maxillary  artery;  and  still 

more  inferiorly  the  in- 
Fig.  122. — Temporo-maxillary  Articulation.    Internal  View.  ferior  dental  vessels  and 

nerve  separate  it  from 
the  ramus  of  the  jaw. 
Internally  it  is  in  rela- 
tion with  the  Internal 
pterygoid. 

The  Stylo-maxillary 
Ligament  is  a  thin  apo- 
neurotic cord,  which  ex- 
tends from  near  the  apex  ' 
of  the  styloid  process  of 
the  temporal  bone,  to 
the  angle  and  posterior 
border  of  the  ramus  of 
the  lower  jaw,  between 
the  Masseter  and  In- 
ternal pterygoid  mus- 
cles. This  ligament 
separates  the  parotid 
from  the  submaxillary 
gland,  and  has  attached 
to  its  inner  side,  part  of 
the  fibres  of  origin  of 
the  Stylo-glossus  muscle.  Although  usually  classed  among  the  ligaments  of  the 
law,  it  can  only  be  considered  as  an  accessory  in  the  articulation. 


TEMP  ORO-M  AXILLARY. 


197 


Articulation. 


The  Capsular  Ligament  consists  of  a  thin  and  loose  ligamentous  capsule, 
attached  above  to  the  circumference  of  the  glenoid  cavity  and  the  articular  surface 
immediately  in  front;  below,  to  the  neck  of  the  condyle  of  the  lower  jaw.  It 
consists  of  a  few,  thin  scattered  fibres,  and  can  hardly  be  considered  as  a  distinct 
ligament ;  it  is  thickest  at  the  back  part  of  the  articulation. 

The  Interarticular  fibro-cartilage  (fig.  123)  is  a  thin  plate  of  an  oval  form, 
placed  horizontally  between  the  condyle  of  the  jaw  and  the  glenoid  cavity.  Its 
upper  surface  is  concave  from  before  backwards,  and  a  little  convex  transversely, 
to  accommodate  itself  to  the  form  of 

the  glenoid  cavity.     Its  under  sur-  s*ction  of  Temporo-m 

face,  where  it  is  in  contact  with  the 
condyle,  is  concave.  Its  circumfer- 
ence is-  connected  externally  to  the 
external  lateral  ligament,  internally 

to  the  capsular  ligament ;  and  in  front  ^^         '  KSPf^^  / 

to  the  tendon  of  the  External  ptery-  ^ 

goid  muscle.  It  is  thicker  at  its  cir- 
cumference, especially  behind,  than 
at  its  centre,  where  it  is  sometimes 
perforated.  The  fibres  of  which  it 
is  composed  have  a  concentric  ar- 
rangement, more  apparent  at  the  cir- 
cumference than  at  the  centre.  Its 
surfaces  are  smooth,  and  divide  the 
joint  into  two  cavities,  each  of  which 

is  furnished  with  a  separate  synovial  membrane.     When  the  fibro-cartilage  is 
perforated,  the  synovial  membranes  are  continuous  with  one  another. 

The  Synovial  Membranes,  two  in  number,  are  placed  one  above,  and  the  other 
below,  the  fibro-cartilage.  The  upper  one,  the  larger  and  looser  of  the  two,  is  con- 
tinued from  the  margin  of  the  cartilage  covering  the  glenoid  cavity  and  eminentia 
articularis,  over  the  upper  surface  of  the  fibro-cartilage.  The  lower  one  is  inter- 
posed between  the  under  surface  of  the  fibro-cartilage  and  the  condyle  of  the  jaw, 
being  prolonged  downwards  a  little  further  behind  than  in  front. 

The  Nerves  of  this  joint  are  derived  from  the  auriculo-temporal,  and  masseteric 
branches  of  the  inferior  maxillary. 

Actions.  The  movements  permitted  in  this  articulation  are  very  extensive. 
Thus,  the  jaw  may  be  depressed  or  elevated,  or  it  may  be  carried  forwards  or 
backwards,  or  from  side  to  side.  It  is  by  the  alternation  of  these  movements 
performed  in  succession,  that  a  kind  of  rotatory  movement  of  the  lower  jaw  upon 
the  upper  takes  place,  which  materially  assists  in  the  mastication  of  the  food. 

If  the  movement  of  depression  is  carried  only  to  a  slight  extent,  the  condyles 
remain  in  the  glenoid  cavities,  their  anterior  part  descending  only  to  a  slight  extent ; 
but  if  depression  is  considerable,  the  condyles  glide  from  the  glenoid  fossae  on  to 
the  eminentia  articularis,  carrying  with  them  the  interarticular  fibro-cartilages. 
When  this  movement  is  carried  to  too  great  an  extent,  as,  for  instance,  during  a 
convulsive  yawn,  dislocation  of  the  condyle  into  the  zygomatic  fossa  occurs;  the 
interarticular  cartilage  being  carried  forwards,  and  the  capsular  ligament  rup- 
tured. When  the  jaw  is  elevated,  the  condyles  and  fibro-cartilages  are  carried 
backwards  into  their  original  position.  When  the  jaw  is  carried  forwards  or 
backwards,  a  horizontal  gliding  movement  of  the  fibro-cartilages  and  condyles 
upon  the  glenoid  cavities  takes  place  in  the  antero-posterior  direction  j  whilst  in 
the  movement  from  side  to  side,  this  occurs  in  the  lateral  direction. 


Y.  ARTICULATION  OF  THE  RIBS  WITH  THE  VERTEBRAE. 

The  articulation  of  the  ribs  with  the  vertebral  column  may  be  divided  into  two 
sets.     1.  Those  which  connect  the  heads  of  the  ribs  with  the  bodies  of  the  verte- 


198 


ARTICULATIONS. 


Fig.  124. — Costovertebral  and  Costo-transverse  Articulations. 
Anterior  View. 


brae ;    2.  Those  which  connect  the  neck  and  tubercle  of  the  ribs  with  the  trans- 
verse processes. 

1.  Akticulation  between  the  Heads  of  the  Ribs  and  the  Bodies 

OF  THE  VeKTEBB^!. 

These  constitute  a  series  of  angular  ginglymoid  joints,  formed  by  the  articula- 
tion of  the  heads  of  the  ribs  with  the  cavities  on  the  contiguous  margins  of  the 
bodies  of  the  dorsal  vertebrae,  connected  together  by  the  following  ligaments : — 

Anterior  Costo- vertebral  or  Stellate. 

Capsular. 

Interarticular. 

The  Anterior  Costo-vertebral  or  Stellate  Ligament  (fig.  124)  connects  the  anterior 

part  of  the  head  of  each 
rib,  with  the  sides  of  the 
bodies  of  the  vertebrae, 
and  the  intervening  in- 
tervertebral disk.  It  con- 
sists of  three  flat  bundles 
of  ligamentous  fibres, 
which  radiate  from  the 
anterior  part  of  the  head 
of  the  rib.  The  superior 
fasciculus  passes  up- 
wards to  be  connected 
with  the  body  of  the 
vertebra  above ;  the  in- 
ferior one  descends  to 
the  body  of  the  vertebra 
below;  and  the  middle 
one,  the  smallest  and 
least  distinct,  passes  ho- 
rizontally inwards  to  be 
attached  to  the  interver- 
tebral substance. 

delations.  In  front, 
with  the  thoracic  ganglia 
of  the  sympathetic,  the 
pleura,  and,  on  the  right 
side,  with  the  vena  azygos  major ;  behind,  with  the  interarticular  ligament  and 
synovial  membranes. 

In  the  first  rib,  which  articulates  with  a  single  vertebra  only,  this  ligament  does 
not  present  a  distinct  division  into  three  fasciculi ;  its  superior  fibres,  however, 
pass  to  be  attached  to  the  body  of  the  last  cervical  vertebra,  as  well  as  to  the 
body  of  the  vertebra  with  which  the  rib  articulates.  In  the  eleventh  and  twelfth 
ribs,  which  also  articulate  with  a  single  vertebra,  the  same  division  does  not  exist ; 
but  the  upper  fibres  of  the  ligament,  in  each  case,  are  connected  with  the  vertebra 
above,  as  well  as  to  that  with  which  the  ribs  articulate. 

The  Capsular  Ligament  is  a  thin  and  loose  ligamentous  bag,  which  surrounds 
the  joint  between  the  head  of  the  rib  and  the  articular  cavity  formed  by  the  junc- 
tion of  the  vertebrae.  It  is  very  thin,  firmly  connected  with  the  anterior  ligament, 
and  most  distinct  at  the  upper  and  lower  parts  of  the  articulation. 

The  Interarticular  Ligament  is  situated  in  the  interior  of  the  joint.  It  consists 
of  a  short  band  of  fibres,  flattened  from  above  downwards,  attached  by  one  extremity 
to  the  sharp  crest  on  the  head  of  the  rib,  and  by  the  other  to  the  intervertebral 
disk.  It  divides  the  joint  into  two  cavities,  which  have  no  communication  with 
one  another,  and  are  each  lined  by  a  separate  synovial  membrane.     In  the  first. 


Xju.tr  SytiovtaZ 


COSTO-  TRANSVERSE. 


199 


eleventh,  and  twelfth  ribs,  the  interarticular  ligament  does  not  exist;  consequently, 
there  is  but  one  synovial  membrane. 

Actions.  The  movements  permitted  in  these  articulations  are  limited  to  eleva- 
tion, depression,  and  slightly  forwards  and  backwards.  This  movement  varies, 
however,  very  much  in  its  extent  in  different  ribs.  The  first  rib  is  almost  entirely 
immovable,  excepting  in  deep  inspiration.  The  movement  of  the  second  rib  is 
also  not  very  extensive.  In  the  other  ribs,  their  mobility  increases  successively 
to  the  last  two,  which  are  very  movable.  The  ribs  are  generally  more  movable 
in  the  female  than  in  the  male. 

2.  Articulation  between  the  Neck  and  Tubercle  of  the  Ribs  with 
the  Transverse  Processes. 

The  ligaments  connecting  these  parts,  are : — 

Anterior  Costo-transverse. 

Middle  Costo-transverse  (Interosseous). 

Posterior  Costo-transverse. 

Capsular. 

The  Anterior  Costo-transverse  Ligament  (fig.  125)  is  a  broad  and  strong  band 
of  fibres,  attached,  below,  to  the  sharp  crest  on  the  upper  border  of  the  neck  of 
each  rib,  and  passing  obliquely  upwards  and  outwards,  to  the  lower  border  of  the 


Fig.  125. — Costo-transverse  Articulation.    Seen  from  above. 


ANTERIO*  COSTO-TRANSVERSE  LI  C 


MIDDLE    COSTO-TRANSVERSE   or, 
INTEROSSEOUS 


SYNOVIAL    CAVITY 


POSTERIOR  COSTO-TRANSVERSE 


CAPSULAR    MEMBRANC 


transverse  process  immediately  above.  It  is  broader  below  than  above,  broader 
and  thinner  between  the  lower  ribs  than  between  the  upper,  and  more  distinct  in 
front  than  behind.  This  ligament  is  in  relation,  in  front,  with  the  intercostal 
vessels  and  nerves;  behind,  with  the  Longissimus  dorsi.  Its  internal  border 
completes  an  aperture  formed  between  it  and  the  articular  processes,  through 
which  pass  the  posterior  branches  of  the  intercostal  vessels  and  nerves.  Its  ex- 
ternal border  is  continuous  with  a  thin  aponeurosis,  which  covers  the  External 
intercostal  muscle. 

The  first  and  last  ribs  have  no  anterior  costo-transverse  ligament. 

The  Middle  Costo-transverse  or  Interosseous  Ligament  consists  of  short,  but 
strong,  fibres,  which  pass  between  the  rough  surface  on  the  posterior  part  of  the 


200  ARTICULATIONS. 

neck  of  each  rib,  and  the  anterior  surface  of  the  adjacent  transverse  process.  In 
order  fully  to  expose  this  ligament,  a  horizontal  section  should  be  made  across 
the  transverse  process  and  corresponding  part  of  the  rib ;  or  the  rib  may  be 
forcibly  separated  from  the  transverse  process,  and  its  fibres  torn  asunder. 

In  the  eleventh  and  twelfth  ribs,  this  ligament  is  quite  rudimentary. 

The  Posterior  Costo-transverse  Ligament  is  a  short,  but  thick  and  strong  fasci- 
culus, which  passes  obliquely  from  the  summit  of  the  transverse  process  to  the 
rough  non-articular  portion  of  the  tubercle  of  the  rib.  This  ligament  is  shorter 
and  more  oblique  in  the  upper  than  in  the  lower  ribs.  Those  corresponding  to 
the  superior  ribs  ascend,  and  those  of  the  inferior  ones  slightly  descend. 

In  the  eleventh  and  twelfth  ribs,  this  ligament  is  wanting. 

The  articular  portions  of  the  tubercle  of  the  rib,  and  adjacent  transverse  pro- 
cess, form  an  arthrodial  joint,  provided  with  a  thin  capsular  ligament  attached  to 
the  circumference  of  the  articulating  surfaces,  and  inclosing  a  small  synovial 
membrane. 

In  the  eleventh  and  twelfth  ribs,  this  articulation  is  wanting. 

Actions.  The  movement  permitted  in  these  joints  is  limited  to  a  slight  gliding 
motion  of  the  articular  surfaces  one  upon  the  other. 


VI.  ARTICULATION   OF  THE  CARTILAGES   OF  THE  RIBS  WITH  THE 

STERNUM. 

The  articulations  of  the  cartilages  of  the  true  ribs  with  the  sternum  are  arthro- 
dial joints.     The  ligaments  connecting  them  are : — 

Anterior  Costo-sternal. 
Posterior  Costo-sternal. 
Capsular. 

The  Anterior  Costo-sternal  Ligament  (fig.  126)  is  a  broad  and  thin  membranous 
band  that  radiates  from  the  inner  extremity  of  the  cartilages  of  the  true  ribs,  to 
the  anterior  surface  of  the  sternum.  It  is  composed  of  fasciculi,  which  pass  in 
different  directions.  The  superior  fasciculi  ascend  obliquely,  the  inferior  pass 
obliquely  downwards,  and  the  middle  fasciculi  horizontally.  The  superficial  fibres 
of  this  ligament  are  the  longest ;  they  intermingle  with  the  fibres  of  the  ligaments 
above  and  below  them,  with  those  of  the  opposite  side,  and  with  the  tendinous 
fibres  of  origin  of  the  Pectoralis  major ;  forming  a  thick  fibrous  membrane,  which 
covers  the  surface  of  the  sternum.  This  is  more  distinct  at  the  lower  than  at  the 
upper  part. 

The  Posterior  Costo-sternal  Ligament*  less  thick  and  distinct  than  the  anterior, 
is  composed  of  fibres  which  radiate  from  the  posterior  surface  of  the  sternal  end 
of  the  cartilages  of  the  true  ribs,  to  the  posterior  surface  of  the  sternum,  becom- 
ing blended  with  the  periosteum. 

The  Capsular  Ligament  surrounds  the  joints  formed  between  the  cartilages  of 
the  true  ribs  and  the  sternum.  It  is  very  thin,  intimately  blended  with  the 
anterior  and  posterior  ligaments,  and  strengthened  at  the  upper  and  lower  part 
of  the  articulation  by  a  few  fibres,  which  pass  from  the  cartilage  to  the  side  of 
the  sternum.     These  ligaments  protect  the  synovial  membranes. 

Synovial  Membranes.  The  cartilage  of  the  first  rib  is  directly  continuous  with 
the  sternum,  the  synovial  membrane  being  absent.  The  cartilage  of  the  second 
rib  is  connected  with  the  sternum  by  means  of  an  interarticular  ligament,  attached 
by  one  extremity  to  the  cartilage  of  the  second  rib,  and  by  the  other  extremity 
to  the  cartilage  which  unites  the  first  and  second  pieces  of  the  sternum.  This 
articulation  is  provided  with  two  synovial  membranes.  That  of  the  third  rib  has 
also  two  synovial  membranes;  and  that  of  the  fourth,  fifth,  sixth,  and  seventh, 
each  a  single  synovial  membrane.  Thus  there  are  eight  synovial  cavities  in  the 
articulations  between  the  costal  cartilages  of  the  true  ribs  and  the  sternum.    They 


COSTO-STERNAL  AND   INTERCOSTAL. 


201 


may  be  demonstrated  by  removing  a  thin  section  from  the  anterior  surface  of  the 
sternum  and  cartilages,  as  seen  in  fig.  126.  After  middle  life,  the  articular 
surfaces  lose  their  polish,  become  roughened,  and  the  synovial  membranes  appear 
to  be  wanting.  In  old  age,  the  articulations  do  not  exist,  the  cartilages  of  most 
of  the  ribs  becoming  firmly  united  to  the  sternum.     The  cartilage  of  the  seventh 


Fig.  126. — Costo^sternal,  Costo-xiphoid,  and  Intercostal  Articulations.    Anterior  View. 

The  eynovidl  cavities    expoted 
by  a  vcrUcal  section,  {f  the  Sternum  k  Cxrtuageff 


continuous  with  SttmuMr 


1  NTCR-ARTICU  IAR     1 1  C  ! 

two  iSynovva,LmemoraneS 


Single  Synovial 
Membrane 


rib,  and  occasionally  also  that  of  the  sixth,  is  connected  to  the  anterior  surface  of 
the  ensiform  appendix,  by  a  band  of  ligamentous  fibres,  which  varies  in  length 
and  breadth  in  different  subjects.     It  is  called  the  costo-xiphoid  ligament. 

Actions.     The  movements  which  are  permitted  in  the  costo-sternal  articulations 
are  limited  to  elevation  and  depression ;  and  these  only  to  a  slight  extent 


; 


202  ARTICULATIONS. 

Articulation  of  the  Cartilages  of  the  Ribs  with  each  other. 

The  cartilages  of  the  sixth,  seventh,  and  eighth  ribs  articulate,  by  their  lower 
borders,  with  the  corresponding  margin  of  the  adjoining  cartilages,  by  means  of  a 
small,  smooth,  oblong-shaped  facet.  Each  articulation  is  inclosed  in  a  thin 
capsular  ligament,  lined  by  synovial  membrane,  and  strengthened  externally  and 
internally  by  ligamentous  fibres  (intercostal  ligaments),  which  pass  from  one 
cartilage  to  the  other.  Sometimes  the  cartilage  of  the  fifth  rib,  more  rarely 
that  of  the  ninth,  articulates,  by  its  lower  border,  with  the  adjoining  cartilage 
by  a  small  oval  facet;  more  frequently  they  are  connected  together  by  a  few 
ligamentous  fibres.  Occasionally,  the  articular  surfaces  above  mentioned  are  found 
wanting. 

Articulation  of  the  Ribs  with  their  Cartilages. 

The  outer  extremity  of  each  costal  cartilage  is  received  into  a  depression  in  the 
sternal  end  of  the  ribs,  and  held  together  by  the  periosteum. 

Fig.  127. — Articulations  of  Pelvis  and  Hip.    Anterior  View. 


Jihirim-r  of  eomnumieukon 
Jiurstt  of  PSOAS    Ml.  ILIACLJ 


VII.    LIGAMENTS  OF  THE  STERNUM. 

The  first  and  second  pieces  of  the  Sternum  are  united  by  a  layer  of  cartilage 
which  rarely  ossifies,  except  at  an  advanced  period  of  life.  These  two  segments 
are  connected  by  an  anterior  and  posterior  ligament. 

The  anterior  sternal  ligament  consists  of  a  layer  of  fibres,  having  a  longitudinal 
direction;  it  blends  with  the  fibres  of  the  anterior  costo-sternal  ligaments  on 
both  sides,  and  with  the  aponeurosis  of  origin  of  the  Pectoralis  major.  This 
ligament  is  rough,  irregular,  and  much  thicker  at  the  lower  than  at  the  upper  part 
of  the  bone. 


SACRO-ILIAC. 


203 


The  posterior  sternal  ligament  is  disposed  in  a  somewhat  similar  manner  on  ths 
posterior  surface  of  the  articulation. 

VIII.  ARTICULATIONS  OF  THE  PELVIS  WITH  THE  SPINE. 

The  ligaments  connecting  the  last  lumbar  vertebra  with  the  sacrum  are  similar 
to  those  which  connect  the  segments  of  the  spine  with  each  other,  viz. :  1.  The 
continuation  downwards  of  the  anterior  and  posterior  common  ligaments.  2.  The 
intervertebral  substance  connecting  the  flattened  oval  surfaces  of  the  two  bones, 
thus  forming  an  amphiarthrodial  joint.  3.  Ligamenta  subflava,  connecting  the 
arch  of  the  last  lumbar  vertebra  with  the  posterior  border  of  the  sacral  canal. 
4.  Capsular  ligaments  connecting  the  articulating  processes  and  forming  a  double 
arthrodia.     5.  Inter-spinous  and  supra-spinous  ligaments. 

The  two  proper  ligaments  connecting  the  pelvis  with  the  spine  are  the  lumbo- 
sacral and  lumbo-iliac. 

The  Lumbosacral  Ligament  (fig.  127)  is  a  short,  thick,  triangular  fasciculus, 
connected  above  to  the  lower  and  front  part  of  the  transverse  process  of  the  last 
lumbar  vertebra,  and,  passing  obliquely  outwards,  is  attached  below  to  the  lateral 

Fig.  128. — Articulations  of  Pelvis  and  Hip.    Posterior  View. 


surface  of  the  base  of  the  sacrum,  becoming  blended  with  the  anterior  sacro-iliac 
ligament.     This  ligament  is  in  relation  in  front  with  the  Psoas  muscle. 

The  Lumbo-iliac  Ligament  (fig.  127)  passes  horizontally  outwards  from  the 
apex  of  the  transverse  process  of  the  last  lumbar  vertebra,  to  that  portion  of  the 
crest  of  the  ilium  immediately  in  front  of  the  sacro-iliac  articulation.  It  is  of  a 
triangular  form,  thick  and  narrow  internally,  broad  and  thinner  externally.  It  is 
in  relation,  in  front,  with  the  Psoas  muscle ;  behind,  with  the  muscles  occupying 
the  vertebral  groove ;  above,  with  the  Quadratus  lumborum. 


204  ARTICULATIONS. 


IX.  ARTICULATIONS  OF  THE  PELVIS. 

The  Ligaments  connecting  the  bones  of  the  pelvis  with  each  other  may  be 
divided  into  four  groups.  1.  Those  connecting  the  sacrum  and  ilium.  2.  Those 
passing  between  the  sacrum  and  ischium.  3.  Those  connecting  the  sacrum  and 
coccyx.    4.  Those  between  the  two  pubic  bones. 

1.  Articulation  of  the  Sacrum  and  Ilium. 

The  sacro-iliac  articulation  is  an  amphiarthrodial  joint,  formed  between  the 
lateral  surfaces  of  the  sacrum  and  ilium.  The  anterior  or  auricular  portion  of 
each  articular  surface  is  covered  with  a  thin  plate  of  cartilage,  thicker  on  the 
sacrum  than  on  the  ilium.  The  surfaces  of  these  cartilages  in  the  adult  are  rough 
and  irregular,  and  separated  from  one  another  by  a  soft  yellow  pulpy  substance. 
At  an  early  period  of  life,  occasionally  in  the  adult,  and  in  the  female  during 
pregnancy,  they  are  smooth  and  lined  by  a  delicate  synovial  membrane.  The 
ligaments  connecting  these  surfaces  are  the  anterior  and  posterior  sacro-iliac. 

The  Anterior  Sacro-iliac  Ligament  consists  of  numerous  thin  ligamentous  bands, 
which  connect  the  anterior  surfaces  of  the  sacrum  and  ilium. 

The  Posterior  Sacro-iliac  (fig.  128)  is  a  strong  interosseous  ligament,  situated 
in  the  deep  depression  between  the  sacrum  and  ilium  behind,  and  forming  the 
chief  bond  of  connection  between  these  bones.  It  consists  of  numerous  strong 
fasciculi,  which  pass  between  the  bones  in  various  directions.  Three  of  these  are 
of  large  size ;  the  two  superior,  nearly  horizontal  in  direction,  arise  from  the  first 
and  second  transverse  tubercles  on  the  posterior  surface  of  the  sacrum,  and  are 
inserted  into  the  rough  uneven  surface  at  the  posterior  part  of  the  inner  surface 
of  the  ilium.  The  third  fasciculus,  oblique  in  direction,  is  attached  by  one  ex- 
tremity to  the  third  or  fourth  transverse  tubercle  on  the  posterior  surface  of  the 
sacrum,  and  by  the  other  to  the  posterior  superior  spine  of  the  ilium ;  it  is  some- 
times called  the  oblique  sacro-iliac  ligament. 

2.  Articulation  of  the  Sacrum  and  Ischium. 

The  Great  or  Posterior  Sacro-sciatic . 
The  Lesser  or  Anterior  Sacro-sciatic. 

The  Great  or  Posterior  Sacro-sciatic  Ligament  is  situated  at  the  lower  and  back 
part  of  the  pelvis.  It  is  thin,  flat,  and  triangular  in  form,  narrower  in  the  middle 
than  at  the  extremities,  attached  by  its  broad  base  to  the  posterior  inferior  spine 
of  the  ilium,  to  the  third  and  fourth  transverse  tubercles  on  the  sacrum,  and  to 
the  lower  part  of  the  lateral  margin  of  that  bone  and  the  coccyx;  passing 
obliquely  downwards,  outwards,  and  forwards,  it  becomes  narrow  and  thick,  and, 
at  its  insertion  into  the  inner  margin  of  the  tuberosity  of  the  ischium,  it  increases 
in  breadth,  and  is  prolonged  forwards  along  the  inner  margin  of  the  ramus  forming 
the  falciform  ligament.  The  free  concave  edge  of  this  ligament  has  attached  to  it 
the  obturator  fascia,  with  which  it  forms  a  kind  of  groove,  protecting  the  internal 
pudic  vessels  and  nerve.  One  of  its  surfaces  is  turned  towards  the  perineum,  the 
other  towards  the  Obturator  internus  muscle. 

The  posterior  surface  of  this  ligament  gives  origin,  by  its  whole  extent,  to  fibres 
of  the  Gluteus  maximus.  Its  anterior  surface  is  united  to  the  lesser  sacro-sciatic 
ligament.  Its  superior  border  forms  the  lower  boundary  of  the  lesser  sacro-sciatic 
foramen.  Its  lower  border  forms  part  of  the  boundary  of  the  perineum.  This 
ligament  is  pierced  by  the  coccygeal  branch  of  the  sciatic  artery. 

The  Lesser  or  Anterior  Sacro-sciatic  Ligament,  much  shorter  and  smaller  than 
the  preceding,  is  thin,  triangular  in  form,  attached  by  its  apex  to  the  spine  of  the 
ischium,  and  internally,  by  its  broad  base,  to  the  lateral  margin  of  the  sacrum 
and  coccyx,  anterior  to  the  attachment  of  the  great  sacro-sciatic  ligament,  with 
which  its  fibres  are  intermingled. 


SACRO-COCCYGEAL.  205 

It  is  in  relation,  anteriorly,  with  the  Coccygeus  muscle ;  posteriorly,  it  is  covered 
by  the  posterior  ligament,  and  crossed  by  the  pudic  vessels  and  nerve.  Its  supe- 
rior border  forms  the  lower  boundary  of  the  great  sacro-sciatic  foramen ;  its  infe- 
rior border,  part  of  the  lesser  sacro-sciatic  foramen. 

These  two  ligaments  convert  the  sacro-sciatic  notches  into  foramina.  The 
superior  or  great  sacro-sciatic  foramen  is  bounded,  in  front  and  above,  by  the  pos- 
terior border  of  the  os  innominatum ;  behind,  by  the  great  sacro-sciatic  ligament ; 
and  below,  by  the  lesser  ligament.  It  is  partially  filled  up,  in  the  recent  state, 
by  the  Pyriformis  muscle.  Above  this  muscle,  the  gluteal  vessels  and  nerve 
emerge  from  the  pelvis ;  and  below  it,  the  ischiatic  vessels  and  nerves,  the  internal 
pudic  vessels  and  nerve,  and  the  nerve  to  the  Obturator  internus.  The  inferior 
or  lesser  sacro-sciatic  foramen  is  bounded,  in  front,  by  the  tuber  ischii ;  above,  by 
the  spine  and  lesser  ligament;  behind,  by  the  greater  ligament.  It  transmits 
the  tendon  of  the  Obturator  internus  muscle,  its  nerve,  and  the  pudic  vessels  and 
nerve. 

3.  Articulation  of  the  Sacrum  and  Coccyx. 

This  articulation  is  an  amphiarthrodial  joint,  formed  between  the  oval  surface 
on  the  summit  of  the  sacrum,  and  the  base  of  the  coccyx.  It  is  analogous  to  the 
joints  between  the  bodies  of  the  vertebrae,  and  is  connected  by  similar  ligaments. 
They  are  the — 

Anterior  Sacro-coccygeal. 

Posterior  Sacro-coccygeal. 

Interarticular  Fibro-cartilage. 

The  Anterior  Sacro-coccygeal  Ligament  consists  of  a  few  irregular  fibres,  which 
descend  from  the  anterior  surface  of  the  sacrum  to  the  front  of  the  coccyx,  becom- 
ing blended  with"  the  periosteum. 

The  Posterior  Sacro-coccygeal  Ligament  is  a  flat  band  of  ligamentous  fibres,  of  a 
pearly  tint,  which  arises  from  the  margin  of  the  lower  orifice  of  the  sacral  canal, 
and  descends  to  be  inserted  into  the  posterior  surface  of  the  coccyx.  This  liga- 
ment completes  the  lower  and  back  part  of  the  sacral  canal.  Its  superficial  fibres 
are  much  longer  than  the  deep-seated ;  the  latter  extend  from  the  apex  of  the 
sacrum  to  the  upper  cornua  of  the  coccyx.  This  ligament  is  in  relation  in  front 
with  the  arachnoid  membrane  of  the  sacral  canal,  a  portion  of  the  sacrum,  and 
almost  the  whole  of  the  posterior  surface  of  the  coccyx ;  behind  with  the  Gluteus 
maximus. 

An  Interarticular  Fibro-cartilage  is  interposed  between  the  contiguous  surfaces 
of  the  sacrum  and  coccyx ;  it  differs  from  that  interposed  between  the  bodies  of 
the  vertebrae,  in  being  thinner,  and  its  central  part  more  firm  in  texture.  It  is 
somewhat  thicker  in  front  and  behind,  than  at  the  sides.  Occasionally  a  synovial 
membrane  is  found  where  the  coccyx  is  freely  movable,  which  is  more  especially 
the  case  during  pregnancy. 

The  different  segments  of  the  coccyx  are  connected  together  by  an  extension 
downwards  of  the  anterior  and  posterior  sacro-coccygeal  ligaments,  a  thin  annular 
disk  of  fibro-cartilage  being  interposed  between  each  of  the  bones.  In  the  adult 
male  all  the  pieces  become  ossified ;  but  in  the  female,  this  does  not  commonly 
occur  until  a  later  period  of  life.  The  separate  segments  of  the  coccyx  are  first 
united,  and  at  a  more  advanced  age  the  joint  between  the  sacrum  and  the 
coccyx. 

Actions.  The  movements  which  take  place  between  the  sacrum  and  coccyx, 
and  between  the  different  pieces  of  the  latter  bone,  are  slightly  forwards  and  back- 
wards ;  they  are  very  limited.     Their  mobility  increases  during  pregnancy. 

4.  Articulation  of  the  Pubes. 
The  articulation  between  the  pubic  bones  is  an  amphiarthrodial  joint,  formed 


206 


ARTICULATIONS. 


by  the  junction  of  the  two  oval  surfaces  which  has  received  the  name  of  the 
symphysis.     The  ligaments  of  this  articulation  are  the — 

Anterior  Pubic.  Posterior  Pubic. 

Superior  Pubic.  Subpubic. 

Interarticular  Fibro-cartilage. 

The  Anterior  Pubic  Ligament  consists  of  several  superimposed  layers,  which 
pass  across  the  front  of  the  articulation.  The  superficial  fibres  pass  obliquely 
from  one  bone  to  the  other,  decussating  and  forming  an  interlacement  with  the 
fibres  of  the  aponeurosis  of  the  External  oblique  muscle.  The  deep  fibres  pass 
transversely  across  the  symphysis,  and  are  blended  with  the  interarticular  fibro- 
cartilage. 

The  Posterior  Pubic  Ligament  consists  of  a  few  thin,  scattered  fibres,  which  unite 
the  two  pubic  bones  posteriorly. 

The  Superior  Pubic  Ligament  is  a  band  of  fibres,  which  connects  together  the 
two  pubic  bones  superiorly. 

The  Subpubic  Ligament  is  a  thick,  triangular  arch  of  ligamentous  fibres,  con- 
necting together  the  two  pubic  bones  below,  and  forming  the  upper  boundary  of 
the  pubic  arch.  Above,  it  is  blended  with  the  interarticular  fibro-cartilage; 
laterally,  with  the  rami  of  the  pubes.  Its  fibres  are  of  a  yellowish  color,  closely 
connected,  and  have  an  arched  direction. 

Fig.  129. — Vertical  Section  of  the  Symphysis  Pubis. 
Made  near  its  Posterior  Surface. 

Two  Flhro-Cartilaginoiis  plates 
In.twmejlia.te  elaeUc  tissue 
Synovial  cavity    at  upper  &■  haek  part 


The  Interarticular  Fibro-cartilage  consists  of  two  oval-shaped  plates,  one  cover- 
ing the  surface  of  each  symphysis  pubis.  They  vary  in  thickness  in  different 
subjects,  and  project  somewhat  beyond  the  level  of  the  bones,  especially  behind. 
The  outer  surface  of  each  plate  is  firmly  connected  to  the  bone  by  a  series  of 
nipple-like  processes,  which  accurately  fit  within  corresponding  depressions  on  the 
osseous  surface.  Their  opposed  surfaces  are  connected,  in  the  greater  part  of  their 
extent,  by  an  intermediate  fibrous  elastic  tissue ;  and  by  their  circumference  to  the 
various  ligaments  surrounding  the  joint.  An  interspace  is  left  between  the  plates 
at  the  upper  and  back  part  of  the  articulation,  where  the  fibrous  tissue  is  deficient, 
and  the  surface  of  the  fibro-cartilage  is  lined  by  epithelium.  The  space  is  found 
at  all  periods  of  life,  both  in  the  male  and  female ;  but  it  is  larger  in  the  latter, 
especially  during  pregnancy,  and  after  parturition.  It  is  most  frequently  limited 
to  the  upper  and  back  part  of  the  joint ;  but  it  occasionally  reaches  to  the  front, 
and  may  extend  the  entire  length  of  the  cartilages.  This  structure  may  be  easily 
demonstrated,  by  making  a  vertical  section  of  the  symphysis  pubis  near  its  pos- 
terior surface. 


STERNO-CLAVICULAR. 


207 


The  Obturator  Ligament  is  a  dense  membranous  layer,  consisting  of  fibres  which 
interlace  in  various  directions.  It  is  attached  to  the  circumference  of  the  obtu- 
rator foramen,  which  it  closes  completely,  except  at  its  upper  and  outer  part, 
where  a  small  oval  canal  is  left  for  the  passage  of  the  obturator  vessels  and  nerve. 
It  is  in  relation,  in  front,  with  the  Obturator  externus ;  behind,  with  the  Obtura- 
tor internus ;  both  of  which  muscles  are  in  part  attached  to  it. 


ARTICULATIONS  OF  THE  UPPER  EXTREMITY. 

The  articulations  of  the  Upper  Extremity  may  be  arranged  into  the  following 
groups: — 1.  Sterno-clavicular  articulation.  2.  Scapuloclavicular  articulation. 
3.  Ligaments  of  the  Scapula.  4.  Shoulder-joint.  5.  Elbow-joint.  6.  Radio- 
ulnar articulation.  7.  Wrist-joint.  8.  Articulations  of  the  Carpal  bones.  9. 
Carpo-metacarpal  articulations.  10.  Metacarpo-phalangeal  articulations.  1L 
Articulations  of  the  Phalanges. 

Fig.  130. — Sterno-clavicular  Articulation.     Anterior  View. 


1.  Sterno-clavicular  Articulation. 

The  Sterno-clavicular  is  an  arthrodial  joint.  The  parts  entering  into  its  forma- 
tion are  the  sternal  end  of  the  clavicle,  the  upper  and  lateral  part  of  the  first 
piece  of  the  sternum,  and  the  cartilage  of  the  first  rib.  The  articular  surface  of 
the  clavicle  is  much  longer  than  that  of  the  sternum,  and  invested  with  a  layer 
of  cartilage,1  which  is  considerably  thicker  than  that  on  the  latter  bone.  The 
ligaments  of  this  joint  are  the 

Anterior  Sterno-clavicular.  Interclavicular. 

Posterior  Sterno-clavicular.  Costo-clavicular  or  rhomboid. 

Interarticular  Fibro-Cartilage. 

The  Anterior  Sterno-clavicular  Ligament  is  a  broad  band  of  ligamentous  fibres, 
which  covers  the  anterior  surface  of  the  articulation,  being  attached,  above,  to  the 
upper  and  front  part  of  the  inner  extremity  of  the  clavicle ;  and,  passing  obliquely 
downwards  and  inwards,  is  attached,  below,  to  the  front  and  upper  part  of  the 
first  piece  of  the  sternum.     This  ligament  is  covered  in  front  by  the  sternal  por- 


1  According  to  Bruch,  the  sternal  end  of  the  clavicle  is  covered  by  a  tissue  which  is  more 
fibrous  than  cartilaginous  in  structure. 


208  ARTICULATIONS. 

tion  of  the  Sterno-cleido-mastoid  and  the  integument;  behind,  it  is  in  relation 
with  the  interarticular  fibro-cartilage  and  the  two  synovial  membranes. 

The  Posterior  Sternoclavicular  Ligament  is  a  broad  band  of  fibres,  which  covers 
the  posterior  surface  of  the  articulation,  being  attached,  above,  to  the  posterior 
part  of  the  inner  extremity  of  the  clavicle ;  and,  passing  obliquely  downwards 
and  inwards,  is  connected,  below,  to  the  posterior  and  upper  part  of  the  sternum. 
It  is  in  relation,  in  front,  with  the  interarticular  fibro-cartilage  and  synovial  mem- 
branes ;  behind,  with  the  Sterno-hyoid  and  Sterno-thyroid  muscles. 

The  Interclavicular  Ligament  is  a  flattened  ligamentous  band,  which  varies 
considerably  in  form  and  size  in  different  individuals ;  it  passes  from  the  upper 
part  of  the  inner  extremity  of  one  clavicle  to  the  other,  and  is  closely  attached  to 
the  upper  margin  of  the  sternum.  It  is  in  relation,  in  front,  with  the  integument ; 
behind  with  the  Sterno-thyroid  muscles. 

The  Costo-clavicular  or  rhomboid  Ligament  is  a  short,  flat,  and  strong  band  of 
ligamentous  fibres  of  a  rhomboid  form,  attached,  below,  to  the  upper  and  inner 
part  of  the  cartilage  of  the  first  rib ;  and,  ascending  obliquely  backwards  and  out- 
wards, is  attached,  above,  to  the  rhomboid  depression  on  the  under  surface  of  the 
clavicle.  It  is  in  relation,  in  front,  with  the  tendon  of  origin  of  the  Subclavius ; 
behind,  with  the  subclavian  vein. 

The  Interarticular  Fibro-cartilage  is  a  flat  and  nearly  circular  disk,  interposed 
between  the  articulating  surfaces  of  the  sternum  and  clavicle.  It  is  attached, 
above,  to  the  upper  and  posterior  border  of  the  clavicle ;  below,  to  the  cartilage 
of  the  first  rib,  at  its  junction  with  the  sternum ;  and  by  its  circumference  to  the 
anterior  and  posterior  sterno-clavicular  ligaments.  It  is  thicker  at  the  circum- 
ference, especially  its  upper  and  back  part,  than  at  its  centre,  or  below.  It 
divides  the  joint  into  two  cavities,  each  of  which  is  furnished  with  a  separate 
synovial  membrane ;  when  the  fibro-cartilage  is  perforated,  which  not  unfrequently 
occurs,  the  synovial  membranes  communicate. 

Of  the  two  Synovial  Membranes  found  in  this  articulation,  one  is  reflected  from 
the  sternal  end  of  the  clavicle,  over  the  adjacent  surface  of  the  fibro-cartilage,  and 
cartilage  of  the  first  rib ;  the  other  is  placed  between  the  articular  surface  of  the 
sternum  and  adjacent  surface  of  the  fibro-cartilage.  The  latter  is  the  more  loose 
of  the  two ;  they  seldom  contain  much  synovia. 

Actions.  This  articulation  is  the  centre  of  the  movements  of  the  shoulder,  and 
admits  of  motion  in  nearly  every  direction,  upwards,  downwards,  backwards, 
forwards,  as  well  as  circumduction ;  the  sternal  end  of  the  clavicle  and  the  inter- 
articular cartilage  gliding  on  the  articular  surface  of  the  sternum. 

2.  Scapuloclavicular  Articulation". 

The  Scapuloclavicular  is  an  arthrodial  joint,  formed  between  the  outer  ex- 
tremity of  the  clavicle,  and  the  upper  edge  of  the  acromion  process  of  the  scapula. 
Its  ligaments  are  the 

Superior  Acromio-clavicular. 

Inferior  Acromio-clavicular. 

n  t     .     i      I  Trapezoid. 

(Joraco-clavicular  <  n    r., 
(  Conoid. 

Interarticular  Fibro-cartilage. 

The  Superior  Acromio-clavicular  Ligament  is  a  broad  band  of  fibres,  of  a  quad- 
rilateral form,  which  covers  the  superior  part  of  the  articulation,  extending 
between  the  upper  part  of  the  outer  end  of  the  clavicle,  and  the  adjoining  part  of 
the  acromion.  It  is  composed  of  parallel  fibres,  which  interlace  with  the 
aponeurosis  of  the  Trapezius  and  Deltoid  muscles ;  below,  it  is  in  contact  with 
the  interarticular  fibro-cartilage  and  synovial  membranes. 

The  Inferior  Acromio-clavicular  Ligament,  somewhat  thinner  than  the  preceding, 
covers  the  under  part  of  the  articulation,  and  is  attached  to  the  adjoining  surfaces 


SCAPULOCLAVICULAR. 


209 


of  the  two  bones.  It  is  in  relation,  above,  with  the  interarticular  fibro-cartilage 
(when  it  exists)  and  the  synovial  membranes;  below,  with  the  tendon  of  the 
Supra-spinatus.  These  two  ligaments  are  continuous  with  each  other  in  front 
and  behind,  and  form  a  complete  capsule  around  the  joint. 

The  Coraco -clavicular  Ligament  serves  to  connect  the  clavicle  with  the  coracoid 
process  of  the  scapula.  It  consists  of  two  fasciculi,  called  the  trapezoid  and  conoid 
ligaments. 

The  Trapezoid  ligament,  the  anterior  and  external  lasciculus,  is  a  broad,  thin, 
quadrilateral-shaped  band  of  fibres,  placed  obliquely  between  the  coracoid  process 
aud   the   clavicle.     It  is  attached,  below,  to  the  upper  surface  of  the  coracoid 


Fig.  131.- 


-The  Lett  Shoulder-joint,  Scapuloclavicular  Articulations, 
and  Proper  Ligaments  of  Scapula- 


process ;  above,  to  the  oblique  line  on  the  under  surface  of  the  clavicle.  Its 
anterior  border  is  free ;  its  posterior  border  is  joined  with  the  conoid  ligament, 
the  two  forming  by  their  junction  a  projecting  angle. 

The  Conoid  ligament,  the  posterior  and  internal  fasciculus,  is  a  dense  band  of 
fibres,  conical  in  form,  the  base  being  turned  upwards,  the  summit  downwards. 
It  is  attached  by  its  apex  to  a  rough  depression  at  the  base  of  the  coracoid  process, 
internal  to  the  preceding ;  above,  by  its  expanded  base,  to  the  conoid  tubercle  on 
the  under  surface  of  the  clavicle,  and  into  a  line  proceeding  internally  from  it 
for  half  an  inch.  These  ligaments  are  in  relation,  in  front,  with  the  Subclavius; 
behind,  with  the  Trapezius :  they  serve  to  limit  rotation  of  the  scapula  forwards 
and  backwards. 

The  Interarticular  Fibro-cartilage  is  most  frequently  absent  in  this  articulation. 
When  it  exists,  it  generally  only  partially  separates  the  articular  surfaces,  and 
14 


210  ARTICULATIONS. 

occupies  the  upper  part  of  the  articulation.  More  rarely,  it  completely  separates 
the  joint  into  two  cavities. 

There  are  two  Synovial  Membranes  where  a  complete  interarticular  cartilage 
exists ;  more  frequently,  there  is  only  one  synovial  membrane. 

Actions.  The  movements  of  this  articulation  are  of  two  kinds,  x.  A  gliding 
motion  of  the  articular  end  of  the  clavicle  on  the  acromion.  2.  Rotation  of  the 
scapula  forwards  and  backwards  upon  the  clavicle,  the  extent  of  this  rotation  being 
limited  by  the  two  portions  of  the  coraco-clavicular  ligament. 

3.  Proper  Ligaments  of  the  Scapula. 
The  proper  ligaments  of  the  scapula  are,  the 

Coraco-acromial.  Transverse. 

The  Coraco-acromial  Ligament  is  a  broad,  thin,  flat  band,  of  a  triangular  shape, 
extended  transversely  above  the  upper  part  of  the  shoulder-joint,  between  the 
coracoid  and  acromion  processes.  It  is  attached,  by  its  apex,  to  the  summit  of  the 
acromion  just  in  front  of  the  articular  surface  for  the  clavicle ;  and  by  its  broad 
base,  to  the  whole  length  of  the  outer  border  of  the  coracoid  process.  Its  posterior 
fibres  are  directed  obliquely  backwards  and  outwards,  its  anterior  fibres  trans- 
versely. This  ligament  completes  the  vault  formed  by  the  coracoid  and  acromion 
processes  for  the  protection  of  the  head  of  the  humerus.  It  is  in  relation,  above, 
with  the  clavicle  and  under  surface  of  the  Deltoid ;  below,  with  the  tendon  of  the 
Supra-spinatus  muscle,  a  bursa  being  interposed.  Its  anterior  border  is  continuous 
with  a  dense  cellular  lamina  that  passes  beneath  the  Deltoid  upon  the  tendons  of 
the  Supra-spinati  and  Infra-spinati  muscles. 

The  Transverse  or  Coracoid  Ligament  converts  the  suprascapular  notch  into  a 
foramen.  It  is  a  thin  and  flat  fasciculus,  narrower  at  the  middle  than  at  the 
extremities,  attached,  by  one  end,  to  the  base  of  the  coracoid  process,  and  by  the 
other,  to  the  inner  extremity  of  the  scapular  notch.  The  suprascapular  nerve 
passes  through  the  foramen ;  its  accompanying  vessels  above  it. 

4.  Shoulder-joint. 

The  Shoulder  is  an  enarthrodial  or  ball-and-socket  joint.  The  bones  entering 
into  its  formation  are  the  large  globular  head  of  the  humerus,  which  is  received 
into  the  shallow  glenoid  cavity  of  the  scapula,  an  arrangement  which  permits  of 
very  considerable  movement,  whilst  the  joint  itself  is  protected  against  displace- 
ment by  the  strong  ligaments  and  tendons  which  surround  it,  and  above  by  an 
arched  vault,  formed  by  the  under  surface  of  the  coracoid  and  acromion  processes, 
and  the  coraco-acromial  ligament.  The  articular  surfaces  are  covered  by  a 
layer  of  cartilage :  that  on  the  head  of  the  humerus  is  thicker  at  the  centre  than 
at  the  circumference,  the  reverse  being  observed  in  the  glenoid  cavity.  Its  liga- 
ments are  the 

Capsular.  Coraco-humeral. 

Glenoid. 

The  Capsular  Ligament  completely  encircles  the  articulation ;  being  attached, 
above,  to  the  circumference  of  the  glenoid  cavity  beyond  the  glenoid  ligament ; 
below,  to  the  anatomical  neck  of  the  humerus,  approaching  nearer  to  the  articular 
cartilage  above,  than  in  the  rest  of  its  extent.  It  is  thicker  above  than  below, 
remarkably  loose  and  lax,  and  much  larger  and  longer  than  is  necessary  to  keep 
the  bones  in  contact,  allowing  them  to  be  separated  from  each  other  more  than  an 
inch,  an  evident  provision  for  that  extreme  freedom  of  movement  which  is  peculiar 
to  this  articulation.  Its  external  surface  is  strengthened,  above,  by  the  Supra- 
spinatus  ;  above  and  internally,  by  the  coraco-humeral  ligament ;  below,  by  the 
long  head  of  the  Triceps ;  externally,  by  the  tendons  of  the  Infra-spinatus  and 


ELBOW-JOINT.  211 


Teres  minor ;  and  internally,  by  the  tendon  of  the  Subscapularis.  The  capsular 
ligament  usually  presents  three  openings ;  one  at  its  inner  side,  below  the  coracoid 
process,  partially  filled  up  by  the  tendon  of  the  Subscapularis ;  it  establishes  a 
communication  between  the  synovial  membrane  of  the  joint  and  a  bursa  beneath 
the  tendon  of  that  muscle ;  a  second,  not  constant,  at  its  outer  part,  where  a  com- 
munication sometimes  exists  between  the  joint  and  a  bursal  sac  belonging  to  the 
Infra-spinatus  muscle.  The  third  is  seen  in  the  lower  border  of  the  ligament, 
between  the  two  tuberosities,  for  the  passage  of  the  tendon  of  the  Biceps  muscle. 

The  Coraco-humeral  or  Accessory  Ligament  is  a  broad  band  which  strengthens 
the  upper  and  inner  part  of  the  capsular  ligament.  It  arises  from  the  outer  border 
of  the  coracoid  process,  and  descends  obliquely  downwards  and  outwards  to  the 
front  of  the  great  tuberosity  of  the  humerus,  being  blended  with  the  tendon  of  the 
Supra-spinatus  muscle.  This  ligament  is  intimately  united  to  the  capsular  in  the 
greater  part  of  its  extent. 

The  Glenoid  Ligament  is  a  firm  fibrous  band  attached  round  the  margin  of 
the  glenoid  cavity.  It  is  triangular  on  section,  the  thickest  portion  being  fixed  to 
the  circumference  of  the  cavity,  the  free  edge  being  thin  and  sharp.  It  is  con- 
tinuous above  with  the  long  tendon  of  the  Biceps  muscle,  which  bifurcates  at  the 
upper  part  of  the  cavity  into  two  fasciculi,  which  encircle  its  margin,  and  unite 
at  its  lower  part.  This  ligament  deepens  the  cavity  for  articulation,  and  protects 
the  edges  of  the  bone.     It  is  lined  by  the  synovial  membrane. 

The  Synovial  Membrane  lines  the  margin  of  the  glenoid  cavity  and  the  fibro- 
cartilaginous rim  surrounding  it ;  it  is  then  reflected  over  the  internal  surface  of  the 
capsular  ligament,  covers  the  lower  part  and  sides  of  the  neck  of  the  humerus,  and 
is  continued  a  short  distance  over  the  cartilage  covering  the  head  of  this  bone.  The 
long  tendon  of  the  Biceps  muscle  which  passes  through  the  joint  is  inclosed  in  a 
tubular  sheath  of  synovial  membrane,  which  is  reflected  upon  it  at  the  point  where 
it  perforates  the  capsule,  and  is  continued  around  it  as  far  as  the  summit  of  the 
glenoid  cavity.  The  tendon  of  the  Biceps  is  thus  enabled  to  traverse  the  articu- 
lation, but  is  not  contained  in  the  interior  of  the  synovial  cavity.  The  synovial 
membrane  communicates  with  a  large  bursal  sac  beneath  the  tendon  of  the  Sub- 
scapularis, by  an  opening  at  the  inner  side  of  the  capsular  ligament;  it  also 
occasionally  communicates  with  another  bursal  sac,  beneath  the  tendon  of  the 
Infra-spinatus,  through  an  orifice  at  its  outer  part.  A  third  bursal  sac,  which 
does  not  communicate  with  the  joint,  is  placed  between  the  under  surface  of  the 
deltoid  and  the  outer  surface  of  the  capsule. 

The  Muscles  in  relation  with  the  joint  are,  above,  the  Supra-spinatus ;  below, 
the  long  head  of  the  Triceps ;  internally,  the  Subscapularis ;  externally,  the  Infra- 
spinatus, and  Teres  minor;  within,  the  long  tendon  of  the  Biceps.  The  Deltoid 
is  placed  most  externally,  and  covers  the  articulation  on  its  outer  side,  and  in  front 
and  behind. 

The  Arteries  supplying  the  joint  are  articular  branches  of  the  anterior  and 
posterior  circumflex,  and  suprascapular. 

The  Nerves  are  derived  from  the  circumflex  and  suprascapular. 

Actions.  The  shoulder-joint  is  capable  of  movement  in  almost  any  direction, 
forwards,  backwards,  abduction,  adduction,  circumduction,  and  rotation. 

5.  Elbow-joint. 

The  Elbow  is  a  ginglymoid  or  hinge  joint.  The  bones  entering  into  its  forma- 
tion are  the  trochlear  surface  of  the  humerus,  which  is  received  in  the  greater 
sigmoid  cavity  of  the  ulna,  and  admits  of  the  movements  peculiar  to  this  joint, 
those  of  flexion  and  extension,  whilst  the  cup-shaped  depression  of  the  head  of  the 
radius  articulates  with  the  radial  tuberosity  of  the  humerus,  its  circumference 
with  the  lesser  sigmoid  cavity  of  the  ulna,  allowing  of  the  movement  of  rotation  of 
the  radius  on  the  ulna,  the  chief  action  of  the  superior  radio-ulnar  articulation. 


212 


ARTICULATIONS. 


The  articular  surfaces  are  covered  with  a  thin  layer  of  cartilage,  and  connected 
together  by  the  following  ligaments : — 

Anterior  Ligament.  Internal  Lateral. 


Posterior  Ligament. 


External  Lateral. 


The  Anterior  Ligament  (fig.  132)  is  a  broad  and  thin  fibrous  layer,  which  covers 
the  anterior  surface  of  the  joint 


Fig.  132.— Left  Elbow-Joint,  showing  Ante- 
rior and  Internal  Lateral  Ligaments. 


It  is  attached  to  the  front  of  the  humerus 
immediately  above  the  coronoid  fossa; 
below,  to  the  anterior  surface  of  the 
coronoid  process  of  the  ulna  and  orbicu- 
lar ligament,  being  continuous  on  each 
side  with  the  lateral  ligaments.  Its  super- 
ficial or  oblique  fibres  pass  from  the  inner 
condyle  of  the  humerus  outwards  to  the 
orbicular  ligament.  The  middle  fibres, 
vertical  in  direction,  pass  from  the  upper 
part  of  the  coronoid  depression,  and 
become  blended  with  the  preceding.  A 
third,  or  transverse  set,  intersect  these  at 
right  angles.  This  ligament  is  in  relation, 
in  front,  with  the  Brachialis  anticus; 
behind,  with  the  synovial  membrane. 

The  Posterior  Ligament  is  a  thin  and 
loose  membranous  fold,  attached,  above, 
to  the  lower  end  of  the  humerus,  imme- 
diately above  the  olecranon  depression ; 
below,  to  the  margin  of  the  olecranon. 
The  superficial  or  transverse  fibres  pass 
between  the  adjacent  margins  of  the  ole- 
cranon fossa.  The  deeper  portion  consists 
of  vertical  fibres,  which  pass  from  the 
upper  part  of  the  olecranon  fossa  to  the 
margin  of  the  olecranon.  This  ligament 
is  in  relation,  behind,  with  the  tendon  of 
the  Triceps  and  Anconeus ;  in  front,  with 
the  synovial  membrane. 

The  Internal  Lateral  Ligament  is  a 
thick  triangular  band  of  ligamentous 
fibres,  consisting  of  two  distinct  portions, 
an  anterior  and  posterior.  The  anterior 
portion,  directed  obliquely  forwards,  is 
attached,  above,  by  its  apex,  to  the  front 
part  of  the  internal  condyle  of  the  humerus ;  and,  below,  by  its  broad  base,  to  the 
inner  margin  of  the  coronoid  process.  The  posterior  portion,  also  of  triangular 
form,  is  attached,  above,  by  its  apex,  to  the  lower  and  back  part  of  the  internal 
condyle ;  below,  to  the  inner  margin  of  the  olecranon.  This  ligament  is  in  rela- 
tion, internally,  with  the  Triceps  and  Flexor  carpi  ulnaris  muscles,  and  the  ulnar 
nerve. 

The  External  Lateral  Ligament  (fig.  133)  is  a  short  and  narrow  fibrous  fasci- 
culus, less  distinct  than  the  internal,  attached,  above,  to  the  external  condyle  of 
the  humerus ;  below,  to  the  orbicular  ligament,  some  of  its  most  posterior  fibres 
passing  over  that  ligament,  to  be  inserted  into  the  outer  margin  of  the  ulna. 
This  ligament  is  intimately  blended  with  the  tendon  of  origin  of  the  Supinator 
brevjs  muscle. 

The  Synovial  Membrane  is  very  extensive.  It  covers  the  margin  of  the  arti- 
cular surface  of  the  humerus,  and  lines  the  coronoid  and  olecranon  depressions  on 
that  bone;  from  these  points,  it  is  reflected  over  the  anterior,  posterior,  and  lateral 


RADIO-ULNAR. 


213 


ligaments,    and    forms    a    pouch    between      Fig.  133.-Left  Elbow-Joint  showing  Tosterior 
,o      ,  '       •  -i  -i        xi         •    i.  i  and  External  Lateral  Ligaments. 

the  lesser  sigmoid  cavity,  the  internal 
surface  of  the  annular  ligament,  and  the 
circumference  of  the  head  of  the  radius. 

The  Muscles  in  relation  with  the  joint 
are,  in  front,  the  Brachialis  anticus; 
behind,  the  Triceps  and  Anconeus;  ex- 
ternally, the  Supinator  brevis,  and  the 
common  tendon  of  origin  of  the  Extensor 
muscles;  internally,  the  common  tendon 
of  origin  of  the  Flexor  muscles,  the 
Plexor  carpi  ulnaris,  and  ulnar  nerve. 

The  Arteries  supplying  the  joint  are  de- 
rived from  the  communicating  branches 
between  the  superior  profunda,  inferior 
profunda,  and  anastomotic  branches  of 
the  brachial,  with  the  anterior,  posterior 
and  interosseous  recurrent  branches  of 
the  ulnar,  and  the  recurrent  branch  of  the 
radial.  These  vessels  form  a  complete 
chain  of  inosculation  around  the  joint. 

The  Nerves  are  derived  from  the  ulnar, 
as  it  passes  between  the  internal  condyle 
and  the  olecranon ;  and  a  few  filaments 
from  the  musculo-cutaneous. 

Actions.  The  elbow  is  one  of  the  most 
perfect  hinge-joints  in  the  body ;  its  move- 
ments are,  consequently,  limited  to  flexion 
and  extension,  the  exact  apposition  of 
the  articular  surfaces  preventing  the  least 
lateral  motion. 

6.  Radioulnar  Articulations. 

The  articulation  of  the  radius  with  the  ulna  is  effected  by  ligaments,  which 
connect  together  both  extremities  as  well  as  the  shafts  of  these  bones.  They  may, 
consequently,  be  subdivided  into  three  sets :  1,  the  superior  radio-ulnar ;  2,  the 
middle  radio-ulnar ;  and  3,  the  inferior  radio-ulnar  articulations. 

1.  Superior  Radio-ulnar  Articulation. 

This  articulation  is  a  lateral  ginglymoid  joint.  The  bones  entering  into  its  for- 
mation are  the  inner  side  of  the  circumference  of  the  head  of  the  radius,  which 
rotates  within  the  lesser  sigmoid  cavity  of  the  ulna.  These  surfaces  are  covered 
with  cartilage,  and  invested  with  a  duplicature  of  synovial  membrane,  continuous 
with  that  which  lines  the  elbow-joint.     Its  only  ligament  is 


The  Annular  or  Orbicular. 

The  Orbicular  Ligament  (fig.  133)  is  a  strong  flat  band  of  ligamentous  fibres, 
which  surrounds  the  head  of  the  radius,  and  retains  it  in  firm  connection  with  the 
lesser  sigmoid  cavity  of  the  ulna.  It  forms  about  three-fourths  of  a  fibrous  ring 
attached  by  each  end  to  the  extremities  of  the  sigmoid  cavity,  and  is  broader  at  the 
upper  part  of  its  circumference  than  below,  by  which  means  the  head  of  the  radius 
is  more  securely  held  in  its  position.  Its  outer  surface  is  strengthened  by  the  ex- 
ternal lateral  ligament  of  the  elbow,  and  affords  partial  origin  to  the  Supinator 
brevis  muscle.     Its  inner  surface  is  smooth,  and  lined  by  synovial  membrane. 

Actions.  The  movement  which  takes  place  in  this  articulation  is  limited  to 
rotation  of  the  head  of  the  radius  within  the  orbicular  ligament,  and  upon  the 


214  ARTICULATIONS. 

lesser  sigmoid  cavity  of  the  ulna ;  rotation  forwards  being  called  pronation  ;  rota- 
tion backward,  supination. 

2.  Middle  Radioulnar  Articulation. 

The  interval  between  the  shafts  of  the  radius  and  ulna  is  occupied  by  two  liga- 
ments. 

Oblique.  Interosseous. 

The  Oblique  or  Round  Ligament  (fig.  132)  is  a  small  round  fibrous  cord,  which 
extends  obliquely  downwards  and  outwards,  from  the  tubercle  of  the  ulna  at  the 
base  of  the  coronoid  process,  to  the  radius  a  little  below  the  bicipital  tuberosity. 
Its  fibres  run  in  the  opposite  direction  to  those  of  the  interosseous  ligament ;  and 
it  appears  to  be  placed  as  a  substitute  for  it  in  the  upper  part  of  the  interosseous 
interval.     This  ligament  is  sometimes  wanting. 

The  Interosseous  Membrane  is  a  broad  and  thin  plane  of  aponeurotic  fibres, 
descending  obliquely  downwards  and  inwards,  from  the  interosseous  ridge  on  the 
radius  to  that  on  the  ulna.  It  is  deficient  above,  commencing  about  an  inch  be- 
neath the  tubercle  of  the  radius ;  is  broader  in.the  middle  than  at  either  extremity ; 
and  presents  an  oval  aperture  just  above  its  lower  margin  for  the  passage  of  the 
anterior  interosseous  vessels  to  the  back  of  the  forearm.  This  ligament  serves  to 
connect  the  bones,  and  to  increase  the  extent  of  surface  for  the  attachment  of  the 
deep  muscles.  Between  its  upper  border  and  the  oblique  ligament  an  interval 
exists,  through  which  the  posterior  interosseous  vessels  pass.  Two  or  three  fibrous 
bands  are  occasionally  found  on  the  posterior  surface  of  this  membrane,  which 
descend  obliquely  from  the  ulna  towards  the  radius,  and  which  have  consequently 
a  direction  contrary  to  that  of  the  other  fibres.  It  is  in  relation,  in  front,  by  its 
upper  three-fourths  (radial  margin)  with  the  Flexor  longus  pollicis  (ulnar  margin), 
with  the  Flexor  profundus  digitorum,  lying  upon  the  interval  between  which  are 
the  anterior  interosseous  vessels  and  nerve,  by  its  lower  fourth  with  the  Pronator 
quadratus ;  behind,  with  the  Supinator  brevis,  Extensor  ossis  metacarpi  pollicis, 
Extensor  primi  internodii  pollicis,  Extensor  secundi  internodii  pollicis,  Extensor 
indicis ;  and,  near  the  wrist,  with  the  anterior  interosseous  artery  and  posterior 
interosseous  nerve. 

3.  Inferior  Radio-ulnar  Articulation. 

This  is  a  lateral  ginglymoid  joint,  formed  by  the  head  of  the  ulna  being  received 
into  the  sigmoid  cavity  at  the  inner  side  of  the  lower  end  of  the  radius.  The 
articular  surfaces  are  covered  by  a  thin  layer  of  cartilage,  and  connected  together 
by  the  following  ligaments. 

Anterior  radio-ulnar. 

Posterior  radio-ulnar. 

Triangular  Interarticular  Fibro-cartilage. 

The  Anterior  Radio-ulnar  Ligament  (fig.  134)  is  a  narrow  band  of  fibres,  ex- 
tending from  the  anterior  margin  of  the  sigmoid  cavity  of  the  radius  to  the  anterior 
surface  of  the  head  of  the  ulna. 

The  Posterior  Radio-ulnar  Ligament  (fig.  135)  extends  between  similar  points 
on  the  posterior  surface  of  the  articulation. 

The  Triangular  Fibro-cartilage  (fig.  136)  is  placed  transversely  beneath  the 
head  of  the  ulna,  binding  the  lower  end  of  this  bone  and  the  radius  firmly  together. 
Its  circumference  is  thicker  than  its  centre,  which  is  thin  and  occasionally  per- 
forated. It  is  attached  by  its  apex  to  a  depression  which-  separates  the  styloid 
process  of  the  ulna  from  the  head  of  that  bone;  and,  by  its  base,  which  is  thin, 
to  the  prominent  edge  of  the  radius,  which  separates  the  sigmoid  cavity  from 
the  carpal  articulating  surface.  Its  margins  are  united  to  the  ligaments  of  the 
wrist-joint.  Its  upper  surface,  smooth  and  concave,  is  contiguous  with  the  head 
of  the  ulna ;  its  tinder  surface,  also  concave  and  smooth,  with  the  cuneiform  bone. 
Both  surfaces  are  lined  by  a  synovial  membrane :  the  upper  surface,  by  one  peculiar 


RADIO-TTLNAR. 


215 


to  the  radioulnar  articulation ;  the  under  surface,  by  the  synovial  membrane  of 
the  wrist. 

Fig.  134. — Ligaments  of  "Wrist  and  Hand.    Anterior  View. 


NFERIOR  RADIO-ULNAR  ARTICJ 


WRIST-JOINT 


CARPAL    ARTICf? 


CARPO-METACARPAL  ARTIC  •« 


The  Synovial  Membrane  of  this  articulation  has  been  called,  from  its  extreme 
looseness,  the  membrana  sacciformis  ;  it  covers  the  margin  of  the  articular  surface 
of  the  head  of  the  ulna  and  where  reflected  from  this  bone  on  to  the  radius  forms 


Fig.  135. — Ligaments  of  Wrist  and  Hand.     Posterior  View. 


Inferior 
Hadio  -ulnar  Artie 

~Wrl*t-  Joint 


Carpal    Artio7^ 


Carpo-M^etaearpal      /SpS; 
ArtieV* 


a  very  loose  cul-de-sac ;  from  the  radius,  it  is  continued  over  the  upper  surface 
of  the  fibro-cartilage.     The  quantity  of  synovia  which  it  contains  is  usually 


216  ARTICULATIONS. 

considerable.     When  the  fibro-cartilage  is  perforated,  the  synovial  membrane  is 
continuous  with  that  which  lines  the  wrist. 

Actions.  The  movement  which  occurs  in  the  inferior  radio-ulnar  articulation  is 
just  the  reverse  of  that  which  takes  place  between  the  two  bones  above ;  it  is 
limited  to  rotation  of  the  radius  round  the  head  of  the  ulna ;  rotation  forwards 
being  termed  pronation,  rotation  backwards  supination.  In  pronation,  the  sigmoid 
cavity  glides  forward  on  the  articular  edge  of  the  ulna ;  in  supination,  it  rolls  in 
the  opposite  direction,  the  extent  of  these  movements  being  limited  by  the  anterior 
and  posterior  ligaments. 

7.  Wrist-joint. 

The  Wrist  presents  most  of  the  characters  of  an  enarthrodial  joint.  The  parts 
entering  into  its  formation  are,  the  lower  end  of  the  radius,  and  under  surface  of 
the  triangular  interarticular  fibro-cartilage,  above ;  and  the  scaphoid,  semilunar, 
and  cuneiform  bones  below.  The  articular  surfaces  of  the  radius  and  interarticular 
fibro-cartilage  form  a  transversely  elliptical  concave  surface.  The  radius  is  sub- 
divided into  two  parts  by  a  line  extending  from  before  backwards ;  and  these, 
together  with  the  interarticular  cartilage,  form  three  facets,  one  for  each  carpal 
bone.  The  three  carpal  bones  are  connected  together,  and  form  a  convex  surface, 
which  is  received  into  the  concavity  above  mentioned.  All  the  bony  surfaces  of 
the  articulation  are  covered  with  cartilage,  and  connected  together  by  the  follow- 
ing ligaments. 

External  Lateral.  Anterior. 

Internal  Lateral.  Posterior. 

The  External  Lateral  Ligament  extends  from  the  summit  of  the  styloid  process 
of  the  radius  to  the  outer  side  of  the  scaphoid,  some  of  its  fibres  being  prolonged 
to  the  trapezium  and  annular  ligament. 

The  Internal  Lateral  Ligament  is  a  rounded  cord,  attached,  above,  to  the  ex- 
tremity of  the  styloid  process  of  the  ulna ;  below,  it  divides  into  two  fasciculi, 
which  are  attached,  one  to  the  inner  side  of  the  cuneiform  bone,  the  other  to  the 
pisiform  bone  and  annular  ligament. 

The  Anterior  Ligament  is  a  broad  membranous  band,  consisting  of  three  fasci- 
culi, attached,  above,  to  the  anterior  margin  of  the  lower  end  of  the  radius,  its 
styloid  process,  and  the  ulna;  its  fibres  pass  downwards  and  inwards,  to  be 
inserted  into  the  palmar  surface  of  the  scaphoid,  semilunar,  and  cuneiform  bones. 
This  ligament  is  perforated  by  numerous  apertures  for  the  passage  of  vessels,  and 
is  in  relation,  in  front,  with  the  tendons  of  the  Flexor  profundus  digitorum  and 
Flexor  longus  pollicis ;  behind,  with  the  synovial  membrane  of  the  wrist-joint. 

The  Posterior  Ligament,  less  thick  and  strong  than  the  anterior,  is  attached, 
.above,  to  the  posterior  border  of  the  lower  end  of  the  radius ;  its  fibres  descend 
obliquely  downwards  and  inwards  to  be  attached  to  the  dorsal  surface  of  the 
scaphoid,  semilunar,  and  cuneiform  bones,  its  fibres  being  continuous  with  those 
of  the  dorsal  carpal  ligaments.  This  ligament  is  in  relation,  behind,  with  the 
extensor  tendons  of  the  fingers ;  in  front,  with  the  synovial  membrane  of  the 
wrist. 

The  Synovial  Membrane  lines  the  under  surface  of  the  triangular  interarticular 
fibro-cartilage  above ;  and  is  reflected  on  the  inner  surface  of  the  ligaments  above 
mentioned. 

Relations.  The  wrist-joint  is  covered  in  front  by  the  flexor,  and  behind  by  the 
extensor  tendons ;  it  is  also  in  relation  with  the  radial  and  ulnar  arteries. 

The  Arteries  supplying  the  joint  are  the  anterior  and  posterior  carpal  branches 
of  the  radial  and  ulnar,  the  anterior  and  posterior  interosseous,  and  some  ascend- 
ing branches  from  the  deep  palmar  arch. 

The  Nerves  are  derived  from  the  ulnar. 

Actions.     The  movements  permitted  in  this  joint  are  flexion,  extension,  abduc- 


OF   THE    CARPUS.  217 

tion,  adduction,  and  circumduction.   '  It  is  totally  incapable  of  rotation,  one  of  the 
characteristic  movements  in  true  enarthrodial  joints. 

8.  Articulations  of  the  Carpus. 
These  articulations  may  be  subdivided  into  three  sets : — 

1.  The  articulation  of  the  first  row  of  carpal  bones. 

2.  The  articulation  of  the  second  row  of  carpal  bones. 

3.  The  articulation  of  the  two  rows  with  each  other. 

1.  Articulation  of  the  First  Row  of  Carpal  Bones. 

These  are  arthrodial  joints.  The  articular  surfaces  are  covered  with  cartilage 
and  connected  together  by  the  following  ligaments : — 

Two  Dorsal.  Two  Palmar. 

Two  Interosseous. 

The  Dorsal  Ligaments,  two  in  number,  are  placed  transversely  behind  the 
bones  of  the  first  row ;  they  connect  the  scaphoid  and  semilunar,  and  the  semilunar 
and  cuneiform. 

The  Palmar  Ligaments,  also  two  in  number,  connect  the  scaphoid  and  semi- 
lunar, and  the  semilunar  and  cuneiform  bones ;  they  are  less  strong  than  the  dorsal, 
and  placed  very  deep  under  the  anterior  ligament  of  the  wrist. 

The  Interosseous  Ligaments  (fig.  135)  are  two  narrow  bundles  of  fibrous  tissue, 
connecting  the  semilunar  bone,  on  one  side  with  the  scaphoid,  on  the  other  with 
the  cuneiform.  They  close  the  upper  part  of  the  interspaces  between  the  scaphoid, 
semilunar,  and  cuneiform  bones,  their  upper  surfaces  being  smooth,  and  lined  by 
the  synovial  membrane  of  the  wrist-joint. 

The  articulation  of  the  pisiform  with  the  cuneiform  is  provided  with  a  separate 
synovial  membrane,  protected  by  a  thin  capsular  ligament.  There  are  also  two 
strong  fibrous  fasciculi,  which  connect  this  bone  to  the  unciform,  and  base  of  the 
fifth  metacarpal  bone. 

2.  Articulation  of  the  Second  Row  of  Carpal  Bones. 

These  are  arthrodial  joints,  the  articular  surfaces  are  covered  with  cartilage, 
and  connected  by  the  following  ligaments : — 

Three  Dorsal.  Three  Palmar. 

Two  Interosseous. 

The  three  Dorsal  Ligaments  extend  transversely  from  one  bone  to  another  on 
the  dorsal  surface,  connecting  the  trapezium  with  the  trapezoid,  the  trapezoid  with 
the  os  magnum,  and  the  os  magnum  with  the  unciform. 

The  three  Palmar  Ligaments  have  a  similar  arrangement  on  the  palmar  surface.- 
The  two  Interosseous  Ligaments,  much  thicker  than  those  of  the  first  row,  are 
placed  one  on  each  side  of  the  os  magnum,  connecting  it  with  the  trapezoid  exter- 
nally, and  the  unciform  internally.     The  former  is  less  distinct  than  the  latter. 

3.  Articulation  of  the  Two  Rows  of  Carpal  Bones  with  each  other. 

The  articulation  between  the  two  rows  of  the  carpus  consists  of  an  enarthrodial 
joint  in  the  middle,  formed  by  the  reception  of  the  os  magnum  into  a  cavity 
formed  by  the  scaphoid  and  semilunar  bones,  and  of  an  arthrodial  joint  on  each 
side,  the  outer  one  formed  by  the  articulation  of  the  scaphoid  with  the  trapezium 
and  trapezoid,  the  internal  one  by  the  articulation  of  the  cuneiform  and  unciform. 
The  articular  surfaces  are  covered  by  a  thin  layer  of  cartilage,  and  connected  by 
the  following  ligaments : — 

Anterior  or  Palmar.  External  Lateral. 

Posterior  or  Dorsal.  Internal  Lateral. 


218  ARTICULATIONS. 

The  Anterior  or  Palmar  Ligaments  consist  of  short  fibres,  which  pass  obliquely 
between  the  bones  of  the  first  and  second  row  on  the  palmar  surface. 

The  Posterior  or  Dorsal  Ligaments  have  a  similar  arrangement  on  the  dorsal 
surface  of  the  carpus. 

The  Lateral  Ligaments  are  very  short ;  they  are  placed,  one  on  the  radial,  the 
other  on  the  ulnar  side  of  the  carpus ;  the  former,  the  stronger  and  more  distinct, 
connecting  the  scaphoid  and  trapezium  bones,  the  latter  the  cuneiform  and  unci- 
form :  they  are  continuous  with  the  lateral  ligaments  of  the  wrist-joint. 

There  are  two  Synovial  Membranes  found  in  the  articulation  of  the  carpal 
bones  with  each  other.  The  first  of  these,  the  more  extensive,  lines  the  under 
surface  of  the  scaphoid,  semilunar,  and  cuneiform  bones,  sending  upwards  two 
prolongations  between  their  contiguous  surfaces;  it  is  then  reflected  over  the 
bones  of  the  second  row,  and  sends  down  three  prolongations  between  them,  which 
line  their  contiguous  surfaces,  and  invest  the  carpal  extremities  of  the  four  outer 
metacarpal  bones.  The  second  is  the  synovial  membrane  between  the  pisiform 
and  cuneiform  bones. 

Actions.  The  partial  movement  which  takes  place  between  the  bones  of  each 
row  is  very  inconsiderable ;  the  movement  between  the  two  rows  is  more  marked, 
but  limited  chiefly  to  flexion  and  extension. 

9.  Carpo-metacarpal  Articulations. 

Articulation  of  the  Metacarpal  Bone  of  the  Thumb  with  the  Trapezium. 

This  is  an  enarthrodial  joint.  Its  ligaments  are  a  capsular  and  synovial  mem- 
brane. The  capsular  ligament  is  a  thick  but  loose  capsule,  which  passes  from 
the  circumference  of  the  upper  extremity  of  the  metacarpal  bone,  to  the  rough 
edge  bounding  the  articular  surface  of  the  trapezium ;  it  is  thickest  externally 
and  behind,  and  lined  by  a  separate  synovial  membrane. 

Articulation  of  the  Metacarpal  Bones  of  the  Fingers  with  the  Carpus. 

The  joints  formed  between  the  carpus  and  four  inner  metacarpal  bones  are 
connected  together  by  dorsal,  palmar,  and  interosseous  ligaments. 

The  Dorsal  Ligaments,  the  strongest  and  most  distinct,  connect  the  carpal  and 
metacarpal  bones  on  their  dorsal  surface.  The  second  metacarpal  bone  receives 
two  fasciculi,  one  from  the  trapezium,  the  other  from  the  trapezoid ;  the  third 
metacarpal  receives  one  from  the  os  magnum ;  the  fourth  two,  one  from  the  os 
magnum,  and  one  from  the  unciform ;  the  fifth  receives  a  single  fasciculus  from 
the  unciform  bone. 

The  Palmar  Ligaments  have  a  somewhat  similar  arrangement  on  the  palmar 
surface,  with  the  exception  of  the  third  metacarpal,  which  has  three  ligaments,  an 
external  one  from  the  trapezium,  situated  above  the  sheath  of  the  tendon  of  the 
Flexor  carpi  radialis ;  a  middle  one,  from  the  os  magnum ;  and  an  internal  one, 
from  the  unciform. 

The  Interosseous  Ligaments  consist  of  short  thick  fibres,  which  are  limited  to 
one  part  of  the  carpo-metacarpal  articulation ;  they  connect  the  contiguous  inferior 
angles  of  the  os  magnum  and  unciform,  with  the  adjacent  surfaces  of  the  third 
and  fourth  metacarpal  bones. 

The  Synovial  Membrane  is  a  continuation  of  that  between  the  two  rows  of 
carpal  bones.  Occasionally,  the  articulation  of  the  unciform  with  the  fourth 
and  fifth  metacarpal  bones  has  a  separate  synovial  membrane. 

The  Synovial  Membranes  of  the  wrist  (fig.  136)  are  thus  seen  to  be  five  in 
number.  The  first,  the  membrana  sacciformis,  lining  the  lower  end  of  the  ulna, 
the  sigmoid  cavity  of  the  radius,  and  upper  surface  of  the  triangular  interarticular 
fibro-cartilage.  The  second  lines  the  lower  end  of  the  radius  and  interarticular 
fibro-cartilage  above,  and  the  scaphoid,  semilunar,  and  cuneiform  bones  below.  The 
third,  the  most  extensive,  covers  the  contiguous  surfaces  of  the  two  rows  of  carpal 


CARPO-MET  A  CARPAL. 


219 


bones,  and,  passing  between  the  bones  of  the  second  range,  lines  the  carpal  extre- 
mities of  the  four  inner  metacarpal  bones.  The  fourth  lines  the  adjacent 
surfaces  of  the  trapezium  and  metacarpal  bone  of  the  thumb.  And  the  fifth  the 
adjacent  surfaces  of  the  cuneiform  and  pisiform  bones. 

Actions.  The  movement  permitted  in  the  carpo-metacarpal  articulations  is  limited 
to  a  slight  gliding  of  the  articular  surfaces  upon  each  other,  the  extent  of  which 
varies  in  the  different  joints.  Thus  the  articulation  of  the  metacarpal  bone  of  the 
thumb  with  the  trapezium  is  most  movable,  then  the  fifth  metacarpal,  and  then 
the  fourth.  The  second  and  third  are  almost  immovable.  In  the  articulation  of 
the  metacarpal  bone  of  the  thumb  with  the  trapezium,  the  movements  permitted 
are  flexion,  extension,  adduction,  abduction,  and  circumduction. 


Fig.  136. 


-Vertical  Section  through  the  Articulations  at  the  Wrist,  showing  the  five  Synovial 
Membranes. 


Articulations  of  the  Metacarpal  Bones  with  each  other. 

The  carpal  extremities  of  the  metacarpal  bones  articulate  with  one  another  at 
each  side  by  small  surfaces  covered  with  cartilage,  and  connected  together  by 
dorsal,  palmar,  and  interosseous  ligaments. 

The  Dorsal  and  Palmar  Ligaments  pass  transversely  from  one  bone  to  another 
on  the  dorsal  and  palmar  surfaces.  The  Interosseous  Ligaments  pass  between 
their  contiguous  surfaces,  just  beneath  their  lateral  articular  facets. 

The  Synovial  Membrane  lining  the  lateral  facets  is  a  reflection  from  that 
between  the  two  rows  of  carpal  bones. 

The  digital  extremities  of  the  metacarpal  bones  are  connected  together  by  a 
narrow  fibrous  band,  the  transverse  ligament,  which  passes  transversely  across 
their  under  surfaces,  and  is  blended  with  the  ligaments  of  the  metacarpophalan- 
geal articulations.  Its  anterior  surface  presents  four  grooves  for  the  passage  of 
the  flexor  tendons. ,  Its  posterior  surface  blends  with  the  ligaments  of  the  meta- 
carpophalangeal articulation. 


220 


ARTICULATIONS. 


LATERAL      LICAMENT 


Metacurpo  -jihala.  n/jeal 
Artie*! 


10.  Metacarpophalangeal  Articulations  (fig.  137). 

These  articulations  are  of  the  ginglymoid  kind,  formed  by  the  reception  of  the 
rounded  head  of  the  metacarpal  bone,  into  a  superficial  cavity  in  the  extremity 
of  the  first  phalanx.     They  are  connected  by  the  following  ligaments : — 
Anterior.  Two  Lateral. 

The  Anterior  Ligaments  are  thick,  dense,  and  fibro-cartilaginous  in  texture. 

Each  is  placed  on  the  palmar 
Fig.  l37.-Articulations  of  the  Phalanges.  surface   of  the  joint,  in  the 

interval  between  the  lateral 
ligaments,  to  which  they  are 
connected ;  they  are  loosely 
united  to  the  metacarpal  bone, 
but  very  firmly  to  the  base  of 
the  first  phalanges.  Their 
palmar  surface  is  intimately 
blended  with  the  transverse 
ligament,  each  ligament  form- 
ing with  it  a  groove  for  the 
passage  of  the  flexor  tendons, 
the  sheath  surrounding  which 
is  connected  to  it  at  each  side. 
By  their  internal  surface,  they 
form  part  of  the  articular 
surface  for  the  head  of  the 
metacarpal  bone,  and  are  lined 
by  a  synovial  membrane. 

The  Lateral  Ligaments  are 
strong  rounded  cords,  placed 
one  on  each  side  of  the  joint, 
each  being  attached  by  one 
extremity  to  the  tubercle  on 
the  side  of  the  head  of  the 
metacarpal  bone,  and  by  the 
other  to  the  contiguous  ex- 
tremity of  the  phalanx. 

The  Posterior  Ligament  is 
supplied  by  the  extensor  ten- 
don placed  over  the  back  of 
each  joint. 

Actions.  The  movements 
which  occur  in  these  joints 
are  flexion,  extension,  adduc- 
tion, abduction,  and  circumduction ;  the  lateral  movements  are  very  limited. 

11.  Articulations  of  the  Phalanges  (fig.  137). 

These  are  ginglymoid  joints,  connected  by  the  following  ligaments : — 
Anterior.  Two  Lateral. 

The  arrangement  of  these  ligaments  is  similar  to  those  in  the  metacarpo-pha- 
langeal  articulations;  the  extensor  tendon  supplies  the  place  of  a  posterior 
ligament. 

Actions.  The  only  movements  permitted  in  the  phalangeal  joints  are  flexion 
and  extension ;  these  movements  are  more  extensive  between  the  first  and  second 
phalanges  than  between  the  second  and  third.  The  movement  of  flexion  is  very 
extensive,  but  extension  is  limited  by  the  anterior  and  lateral  ligaments. 


FJi&lantfeal 

Artie Vf 


HIP-JOINT. 


221 


ARTICULATIONS  OP  THE  LOWER  EXTREMITY. 

The  articulations  of  the  Lower  Extremity  comprise  the  following  groups.  1. 
The  hip-joint.  2.  The  knee-joint.  3.  The  articulations  between  the  tibia  and 
fibula.  4.  The  ankle-joint.  5.  The  articulations  of  the  tarsus.  6.  The  tarso- 
metatarsal articulations.  7.  The  metatarso-phalangeal  articulations.  8.  The 
articulation  of  the  phalanges. 

1.  Hip-joint  (fig.  138). 

This  articulation  is  an  enarthrodial  or  ball-and-socket  joint,  formed' by  the 
reception  of  the  head  of  the  femur  into  the  cup-shaped  cavity  of  the  acetabulum. 
The  articulating  surfaces  are  covered  with  cartilage,  that  on  the  head  of  the  femur 
being  thicker  at  the  centre  than  at  the  circumference,  and  covering  the  entire 
surface  with  the  exception  of  a  depression  just  below  its  centre  for  the  ligamen- 
tum  teres ;  that  covering  the  acetabulum  is  much  thinner  at  the  centre  than  at  the 
circumference,  being  deficient  in  the  situation  of  the  circular  depression  at  the 
bottom  of  this  cavity.     The  ligaments  of  the  joint  are  the 

Capsular.  Teres. 

Ilio-femoral.  Cotyloid. 

Transverse. 

Fig.  138. — Left  Hip-joint  laid  open. 


The  Capsular  Ligament  is  a  strong,  dense,  ligamentous  capsule,  embracing  the 
margin  of  the  acetabulum  above,  and  surrounding  the  neck  of  the  femur  below. 
Its  upper  circumference  is  attached  to  the  acetabulum  two  or  three  lines  external 
to  the  cotyloid  ligament ;  but,  opposite  the  notch  where  the  margin  of  this  cavity 
is  deficient,  it  is  connected  with  the  transverse  ligament,  and  by  a  few  fibres  to  the 
edge  of  the  obturator  foramen.  Its  lower  circumference  surrounds  the  neck  of  the 
femur,  being  attached,  in  front,  to  the  spiral  or  anterior  inter-trochanteric  line ; 
above,  to  the  base  of  the  neck ;  behind,  to  the  middle  of  the  neck  of  the  bone, 
about  half  an  inch  from  the  posterior  inter-trochanteric  line.     It  is  much  thicker 


222  •  ARTICULATIONS. 

at  the  upper  and  fore  part  of  the  joint  where  the  greatest  amount  of  resistance  is 
required,  than  below  where  it  is  thin,  loose,  and  longer  than  in  any  other  situation. 
Its  external  surface  is  rough,  covered  by  numerous  muscles,  and  separated  in  front 
from  the  Psoas  and  Iliacus  by  a  synovial  bursa,  which  not  unfrequently  commu- 
nicates by  a  circular  aperture  with  the  cavity  of  the  joint.  It  differs  from  the 
capsular  ligament  of  the  shoulder,  in  being  much  less  loose  and  lax,  and  in  not 
being  perforated  for  the  passage  of  a  tendon. 

The  llio-femoral  Ligament  (fig.  127)  is  an  accessory  band  of  fibres,  extending 
obliquely  across  the  front  of  the  joint:  it  is  intimately  connected  with  the  capsular 
ligament,  and  serves  to  strengthen  it  in  this  situation.  It  is  attached,  above,  to  the 
anterior  inferior  spine  of  the  ilium ;  below,  to  the  anterior  intertrochanteric  line. 
The  Ligamentum  Teres  is  a  triangular  band  of  fibres,  implanted,  by  its  apex, 
into  the  depression  a  little  behind  and  below  the  centre  of  the  head  of  the  femur; 
and  by  its  broad  base,  which  consists  of  two  bundles  of  fibres,  into  the  margins  of 
the  notch  at  the  bottom  of  the  acetabulum,  becoming  blended  with  the  transverse 
ligament.  It  is  formed  of  a  bundle  of  fibres,  the  thickness  and  strength  of  which 
are  very  variable,  surrounded  by  a  tubular  sheath  of  synovial  membrane.  Some- 
times, the  synovial  fold  only  exists,  or  the  ligament  may  be  altogether  absent. 
The  use  of  the  round  ligament  is  to  check  rotation  outwards,  when  combined  with 
flexion :  it  thus  assists  in  preventing  dislocation  of  the  head  of  the  femur  forwards 
and  outwards,  an  accident  likely  to  occur  from  the  necessary  mechanism  of  the  joint, 
if  not  provided  against  by  this  ligament  and  the  thick  anterior  part  of  the  capsule.1 

The  Cotyloid  Ligament  is  a  fibro -cartilaginous  rim  attached  to  the  margin  of 
the  acetabulum,  the  cavity  of  which  it  deepens  ;  at  the  same  time  it  protects  the 
edges  of  the  bone,  and  fills  up  the  inequalities  on  its  surface.  It  is  prisnioid  in 
form,  its  base  being  attached  to  the  margin  of  the  acetabulum,  its  opposite  edge 
being  free  and  sharp ;  whilst  its  two  surfaces  are  invested  by  synovial  membrane, 
the  external  one  being  in  contact  with  the  capsular  ligament,  the  internal  one 
being  inclined  inwards  so  as  to  narrow  the  acetabulum  and  embrace  the  cartila- 
ginous surface  of  the  head  of  the  femur.  It  is  much  thicker  above  and  behind 
than  below  and  in  front,  and  consists  of  close  compact  fibres,  which  arise  from 
different  points  of  the  circumference  of  the  acetabulum,  and  interlace  with  each 
other  at  very  acute  angles. 

The  Transverse  Ligament  is  a  strong  flattened  band  of  fibres,  which  crosses  the 
notch  at  the  lower  part  of  the  acetabulum,  and  converts  it  into  a  foramen.  It  is 
continuous  at  each  side  with  the  cotyloid  ligament.  An  interval  is  left  beneath 
the  ligament  for  the  passage  of  nutrient  vessels  to  the  joint. 

The  Synovial  Membrane  is  very  extensive.  Commencing  at  the  margin  of  the 
cartilaginous  surface  of  the  head  of  the  femur,  it  covers  all  that  portion  of  the 
neck  which  is  contained  within  the  joint ;  from  this  point  it  is  reflected  on  the 
internal  surface  of  the  capsular  ligament,  covers  both  surfaces  of  the  cotyloid 
ligament,  and  the  mass  of  fat  contained  in  the  fossa  at  the  bottom  of  this  cavity, 
and  is  prolonged  in  the  form  of  a  tubular  sheath  around  the  ligamentum  teres, 
as  far  as  the  head  of  the  femur. 

The  Muscles  in  relation  with  the  joint  are,  in  front,  the  Psoas  and  Iliacus,  sepa- 
rated from  the  capsular  ligament  by  a  synovial  bursa ;  above,  the  short  head  of 
the  Rectus  and  Gluteus  minimus,  the  latter  being  closely  adherent  to  it ;  internally, 
the  Obturator  externus  and  Pectineus ;  behind,  the  Pyriformis,  Gemellus  superior, 
Obturator  internus,  Gemellus  inferior,  Obturator  externus,  and  Quadratus  femoris. 

The  Arteries  supplying  it  are  derived  from  the  obturator,  sciatic,  internal  cir- 
cumflex, and  gluteal. 

The  Nerves  are  articular  branches  from  the  sacral  plexus,  great  sciatic,  obtu- 
rator, and  accessory  obturator  nerves. 

Actions.  The  movements  of  the  hip,  like  all  enarthrodial  joints,  are  very  exten- 
sive; they  are,  flexion,  extension,  adduction,  abduction,  circumduction,  and  rotation. 

1  See  an  interesting  paper,  "On  the  Use  of  the  Round  Ligament  of  the  Hip-joint,"  by  Dr.  J. 
Struthers.     Edinburgh  Medical  Journal,  1858. 


223 




are,  the  condyles  of  the  femur  above,  the  head  of  the  tibia  below,  and  the  patella 
in  front.  The  articular  surfaces  are  covered  with  cartilage,  and  connected  toge- 
ther by  ligaments,  some  of  which  are  placed  on  the  exterior  of  the  joint,  whilst 
others  occupy  its  interior. 


KNEE-JOINT. 


2.  Knee-joint. 


External  Ligaments. 

Anterior  or  Ligamentum  Pa- 
tellae. 

Posterior  or  Ligamentum 
Posticum  Winslowii. 

Internal  Lateral. 

Two  External  Lateral. 

Capsular. 


Internal  Ligaments. 

Anterior  or  External  Crucial. 

Posterior  or  Internal  Crucial. 

Two  Semilunar  Fibro-cartilages. 

Transverse. 

Coronary. 

Ligamentum  mucosum. 

Ligamenta  alaria. 


The  Anterior  Ligament  cr  Ligamentum  Patellse  (fig.  139)  is  that  portion  of 
the  common  tendon  of  the  extensor  muscles  of  the  thigh  which  is  continued  from 


Fig.  139.— Right  Knee-joint.     Anterior  "View.  Fig.  140.— Right  Knee-joint.     Posterior  View. 


the  patella  to  the  tubercle  of  the  tibia,  supplying  the  place  of  an  anterior  ligament, 
It  is  a  strong,  flat,  ligamentous  band,  about  three  inches  in  length,  attached,  above, 
to  the  apex  of  the  patella  and  the  rough  depression  on  its  posterior  surface ;  below, 
to  the  lower  part  of  the  tuberosity  of  the  tibia ;  its  superficial  fibres  being  continu- 
ous across  the  front  of  the  patella  with  those  of  the  tendon  of  the  Quadriceps  ex- 
tensor. Two  synovial  bursas  are  connected  with  this  ligament  and  the  patella  ;  one 
is  interposed  between  the  patella  and  the  skin  covering  its  anterior  surface ;  the 


224  ARTICULATIONS. 

other,  of  small  size,  between  the  ligamentum  patellae  and  the  upper  part  of  the 
tuberosity  of  the  tibia.  The  posterior  surface  of  this  ligament  is  separated  above 
from  the  knee-joint  by  a  large  mass  of  adipose  tissue ;  its  lateral  margins  are  con- 
tinuous with  the  aponeuroses  derived  from  the  Vasti  muscles. 

The  Posterior  Ligament  or  Ligamentum,  Posticum  Winslowii  (fig.  140)  is  a  broad, 
flat,  fibrous  band,  which  covers  over  the  whole  of  the  back  part  of  the  joint.  It 
consists  of  two  lateral  portions,  formed  chiefly  of  vertical  fibres,  which  arise  above 
from  the  condyles  of  the  femur,  and  are  connected  below  with  the  back  part  of 
the  head  of  the  tibia,  being  closely  united  with  the  tendons  of  the  Gastrocnemius, 
Plantaris,  and  Popliteus  muscles ;  the  central  portion  is  formed  of  fasciculi  ob- 
liquely directed  and  separated  from  one  another  by  apertures  for  the  passage  of 
vessels.  The  strongest  of  these  fasciculi  is  derived  from  the  tendon  of  the  Semi- 
membranosus ;  it  passes  from  the  back  part  of  the  inner  tuberosity  of  the  tibia, 
obliquely  upwards  and  outwards,  to  the  back  part  of  the  outer  condyle  of  the 
femur.  The  posterior  ligament  forms  part  of  the  floor  of  the  popliteal  space,  and 
upon  it  rests  the  popliteal  artery. 

The  Internal  Lateral  Ligament  is  a  broad,  flat,  membranous  band,  thicker  behind 
than  in  front,  and  situated  nearer  to  the  back  than  the  front  of  the  joint.  It  is 
attached,  above,  to  the  inner  tuberosity  of  the  femur ;  below,  to  the  inner  tuberosity 
and  inner  surface  of  the  shaft  of  the  tibia,  to  the  extent  of  about  two  inches.  It 
is  crossed,  at  its  lower  part,  by  the  aponeurosis  of  the  Sartorius,  and  the  tendons 
of  the  Gracilis  and  Semi-tendinosus  muscles,  a  synovial  bursa  being  interposed. 
Its  deep  surface  covers  the  anterior  portion  of  the  tendon  of  the  Semi-membra- 
nosus,  the  synovial  membrane  of  the  joint,  and  the  inferior  internal  articular 
artery ;  it  is  intimately  adherent  to  the  internal  semilunar  fibro-cartilage. 

The  Long  External  Lateral  Ligament  is  a  strong,  rounded,  fibrous  cord,  situated 
nearer  to  the  back  than  the  front  of  the  joint.  It  is  attached,  above,  to  the  outer 
condyle  of  the  femur ;  below,  to  the  outer  part  of  the  head  of  the  fibula.  Its 
outer  surface  is  covered  by  the  tendon  of  the  Biceps,  which  divides  into  two 
parts,  separated  by  the  ligament,  at  its  insertion.  It  has,  passing  beneath  it, 
the  tendon  of  the  Popliteus  muscle,  and  the  inferior  external  articular  vessels  and 
nerve. 

The  Short  External  Lateral  Ligament  is  an  accessory  bundle  of  fibres,  placed 
behind  and  parallel  with  the  preceding ;  attached,  above,  to  the  lower  part  of  the 
outer  condyle  of  the  femur ;  below,  to  the  summit  of  the  styloid  process  of  the 
fibula.  This  ligament  is  intimately  connected  with  the  capsular  ligament,  and 
has,  passing  beneath  it,  the  tendon  of  the  Popliteus  muscle. 

The  Capsular  Ligament  consists  of  an  exceedingly  thin,  but  strong,  fibrous 
membrane,  which  fills  in  the  intervals  left  by  the  preceding  ligaments.  It  is 
attached  to  the  femur  immediately  above  its  articular  surface ;'  below,  to  the  upper 
border  and  sides  of  the  patella,  the  margins  of  the  head  of  the  tibia  and  inter- 
articular  cartilages,  and  is  continuous  behind  with  the  posterior  ligament.  This 
membrane  is  strengthened  by  fibrous  expansions,  derived  from  the  fascia  lata,  from 
the  Vasti  and  Crureus  muscles,  and  from  the  Biceps,  Sartorius,  and  tendon  of  the 
Sami-membranosus. 

The  Crucial  are  two  interosseous  ligaments  of  considerable  strength,  situated' 
in  the  interior  of  the  joint,  nearer  its  posterior  than  its  anterior  part.  They  are 
called  crucial,  because  they  cross  each  other,  somewhat  like  the  lines  of  the  letter 
X ;  and  have  received  the  names  anterior  and  posterior,  from  the  position  of  their 
attachment  to  the  tibia. 

The  Anterior  or  External  Crucial  Ligament  (fig.  141),  smaller  than  the  poste- 
rior, is  attached  to  the  inner  side  of  the  depression  in  front  of  the  spine  of  the 
tibia,  being  blended  with  the  anterior  extremity  of  the  external  semilunar  fibro- 
cartilage,  and  passing  obliquely  upwards,  backwards,  and  outwards,  is  inserted 
into  the  inner  and  back  part  of  the  outer  condyle  of  the  femur. 

The  Posterior  or  Internal  Crucial  Ligament  is  Larger  in  size,  but  less  oblique 
v.\  its  direction  than  the  anterior.     It  is  attached  to  the  back  part  of  the  depres- 


KNEE-JOINT. 


225 


Fig.  141. — Right  Knee-joint.     Showing  Internal 
Ligaments. 


sion  behind  the  spine  of  the  tibia,  and  to  the  posterior  extremity  of  the  external 
semilunar  fibro-cartilage ;  passing  upwards,  forwards,  and  inwards,  it  is  inserted 
into  the  outer  and  fore  part  of  the  inner  condyle  of  the  femur.  As  it  crosses  the 
anterior  crucial  ligament,  a  fasciculus  is 
given  off  from  it,  which  blends  with  its 
posterior  part.  It  is  in  relation,  in  front, 
with  the  anterior  crucial  ligament;  behind, 
with  the  ligamentum  posticum  Winslowii. 

The  Semilunar  Fibro-cartilages  (fig. 
142)  are  two  crescentic  lamellae  attached 
to  the  margins  of  the  head  of  the  tibia, 
serving  to  deepen  its  surface  for  articula- 
tion with  the  condyles  of  the  femur.  The 
circumference  of  each  cartilage  is  thick 
and  convex ;  the  inner  free  border,  thin 
and  concave.  Their  upper  surfaces  are 
concave,  and  in  relation  with  the  condyles 
of  the  femur;  their  lower  surfaces  are 
flat,  and  rest  upon  the  head  of  the  tibia. 
Each  cartilage  covers  nearly  the  outer 
two-thirds  of  the  corresponding  articular 
surface  of  the  tibia,  the  inner  third  being 
uncovered ;  both  surfaces  are  smooth,  and 
invested  by  synovial  membrane. 

The  Internal  Semilunar  Fibro-cartilage 
is  nearly  semicircular  in  form,  a  little 
elongated  from  before  backwards,  and 
broader  behind  than  in  front ;  its  convex 
border  is  united  to  the  internal  lateral 
ligament,  and  to  the  head  of  the  tibia, 
by  means  of  the  coronary  ligaments^  its 
anterior  extremity,  thin  and  pointed,  is 
firmly  implanted  into  a  depression  in  front 
of  the  inner  articular  surface  of  the  tibia; 
its  posterior  extremity  to  the  depression  behind  the  spine,  between  the  attach- 
ment of  the  external  cartilage  and  posterior  crucial  ligament. 

The  External  Semilunar  Fibro-cartilage  forms  nearly  an  entire  circle,  covering 
a  larger  portion  of  the  articular  surface 
than  the  internal  one.  It  is  grooved  on 
its  outer  side,  for  the  tendon  of  the  Pop- 
liteus  muscle.  Its  circumference  is  held 
in  connection  with  the  head  of  the  tibia, 
by  means  of  the  coronary  ligaments; 
and  its  two  extremities  are  firmly  im- 
planted in  the  depressions  in  front  and 
behind  the  spine  of  the  tibia.  These  ex- 
tremities, at  their  insertion,  are  interposed 
between  the  attachments  of  the  internal 
cartilage.  The  external  semilunar  fibro- 
cartilage  gives  off  from  its  anterior  bor- 
der a  fasciculus,  which  forms  the  trans- 
verse ligament.  By  its  anterior  extremity,  it  is  continuous  with  the  anterior 
crucial  ligament.  Its  posterior  extremity  divides  into  three  slips ;  two  of  these 
pass  upwards  and  forwards,  and  are  inserted  into  the  outer  side  of  the  inner 
condyle,  one  in  front,  the  other  behind  the  posterior  crucial  ligament ;  the  third 
fasciculus  is  inserted  into  the  back  part  of  the  anterior  crucial  ligament. 

The  Transverse  Ligament  is  a  band  of  fibres,  which  passes  transversely  be- 
15 


Fig.  142.— Head  of  Tibia,  with  Semilnnai 

Cartilages,  etc.     Seen  from  above. 

Right  Side. 


226  ARTICULATIONS. 

tween  the  anterior  convex  margin  of  the  external  semilunar  cartilage,  to  the 
anterior  extremity  of  the  internal  cartilage ;  its  thickness  varies  considerably  in 
different  subjects. 

The  Coronary  Ligaments  consist  of  numerous  short  fibrous  bands,  which  con- 
nect the  convex  border  of  the  semilunar  cartilages  with  the  circumference  of  the 
head  of  the  tibia,  and  with  the  other  ligaments  surrounding  the  joint. 

The  Synovial  Membrane  of  the  knee-joint  is  the  largest  and  most  extensive  in 
the  body.  Commencing  at  the  upper  border  of  the  patella,  it  forms  a  large  cul- 
de-sac  beneath  the  Extensor  tendon  of  the  thigh :  this  is  sometimes  replaced  by  a 
synovial  bursa  interposed  between  the  tendon  and  the  front  of  the  femur,  which 
in  some  subjects  communicates  with  the  synovial  membrane  of  the  knee-joint,  by 
an  orifice  of  variable  size.  On  each  side  of  the  patella,  the  synovial  membrane 
extends  beneath  the  aponeurosis  of  the  Vasti  muscles,  and  more  especially  beneath 
that  of  the  Vastus  internus ;  and,  beneath  the  patella,  it  is  separated  from  the 
anterior  ligament  by  a  considerable  quantity  of  -adipose  tissue.  In  this  situation, 
it  sends  off  a  triangular-shaped  prolongation,  containing  a  few  ligamentous  fibres, 
which  extends  from  the  anterior  part  of  the  joint  below  the  patella,  to  the  front 
of  the  intercondyloid  notch.  This  fold  has  been  termed  the  ligamentum  mucosum. 
The  ligamenta  alaria  consist  of  two  fringe-like  folds,  which  extend  from  the  sides 
of  the  ligamentum  mucosum,  upwards  and  outwards,  to  the  sides  of  the  patella. 
The  synovial  membrane  invests  the  semilunar  fibro-cartilages,  and  on  the  back 
part  of  the  external  one  forms  a  cul-de-sac  between  the  groove  on  its  surface  and 
the  tendon  of  the  Popliteus ;  it  is  continued  to  the  articular  surface  of  the  tibia, 
surrounds  the  crucial  ligaments,  and  the  inner  surface  of  the  ligaments  which 
inclose  the  joint ;  lastly,  it  approaches  the  condyles  of  the  femur,  and  from  them  is 
continued  on  to  the  lower  part  of  the  front  of  the  shaft.  The  pouch  of  synovial 
membrane  between  the  Extensor  tendon  and  front  of  the  femur  is  supported, 
during  the  movements  of  the  knee,  by  a  small  muscle,  the  Subcrureus,  which  is 
inserted  into  it. 

The  Arteries  supplying  the  joint  are  derived  from  the  anastomotic  branch  of 
the  femoral,  articular  branches  of  the  pqrjliteal,  and  recurrent  branch  of  the 
anterior  tibial. 

The  Nerves  are  derived  from  the  obturator,  anterior  crural,  and  external  and 
internal  popliteal. 

Actions.  The  chief  movements  of  this  joint  are  flexion  aud  extension ;  but  it  is 
also  capable  of  performing  some  slight  rotatory  movement.  During  flexion,  the 
articular  surfaces  of  the  tibia,  covered  by  their  interarticular  cartilages,  glide 
backwards  upon  the  condyles  of  the  femur,  the  lateral,  posterior,  and  crucial  liga- 
ments are  relaxed,  the  ligamentum  patella?  is  put  upon  the  stretch,  the  patella 
filling  up  the  vacuity  in  front  of  the  joint  between  the  femur  and  tibia.  In 
extension,  the  tibia  and  interarticular  cartilages  glide  forwards  upon  the  femur; 
all  the  ligaments  are  stretched,  with  the  exception  of  the  ligamentum  patellae, 
which  is  relaxed,  and  admits  of  considerable  lateral  movement.  The  movement 
of  rotation  is  permitted  when  the  knee  is  semi-flexed,  rotation  outwards  being 
most  extensive. 

3.  Articulation  between  the  Tibia  and  Fibula. 

The  articulations  between  the  tibia  and  fibula  are  effected  by  ligaments  which 
connect  both  extremities,  as  well  as  the  shaft  of  these  bones.  They  may,  con- 
sequently, be  subdivided  into  three  sets.  1.  The  Superior  Tibio-fibular  articula- 
tion. 2.  The  Middle  Tibio-fibular  articulation.  3.  The  Inferior  Tibio-fibular 
articulation. 

1.  Superioe  Tibio-fibular  Articulation. 
This  articulation  is  an  arthrodial  joint.     The  contiguous  surfaces  of  the  bode." 


TIBIO-FIBULAR.  227 

present  two  flat  oval  surfaces  covered  with,  cartilage,  and  connected  together  by 
the  following  ligaments. 

Anterior  Superior  Tibio-fibular. 
Posterior  Superior  Tibio-fibular. 

The  Anterior  Superior  Ligament  (fig.  141)  consists  of  two  or  three  broad  and 
flat  bands,  which  pass  obliquely  upwards  and  inwards,  from  the  head  of  the  fibula 
to  the  outer  tuberosity  of  the  tibia. 

The  Posterior  Superior  Ligament  is  a  single  thick  and  broad  band,  which 
passes  from  the  back  part  of  the  head  of  the  fibula  to  the  back  part  of  the  outer 
tuberosity  of  the  tibia.     It  is  covered  in  by  the  tendon  of  the  Popliteus  muscle. 

A  Synovial  Membrane  lines  this  articulation.  It  is  occasionally  continuous 
with  that  of  the  knee-joint  at  its  upper  and  back  part. 

2.  Middle  Tibio-fibular  Articulation". 

An  interosseous  membrane  extends  between  the  contiguous  margins  of  the  tibia 
and  fibula,  and  separates  the  muscles  on  the  front  from  those  on  the  back  of  the 
leg.  It  consists  of  a  thin  aponeurotic  lamina  composed  of  oblique  fibres,  which 
pass  between  the  interosseous  ridges  on  the  two  bones.  It  is  broader  above  than 
below,  and  presents  at  its  upper  part  a  large  oval  aperture  for  the  passage  of  the 
anterior  tibial  artery  forwards  to  the  anterior  aspect  of  the  leg ;  and  at  its  lower 
part,  an  opening  for  the  passage  of  the  anterior  peroneal  vessels.  It  is  continuous 
below  with  the  inferior  interosseous  ligament ;  and  is  perforated  in  numerous  parts 
for  the  passage  of  small  vessels.  It  is  in  relation  in  front  with  the  Tibialis  anticus, 
Extensor  longus  digitorum,  Extensor  proprius  pollicis,  Peroneus  tertius,  and  the 
anterior  tibial  vessels  and  nerve ;  behind,  with  the  Tibialis  posticus  and  Flexor 
longus  pollicis. 

3.  Inferior  Tibio-fibular  Articulation. 

This  articulation  is  formed  by  the  rough  convex  surface  at  the  inner  side  of 
the  lower  end  of  the  fibula,  being  connected  with  a  similar  rough  surface  on 
the  outer  side  of  the  tibia.  Below,  to  the  extent  of  about  two  lines,  these  surfaces 
are  smooth  and  covered  with  cartilage,  which  is  continuous  with  that  of  the  ankle- 
joint.     Its  ligaments  are — 

Inferior  Interosseous.  Posterior  Inferior  Tibio-fibular. 

Anterior  Inferior  Tibio-fibular.        Transverse. 

The  Inferior  Interosseous  Ligament  consists  of  numerous  short,  strong  fibrous 
bands,  which  pass  between  the  contiguous  rough  surfaces  of  the  tibia  and  fibula, 
constituting  the  chief  bond  of  union  between  these  bones.  It  is  continuous,  above, 
with  the  interosseous  membrane. 

The  Anterior  Inferior  Ligament  (fig.  144)  is  a  flat  triangular  band  of  fibres, 
broader  below  than  above,  which  extends  obliquely  downwards  and  outwards 
between  the  adjacent  margins  of  the  tibia  and  fibula  on  the  front  aspect  of  the 
articulation.  It  is  in  relation,  in  front,  with  the  Peroneus  tertius,  the  aponeurosis 
of  the  leg,  and  the  integument ;  behind,  with  the  inferior  interosseous  ligament, 
and  lies  in  contact  with  the  cartilage  covering  the  astragalus. 

The  Posterior  Inferior  Ligament,  smaller  than  the  preceding,  is  disposed  in  a 
similar  manner  on  the  posterior  surface  of  the  articulation. 

The  Transverse  Ligament  is  a  long  narrow  band  of  ligamentous  fibres,  con- 
tinuous with  the  preceding,  passing  transversely  across  the  back  of  the  joint, 
from  the  external  malleolus  to  the  tibia,  a  short  distance  from  its  malleolar  process. 
This  ligament  projects  below  the  margins  of  the  bones,  and  forms  part  of  the 
articulating  surface  for  the  astragalus. 

The  Synovial  Membrane  lining  the  articular  surfaces  is  derived  from  that  of 
the  ankle-joint. 


228 


ARTICULATIONS. 


Actions.  The  movement  permitted  in  these  articulations  is  limited  to  a  very 
slight  gliding  of  the  articular  surfaces  one  upon  another. 

4.  Ankle-joint. 

^  The  Ankle  is  a  ginglymoid  or  hinge-joint.  The  bones  entering  into  its  forma- 
tion are  the  lower  extremity  of  the  tibia  and  its  malleolus,  and  the  malleolus  of 
the  fibula,  above,  which,  united,  form  an  arch,  in  which  is  received  the  upper 
convex  surface  of  the  astragalus  and  its  two  lateral  facets.  These  surfaces  are 
covered  with  cartilage,  and  connected  together  by  the  following  ligaments : — 

Anterior.  Internal  Lateral. 

External  Lateral. 

The  Anterior  Ligament  (fig.  143)  is  a  broad,  thin,  membranous  layer,  attached 
above,  to  the  margin  of  the  articular  surface  of  the  tibia ;  below,  to  the  margin  of 


Fig.  143. — Ankle-joint :  Tarsal  and  Tarso-metatarsal  Articulations.     Internal  View.     Right  bide. 


T»S30- MCTATAR 
ANTIC  ?! 


TARSAL     ARTI  C 


the  astragalus,  in  front  of  its  articular  surface.  It  is  in  relation,  in  front,  with 
the  Extensor  tendons  of  the  toes,  the  tendons  of  the  Tibialis  anticus  and  Peroneus 
tertius,  and  the  anterior  tibial  vessels  and  nerve ;  behind,  it  lies  in  contact  with 
the  synovial  membrane. 

The  Internal  Lateral  or  Deltoid  Ligament  consists  of  two  layers,  superficial 
and  deep.  The  superficial  layer  is  a  strong,  flat,  triangular  band,  attached,  above, 
to  the  apex  and  anterior  and  posterior  borders  of  the  inner  malleolus.  The  most 
anterior  fibres  pass  forwards  to  be  inserted  into  the  scaphoid ;  the  middle  descend 
almost  perpendicularly  to  be  inserted  into  the  os  calcis ;  and  the  posterior  fibres 
pass  backwards  and  outwards  to  be  attached  to  the  inner  side  of  the  astragalus. 
The  deep  layer  consists  of  a  short,  thick,  and  strong  fasciculus  which  passes 
from  the  apex  of  the  malleolus  to  the  inner  surface  of  the  astragalus,  below  the 
articular  surface.  This  ligament  is  covered  in  by  the  tendons  of  the  Tibialis 
posticus  and  Flexor  longus  digitorum  muscles. 

The  External  Lateral  Ligament  (fig.  144)  consists  of  three  fasciculi,  taking 
different  directions,  and  separated  by  distinct  intervals. 


ANKLE-JOINT. 


229 


The  anterior  fasciculus,  the  shortest  of  the  three,  passes  from  the  anterior  margin 
of  the  summit  of  the  external  malleolus,  downwards  and  forwards,  to  the  astra- 
galus, in  front  of  its  external  articular  facet. 

The  posterior  fasciculus,  the  most  deeply  seated,  passes  from  the  depression  at  the 
inner  and  back  part  of  the  external  malleolus  to  the  astragalus,  behind  its  external 
malleolar  facet.     Its  fibres  are  almost  horizontal  in  direction. 

The  middle  fasciculus,  the  longest  of  the  three,  is  a  narrow  rounded  cord,  pass- 
ing from  the  apex  of  the  external  malleolus  downwards  and  slightly  backwards 
to  the  middle  of  the  outer  side  of  the  os  calcis.  It  is  covered  by  the  tendons  of 
the  Peroneus  longus  and  brevis.  There  is  no  posterior  ligament,  its  place  being 
supplied  by  the  transverse  ligament  of  the  tibia  and  fibula. 

The  Synovial  Membrane  invests  the  inner  surface  of  the  ligaments,  and  sends 
a  duplicature  upwards  between  the  lower  extremities  of  the  tibia  and  fibula  for  a 
short  distance. 


Fig.  144. — Ankle-joint :   Tarsal  and  Tarso- metatarsal  Articulations.    External  View.     Right  Side. 


NFERIOR  TlBlO-FlBULAf* 
ARTIES 


ANKLE-JOINT 

TARSAL  ARTIC"? 

TARSO-METATARSAL  ARTIC55 


Relations.  The  tendons,  vessels,  and  nerves  in  connection  with  the  joint  are, 
in  front,  from  within  outwards,  the  Tibialis  anticus,  Extensor  proprius  pollicis, 
anterior  tibial  vessels,  anterior  tibial  nerve,  Extensor  communis  digitorum,  and 
Peroneus  tertius ;  behind,  from  within  outwards,  Tibialis  posticus,  Flexor  longus 
digitorum,  posterior  tibial  vessels,  posterior  tibial  nerve,  Flexor  longus  pollicis, 
and,  in  the  groove  behind  the  external  malleolus,  the  tendons  of  the  Peroneus 
longus  and  Peroneus  brevis. 

The  Arteries  supplying  the  joint  are  derived  from  the  malleolar  branches  of 
the  anterior  tibial  and  peroneal. 

The  Nerves  are  derived  from  the  anterior  tibial. 

Actions.  The  movements  of  the  joint  are  limited  to  flexion  and  extension. 
There  is  no  lateral  motion. 


5.  Articulations  of  the  Tarsus. 

These  articulations  may  be  subdivided  into  three  sets :  1.  The  articulation  of 
the  first  row  of  tarsal  bones.  2.  The  articulation  of  the  second  row  of  tarsal 
bones.     3.  The  articulations  of  the  two  rows  with  each  other. 


230  ARTICULATIONS. 


1.  Articulation  of  the  First  Eow  of  Tarsal  Bones. 

The  articulation  between  the  astragalus  and  os  calcis  is  an  arthrodial  joint 
connected  together  by  three  ligaments : — 

External  Calcaneo-astragaloid.  Posterior  Calcaneo-astragaloid. 

Interosseous. 

The  External  Calcaneo-astragaloid  Ligament  (fig.  144)  is  a  short,  strong  fasci- 
culus, passing  from  the  outer  surface  of  the  astragalus,  immediately  beneath  its 
external  malleolar  facet,  to  the  outer  edge  of  the  os  calcis.  It  is  placed  in  front 
of  the  middle  fasciculus  of  the  external  lateral  ligament  of  the  ankle-joint,  with 
the  fibres  of  which  it  is  parallel. 

The  Posterior  Calcaneo-astragaloid  Ligament  (fig.  143)  connects  the  posterior 
extremity  of  the  astragalus  with  the  upper  contiguous  surface  of  the  os  calcis ;  it 
is  a  short  narrow  band,  the  fibres  of  which  are  directed  obliquely  backwards  and 
inwards. 

The  Interosseous  Ligament  forms  the  chief  bond  of  union  between  these  bones. 
It  consists  of  numerous  vertical  and  oblique  fibres,  attached,  by  one  extremity, 
to  the  groove  between  the  articulating  surfaces  of  the  astragalus;  by  the  other, 
to  a  corresponding  depression  on  the  upper  surface  of  the  os  calcis.  It  is  very 
thick  and  strong,  being  at  least  an  inch  in  breadth  from  side  to  side,  and  serves 
to  unite  the  os  calcis  and  astragalus  solidly  together. 

The  Synovial  Membranes  (fig.  146)  are  two  in  number ;  one  for  the  posterior 
calcaneo-astragaloid  articulation;  a  second  for  the  anterior  calcaneo-astragaloid 
joint.  The  latter  synovial  membrane  is  continued  forwards  between  the  contigu- 
ous surfaces  of  the  astragalus  and  scaphoid  bones. 

2.  Articulations  of  the  Second  Row  of  Tarsal  Bones. 

The  articulations  between  the  scaphoid,  cuboid,  and  three  cuneiform  are  effected 
by  the  following  ligaments : — 

Dorsal.  Plantar. 

Interosseous. 

The  Dorsal  Ligaments  are  small  bands  of  parallel  fibres,  which  pass  from  each 
bone  to  the  neighboring  bones  with  which  it  articulates. 

The  Plantar  Ligaments  have  the  same  arrangement  on  the  plantar  surface. 

The  Interosseous  Ligaments  are  four  in  number.  They  consist  of  strong  trans- 
verse fibres,  which  pass  between  the  rough  non-articular  surfaces  of  adjoining 
bones.  There  is  one  between  the  sides  of  'the  scaphoid  and  cuboid ;  a  second 
between  the  internal  and  middle  cuneiform  bones ;  a  third  between  the  middle  and 
external  cuneiform ;  and  a  fourth  between  the  external  cuneiform  and  cuboid. 
The  scaphoid  and  cuboid,  when  in  contact,  present  each  a  small  articulating  facet, 
covered  with  cartilage,  and  lined  either  by  a  separate  synovial  membrane,  or  by 
an  offset  from  the  common  tarsal  synovial  membrane. 

3.  Articulations  of  the  Two  Rows  of  the  Tarsus  with  each  other. 

These  articulations  may  be  conveniently  divided  into  three  sets.  ] .  The  arti- 
culation of  the  os  calcis' with  the  cuboid.  2.  The  os  calcis  with  the  scaphoid. 
3.  The  astragalus  with  the  scaphoid. 

1.  The  ligaments  connecting  the  os  calcis  with  the  cuboid  are  four  in  number : — 

j.        ,  j  Superior  Calcaneo-cuboid. 

.Dorsal.  -j  jnterna]  Calcaneo-cuboid  or  Interosseous. 

•p,  j  Long  Calcaneo-cuboid. 

riantar.  <  ghort  Calcaneo-cuboid. 


OF   THE   TARSUS. 


23J 


The  Superior  Calcaneo-cuboid  Ligament  (fig.  144)  is  a  thin  and  narrow  fasci- 
culus, which  passes  between  the  contiguous  surfaces  of  the  os  calcis  and  cuboid, 
on  the  dorsal  surface  of  the  joint. 

The  Internal  Calcaneo-cuboid  or  Interosseous  Ligament  (fig.  144)  is  a  short,  but 
thick  and  strong,  band  *of  fibres,  arising  from  the  os  calcis,  in  the  deep  groove 
which  intervenes  between  it  and  the  astragalus;  being  closely  blended,  at  its  ori- 
gin, with  the  superior  calcaneo-scaphoid  ligament.  It  is  inserted  into  the  inner 
side  of  the  cuboid  bone.  This  ligament  forms  one  of  the  chief  bonds  of  union 
between  the  first  and  second  row  of  the  tarsus. 

The    Long      Calcaneo-cuboid    (fig.     145),      F%-  145. -Ligaments  of  Plantar  Surface  of  the 

the  most  superficial  of  the  two  plantar 
ligaments,  is  the  longest  of  all  the  liga- 
ments of  the  tarsus,  being  attached  to  the 
under  surface  of  the  os  calcis,  from  near 
the  tuberosities,  as  far  forwards  as  the 
anterior  tubercle ;  its  fibres  pass  forwards 
to  be  attached  to  the  ridge  on  the  under 
surface  of  the  cuboid  bone,  the  more  su- 
perficial fibres  being  continued  onwards 
to  the  bases  of  the  second,  third,  and 
fourth  metatarsal  bones.  This  ligament 
crosses  the  groove  on  the  under  surface 
of  the  cuboid  bone,  converting  it  into  a 
canal  for  the  passage  of  the  tendon  of  the 
Peroneus  longus. 

The  Short  Calcaneo-cuboid  Ligament 
lies  nearer  to  the  bones  than  the  preceding, 
from  which  it  is  separated  by  a  little  areo- 
lar adipose  tissue.  It  is  exceedingly 
broad,  about  an  inch  in  length,  and  ex- 
tends from  the  tubercle  and  the  depression 
in  front  of  it  on  the  fore  part  of  the  under 
surface  of  the  os  calcis,  to  the  inferior  sur- 
face of  the  cuboid  bone  behind  the  peroneal 
groove.  A  synovial  membrane  is  found  in 
this  articulation. 

2.  The  ligaments  connecting  the  os 
calcis  with  the  scaphoid,  are  two  in  num- 
ber:— 

Superior  Calcaneo-scaphoid. 
Inferior  Calcaneo-scaphoid. 


The  Superior  Calcaneo-scaphoid  (fig.  144)  arises,  as  already  mentioned,  with  the 
internal  calcaneo-cuboid,  in  the  deep  groove  between  the  astragalus  and  os  calcis ; 
it  passes  forward  from  the  inner  side  of  the  anterior  extremity  of  the  os  calcis  to 
the  outer  side  of  the  scaphoid  bone.  These  two  ligaments  resemble  the  letter  Y, 
being  blended  together  behind,  but  separated  in  front. 

The  Inferior  Calcaneo-scaphoid  (fig.  145)  is  by  far  the  largest  and  strongest  of 
the  two  ligaments  of  this  articulation ;  it  is  a  broad  and  thick  band  of  ligamentous 
fibres,  which  passes  forwards  and  inwards  from  the  anterior  and  inner  extremity 
of  the  os  calcis,  to  the  under  surface  of  the  scaphoid  bone.  This  ligament  not 
only  serves  to  connect  the  os  calcis  and  scaphoid,  but  supports  the  head  of  the 
astragalus,  forming  part  of  the  articular  cavity  in  which  it  is  received.  Its  upper 
surface  is  lined  by  the  synovial  membrane  continued  from  the  anterior  calcaneo- 
astragaloid  articulation.  Its  under  surface  is  in  contact  with  the  tendon  of  the 
Tibialis  posticus  muscle. 


232 


ARTICULATIONS. 


3.  The  articulation  between  the  astragalus  and  scaphoid  is  an  enarthrodial 
joint ;  the  rounded  head  of  the  astragalus  being  received  into  the  concavity  formed 
by  the  posterior  surface  of  the  scaphoid,  the  anterior  articulating  surface  of  the 
calcaneum,  and  the  upper  surface  of  the  calcaneo-scaphoid  ligament,  which  fills  up 
the  triangular  interval  between  these  bones.  The  only  •ligament  of  this  joint  is 
the  superior  astragalo-scaphoid,  a  broad  band  of  ligamentous  fibres,  which  passes 
obliquely  forwards  from  the  neck  of  the  astragalus,  to  the  superior  surface  of  the 
scaphoid  bone.  It  is  thin  and  weak  in  texture,  and  covered  by  the  Extensor 
tendons.  The  inferior  calcaneo-scaphoid  supplies  the  place  of  an  inferior  liga- 
ment. 

The  Synovial  Membrane  which  lines  the  joint  is  continued  forwards  from  the 
anterior  calcaneo-astragaloid  articulation.  This  articulation  permits  of  consider- 
able mobility ;  but  its  feebleness  is  such  as  to  occasionally  allow  of  dislocation 
of  the  astragalus. 

The  Synovial  Membranes  (fig.  146)  found  in  the  articulations  of  the  tarsus  are 
four  in  number :  one  for  the  posterior  calcaneo-astragaloid  articulation ;  a  second 
for  the  anterior  calcaneo-astragaloid  and  astragalo-scaphoid  articulations  ;  a  third 


Fig.  146. 


-Oblique  Section  of  the  Articulations  of  the  Tarsus  and  Metatarsus. 
Showing  the  Six  Synovial  Membranes. 


for  the  calcaneo-cuboid  articulation;  and  a  fourth  for  the  articulations  between 
the  scaphoid  and  the  three  cuneiform,  the  three  cuneiform  with  each  other,  the 
external  cuneiform  with  the  cuboid,  and  the  middle  and  external  cuneiform  with 
the  bases  of  the  second  and  third  metatarsal  bones.  The  prolongation  which  lines 
the  metatarsal  bones  passes  forwards  between  the  external  and  middle  cuneiform 
bones.  A  small  synovial  membrane  is  sometimes  found  between  the  contiguous 
surfaces  of  the  scaphoid  and  cuboid  bones. 

Actions.  The  movements  permitted  between  the  bones  of  the  first  row,  the 
astragalus  and  os  calcis,  are  limited  to  a  gliding  upon  each  other  from  before 
backwards,  and  from  side  to  side.  The  gliding  movement  which  takes  place 
between  the  bones  of  the  second  row  is  very  slight,  the  articulation  between  the 
scaphoid  and  cuneiform  bones  being  more  movable  than  those  of  the  cuneiform 
with  each  other  and  with  the  cuboid.  The  movement  which  takes  place  between 
the  two  rows  is  more  extensive,  and  consists  in  a  sort  of  rotation,  by  means  of 
which  the  sole  of  the  foot  may  be  slightly  flexed,  and  extended,  or  carried  inwards 
and  outwards. 


TARSO-METATARSAL.  233 

6.  Takso-metatarsal  Articulations. 

These  are  arthrodial  joints.  The  bones  entering  into  their  formation  are  the 
internal,  middle,  external  cuneiform,  and  cuboid,  which  articulate  with  the  meta- 
tarsal bones  of  the  five  toes.  The  metatarsal  bone  of  the  great  toe  articulates  with 
the  internal  cuneiform ;  that  of  the  second  is  deeply  wedged  in  between  the  in- 
ternal and  external  cuneiform,  resting  against  the  middle  cuneiform,  and  being  the 
most  strongly  articulated  of  all  the  metatarsal  bones ;  the  third  metatarsal  articu- 
lates with  the  extremity  of  the  external  cuneiform ;  the  fourth  with  the  cuboid 
and  external  cuneiform ;  and  the  fifth  with  the  cuboid.  The  articular  surfaces 
are  covered  with  cartilage,  lined  by  synovial  membrane,  and  connected  together 
by  the  following  ligaments  : — 

Dorsal.  Plantar. 

Interosseous. 

The  Dorsal  Ligaments  consist  of  strong,  flat,  fibrous  bands,  which  connect  the 
tarsal  with  the  metatarsal  bones.  The  first  metatarsal  is  connected  to  the  internal 
cuneiform  by  a  single  broad,  thin,  fibrous  band;  the  second  has  three  dorsal 
ligaments,  one  from  each  cuneiform  bone ;  the  third  has  one  from  the  external 
cuneiform ;  and  the  fourth  and  fifth  have  one  each  from  the  cuboid. 

The  Plantar  Ligaments  consist  of  longitudinal  and  oblique  fibrous  bands  con- 
necting the  tarsal  and  metatarsal  bones,  but  disposed  with  less  regularity  than  on 
the  dorsal  surface.  Those  for  the  first  and  second  metatarsal  are  the  most  strongly 
marked ;  the  second  and  third  receive  strong  fibrous  bands,  which  pass  obliquely 
across  from  the  internal  cuneiform ;  the  plantar  ligaments  of  the  fourth  and  fifth 
consist  of  a  few  scanty  fibres  derived  from  the  cuboid. 

The  Interosseous  Ligaments  are  three  in  number :  internal,  middle,  and  external. 
The  internal  one  passes  from  the  outer  extremity  of  the  internal  cuneiform,  to  the 
adjacent  angle  of  the  second  metatarsal.  The  middle  one,  less  strong  than  the 
preceding,  connects  the  external  cuneiform  with  the  adjacent  angle  of  the  second 
metatarsal.  The  external  interosseous  ligament  connects  the  outer  angle  of  the 
external  cuneiform  with  the  adjacent  side  of  the  third  metatarsal. 

The  Synovial  Membranes  of  these  articulations  are  three  in  number :  one  for 
the  metatarsal  bone  of  the  great  toe,  with  the  internal  cuneiform ;  one  for  the  second 
and  third  metatarsal  bones,  with  the  middle  and  external  cuneiform,  which  is 
continuous  with  the  great  tarsal  synovial  membrane ;  and  one  for  the  fourth  and 
fifth  metatarsal  bones  with  the  cuboid.  The  synovial  membranes  of  the  tarsus 
and  metatarsus  are  thus  seen  to  be  six  in  number  (fig.  146). 
i 
Articulations  of  the  Metatarsal  Bones  with  each  other. 

The  bases  of  the  metatarsal  bones,  except  the  first,  are  connected  together  by 
dorsal,  plantar,  and  interosseous  ligaments.  The  dorsal  and  plantar  ligaments 
pass  from  one  metatarsal  bone  to  another.  The  interosseous  ligaments  lie  deeply 
between  the  rough  non-articular  portions  of  their  lateral  surfaces.  The  articular 
surfaces  are  covered  with  cartilage,  and  provided  with  synovial  membrane,  con- 
tinued forwards  from  the  tarso-metatarsal  joints.  The  digital  extremities  of  the 
metatarsal  bones  are  united  by  the  transverse  metatarsal  ligament.  It  connects 
the  great  toe  with  the  rest  of  the  metatarsal  bones ;  in  this  respect  it  differs  from 
the  transverse  ligament  in  the  hand. 

Actions.  The  movement  permitted  in  the  tarsal  ends  of  the  metatarsal  bones  is 
limited  to  a  slight  gliding  of  the  articular  surfaces  upon  one  another ;  considerable 
motion,  however,  takes  place  in  their  digital  extremities. 

Metatarsophalangeal  Articulations. 

The  heads  of  the  metatarsal  bones  are  connected  with  the  concave  articular 
surfaces  of  the  first  phalanges  by  the  following  ligaments : — 

Anterior  or  Plantar.  Two  Lateral. 


234  ARTICULATIONS. 

They  are  arranged  precisely  similar  to  the  corresponding  parts  in  the  hand. 
The  expansion  of  the  Extensor  tendon  supplies  the  place  of  a  posterior  ligament. 

Actions.  The  movements  permitted  in  the  metatarso-phalangeal  articulations 
are  flexion,  extension,  abduction,  and  adduction. 

Akticulation  of  the  Phalanges. 

The  ligaments  of  these  articulations  are  similar  to  those  found  in  the  hand ; 
each  pair  of  phalanges  being  connected  by  an  anterior  or  plantar  and  two  lateral 
ligaments,  and  their  articular  surfaces  lined  by  synovial  membrane.  Their  actions 
are  also  similar. 


For  further  information  on  this  subject,  the  Student  is  referred  to  Cruveilhier's  "Anatomie 
Descriptive ;"  to  Mr.  Humphry's  able  work  on  the  "  Human  Skeleton,  including  the  Joints ;" 
and  to  Arnold's  "  Tabulae  Anatomicse,"  Fascic.  4.  Pars  2,  "  Icones  articulorum  et  ligamentorum.'' 
On  the  textures  composing  the  Joints  refer  to  Todd  and  Bowman's  "  Physiological  Anatomy," 
and  Kblliker's  "  Manual  of  Human  Microscopic  Anatomy." 


The  Muscles  and  Fasciae. 

The  Muscles  are  the  active  organs  of  locomotion.  They  are  formed  of  bundles 
of  reddish  fibres,  consisting  chemically  of  fibrine,  and  endowed  with  the  pro- 
perty of  contractility.  Two  kinds  of  muscular  tissue  are  found  in  the  animal 
body,  viz.,  that  of  voluntary  or  animal  life,  and  that  of  involuntary  or  organic 
life. 

The  muscles  of  animal  life  {striped  muscles)  are  capable  of  being  either  exerted 
or  controlled  by  the  efforts  of  the  will.  They  are  composed  of  bundles  of  fibres 
inclosed  in  a  delicate  web  of  areolar  tissue.  Each  bundle  consists  of  numerous 
smaller  ones,  inclosed  in  a  similar  fibro-areolar  covering,  and  these  again  of  primi- 
tive fasciculi. 

The  primitive  fasciculi  consist  of  a  number  of  filaments,  inclosed  in  a  tubular 
sheath  of  transparent,  elastic,  and  apparently  homogeneous  membrane,  named  by 
Bowman  the  "  Sarcolemma."  The  primitive  fasciculi  are  cylindriform  or  prismatic. 
Their  breadth  varies  in  man  from  5^  to  5^  of  an  inch,  the  average  of  the  ma- 
jority being  about  ^11 ;  their  length  is  not  always  in  proportion  to  the  length  of 
the  muscle,  but  depends  on  the  arrangement  of  the  tendons.  This  form  of  muscular 
fibre  is  especially  characterized  by  being  apparently  marked  with  very  fine,  dark, 
parallel  lines  or  strise,  which  pass  transversely  round  them,  in  curved  or  wavy 
parallel  lines,  from  t^^tt  to  j^^s  °f  an  mcn  apart.  Other  striae  pass  longitu- 
dinally over  the  tubes,  indicating  the  direction  of  the  primitive  fibrils  of  which 
the  primitive  fasciculus  is  composed.     They  are  less  distinct  than  the  former. 

The  primitive  fibrils  constitute  the  proper  contractile  tissue  of  the  muscle. 
Each  fibril  is  cylindriform,  somewhat  flattened,  about  th^tttf  oi>  an  inch  m  thick- 
ness, and  marked  by  transverse  strise  placed  at  the  same  distance  from  each  other 
as  the  striae  on  the  surface  of  the  fasciculus.  Each  fibril  apparently  consists  of  a 
single  row  of  minute  particles,  named  "  sarcous  elements"  by  Bowman,  connected 
together  like  a  string  of  beads.  Closer  examination,  however,  shows  that  the 
elementary  particles  are  little  masses  of  pellucid  substance,  having  a  rectangular 
outline,  and  appearing  dark  in  the  centre.  These  appearances  would  favor  the 
suggestion  that  the  elementary  particles  of  which  the  fibrils  are  composed  are 
possibly  nucleated  cells,  cohering  in  a  linear  series,  the  transverse  marks  between 
them  corresponding  to  their  line  of  junction.  Kolliker,  however,  considers  "the 
sarcous  elements  as  artificial  products,  occasioned  by  the  breaking  up  of  the  fibrils 
at  the  parts  where  they  are  thinner." 

This  form  of  muscular  fibre  composes  the  whole  of  the  voluntary  muscles,  all 
the  muscles  of  the  ear,  those  of  the  larynx,  pharynx,  tongue,  and  upper  half  of 
the  oesophagus,  the  heart,  and  the  walls  of  the  large  veins  at  the  point  where  they 
open  into  it. 

The  muscles  of  organic  life  (unstriped  muscles)  consist  of  flattened  bands,  or  of 
elongated,  spindle-shaped  fibres,  flattened,  of  a  pale  color,  from  j^^  to  3^77  of 
an  inch  broad,  homogeneous  in  texture,  having  a  finely  mottled  aspect,  which 
sometimes  appears  granular,  the  granules  being  occasionally  arranged  in  a  linear 
series,  so  as  to  present  a  striated  appearance.     Each  fibre  contains  a  cylindrical 

1  The  Muscles  and  Fasciae  are  described  conjointly,  in  order  that  the  student  may  consider  the 
arrangement  of  the  latter  in  his  dissection  of  the  former.  It  is  rare  for  the  student  of  anatomy 
in  this  country  to  have  the  opportunity  of  dissecting  the  fasciae  separately ;  and  it  is  for  this 
reason,  as  well  as  from  the  close  connection  that  exists  between  the  muscles  and  their  investing 
aponeuroses,  that  they  are  considered  together.  Some  general  observations  are  first  made  on 
the  anatomy  of  the  muscles  and  fasciae,  the  special  description  being  given  in  connection  with 
the  different  regions. 

235 


236  MUSCLES   AND   FASCIAE. 


rod-shaped  nucleus,  which  sometimes  appears  as  a  narrow,  continuous,  dark  streak 
The  fibres  are  united  into  bundles,  which  are  connected  together  by  areolar  tissue 
and  elastic  fibres.  This  form  of  muscular  tissue  occurs  either  scattered"  in  the 
areolar  tissue,  or  exists  in  the  form  of  a  muscular  membrane,  the  bundles  being 
arranged  parallel,  or  forming  a  close  interlacement,  crossing  each  other  at  various 
angles.  The  muscular  fibre  of  organic  life  is  found  in  the  alimentary  canal,  form- 
ing the  muscular  coat  of  the  digestive  tube  from  the  middle  of  the  oesophagus  to 
the  internal  sphincter  of  the  anus ;  in  the  posterior  wall  of  the  trachea,  and  in  the 
bronchi;  in  the  ducts  of  the  submaxillary  glands;  in  the  gall-bladder  and  common 
bile  duct ;  in  the  calyces  and  pelvis  of  the  kidney ;  in  the  ureters  and  bladder ; 
and,  scantily,  in  the  urethra.  In  the  female  it  is  met  with  in  the  vagina,  the 
uterus,  Fallopian  tubes,  and  broad  ligaments ;  in  the  male,  in  the  scrotum,  the  epi- 
didymis, the  vas  deferens,  vesiculoe  seminales,  the  prostate ;  and  in  the  cavernous 
bodies,  in  both  sexes.  It  is  found  also  in  the  coats  of  all  arteries,  in  most  veins, 
and  lymphatic  vessels ;  in  the  iris  and  ciliary  muscle,  and  in  the  skin. 

Bloodvessels  are  distributed  in  considerable  abundance  to  the  muscular  tissue. 
In  the  voluntary  muscles  the  capillaries,  which  are  of  extremely  minute  size, 
form  narrow,  oblong  meshes,  which  run  in  the  direction  of  the  fibres. 

The  lymphatic  vessels  in  muscles  are  few  in  number,  and  appear  to  exist  only 
in  the  largest  muscles.  The  nerves  of  voluntary  muscles  are  of  large  size.  The 
larger  branches  pass  between  the  fasciculi,  and,  subdividing,  unite  to  form  primary 
plexuses ;  from  these,  finer  bundles,  or,  single  nerve  tubes,  pass  between  the  mus- 
cular fibres,  and,  forming  loops,  return  to  the  plexus. 

Each  muscle  is  invested  externally  by  a  thin  cellular  layer,  forming  what  is 
called  its  sheath,  which  not  only  covers  its  outer  surface,  but  penetrates  into  its 
interior  in  the  intervals  between  the  fasciculi,  surrounding  these,  and  serving  as 
a  bond  of  connection  between  them. 

The  muscles  are  connected  with  the  bones,  cartilages,  ligaments  and  skin,  either 
directly  or  through  the  intervention  of  fibrous  structures,  called  tendons  or  apo- 
neuroses. Where  a  muscle  is  attached  to  bone  or  cartilage,  the  fibres  terminate 
in  blunt  extremities  upon  the  periosteum  or  perichondrium,  and  do  not  come  into 
direct  relation  with  the  osseous  or  cartilaginous  tissue.  Where  muscles  are  con- 
nected with  the  skin,  they  either  lie  as  a  flattened  layer  beneath  it,  or  are  con- 
nected with  its  areolar  tissue  by  larger  or  smaller  bundles  of  fibres,  as  in  the 
muscles  of  the  face. 

The  muscles  vary  considerably  in  their  form.  In  the  limbs,  they  are  of  con- 
siderable length,  especially  the  more  superficial  ones,  the  deep  ones  being  generally 
broad ;  they  surround  the  bones,  and  form  an  important  protection  to  the  various 
joints.  In  the  trunk,  they  are  broad,  flattened,  and  expanded,  forming  the  parietes 
of  the  cavities  which  they  inclose ;  hence  the  reason  of  the  terms,  long,  broad, 
short,  etc.,  used  in  the  description  of  a  muscle. 

There  is  considerable  variation  in  the  arrangement  of  the  fibres  of  certain 
muscles,  to  the  tendons  to  which  they  are  attached.  In  some,  the  fibres  are 
arranged  longitudinally,  and  terminate  at  either  end  in  a  narrow  tendon.  If  the 
fibres  converge,  like  the  plumes  of  a  pen,  to  one  side  of  a  tendon,  which  runs  the 
entire  length  of  a  muscle,  it  is  said,  to  be  penniform,  as  the  Peronei ;  or,  if  they 
converge  to  both  sides  of  a  tendon,  they  are  called  bipenniform,  as  the  Rectus 
femoris ;  if  they  converge  from  a  broad  surface  to  a  narrow  tendinous  point,  they 
are  then  said  to  be  radiated,  as  the  Temporal  and  Glutei  muscles. 

Their  size  presents  considerable  variation ;  the  Gastrocnemius  forms  the  chief 
bulk  of  the  back  of  the  leg,  and  the  fibres  of  the  Sartorius  are  nearly  two  feet  in 
length,  whilst  the  Stapedius,  a  small  muscle  of  the  internal  ear,  weighs  about  a 
grain,  and  its  fibres  are  not  mpre  than  two  lines  in  length.  Tn  each  case,  how- 
ever, they  are  admirably  adapted  to  execute  the  various  movements  they  are 
required  to  perform. 

The  names  applied  to  the  various  muscles  have  been  derived :  1,  from  their  situa- 
tion, as  the  Tibialis,  Radialis,  Ulnaris,  Peroneus ;  2,  from  their  direction,  as  the 


GENERAL   ANATOMY.  23T 

Rectus  abdominis,  Obliquus  capitis,  Transversalis ;  3,  from  their  uses,  as  Flexors, 
Extensors,  Abductors,  etc. ;  4,  from  their  shape,  as  the  Deltoid,  Trapezius,  Rhom- 
boideus ;  5,  from  the  number  of  their  divisions,  as  the  Biceps  from  having  two 
heads,  the  Triceps  from  having  three  heads ;  6,  from  their  points  of  attachment, 
as  the  Sterno-cleido-mastoid,  Sterno-hyoid,  Sterno-thyroid. 

In  the  description  of  a  muscle,  the  term  origin  is  meant  to  imply  its  more  fixed 
or  central  attachment;  and  the  term  insertion,  the  movable  point  upon  which  the 
force  of  the  muscle  is  directed :  this  holds  true,  however,  for  only  a  very  small 
number  of  muscles,  such  as  those  of  the  face,  which  are  attached  by  one  extremity 
to  the  bone,  and  by  the  other  to  the  movable  integument ;  in  the  greater  number, 
the  muscle  can  be  made  to  act  from  either  extremity. 

In  the  dissection  of  the  muscles,  the  student  should  pay  especial  attention  to 
the  exact  origin,  insertion,  and  actions  of  each,  and  its  more  important  relations 
with  surrounding  parts.  An  accurate  knowledge  of  the  points  of  attachment  of 
the  muscles  is  of  great  importance  in  the  determination  of  their  action.  By  a 
knowledge  of  the  action  of  the  muscles,  the  surgeon  is  able  at  once  to  explain  the 
causes  of  displacement  in  the  various  forms  of  fracture,  or  the  causes  which  produce 
distortion  in  various  forms  of  deformities,  and,  consequently,  to  adopt  appropriate 
treatment  in  each  case.  The  relations,  also,  of  some  of  the  muscles,  especially 
those  in  immediate  apposition  with  the  larger  bloodvessels,  and  the  surface- 
markings  they  produce,  should  be  especially  remembered,  as  they  form  most  useful 
guides  to  the  surgeon  in  the  application  of  a  ligature  to  these  vessels. 

Tendons  are  white,  glistening,  fibrous  cords,  varying  in  length  and  thickness, 
sometimes  round,  sometimes  flattened,  of  considerable  strength,  and  only  slightl  v 
elastic.  They  consist  almost  entirely  of  white  fibrous  tissue,  the  fibrils  of  which 
have  an  undulating  course  parallel  with  each  other,  and  firmly  united  together. 
They  are  very  sparingly  supplied  with  bloodvessels,  the  smaller  tendons  pre- 
senting in  their  interior  not  a  trace  of  them.  Nerves  also  are  not  present  in  the 
smaller  tendons ;  but  the  larger  ones,  as  the  tendo  A  chillis,  receive  nerves  which 
accompany  the  nutrient  vessels.  The  tendons  consist  principally  of  a  substance 
which  yields  gelatine. 

Aponeuroses  are  fibrous  membranes,  of  a  pearly- white  color,  iridescent,  glisten- 
ing, and  similar  in  structure  to  the  tendons.  They  are  destitute  of  nerves,  and 
the  thicker  ones  are  only  sparingly  supplied  with  bloodvessels. 

The  tendons  and  aponeuroses  are  connected,  on  the  one  hand,  with  the  muscles ; 
and,  on  the  other  hand,  with  the  movable  structures,  as  the  bones,  cartilages, 
ligaments,  fibrous  membranes  (the  sclerotic,  for  instance),  and  the  synovial  mem- 
branes, the  subcrureus  and  subanconeus  for  example.  Where  the  muscular 
fibres  are  continuous  in  a  direct  line,  with  those  of  the  tendon  or  aponeurosis,  the 
two  are  directly  continuous,  the  muscular  fibre  being  distinguishable  from  that 
of  the  tendon  only  by  its  striation.  But  where  the  muscular  fibre  joins  the  tendon 
or  aponeurosis  at  an  oblique  angle,  the  former  terminates,  according  to  Kolliker, 
in  rounded  extremities,  which  are  received  into  corresponding  depressions  on  the 
surface  of  the  latter,  the  connective  tissue  between  the  fibres  being  continuous 
with  that  of  the  tendon.  The  latter  mode  of  attachment  occurs  in  all  the  penni- 
form  and  semi-penniform  muscles,  and  in  those  muscles  the  tendons  of  which 
commence  in  a  membranous  form,  as  the  Gastrocnemius  and  Soleus. 

The  Fasciae  {fascia,  a  bandage)  are  fibro-areolar  or  aponeurotic  laminae,  of 
variable  thickness  and  strength,  found  in  all  regions  of  the  body,  investing  the 
softer  and  more  delicate  organs.  The  fasciae  have  been  subdivided,  from  the 
structure  which  they  present,  into  two  groups,  fibro-areolar  or  superficial  fasciae, 
and  aponeurotic  or  deep  fasciae. 

The  fibro-areolar  fascia  is  found  immediately  beneath  the  integument  over 
almost  the  entire  surface  of  the  body,  and  is  generally  known  as  the  superficial 
fascia.  It  connects  the  skin  with  the  deep  or  aponeurotic  fascia,  and  consists  of 
fibro-areolar  tissue,  containing  in  its  meshes  pellicles  of  fat  in  varying  quantity. 
In  the  eyelids  and  scrotum,  where  adipose  tissue  is  rarely  deposited,  this  tissue  is 


238  MUSCLES   AND   FASCIJE. 

very  liable  to  serous  infiltration.  The  superficial  fascia  varies  in  thickness  in 
different  parts  of  the  body :  in  the  groin  it  is  so  thick  as  to  be  capable  of  being 
subdivided  into  several  laminae,  but  in  the  palm  of  the  hand  it  is  of  extreme 
thinness,  and  intimately  adherent  to  the  integument.  The  superficial  fascia  is 
capable  of  separation  into  two  or  more  layers,  between  which  are  found  the 
superficial  vessels  and  nerves,  and  superficial  lymphatic  glands ;  as  the  superficial 
epigastric  vessels  in  the  abdominal  region,  the  radial  and  ulnar  veins  in  the  fore- 
arm, the  saphenous  veins  in  the  leg  and  thigh,  and,  in  certain  situations,  cutaneous 
muscles,  as  the  Platysma  myoides  in  the  neck,  Orbicularis  palpebrarum  around 
the  eyelids.  It  is  most  distinct  at  the  lower  part  of  the  abdomen*  the  scrotum, 
perineum,  and  in  the  extremities ;  is  very  thin  in  those  regions  where  muscular 
fibres  are  inserted  into  the  integument,  as  on  the  side  of  the  neck,  the  face,  and 
around  the  margin  of  the  anus,  and  almost  entirely  wanting  in  the  palms  of  the 
hands  and  soles  of  the  feet,  where  the  integument  is  adherent  to  the  subjacent 
aponeurosis.  The  superficial  fascia  connects  the  skin  to  the  subjacent  parts,  serves 
as  a  soft  nidus  for  the  passage  of  vessels  and  nerves  to  the  integument,  and  retains 
the  warmth  of  the  body,  from  the  adipose  tissue  contained  in  its  areolae  being  a 
bad  conductor  of  caloric. 

The  aponeurotic  or  deep  fascia  is  a  dense,  inelastic  and  unyielding  fibrous 
membrane,  forming  sheaths  for  the  muscles,  and  affording  them  broad  surfaces  for 
attachment ;  it  consists  of  shining  tendinous  fibres,  placed  parallel  with  one  another, 
and  connected  together  by  other  fibres  disposed  in  a  reticular  manner.  It  is 
usually  exposed  on  the  removal  of  the  superficial  fascia,  forming  a  strong  invest- 
ment, which  not  only  binds  down  collectively  the  muscles  in  each  region,  but 
gives  a  separate  sheath  to  each,  as  well  as  to  the  vessels  and  nerves.  The  fasciae 
are  thick  in  unprotected  situations,  as  on  the  outer  side  of  a  limb,  and  thinner  on 
the  inner  side.  Aponeurotic  fasciae  are  divided  into  two  classes,  aponeuroses  of 
insertion,  and  aponeuroses  of  investment. 

The  aponeuroses  of  insertion  serve  for  the  insertion  of  muscles.  Some  of  these 
are  formed  by  the  expansion  of  a  tendon  into  an  aponeurosis,  as,  for  instance,  the 
tendon  of  the  Sartorius ;  others  do  not  originate  in  tendons,  as  the  aponeuroses 
of  the  abdominal  muscles. 

The  aponeuroses  of  investment  form  a  sheath  for  the  entire  limb,  as  well  as  for 
each  individual  muscle.  Many  aponeuroses,  however,  serve  both  for  investment 
and  insertion.  Thus,  the  aponeurosis  given  off  from  the  tendon  of  the  Biceps 
brachialis  near  its  insertion  is  continuous  with,  and  partly  forms,  the  investing 
fascia  of  the  forearm,  and  gives  origin  to  the  muscles  in  this  region.  The  deep 
fasciae  assist  the  muscles  in  their  action,  by  the  degree  of  tension  and  pressure  they 
make  upon  their  surface ;  and,  in  certain  situations,  this  is  increased  and  regulated 
by  muscular  action,  as,  for  instance,  by  the  Tensor  vaginae  femoris  and  Gluteus 
maximus  in  the  thigh,  by  the  Biceps  in  the  leg,  and  Palmaris  longus  in  the  hand. 
In  the  limbs,  the  fasciae  not  only  invest  the  entire  limb,  but  give  off  septa,  which 
separate  the  various  muscles,  and  are  attached  beneath  to  the  periosteum ;  these 
prolongations  of  fasciae  are  usually  spoken  of  as  intermuscular  septa. 

The  Muscles  and  Fasciae  may  be  arranged,  according  to  the  general  division  of 
the  body,  into,  1.  Those  of  the  head,  face,  and  neck.  2.  Those  of  the  trunk. 
3.  Those  of  the  upper  extremity.     4.  Those  of  the  lower  extremity. 

MUSCLES  AND  FASCIAE  OF  THE  HEAD  AND  FACE. 

The  Muscles  of  the  Head  and  Face  consist  of  ten  groups,  arranged  according 
to  the  region  in  which  they  are  situated. 

1.  Epicranial  Eegion.  6.  Superior  maxillary  Begion. 

2.  Auricular  Begion.  7.  Inferior  maxillary  Begion. 
8.  Palpebral  Begion.  8.  Intermaxillary  Begion. 

4.  Orbital  Begion.  9.  Temporo-maxillary  Begion. 

5.  Nasal  Begion.  10.  Pterygo-maxillary  Begion. 


OCCIPITO-FRONTALIS. 


239 


The  muscles  contained  in  each  of  these 

1.  Epicranial  Region. 
Occipito-frontalis. 

2.  Auricular  Region. 
Attolens  aurem. 
Attrahens  aurem. 
Retrahens  aurem. 

3.  Palpebral  Region. 
Orbicularis  palpebrarum. 
Corrugator  supercilii. 
Tensor  tarsi. 

Levator  palpebrae. 

4.  Orbital  Region. 
Levator  palpebrse. 
Rectus  superior. 
Rectus  inferior. 
Rectus  internus.  •    ■ 

Rectus  externus. 
Obliquus  superior. 
Obliquus  inferior. 

5.  Nasal  Region. 

Pyramidalis  nasi. 

Levator  labii  superioris  alaaque  nasi. 

Dilator  naris  posterior. 


groups  are  the  following: — 

Dilator  naris  anterior. 
Compressor  naris. 
Compressor  narium  minor. 
Depressor  alae  nasi. 

6.  Superior  Maxillary  Region. 
Levator  labii  superioris. 
Levator  anguli  oris. 
Zygomaticus  major. 
Zygomaticus  minor. 

7.  Inferior  Maxillary  Region. 
Levator  labii  inferioris. 
Depressor  labii  inferioris. 
Depressor  anguli  oris. 

8.  Intermaxillary  Region. 
Buccinator. 
Risorius. 
Orbicularis  oris. 

'  9.  Temporo-maxillary  Region. 
Masseter. 
Temporal. 

10.  Ptery go-maxillary  Region. 
Pterygoideus  externus. 
Pterygoideus  internus. 


1.  Epicranial  Region — Occipito-Frontalis. 

Dissection  (fig.  147).  The  head  being  shaved,  and  a  block  placed  beneath  the  back  of  the  neck, 
make  a  vertical  incision  through  the  skin  from  before  backwards,  commencing  at  the  root  of  the 
nose  in  front,  and  terminating  behind  at  the  occipital  protuberance ;  make  a  second  incision  in  a 
horizontal  direction  along  the  forehead  and  round  the  side  of  the  head,  from  the  anterior  to  the 

Fig.  147. — Dissection  of  the  Head,  Face,  and  Neck. 


-/  Dissection  of  scalp 


2.3.qf  AURICULAR  REC1CW 


4-.5.G.cf   FACE 


%.8.<f  KECK 


posterior  extremity  of  the  preceding.  Raise  the  skin  in  front  from  the  subjacent  muscle  from 
below  upwards;  this  must  be  done  with  extreme  care,  on  account  of  their  intimate  union.  The 
tendon  of  the  muscle  is  best  avoided  by  removing  the  integument  from  the  outer  surface  of  the 
vessels  and  nerves  which  lie  between  the  two. 


240 


MUSCLES   AND   FASCIAE. 


The  superficial  fascia  in  the  epicranial  region  is  a  firm,  dense  layer,  intimately 
adherent  to  the  integument,  and  to  the  Occipito-frontalis  and  its  tendinous  aponeu- 
rosis ;  it  is  continuous,  behind,  with  the  superficial  fascia  at  the  back  part  of  the 
neck;    and,  laterally,  is  continued  over  the  temporal  aponeurosis:   it  contains 


Fig.  148. — Muscles  of  the  Head.  Face,  and  Neck. 


CORRUCATOR   SUPIRCIUI 


O'LATO*  WAR'S  ANTr. 


t. LATCH  NAOIS  POSTEH. 
CCKPM55PH  IIARHIM  MINOR 
*  ALA 


LEVATOR    MENTI 


between  its  layers  the  small  muscles  of  the  auricle,  and  the  superficial  temporal 
vessels  and  nerves. 

The  Occipito-frontalis  (fig.  148)  is  a  broad  musculo-fibrous  layer,  which  covers 
the  whole  of  one  side  of  the  vertex  of  the  skull,  from  the  occiput  to  the  eyebrow. 
It  consists  of  two  muscular  slips,  separated  by  an  intervening  tendinous  aponeu- 
rosis.    The  occipital  portion,  thin,  quadrilateral  in  form,  and  about  an  inch  and  a 


AURICULAR   REGION.  241 

half  in  length,  arises  from  the  outer  two-thirds  of  the  superior  curved  line  of  the 
occipital  bone,  and  from  the  mastoid  portion  of  the  temporal.  Its  fibres  of  origin 
are  tendinous,  but  they  soon  become  muscular,  and  ascend  in  a  parallel  direction 
to  terminate  in  the  tendinous  aponeurosis.  The  frontal  portion  is  thin,  of  a  quad- 
rilateral form,  and  intimately  adherent  to  the  skin.  It  is  broader,  its  fibres  are 
longer,  and  their  structure  paler  than  the  occipital  portion.  Its  internal  fibres  are 
continuous  with  those  of  the  Pyramidalis  nasi.  Its  middle  fibres  become  blended 
with  the  Corrugator  supercilii  and  Orbicularis ;  and  the  outer  fibres  are  also 
blended  with  the  latter  muscle  over  the  external  angular  process.  From  this 
attachment,  the  fibres  are  directed  upwards  and  join  the  aponeurosis  below  the 
coronal  suture.  The  inner  margins  of  the  two  frontal  portions  of  the  muscle  are 
joined  together  for  some  distance  above  the  root  of  the  nose ;  but  between  the 
occipital  portions  there  is  a  considerable,  but  variable,  interval. 

The  aponeurosis  covers  the  upper  part  of  the  vertex  of  the  skull,  being  continu- 
ous across  the  middle  line  with  the  aponeurosis  of  the  opposite  muscle.  Behind, 
it  is  attached,  in  the  interval  between  the  occipital  regions,  to  the  occipital  protu- 
berance and  superior  curved  lines  above  the  attachment  of  the  Trapezius ;  in  fronts 
it  forms  a  short  angular  prolongation  between  the  frontal  portions ;  and  on  each 
side,  it  has  connected  with  it  the  Attollens  aurem  and  Attrahens  aurem  muscles. 
In  this  situation  it  loses  its  aponeurotic  character,  and  is  continued  over  the  temporal 
fascia  to  the  zygoma  by  a  layer  of  laminated  areolar  tissue.  -This  aponeurosis  is 
closely  connected  to  the  integument  by  a  dense  fibro-cellular  tissue,  which  contains 
much  granular  fat,  and  in  which  ramify  the  numerous  vessels  and  nerves  of  the 
integument ;  it  is  loosely  connected  with  the  pericranium  by  a  quantity  of  loose 
cellular  tissue,  which  allows  of  a  considerable  degree  of  movement  of  the  integu- 
ment. 

Nerves.  The  frontal  portion  of  the  Occipito-frontalis  is  supplied  by  the  supra- 
orbital and  facial  nerves ;  the  occipital  portion  by  the  posterior  auricular  branch 
of  the  facial,  and,  sometimes,  by  the  small  occipital. 

Actions.  The  frontal  portion  of  the  muscle  raises  the  eyebrows  and  the  skin 
over  the  root  of  the  nose ;  at  the  same  time  throwing  the  integument  of  the  fore- 
head into  transverse  wrinkles,  a  predominant  expression  in  the  emotions  of  delight. 
By  bringing  alternately  into  action  the  occipital  and  frontal  portions,  the  entire 
scalp  may  be  moved  from  before  backwards. 

2.  Auricular  Region  (fig.  148). 

Attollens  Aurem.  Attrahens  Aurem. 

Retrahens  Aurem. 

These  three  small  muscles  are  placed  immediately  beneath  the  skin  around  the 
external  ear.  In  man,  in  whom  the  external  ear  is  almost  immovable,  they  are 
rudimentary.  They  are  the  analogues  of  large  and  important  muscles  in  some  of 
the  mammalia. 

Dissection.  This  requires  considerable  care,  and  should  be  performed  in  the  following  man- 
ner. To  expose  the  Attollens  aurem,  draw  the  pinna  or  broad  part  of  the  ear  downwards, 
when  a  tense  band  will  be  felt  beneath  the  skin,  passing  from  the  side  of  the  head  to  the  upper 
part  of  the  concha ;  by  dividing  the  skin  over  the  tendon,  in  a  direction  from  below  upwards, 
and  then  reflecting  it  on  each  side,  the  muscle  is  exposed.  To  bring  into  view  the  Attrahens 
aurem,  draw  the  helix  backwards  by  means  of  a  hook,  when  the  muscle  will  be  made  tense,  and 
may  be  exposed  in  a  similar  manner  to  the  preceding.  To  expose  the  Eetrahens  aurem,  draw 
the  pinna  forwards,  when  the  muscle  being  made  tense  may  be  felt  beneath  the  skin,  at  its 
insertion  into  the  back  part  of  the  concha,  and  may  be  exposed  in  the  same  manner  as  the  other 
muscles. 

The  Attollens  Aurem,  the   largest  of  the   three,  is   thin,  and   fan-shaped;    it 
arises  from  the  aponeurosis  of  the  Occipito-frontalis,  and  its  fibres  converge  to 
be  inserted  by  a  thin,  flattened  tendon  into  the  upper  part  of  the  cranial  surface 
of  the  pinna. 
16 


242  MUSCLES   AND   FASCIA. 

Relations.  Externally,  with  the  integument;  internally,  with  the  Temporal 
aponeurosis. 

The  Attrahem  Aurem,  the  smallest  of  the  three,  is  thin,  fan-shaped,  and  its 
fibres  pale  and  indistinct.  It  arises  from  the  lateral  edge  of  the  aponeurosis  of 
the  Occipito-frontalis ;  its  fibres  converge  to  be  inserted  into  a  projection  on  the 
front  of  the  helix. 

Relations.  Externally,  with  the  skin ;  internally,  with  the  temporal  fascia,  which 
separates  it  from  the  temporal  artery  and  vein. 

The  Retrahens  Aurem  consists  of  two  or  three  fleshy  fasciculi,  which  arise 
from  the  mastoid  portion  of  the  temporal  bone  by  short  aponeurotic  fibres.  They 
are  inserted  into  the  lower  part  of  the  cranial  surface  of  the  concha. 

Relations.  Externally,  with  the  integument ;  internally,  with  the  mastoid  portion 
of  the  temporal  bone. 

Nerves.  The  Attollens  aurem  is  supplied  by  the  small  occipital ;  the  Attrahens 
aurem,  by  the  facial  and  auriculotemporal  branch  of  the  inferior  maxillary ;  and 
the  Eetrahens  aurem,  by  the  posterior  auricular  branch  of  the  facial. 

Actions.  In  man,  these  muscles  possess  very  little  action ;  the  Attollens  aurem 
slightly  raises  the  ear,  the  Attrahens  aurem  draws  it  forwards  and  upwards,  and 
the  Eetrahens  aurem  draws  it  backwards. 

3.  Palpebral  Eegion  (fig.  148). 

Orbicularis  Palpebrarum.  Levator  Palpebral 

Corrugator  Supercilii.  .  Tensor  Tarsi. 

Dissection  (fig.  147).  In  order  to  expose  the  muscles  of  the  face,  continue  the  longitudinal 
incision  made  in  the  dissection  of  the  Occipito-frontalis,  down  the  median  line  of  the  face  to  the 
tip  of  the  nose,  and  from  this  point  onwards  to  the  upper  lip  ;  another  incision  should  be  carried 
along  the  margin  of  the  lip  to  the  angle  of  the  mouth,  and  transversely  across  the  face  to  the 
angle  of  the  jaw.  The  integument  should  also  be  divided  by  an  incision  made  in  front  of  the 
external  ear,  from  the  angle  of  the  jaw,  upwards,  to  the  transverse  incision  made  in  exposing 
the  Occipito-frontalis.  These  incisions  include  a  square-shaped  flap  which  should  be  carefully 
removed  in  the  direction  marked  in  the  figure,  as  the  muscles  at  some  points  are  intimately  adhe- 
rent to  the  integument. 

The  Orbicularis  Palpebrarum  is  a  sphincter  muscle  which  surrounds  the  cir- 
cumference of  the  orbit  and  eyelids.  It  arises  from  the  internal  angular  process  of 
the  frontal  bone,  from  the  nasal  process  of  the  superior  maxillary  in  front  of  the 
lachrymal  groove,  and  from  the  anterior  surface  and  borders  of  a  short  tendon,  the 
tendo  palpebrarum,  placed  at  the  inner  angle  of  the  orbit.  From  this  origin,  the 
fibres  are  directed  outwards,  forming  a  broad,  thin,  and  flat  layer,  which  covers 
the  eyelids,  surrounds  the  circumference  of  the  orbit,  and  spreads  out  over  the 
temple,  and  downwards  on  the  cheek,  becoming  blended  with  the  Occipito-fronta- 
lis and  Corrugator  supercilii.  The  palpebral  portion  (ciliaris)  of  the  Orbicularis 
is  thin  and  pale ;  it  arises  from  the  bifurcation  of  the  tendo  palpebrarum,  and 
forms  a  series  of  concentric  curves,  which  are  united  on  the  outer  side  of  the  eyelids 
at  an  acute  angle  by  a  cellular  raphe,  some  being  inserted  into  the  external  tarsal 
ligament  and  malar  bone.  The  orbicular  portion  (orbicularis  latus)  is  thicker,  and 
of  a  reddish  color,  its  fibres,  well  developed,  forming  a  complete  ellipse. 

The  tendo  palpebrarum  (tendo  oculi)  is  a  short  tendon,  about  two  lines  in  length 
and  one  in  breadth,  attached  to  the  nasal  process  of  the  superior  maxillary  bone 
in  front  of  the  lachrymal  groove.  Crossing  the  lachrymal  sac,  it  divides  into  two 
parts,  each  division  being  attached  to  the  inner  extremity  of  the  corresponding 
tarsal  cartilage.  As  the  tendon  crosses  the  lachrymal  sac,  a  strong  aponeurotic 
lamina  is  given  off  from  its  posterior  surface,  which  expands  over  the  sac,  and  is 
attached  to  the  ridge  on  the  lachrymal  bone.  This  is  the  reflected  aponeurosis  of 
the  tendo  palpebrarum. 

Relations.  By  its  superficial  surface,  with  the  integument.  By  its  deep  surface, 
above,  with  the  Occipito-frontalis  and  Corrugator  supercilii,  with  which  it  is 
intimately  blended,  and  with  the  supra-orbital  vessels  and  nerve ;  below,  it  covers 


ORBITAL   REGION.  243 

the  lachrymal  sac,  and  the  origin  of  the  Levator  labii  superioris,  and  the  Levator 
labii  superioris  alasque  nasi  muscles.  Internally,  it  is  occasionally  blended  with 
the  Pyramidalis  nasi.  Externally,  it  lies  on  the  temporal  fascia.  On  the  eyelids, 
it  is  separated  from  the  conjunctiva  by  a  fibrous  membrane  and  the  tarsal  car- 
tilages. 

The  Corrugator  Supercilii  is  a  small,  narrow,  pyramidal  muscle,  placed  at  the 
inner  extremity  of  the  eyebrow  beneath  the  Occipito-frontalis  and  Orbicularis 
palpebrarum  muscles.  It  arises  from  the  inner  extremity  of  the  superciliary  ridge ; 
its  fibres  pass  upwards  and  outwards,  to  be  inserted  into  the  under  surface  of  the 
orbicularis,  opposite  the  middle  of  the  orbital  areh. 

Relations.  By  its  anterior  surface,  with  the  Occipito-frontalis  and  Orbicularis 
palpebrarum  muscles.  By  its  posterior  surface,  with  the  frontal  bone  and  supra- 
trochlear nerve. 

The  Levator  Palpebrse  will  be  described  with  the  muscles  of  the  orbital 
region. 

The  Tensor  Tarsi  is  a  small  thin  muscle,  about  three  lines  in  breadth  and  six  in 
length,  situated  at  the  inner  side  of  the  orbit,  behind  the  tendo  oculi.  It  arises 
from  the  crest  and  adjacent  part  of  the  orbital  surface  of  the  lachrymal  bone,  and, 
passing  across  the  lachrymal  sac,  divides  into  two  slips,  which  cover  the  lachrymal 
canals,  and  are  inserted  into  the  tarsal  cartilages  near  the  puncta  lacrymalia. 
Its  fibres  appear  to  be  continuous  with  those  of  the  palpebral  portion  of  the  Orbi- 
cularis; it  is  occasionally  very  indistinct. 

Nerves.  The  Orbicularis  palpebrarum  and  Corrugator  supercilii  are  supplied  by 
the  facial  and  supra-orbital  nerves ;  the  Tensor  tarsi  by  the  facial. 

Actions.  The  Orbicularis  palpebrarum  is  the  sphincter  muscle  of  the  eyelids. 
The  palpebral  portion  acts  involuntarily  in  closing  the  lids,  and  independently  of 
the  orbicular  portion,  which  is  subject  to  the  will.  When  the  entire  muscle  is 
brought  into  action,  the  integument  of  the  forehead,  temple,  and  cheek  is  drawn 
inwards  towards  the  inner  angle  of  the  eye,  and  the  eyelids  are  firmly  closed. 
The  Levator  palpebroa  is  the  direct  antagonist  of  this  muscle ;  it  raises  the  upper 
eyelid,  and  exposes  the  globe.  The  Corrugator  supercilii  draws  the  eyebrow 
downwards  and  inwards,  producing  the  vertical  wrinkles  of  the  forehead.  This 
muscle  may  be  regarded  as  the  principal  agent  in  the  expression  of  grief.  The 
Tensor  tarsi  draws  the  eyelids  and  the  extremities  of  the  fachrymal  canal  inwards, 
and  compresses  them  against  the  surface  of  the  globe  of  the  eye ;  thus  placing 
them  in  the  most  favorable  situation  for  receiving  the  tears.  It  serves,  also,  to 
compress  the  lachrymal  sac. 

4.  Orbital  Region  (fig.  149). 

Levator  Palpebrse.  Rectus  Internus. 

Rectus  Superior.  Rectus  Externus. 

Rectus  Inferior.  Obliquus  Superior. 
Obliquus  Inferior. 

Dissection.  To  open  the  cavity  of  the  orbit,  the  sknll-cap  and  brain  should  be  first  removed  ; 
then  saw  through  the  frontal  bone  at  the  inner  extremity  of  the  supra-orbital  ridge,  and  externally 
at  its  junction  with  the  malar.  The  thin  roof  of  the  orbit  should  then  be  comminuted  by  a  few 
slight  blows  with  the  hammer,  and  the  superciliary  portion  of  the  frontal  bone  driven  forwards 
by  a  smart  stroke  ;  but  it  must  not  be  removed.  The  several  fragments  may  then  be  detached, 
when  the  periosteum  of  the  orbit  will  be  exposed :  this  being  removed,  together  with  the  fat 
which  fills  the  cavity  of  the  orbit,  the  several  muscles  of  this  region  can  be  examined.  To  facili- 
tate their  dissection,  the  globe  of  the  eye  should  be  distended  ;  this  may  be  effected  by  puncturing 
the  optic  nerve  near  the  eyeball,  with  a  curved  needle,  and  pushing  it  onwards  into  the  globe. 
Through  this  aperture  the  point  of  a  blow-pipe  should  be  inserted,  and  a  little  air  forced  into 
the  cavity  of  the  eyeball ;  then  apply  a  ligature  round  the  nerve,  so  as  to  prevent  the  air  escaping. 
The  globe  should  now  be  drawn  forwards,  when  the  muscles  will  be  put  upon  the  stretch. 

The  Levator  Palpebrse  Stiperioris  is  thin,  flat,  and  triangular  in  shape.  It 
arises  from  the  under  siirface  of  the  lesser  wing  of  the  sphenoid,  immediately  in 


244 


MUSCLES   AND   FASCIAE. 


front  of  the  optic  foramen ;  and  is  inserted,  by  a  broad  aponeurosis,  into  the  upper 
border  of  the  superior  tarsal  cartilage.  At  its  origin,  it  is  narrow  and  tendinous; 
but  soon  becomes  broad  and  fleshy,  and  finally  terminates  in  a  broad  aponeurosis. 
Relations.  By  its  upper  surface,  with  the  frontal  nerve  and  artery,  the  peri- 
osteum of  the  orbit ;  and,  in  front,  with  the  inner  surface  of  the  broad  tarsal 
ligament.  By  its  under  surface,  with  the  Superior  rectus ;  and,  in  the  lid,  with 
the  conjunctiva.     A  small  branch  of  the  third  nerve  enters  its  under  surface. 

Fig.  149.— Muscles  of  the  Right  Orbit. 


The  Rectus  Superior,  the  thinnest  and  narrowest  of  the  four  Eecti,  arises  from 
the  upper  margin  of  the  optic  foramen,  beneath  the  Levator  palpebrae,  and  Supe- 
rior oblique,  and  from  the  fibrous  sheath  of  the  optic  nerve ;  and  is  inserted,  by  a 
tendinous  expansion,  into  the  sclerotic  coat,  about  three  or  four  lines  from  the 
margin  of  the  cornea. 

Relations.  By  its  upper  surface,  with  the  Levator  palpebrce.  By  its  under 
surface,  with  the  optic  nerve,  the  ophthalmic  artery,  and  nasal  nerve;  and,  in 
front,  with  the  tendon  of  the  Superior  oblique,  and  the  globe  of  the  eye. 

The  Inferior  and  Internal  Recti  arise  by  a  common  tendon,  the  ligament  of 
Zinn,  which  is  attached  round  the  circumference  of  the  optic  foramen,  except  at 
its  upper  and  outer  part.  The  External 
rectus  has  two  heads:  the  upper  one  arises 
from  the  outer  margin  of  the  optic  foramen, 
immediately  beneath  the  Superior  rectus ;  the 
lower  head,  partly  from  the  ligament  of  Zinn, 
and  partly  from  a  small  pointed  process  of  bone 
on  the  lower  margin  of  the  sphenoidal  fissure. 
Each  muscle  passes  forward  in  the  position 
implied  by  its  name,  to  be  inserted,  by  a  ten- 
dinous expansion,  into  the  sclerotic  coat,  about 
three  or  four  lines  from  the  margin  of  the 
cornea.  Between  the  two  heads  of  the  External 
rectus  is  a  narrow  interval,  through  which  pass 
the  third,  nasal  branch  of  the  fifth,  and  sixth 
nerves,  and  the  ophthalmic  vein.     Although 

nearly  all  these  muscles  present  a  common  origin,  and  are  inserted  in  a  similar 
manner  in  the  sclerotic  coat,  there  are  certain  differences  to  be  observed  in  them, 
as  regards  their  length  and  breadth.  The  Internal  rectus  is  the  broadest :  the 
External,  the  longest ;  and  the  Superior,  the  thinnest  and  narrowest. 


Fig.  150.— The  relative  Position  and 
Attachment  of  the  Muscles  of  the 
Left  Eyeball. 

IZtrtlis  AujatTLoT 
FalftbraSHptTiar 
Olliqtuis  Superior 


Itcctus  Inferior 


ORBITAL   REGION.  245 

The  Superior  Oblique  is  a  fusiform  muscle,  placed  at  the  upper  and  inner  side 
of  the  orbit,  internal  to  the  Levator  palpebrae.  It  arises  about  a  line  above  the 
inner  margin  of  the  optic  foramen,  and,  passing  forwards  to  the  inner  angle  of  the 
orbit,  terminates  in  a  rounded  tendon,  which  passes  through  a  fibro-cartilagmous 
ring,  attached  by  fibrous  tissue  to  a  depression  beneath  the  internal  angular  pro- 
cess of  the  frontal  bone,  the  contiguous  surfaces  of  the  tendon  and  ring  being  lined 
by  a  delicate  synovial  membrane,  and  inclosed  in  a  thin  fibrous  investment.  The 
tendon  is  reflected  backwards  and  outwards  beneath  the  Superior  rectus  to  the 
outer  part  of  the  globe  of  the  eye,  and  is  inserted  into  the  sclerotic  coat,  midway 
between  the  cornea  and  entrance  of  the  optic  nerve,  the  insertion  of  the  muscle 
lying  between  the  Superior  and  External  recti. 

Relations.  By  its  upper  surface,  with  the  periosteum  covering  the  roof  of  the 
orbit,  and  the  fourth  nerve.  By  its  under  surface,  with  the  nasal  nerve,  and  the 
upper  border  of  the  Internal  rectus. 

The  Inferior  Oblique  is  a  thin,  narrow  muscle,  placed  near  the  anterior  margin 
of  the  orbit.  It  arises  from  a  depression  in  the  orbital  plate  of  the  superior 
maxillary  bone,  external  to  the  lachrymal  groove.  Passing  outwards  and  back- 
wards beneath  the  Inferior  rectus,  and  between  the  eyeball  and  the  External  rectus, 
it  is  inserted  into  the  outer  part  of  the  sclerotic  coat  between  the  Superior  and 
External  rectus,  and  near  the  tendon  of  insertion  of  the  Superior  oblique. 

Relations.  By  its  upper  surface,  with  the  globe  of  the  eye,  and  with  the  Inferior 
rectus.  By  its  under  surface,  with  the  periosteum  covering  the  floor  of  the  orbit, 
and  with  the  External  rectus.  Its  borders  look  forwards  and  backwards ;  the 
posterior  one  receives  a  branch  of  the  third  nerve. 

Nerves.  The  Levator  palpebrae,  Inferior  oblique,  and  all  the  Recti  excepting  the 
External,  are  supplied  by  the  third  nerve ;  the  Superior  oblique,  by  the  fourth ; 
the  External  rectus,  by  the  sixth. 

Actions.  The  Levator  palpebrae  raises  the  upper  eyelid,  and  is  the  direct  anta- 
gonist of  the  Orbicularis  palpebrarum.  The  four  Recti  muscles  are  attached  in 
such  a  manner  to  the  globe  of  the  eye,  that,  acting  singly,  they  will  turn  it  either 
upwards,  downwards,  inwards,  or  outwards,  as  expressed  by  their  names.  If  any 
two  Recti  act  together,  they  carry  the  globe  of  the  eye  in  the  diagonal  of  these 
directions,  viz.,  upwards  and  inwards,  upwards  and  outwards,  downwards  and  in- 
wards, or  downwards  and  outwards.  The  movement  of  circumduction,  as  in 
turning  the  eyes  round  a  room,  is  performed  by  the  alternate  action  of  the  four 
Recti.  By  some  anatomists,  these  muscles  have  been  considered  the  chief  agents 
in  adjusting  the  sight  at  different  distances,  by  compressing  the  globe,  and  so 
lengthening  its  antero-posterior  diameter.  The  Oblique  muscles  rotate  the  eye- 
ball on  its  antero-posterior  axis,  this  kind  of  movement  being  required,  for  the 
correct  viewing  of  an  object,  when  the  head  is  moved  laterally,  as  from  shoulder 
to  shoulder,  in  order  that  the  picture  may  fall  in  all  respects  on  the  same  part  of 
the  retina.1 

Surgical  Anatomy.  The  position  and  exact  point  of  insertion  of  the  tendons  of  the  Internal 
and  External  recti  muscles  into  the  globe,  should  be  carefully  examined  from  the  front  of  the 
eyeball,  as  the  surgeon  is  often  required  to  divide  one  or  the  other  muscle  for  the  cure  of  stra- 
bismus. In  convergent  strabismus,  which  is  the  most  common  form  of  the  disease,  the  eye  is 
turned  inwards,  requiring  the  division  of  the  Internal  rectus.  In  the  divergent  form,  which  is 
more  rare,  the  eye  is  turned  outwards,  the  External  rectus  being  especially  implicated.  The  de- 
formity produced  in  either  case  is  considerable,  and  is  easily  remedied  by  division  of  one  or  the 
other  muscle.  This  operation  is  readily  effected  by  having  the  lids  well  separated  by  retractors 
held  by  an  assistant ;  the  eyeball  being  drawn  outwards,  the  conjunctiva  should  be  raised  by  a 
pair  of  forceps,  and  divided  immediately  beneath  the  lower  border  of  the  tendon  of  the  Internal 
rectus,  a  little  behind  its  insertion  into  the  sclerotic  ;  the  submucous  areolar  tissue  is  then  divided, 
and,  into  the  small  aperture  thus  made,  a  blunt  hook  is  passed  upwards  between  the  muscle  and 
the  globe,  and  the  tendon  of  the  muscle  and  conjunctiva  covering  it  divided  by  a  pair  of  blank 
pointed  scissors.     Or  the  tendon  may  be  divided  by  a  sub-conjunctival  incision,  one  blade  of  the 

1  "  On  the  Oblique  Muscles  of  the  Eye  in  Man  and  Yertebrate  Animals,"  by  John  Strutters,. 
M.  D.     u  Anatomical  and  Physiological  Observations." 


9*6  MUSCLES   AND   FASCIA. 

scissors  being  passed  upwards  between  the  tendon  and  the  conjunctiva,  and  the  other  between 
the  tendon  and  sclerotic.  The  student,  when  dissecting  these  muscles,  should  remove  on  one 
side  of  the  subject  the  conjunctiva  from  the  front  of  the  eye,  in  order  to  see  more  accurately 
the  position  of  these  tendons,  and  on  the  opposite  side  the  operation  may  be  performed. 

5.  Nasal  Region  (fig.  148). 

Pyramidalis  Nasi.  , 

Levator  Labii  Superioris  Alaeque  Nasi. 
Dilator  Naris  Posterior. 
Dilator  Naris  Anterior. 
Compressor  Naris. 
Compressor  Narium  Minor. 
Depressor  Alae  Nasi. 

The  Pyramidalis  Nasi  is  a  small  pyramidal  slip,  prolonged  downwards  from 
the  Occipito-frontalis  upon  the  side  of  the  nose,  where  it  becomes  tendinous,  and 
blends  with  the  Compressor  naris.  As  the  two  muscles  descend,  they  diverge, 
leaving  an  angular  interval  between  them. 

Relations.  By  its  upper  surface,  with  the  skin.  By  its  under  surface,  with  the 
frontal  and  nasal  bones. 

The  Levator  Labii  Superioris  Alseque  Nasi  is  a  thin  triangular  muscle,  placed 
by  the  side  of  the  nose,  and  extending  between  the  inner  margin  of  the  orbit  and 
upper  lip.  It  arises  by  a  pointed  extremity  from  the  upper  part  of  the  nasal  pro- 
cess of  the  superior  maxillary  bone,  and  passing  obliquely  downwards  and  out- 
wards, divides  into  two  slips,  one  of  which  is  inserted  into  the  cartilage  of  the  ala 
of  the  nose,  the  other  is  prolonged  into  the  upper  lip,  becoming  blended  with 
the  Orbicularis  and  Levator  labii  proprius. 

Relations.  In  front,  with  the  integument ;  and  with  a  small  part  of  the  Orbi- 
cularis palpebrarum  above. 

Lying  upon  the  superior  maxillary  bone,  beneath  this  muscle,  is  a  longitudinal 
muscular  fasciculus  about  an  inch  in  length.  It  is  attached  by  one  end  near  the 
origin  of  the  Compressor  naris,  and  by  the  other  to  the  nasal  process  about  an 
inch  above  it;  it  was  described  by  Albinus  as  the  "Musculus  anomalus,"  and  by 
Santorini,  as  the  "  Rhomboideus." 

The  Dilator  naris  posterior  is  a  small  muscle,  which  is  placed  partly  beneath 
the  proper  elevator  of  the  nose  and  lip.  It  arises  from  the  margin  of  the  nasal 
notch  of  the  superior  maxilla,  and  from  the  sesamoid  cartilages,  and  is  inserted 
into  the  skin  near  the  margin  of  the  nostril. 

The  Dilator  naris  anterior  is  a  thin,  delicate  fasciculus,  passing  from  the  carti- 
lage of  the  ala  of  the  nose  to  the  integument  near  its  margin.  This  muscle  is 
situated  in  front  of  the  preceding. 

The  Compressor  Naris  is  a  small,  thin,  triangular  muscle,  arising  by  its  apex 
from  the  superior  maxillary  bone,  above  and  a  little  external  to  the  incisive  fossa ; 
its  fibres  proceed  upwards  and  inwards,  expanding  into  a  thin  aponeurosis  which 
is  attached  to  the  fibro-cartilage  of  the  nose,  and  is  continuous  on  the  bridge  of 
the  nose  with  that  of  the  muscle  of  the  opposite  side,  and  with  the  aponeurosis  of 
the  Pyramidalis  nasi. 

The  Compressor  Narium  Minor  is  a  small  muscle,  attached  by  one  end  to  the 
alar  cartilage,  and  by  the  other  to  the  integument  at  the  end  of  the  nose. 

The  Depressor  Alse  Nasi  is  a  short,  radiated  muscle,  arising  from  the  incisive 
fossa  of  the  superior  maxilla ;  its  fibres  ascend  to  be  inserted  into  the  septum,  and 
back  part  of  the  ala  of  the  nose.  This  muscle  lies  between  the  mucous  membrane 
and  muscular  structure  of  the  lip. 

Nerves.     All  the  muscles  of  this  group  are  supplied  by  the  facial  nerve. 

Actions.  The  Pyramidalis  nasi  draws  down  the  inner  angle  of  the  eyebrow ;  by 
some  anatomists  it  is  also  considered  as  an  elevator  of  the  ala,  and,  consequently, 
a  dilator  of  the  nose.     The  Levator  labii  superioris  alaeque  nasi  draws  upwards 


the  upper  lip  and  ala  of  the  nose ;  its  most  important  action  is  upon  the  nose, 
which  it  dilates  to  a  considerable  extent.  The  action  of  this  muscle  produces  a 
marked  influence  over  the  countenance,  and  is  the  principal  agent  in  the  expression 
of  contempt.  The  two  Dilatores  nasi  enlarge  the  aperture  of  the.  nose,  and  the 
Compressor  naris  appears  to  act  as  a  dilator  of  the  nose  rather  than  as  a  constrictor. 
The  Depressor  alee  nasi  is  a  direct  antagonist  of  the  preceding  muscles,  drawing 
the  ala  of  the  nose  downwards,  and  thereby  constricting  the  aperture  of  the  nares. 

6.  Superior  Maxillary  Kegion  (fig.  148). 

Levator  Labii  Superioris.  Zygomaticus  major. 

Levator  Anguli  Oris.  Zygomaticus  minor. 

The  Levator  Labii  Superioris  is  a  thin  muscle  of  a  quadrilateral  form.  It 
arises  from  the  lower  margin  of  the  orbit  immediately  above  the  infra-orbital 
foramen,  some  of  its  fibres  being  attached  to  the  superior  maxilla,  some  to  the 
malar  bone ;  its  fibres  converge  to  be  inserted  into  the  muscular  substance  of  the 
upper  lip. 

Relations.  By  its  superficial  surface,  with  the  lower  segment  of  the  Orbicu- 
laris palpebrarum;  below,  it  is  subcutaneous.  By  its  deep  surface,  it  conceals 
the  origin  of  the  Compressor  naris  and  Levator  anguli  oris  muscles,  and  the  infra- 
orbital vessels  and  nerves,  as  they  escape  from  the  infra-orbital  foramen. 

The  Levator  Anguli  Oris  arises  from  the  canine  fossa,  immediately  below  the 
infra-orbital  foramen ;  its  fibres  incline  downwards  and  a  little  outwards,  to  be 
inserted  into  the  angle  of  the  mouth,  and  intermingle  with  those  of  the  Zygo- 
matici,  the.  Depressor  anguli  oris,  and  the  Orbicularis. 

Relations.  By  its  superficial  surface,  with  the  Levator  labii  superioris  and  the 
infra-orbital  vessels  and  nerves.  By  its  deep  surface,  with  the  superior  maxilla, 
the  Buccinator,  and  the  mucous  membrane. 

The  Zygomaticus  major  is  a  slender  fasciculus,  which  arises  from  the  malar 
bone,  in  front  of  the  zygomatic  suture,  and,  descending  obliquely  downwards  and 
inwards,  is  inserted  into  the  angle  of  the  mouth,  where  it  blends  with  the  fibres 
of  the  Orbicularis  and  Depressor  anguli  oris. 

Relations.  By  its  superficial  surface,  with  the  subcutaneous  adipose  tissue. 
By  its  deep  surface,  with  the  malar  bone,  the  Masseter  and  Buccinator  muscles. 

The  Zygomaticus  minor  arises  from  the  malar  bone,  immediately  behind  the 
maxillary  suture,  and,  passing  downwards  and  inwards,  is  continuous  with  the 
outer  margin  of  the  Levator  labii  superioris.     It  lies  in  front  of  the  preceding. 

Relations.  By  its  superficial  surface,  with  the  integument  and  the  Orbicularis 
palpebrarum  above.     By  its  deep  surface,  with  the  Levator  anguli  oris. 

Nerves.     This  group  of  muscles  is  supplied  by  the  facial  nerve. 

Actions.  The  Levator  labii  superioris  is  the  proper  elevator  of  the  upper  lip, 
carrying  it  at  the  same  time  a  little  outwards.  The  Levator  anguli  oris  raises  the 
angle  of  the  mouth  and  draws  it  inwards ;  whilst  the  Zygomatici  raise  the  upper 
lip  and  draw  it  somewhat  outwards,  as  in  laughing. 

7.  Inferior  Maxillary  Kegion  (fig.  148). 

Levator  Labii  Inferioris  or  Levator  menti. 
Depressor  Labii  Inferioris  or  Quadratus  menti. 
Depressor  Anguli  Oris  or  Triangularis  menti. 

Dissection.  The  Muscles  in  this  region  maybe  dissected  by  making  a  vertical  incision  through 
the  integument  from  the  margin  of  the  lower  lip  to  the  chin :  a  second  incision  should  then  be 
carried  along  the  margin  of  the  lower  jaw  as  far  as  the  angle,  and  the  integument  carefully 
removed  in  the  direction  shown  in  fig.  147. 

The  Levator  Labii  Inferioris  or  Levator  menti  is  to  be  dissected  by  everting  the 
lower  lip  and  raising  the  mucous  membrane.     It  is  a  small  conical  fasciculus. 


248  MUSCLES   AND   FASCIJ3. 

placed  on  the  side  of  the  frsenum  of  the  lower  lip.  It  arises  from  the  incisive  fossa. 
external  to  the  symphysis  of  the  lower  jaw :  its  fibres  descend  to  be  inserted  into 
the  integument  of  the  chin. 

Relations.  On  its  inner  surface,  with  the  mucous  membrane;  in  the  median 
line,  it  is  blended  with  the  muscle  of  the  opposite  side ;  and  on  its  outer  side,  with 
the  Depressor  labii  inferioris. 

The  Depressor  Labii  Inferioris  or  Quadratics  menti  is  a  small  quadrilateral 
muscle,  situated  at  the  outer  side  of  the  preceding.  It  arises  from  the  external 
oblique  line  of  the  lower  jaw,  between  the  symphysis  and  mental  foramen,  and 
passes  obliquely  upwards  and  inwards,  to  be  inserted  into  the  integument  of  the 
lower  lip,  its  fibres  blending  with  the  Orbicularis,  and  with  those  of  its  fellow  of 
the  opposite  side.  It  is  continuous  with  the  fibres  of  the  Platysma  at  its  origin. 
This  muscle  contains  much  yellow  fat  intermingled  with  its  fibres. 

Relations.  By  its  superficial  surface,  with  part  of  the  Depressor  anguli  oris, 
and  with  the  integument,  to  which  it  is  closely  connected.  By  its  deep  surface, 
with  the  mental  vessels  and  nerves,  the  mucous  membrane  of  the  lower  lip,  the 
labial  glands,  and  the  Levator  menti,  with  which  it  is  intimately  united. 

The  Depressor  Anguli  Oris  is  triangular  in  shape,  arising,  by  its  broad  base, 
from  the  external  oblique  line  of  the  lower  jaw ;  its  fibres  pass  upwards,  to  be 
inserted,  by  a  narrow  fasciculus,  into  the  angle  of  the  mouth.  It  is  continuous 
with  the  Platysma  at  its  origin,  and  with  the  Orbicularis  and  Eisorius  at  its 
insertion. 

Relations.  By  its  superficial  surface,  with  the  integument.  By  its  deep  surface, 
with  the  Depressor  labii  inferioris  and  Buccinator. 

Nerves.     This  group  of  muscles  is  supplied  by  the  facial  nerve. 

Actions.  The  Levator  labii  inferioris  raises  the  lower  lip,  and  protrudes  it  for- 
wards ;  at  the  same  time  it  wrinkles  the  integument  of  the  chin.  The  Depressor 
labii  inferioris  draws  the  lower  lip  directly  downwards  and  a  little  outwards.  The 
Depressor  anguli  oris  depresses  the  angle  of  the  mouth,  being  the  great  antagonist 
to  the  Levator  anguli  oris  and  Zygomaticus  major :  acting  with  these  muscles,  it 
will  draw  the  angle  of  the  mouth  directly  backwards. 

8.  Intermaxillary  Eegion.  n 

Orbicularis  Oris.  Buccinator.  Eisorius. 

Dissection.  The  dissection  of  these  muscles  may  be  consideraoly  facilitated  by  filling  the 
cavity  of  the  mouth  with  tow,  so  as  to  distend  the  cheeks  and  lips ;  the  mouth  should  then  be 
closed  by  a  few  stitches,  and  the  integument  carefully  removed  from  the  surface. 

The  Orbicularis  Oris  is  a  sphincter  muscle,  elliptic  in  form,  composed  of  con- 
centric fibres,  which  surround  the  orifice  of  the  mouth.  It  consists  of  two  thick 
semicircular  planes  of  muscular  fibre,  which  surround  the  oral  aperture,  and 
interlace  on  either  side  with  those  of  the  Buccinator  and  other  muscles  inserted 
into  this  part.  On  the  free  margin  of  the  lips  the  muscular  fibres  are  continued 
uninterruptedly  from  one  lip  to  the  other,  around  the  corner  of  the  mouth,  forming 
a  roundish  fasciculus  of  fine  pale  fibres  closely  approximated.  To  the  outer  part 
of  each  segment  some  special  fibres  are  added,  by  which  the  lips  are  connected 
directly  with  the  maxillary  bones  and  septum  of  the  nose.  The  additional  fibres 
for  the  upper  segment  consist  of  four  bands,  two  of  which,  the  Accessorii  orbicularis 
superioris,  arise  from  the  alveolar  border  of  the  superior  maxilla,  opposite  the 
incisor  teeth,  and,  arching  outwards  on  each  side,  are  continuous  at  the  angles  of 
the  mouth  with  the  other  muscles  inserted  into  this  part.  The  two  remaining 
muscular  slips,  called  the  Naso-labialis,  connect  the  upper  lip  to  the  septum  of  the 
nose :  as  they  descend  from  the  septum,  an  interval  is  left  between  them,  which 
corresponds  to  that  left  by  the  divergence  of  the  accessory  portions  of  the  Orbi- 
cularis above  described.  It  is  this  interval  which  forms  the  depression  seen  on 
the  surface  of  the  skin  beneath  the  septum  of  the  nose. 


TEMPORO-MAXILLARY   REGIO.N.  249 

The  additional  fibres  for  the  lower  segment,  Accessorii  orbicularis  inferioris, 
arise  from  the  inferior  maxilla,  externally  to  the  Levator  labii  inferioris ;  arching 
outwards  to  the  angles  of  the  mouth,  they  join  the  Buccinator  and  the  other 
muscles  attached  to  this  spot. 

Relations.  By  its  superficial  surface,  with  the  integument  to  which  it  is  closely 
connected.  By  its  deep  surface,  with  the  buccal  mucous  membrane,  the  labial 
glands,  and  coronary  vessels.  By  its  outer  circumference,  it  is  blended  with  the 
numerous  muscles  which  converge  to  the  mouth  from  various  parts  of  the  face. 
Its  inner  circumference  is  free,  and  covered  by  mucous  membrane. 

The  Buccinator  is  a  broad,  thin  muscle,  quadrilateral  in  form,  occupying  the 
interval  between  the  jaws  at  the  side  of  the  face.  It  arises  from  the  outer  surface 
of  the  alveolar  processes  of  the  upper  and  lower  jaws,  corresponding  to  the  last 
three  molar  teeth ;  and,  behind,  from  the  anterior  border  of  the  pterygo-maxil- 
lary  ligament.  The  fibres  converge  towards  the  angle  of  the  mouth,  where  the 
central  ones  intersect  each  other,  those  from  below  being  continuous  with  the 
upper  segment  of  the  Orbicularis  oris,  and  those  from  above,  with  the  inferior 
segment ;  but  the  highest  and  lowest  fibres  continue  forward  uninterruptedly  into 
the  corresponding  segment  of  the  lip,  without  decussation. 

Relations.  By  its  superficial  surface,  behind,  with  a  large  mass  of  fat,  which 
separates  it  from  the  ramus  of  the  lower  jaw,  the  Masseter,  and  a  small  portion  of 
the  Temporal  muscle;  anteriorly,  with  the  Zygomatici,  Risorius,  Levator  anguli 
oris,  Depressor  anguli  oris,  and  Stenon's  duct,  which  pierces  it  opposite  the  second 
molar  tooth  of  the  upper  jaw ;  the  facial  artery  and  vein  cross  it  from  below 
upwards,  and  it  is  also  crossed  by  the  branches  of  the  facial  and  buccal  nerves.  By 
its  internal  surface,  with  the  buccal  glands  and  mucous  membrane  of  the  mouth. 

The  ptery go-maxillary  ligament  separates  the  Buccinator  muscle  from  the  Supe- 
rior constrictor  of  the  pharynx.  It  is  a  tendinous  band,  attached  by  one  extremity 
to  the  apex  of  the  internal  pterygoid  plate,  and  by  the  other  to  the  posterior 
extremity  of  the  internal  oblique  line  of  the  lower  jaw.  Its  inner  surface  corre- 
sponds to  the  cavity  of  the  mouth,  and  is  lined  by  mucous  membrane.  Its  outer 
surface  is  separated  from  the  ramus  of  the  jaw  by  a  quantity  of  adipose  tissue. 
Its  posterior  border  gives  attachment  to  the  Superior  constrictor  of  the  pharynx ; 
its  anterior  border,  to  the  fibres  of  the  Buccinator. 

The  Risoruis  of  Santorini  consists  of  a  narrow  bundle  of  fibres,  which  arises  in 
the  fascia  over  the  Masseter  muscle,  and,  passing  horizontally  forwards,  is  inserted 
into  the  angle  of  the  mouth,  joining  with  the  fibres  of  the  Depressor  anguli  oris. 
It  is  placed  superficial  to  the  Platysma,  and  is  broadest  at  its  outer  extremity. 
This  muscle  varies  much  in  its  size  and  form. 

Nerves.  The  Orbicularis  oris  is  supplied  by  the  facial,  the  Buccinator  by  the 
facial  and  buccal  branch  of  the  inferior  maxillary  nerve. 

Actions.  The  Orbicularis  oris  is  the  direct  antagonist  of  all  those  muscles  which 
converge  to  the  lips  from  the  various  parts  of  the  face,  its  action  producing  the 
direct  closure  of  the  lips ;  and  its  forcible  action  throwing  the  integument  into 
wrinkles,  on  account  of  the  firm  connection  between  the  latter  and  the  surface  of 
the  muscle.  The  Buccinators  contract  and  compress  the  cheeks,  so  that,  during 
the  process  of  mastication,  the  food  is  kept  under  the  immediate  pressure  of  the 
teeth. 

9.  Temporo-maxillary  Region"  (fig.  151). 
Masseter.  Temporal. 

The  Masseter  has  been  already  exposed  by  the  removal  of  the  integument  from 
the  side  of  the  face  (fig.  148). 

The  Masseter  is  a  short  thick  muscle,  somewhat  quadrilateral  in  form,  consisting 
of  two  portions,  superficial  and  deep.  The  superficial  portion,  the  largest,  arises 
by  a  thick  tendinous  aponeurosis  from  the  malar  process  of  the  superior  maxilla, 
and  from  the  anterior  two-thirds  of  the  lower  border  of  the  zygomatic  arch :  its 


250 


MUSCLES   AND   FASCIAE. 


fibres  pass  downwards  and  backwards,  to  be  inserted  into  the  angle  and  lower 
half  of  the  ramus  of  the  jaw.  The  deep  portion  is  much  smaller,  and  more  mus- 
cular in  texture,  and  arises  from  the  posterior  third  of  the  lower  border  and  whole 
of  the  inner  surface  of  the  zygomatic  arch ;  its  fibres  pass  downwards  and  for- 
wards to  be  inserted  into  the  upper  half  of  the  ramus  and  outer  surface  of  the 
coronoid  process  of  the  jaw.  The  deep  portion  of  the  muscle  is  partly  concealed, 
in  front,  by  the  superficial  portion ;  behind,  it  is  covered  by  the  parotid  gland. 
The  fibres  of  the  two  portions  are  united  at  their  insertion. 

Relations.  By  its  superficial  surface,  with  the  integument;  above,  with  the 
Orbicularis  palpebrarum  and  Zygomatici ;  and  has  passing  across  it,  transversely, 
Stenon's  duct,  the  branches  of  the  facial  nerve,  and  the  transverse  facial  vessels. 
By  its  deep  surface,  with  the  ramus  of  the  jaw,  and  the  Buccinator,  from  which  it 
is  separated  by  a  mass  of  fat.  Its  posterior  margin  is  overlapped  by  the  parotid 
gland.     Its  anterior  margin  projects  over  the  Buccinator  muscle. 

The  temporal  fascia  is  seen,  at  this  stage  of  the  dissection,  covering  in  the  Tem- 
poral muscle.  It  is  a  strong  aponeurotic  investment,  affording  attachment,  by  its. 
inner  surface,  to  the  superficial  fibres  of  this  muscle.  Above,  it  is  a  single  layer, 
attached  to  the  entire  extent  of  the  temporal  ridge ;  but  below,  where  it  is  attached 
to  the  zygoma,  it  consists  of  two  layers,  one  of  which  is  inserted  into  the  outer, 
and  the  other  into  the  inner  border  of  the  zygomatic  arch.  A  small  quantity  of 
fat,  the  orbital  branch  of  the  temporal  artery,  and  a  filament  from  the  orbital 
branch  of  the  superior  maxillary  nerve,  are  contained  between  these  two  layers. 
It  is  covered,  on  its  outer  surface,  by  the  aponeurosis  of  the  Occipito-frontalis,  the 
Orbicularis  palpebrarum,  and  Attollens  aurem  and  Attrahens  aurem  muscles; 
the  temporal  vessels  and  nerves  cross  it  from  below  upwards. 


Fig.  151. — The  Temporal  Muscle,  the  Zygoma  and  Masseter  having  been  removed. 


Dissection.  In  order  to  expose  the  Temporal  muscle,  this  fascia  should  be  removed ;  this  may 
be  effected  by  separating  it  at  its  attachment  along  the  upper  border  of  the  zygoma,  and  dissect- 
ing it  upwards  from  the  surface  of  the  muscle.  The  zygomatic  arch  should  then  be  divided,  in 
front,  at  its  junction  with  the  malar  bone,  and,  behind,  near  the  external  auditory  meatus,  and 
drawn  downwards  with  the  Masseter.  which  should  be  detached  from  its  insertion  into  the  ramus 
;md  angle  of  the  jaw.     The  whole  extent  of  the  Temporal  muscle  is  then  exposed. 


PTERYGO-MAXILLARY   REGION. 


25i 


The  Temporal  is  a  broad  radiating  muscle  situated  at  the  side  of  the  head,  and 
occupy iug  the  entire  extent  of  the  temporal  fossa.  It  arises  from  the  whole  of 
the  temporal  fossa,  which  extends  from  the  external  angular  process  of  the  frontal 
in  front,  to  the  mastoid  portion  of  the  temporal  behind  ;  and  from  the  curved  line 
on  the  frontal  and  parietal  bones  above,  to  the  pterygoid  ridge  on  the  great  wing 
of  the  sphenoid  below.  It  is  also  attached  to  the  inner  surface  of  the  temporal 
fascia.  Its  fibres  converge  as  they  descend,  and  terminate  in  an  aponeurosis,  the 
fibres  of  which,  radiated  at  its  commencement,  converge  into  a  thick  and  flat 
tendon,  which  is  inserted  into  the  inner  surface,  apex,  and  anterior  border  of  the 
coronoid  process  of  the  jaw,  nearly  as  far  forwards  as  the  last  molar  tooth. 

Relations.  By  its  superficial  surface,  with  the  integument,  the  temporal  fascia, 
aponeurosis  of  the  Occipito-frontalis,  the  Attollens  aurem  and  Attrahens  aurem 
muscles,  the  temporal  vessels  and  nerves,  the  zygoma  and  Masseter.  By  its  deep 
surface,  with  the  temporal  fossa,  the  External  pterygoid  and  part  of  the  Bucci- 
nator muscles,  the  internal  maxillary  artery,  its  deep  temporal  branches,  and 
the  temporal  nerves. 

Nerves.    Both  muscles  are  supplied  by  the  inferior  maxillary  nerve. 

10.  Pterygo-maxillary  Region. 
Internal  Pterygoid.  External  Pterygoid. 

Dissection.  The  Temporal  muscle  having  been  examined,  the  muscles  in  the  pterygo-maxil- 
lary  region  may  be  exposed  by  sawing  through  the  base  of  the  coronoid  process,  and  drawing  it 
upwards,  together  with  the  Temporal  muscle,  which  should  be  detached  from  the  surface  of  the 
temporal  fossa.  Divide  the  ramus  of  the  jaw  just  below  the  condyle,  and,  also,  by  a  transverse 
incision  extending  across  the  commencement  of  its  lower  third,  just  above  the  dental  foramen  ; 
remove  the  fragment,  and  the  Pterygoid  muscles  will  be  exposed. 


Fig.  152. — The  Pterygoid  Muscles  ;  the  Zygomatic  Arch  and  a  portion  of  the 
Ramus  of  the  Jaw  having  been  removed. 


The  Internal  Pterygoid  is  a  thick  quadrilateral  muscle,  and  resembles  the 
Masseter  in  form,  structure,  and  in  the  direction  of  its  fibres.  It  arises  from  the 
pterygoid  fossa,  its  fibres  being  attached  to  the  inner  surface  of  the  external 
pterygoid  plate,  and  to  the  grooved  surface  of  the  tuberosity  of  the  palate  bone ; 


252  MUSCLES   AND   FASCIA. 

its  fibres  pass  downwards,  outwards,  and  backwards,  to  be  inserted,  by  strong 
tendinous  laminae,  into  the  lower  and  back  part  of  the  inner  side  of  the  ramus  and 
angle  of  the  lower  jaw,  as  high  as  the  dental  foramen. 

Relations.  By  its  external  surface,  with  the  ramus  of  the  lower  jaw,  from  which 
it  is  separated,  at  its  upper  part,  by  the  External  Pterygoid,  the  internal  lateral 
ligament,  the  internal  maxillary  artery,  and  the  dental  vessels  and  nerves.  By  its 
internal  surface,  with  the  Tensor  palati,  being  separated  from  the  Superior  con- 
strictor of  the  pharynx  by  a  cellular  interval. 

The  External  Pterygoid  is  a  short  thick  muscle,  somewhat  conical  in  form,  and 
extends  almost  horizontally  between  the  zygomatic  fossa  and  the  condyle  of  the 
jaw.  It  arises  from  the  pterygoid  ridge  on  the  great  wing  of  the  sphenoid,  and 
the  portion  of  bone  included  between  it  and  the  base  of  the  pterygoid  process ; 
from  the  outer  surface  of  the  external  pterygoid  plate ;  and  from  the  tuberosity  of 
the  palate  and  superior  maxillary  bones.  Its  fibres  pass  horizontally  backwards 
and  outwards,  to  be  inserted  into  a  depression  in  front  of  the  neck  of  the  condyle 
of  the  lower  jaw,  and  into  the  corresponding  part  of  the  interarticular  fibro- 
cartilage.  This  muscle,  at  its  origin,  appears  to  consist  of  two  portions  separated 
by  a  slight  interval ;  hence  the  terms  upper  and  lower  head  sometimes  used  in  the 
description  of  the  muscle. 

Relations.  By  its  external  surf  ace,  with  the  ramus  of  the  lower  jaw,  the  internal 
maxillary  artery  which  crosses  it,  the  tendon  of  the  Temporal  muscle,  and  the 
Masseter.  By  its  internal  surface,  it  rests  against  the  upper  part  of  the  Internal 
pterygoid,  the  internal  lateral  ligament,  the  middle  meningeal  artery,  and  inferior 
maxillary  nerve;  by  its  upper  border  it  is  in  relation  with  the  temporal  and 
masseteric  branches  of  the  inferior  maxillary  nerve. 

Nerves.     These  muscles  are  supplied'by  the  inferior  maxillary  nerve. 

Actions.  The  Temporal,  Masseter,  and  Internal  pterygoid  raise  the  lower  jaw 
against  the  upper  with  great  force.  The  two  latter  muscles,  from  the  obliquity 
in  the  direction  of  their  fibres,  assist  the  External  pterygoid  in  drawing  the 
lower  jaw  forwards  upon  the  upper,  the  jaw  being  drawn  back  again  by  the  deep 
fibres  of  the  Masseter,  and  posterior  fibres  of  the  Temporal.  The  External 
pterygoid  muscles  are  the  direct  agents  in  the  trituration  of  the  food,  drawing  the 
lower  jaw  directly  forwards,  so  as  to  make  the  lower  teeth  project  beyond  the 
upper.  If  the  muscle  of  one  side  acts,  the  corresponding  side  of  the  jaw  is  drawn 
forwards,  and  the  other  condyle  remaining  fixed,  the  symphysis  deviates  to  the 
opposite  side.  The  alternation  of  these  movements  on  the  two  sides  produces 
trituration. 


MUSCLES  AND  FASCIAE  OF  THE  NECK. 

The  Muscles  of  the  Neck  may  be  arranged  into  groups,  corresponding  with  the 
region  in  which  they  are  situated. 

These  groups  are  nine  in  number : — 

1.  Superficial  Eegion.  5.  Muscles  of  the  Pharynx. 

2.  Infra-hyoid  Eegion.  6.  Muscles  of  the  Soft  Palate. 

Depressors  of  the  Os  Hyoides 

and  Larvnx.  7.  Muscles  of  the  Anterior  Verte- 

bral Eegion. 

3.  Supra-hyoid  Eegion. 

Elevators  of  the  Os  Hyoides         8.  Muscles  of  the  Lateral  Vertebral 
and  Larynx.  Eegion. 

4.  Lingual  Eegion.  9.  Muscles  of  the  Larynx. 

Muscles  of  the  Tongue. 


SUPERFICIAL   CERVICAL    REGION. 


253 


1.  Superficial  Region. 

Platysraa  myoides. 
Sternocleidomastoid . 

2.  Infra-hyoid  Region. 

Depressors  of  the  Os  Hyoides  and 
Larynx. 

Sterno-hyoid. 
Sterno-thyroid. 
Thyrohyoid. 
Omohyoid. 

3.  Supra-hyoid  Region. 

Elevators  of  the  Os  Hyoides  and 
Larynx. 

Digastric. 
Stylo-hyoid. 
Mylo-hyoid. 
Genio-hyoid. 

4.  Lingual  Region. 
Muscles  of  the  Tongue. 
Genio-hyo-glossus. 
Hyo-glossus. 
Lingualis. 
Stylo-glossus. 
Palato-glossus. 


5.  Muscles  of  the  Pharynx. 
Constrictor  inferior. 
Constrictor  medius. 
Constrictor  superior. 
Stylo-pharyngeus. 
Palato-pharyngeus. 

6.  Muscles  of  the  Soft  Palate. 
Levator  palati. 
Tensor  palati. 
Azygos  uvulae. 
Palato-glossus. 
Palato-pharyngeus. 

7.  Muscles  of  the  Anterior  Vertebral 

Region. 
Rectus  capitis  anticus  major. 
Rectus  capitis  anticus  minor. 
Rectus  lateralis. 
Longus  colli. 

8.  Muscles  of  the  Lateral  Vertebral 

Region. 
Scalenus  anticus. 
Scalenus  medius. 
Scalenus  posticus. 

9.  Muscles  of  the  Larynx. 
(Included  in  the  description  of  the 
Larynx.) 


1.  Superficial  Cervical  Region. 
Platysma  Myoides.  Sterno-cleido-mastoid. 

Dissection.  A  block  having  been  placed  at  the  back  of  the  neck,  and  the  face  turned  to  the 
side  opposite  to  that  to  be  dissected,  so  as  to  place  the  parts  upon  the  stretch,  two  transverse 
incisions  are  to  be  made :  one  from  the  chin,  along  the  margin  of  the  lower  jaw,  to  the  mastoid 
process ;  and  the  other  along  the  upper  border  of  the  clavicle.  These  are  to  be  connected  by  an 
oblique  incision  made  in  the  course  of  the  Sterno-mastoid  muscle,  from  the  mastoid  process  to 
the  sternum;  the  two  flaps  of  integument  having  been  removed  in  the  direction  shown  in  fig.  147, 
the  superficial  fascia  will  be  exposed. 

The  superficial  cervical  fascia  is  exposed  on  the  removal  of  the  integument  from 
the  side  of  the  neck ;  it  is  an  extremely  thin  aponeurotic  lamina,  which  is  hardly 
demonstrable  as  a  separate  membrane.  Beneath  it  is  found  the  Platysma  myoides 
muscle,  the  external  jugular  vein,  and  some  superficial  branches  of  the  cervical 
plexus  of  nerves. 

The  Platysma  Myoides  (fig.  148)  is  a  broad  thin  plane  of  muscular  fibres,  placed 
immediately  beneath  the  skin  on  each  side  of  the  neck.  It  arises  from  the  clavicle 
and  acromion,  and  from  the  fascia  covering  the  upper  part  of  the  Pectoral,  Deltoid, 
and  Trapezius  muscles ;  its  fibres  proceed  obliquely  upwards  and  inwards  along  the 
aide  of  the  neck,  to  be  inserted  into  the  lower  jaw  beneath  the  external  oblique 
line,  some  fibres  passing  forwards  to  the  angle  of  the  mouth,  and  others  becoming 
lost  in  the  cellular  tissue  of  the  face.  The  most  anterior  fibres  interlace,  in  front 
of  the  jaw,  with  the  fibres  of  the  muscle  of  the  opposite  side ;  those  next  in  order 
become  blended  with  the  Depressor  labii  inferioris  and  the  Depressor  anguli  oris ; 
others  are  prolonged  upon  the  side  of  the  cheek,  and  interlace,  near  the  angle  of 
the  mouth,  with  the  muscles  in  this  situation,  and  may  occasionally  be  traced  to 
the  Zygomatic  muscles,  or  to  the  margin  of  the  Orbicularis  palpebrarum.    Beneath 


254  MUSCLES   AND   FASCIAE. 

the  Platysma,  the  external  jugular  vein  may  be  seen  descending  from  the  angle  of 
the  jaw  to  the  clavicle.  It  is  essential  to  remember  the  direction  of  the  fibres  of 
the  Platysma,  in  connection  with  the  operation  of  bleeding  from  this  vessel ;  for 
if  the  point  of  the  lancet  is  introduced  in  the  direction  of  the  muscular  fibres,  the 
orifice  made  will  be  filled  up  by  the  contraction  of  the  muscle,  and  blood  will  not 
flow ;  but  if  the  incision  is  made  in  a  direction  opposite  to  the  course  of  the  fibres, 
they  will  retract,  and  expose  the  orifice  in  the  vein,  and  so  facilitate  the  flow  of 
blood. 

Relations.  By  its  external  surface,  with  the  integument  to  which  it  is  united 
closely  below,  but  more  loosely  above.  By  its  internal  surface,  below  the  clavicle 
which  it  covers,  with  the  Pectoralis  major,  Deltoid,  and  Trapezius.  In  the  neck, 
with  the  external  and  anterior  jugular  veins,  the  deep  cervical  fascia,  the  super- 
ficial cervical  plexus,  the  Sterno-mastoid,  Sterno-hyoid,  Omo-hyoid,  and  Digastric 
muscles.  In  front  of  the  Sterno-mastoid,  it  covers  the  sheath  of  the  carotid  ves- 
sels ;  and  behind  it,  the  Scaleni  muscles  and  the  nerves  of  the  brachial  plexus. 
On  the  face,  it  is  in  relation  with  the  parotid  gland,  the  facial  artery  and  vein,  and 
the  Masseter  and  Buccinator  muscles. 

The  deep  cervical  fascia  is  exposed  on  the  removal  of  the  Platysma  myoides. 
It  is  a  strong  fibrous  layer,  which  invests  the  muscles  of  the  neck,  and  incloses 
the  vessels  and  nerves.  It  commences,  as  an  extremely  thin  layer,  at  the  back 
part  of  the  neck,  where  it  is  attached  to  the  spinous  processes  of  the  cervical 
vertebras,  and  to  the  ligamentum  nuchse ;  and,  passing  forwards  to  the  posterior 
border  of  the  Sterno-mastoid  muscle,  divides  into  two  layers,  one  of  which  passes 
in  front,  and  the  other  behind  it.  These  join  again  at  its  anterior  border ;  and, 
being  continued  forwards  to  the  front  of  the  neck,  blend  with  the  fascia  of  the 
opposite  side.  The  superficial  layer  of  the  deep  cervical  fascia,  that  which  passes 
in  front  of  the  Sterno:mastoid,  if  traced  upwards,  is  found  to  pass  across  the 
parotid  gland  and  Masseter  muscle,  forming  the  parotid  and  masseteric  fasciae, 
and  is  attached  to  the  lower  border  of  the  zygoma,  and  more  anteriorly  ..to  the 
lower  border  of  the  body  of  the  jaw ;  if  the  same  layer  is  traced  downwards,  it  is 
seen  to  pass  to  the  upper  border  of  the  clavicle  and  sternum,  being  pierced  just 
above  the  former  bone  for  the  external  jugular  vein.  In  the  middle  line  of  the 
neck,  the  fascia  is  thin  above,  and  connected  to  the  hyoid  bone ;  but  it  becomes 
thicker  below,  and  divides,  just  below  the  thyroid  gland,  into  two  layers,  the  more 
superficial  of  which  is  attached  to  the  upper  border  of  the  sternum  and  inter- 
clavicular ligament;  the  deeper  and  stronger  layer  is  connected  to  the  posterior 
border  of  that  bone,  covering  in  the  Sterno-hyoid  and  Sterno-thyroid  muscles. 
Between  these  two  layers  is  a  little  areolar  tissue  and  fat,  and  occasionally  a 
small  lymphatic  gland.  The  deep  layer  of  the  cervical  fascia,  that  which  lies 
behind  the  posterior  surface  of  the  Sterno-mastoid,  sends  numerous  prolongations, 
which  invest  the  muscles  and  vessels  of  the  neck ;  if  traced  upwards,  a  process  of 
this  fascia,  of  extreme  density,  passes  behind  and  to  the  inner  side  of  the  parotid 
gland,  and  is  attached  to  the  base  of  the  styloid  process  and  angle  of  the  lower 
jaw,  forming  the  stylo-maxillary  ligament;  if  traced  downwards  and  outwards,  it 
will  be  found  to  inclose  the  posterior  belly  of  the  Omo-hyoid  muscle,  binding  it 
down  by  a  distinct  process,  which  descends  to  be  inserted  into  the  clavicle  and 
cartilage  of  the  first  rib.  The  deep  layer  of  the  cervical  fascia  also  assists  in 
forming  the  sheath  which  incloses  the  common  carotid  artery,  internal  jugular 
vein,  and  pneumogastric  nerve.  There  are  fibrous  septa  intervening  between 
each  of  these  parts,  which,  however,  are  included  together  in  one  common  invest- 
ment. More  internally,  a  thin  layer  is  continued  across  the  trachea  and  thyroid 
gland,  beneath  the  Sterno-thyroid  muscles ;  and  at  the  root  of  the  neck  this  may 
be  traced,  over  the  large  vessels,  to  be  continuous  with  the  fibrous  layer  of  the 
pericardium. 

The  Sterno-cleido-mastoid  (fig.  153)  is  a  large  thick  muscle,  which  passes 
obliquely  across  the  side  of  the  neck,  being  inclosed  between  the  two  layers  of 
the  deep  cervical  fascia.     It  is  thick  and  narrow  at  its  central  part,  but  is  broader 


SUPERFICIAL   CERVICAL   REGION. 


255 


and  thinner  at  each  extremity.  It  arises,  by  two  heads,  from  the  sternum  and 
clavicle.  The  sternal  portion  arises  by  a  rounded  fasciculus,  tendinous  in  front, 
fleshy  behind,  from  the  upper  and  anterior  part  of  the  first  piece  of  the  sternum, 
and  is  directed  upwards  and  backwards.  The  clavicular  portion  arises  from  the 
inner  third  of  the  superior  border  of  the  clavicle,  being  composed  of  fleshy  and 
aponeurotic  fibres ;  it  is  directed  almost  vertically  upwards.  These  two  portions 
are  separated  from  one  another,  at  their  origin,  oy  a  triangular  cellular  interval ; 
but  become  gradually  blended,  below  the  middle  of  the  neck,  into  a  thick  rounded 
muscle,  which  is  inserted,  by  a  strong  tendon,  into  the  outer  surface  of  the  mastoid 
•  process,  from  the  apex  to  its  superior  border,  and  by  a  thin  aponeurosis  into  the 
outer  two-thirds  of  the  superior  curved  line  of  the  occipital  bone.  This  muscle 
varies  much  in  its  extent  of  attachment  to  the  clavicle ;  in  one  case  it  may  be  as 
narrow  as  the  sternal  portion,  in  another  as  much  as  three  inches  in  breadth. 


Fig.  153. — Muscles  of  the  Neck,  and  Boundaries  of  the  Triangles. 


When  the  clavicular  origin  is  broad,  it  is  occasionally  subdivided  into  numerous 
slips,  separated  by  narrow  intervals.  More  rarely,  the  corresponding  margins  of 
the  Sterno-mastoid  and  Trapezius  have  been  found  in  contact.  In  the  application 
of  a  ligature  to  the  third  part  of  the  subclavian  artery,  it  will  be  necessary,  where 
the  muscles  have  an  arrangement  similar  to  that  above-mentioned,  to  divide  a 
portion  of  one  or  of  both,  in  order  to  facilitate  the  operation. 

This  muscle  divides  the  quadrilateral  space  at  the  side  of  the  neck  into  two 
triangles,  an  anterior  and  a  posterior.  The  boundaries  of  the  anterior  triangle 
being,  in  front,  the  median  line  of  the  neck ;  above,  the  lower  border  of  the  body 
of  the  jaw,  and  an  imaginary  line  drawn  from  the  angle  of  the  jaw  to  the  mastoid 


256  MUSCLES   AND   FASCIA. 

process ;  behind,  the  anterior  border  of  the  Sterno-mastoid  muscle.  The  boundaries 
of  the  posterior  triangle  are,  in  front,  the  posterior  border  of  the  Sterno-mastoid ; 
below,  the  upper  border  of  the  clavicle;  behind,  the  anterior  margin  of  the 
Trapezius. 

The  anterior  edge  of  the  muscle  forms  a  very  prominent  ridge  beneath  the 
skin,  which  it  is  important  to  notice,  as  it  forms  a  guide  to  the  surgeon  in  making 
the  necessary  incisions  for  ligature  of  the  common  carotid  artery,  and  for  cesoph- 
agotomy. 

Relations.  By  its  superficial  surface,  with  the  integument  and  Platysma,  from 
which  it  is  separated  by  the  external  jugular  vein,  the  superficial  branches  of  the 
cervical  plexus,  and  the  anterior  layer  of  the  deep  cervical  fascia.  By  its  deep 
surface,  it  rests  on  the  sterno-clavicular  articulation,  the  deep  layer  of  the  cervical 
fascia,  the  Sterno-hyoid,  Sterno-thyroid,  Omo-hyoid,  the  posterior  belly  of  the 
Digastric,  Levator  anguli  scapulae,  the  Splenius  and  Scaleni  muscles.  Below,  with 
the  lower  part  of  the  common  carotid  artery,  internal  jugular  vein,  pneumogastric, 
descendens  noni,  and  communicans  noni  nerves,  and  with  the  deep  lymphatic 
glands ;  with  the  spinal  accessory  nerve,  which  pierces  its  upper  third,  the  cervical 
plexus,  the  occipital  artery,  and  a  part  of  the  parotid  gland. 
•  Nerves.  The  Platysma  myoides  is  supplied  by  the  facial  and  superficial  cer* 
vical  nerves,  the  Sterno-cleido-mastoid  by  the  spinal  accessory  and  deep  branches 
of  the  cervical  plexus. 

Actions.  The  Platysma  myoides  produces  a  slight  wrinkling  of  the  surface  of 
the  skin  of  the  neck,  in  a  vertical  direction,  when  the  entire  muscle  is  brought 
into  action.  Its  anterior  portion,  the  thickest  part  of  the  muscle,  depresses  the 
lower  jaw ;  it  also  serves  to  draw  down  the  lower  lip  and  angle  of  the  mouth  on 
each  sider  being  one  of  the  chief  agents  in  the  expression  of  melancholy.  The 
Sterno-mastoid  muscles,  when  both  are  brought  into  action,  serve  to  depress  the 
head  upon  the  neck,  and  the  neck  upon  the  chest.  Either  muscle,  acting  singly, 
flexes  the  head,  and  combined  with  the  Splenius  draws  it  towards  the  shoulder 
of  the  same  side,  and  rotates  it  so  as  to  carry  the  face  towards  the  opposite  side. 

Surgical  Anatomy.  The  relations' of  the  sternal  and  clavicular  parts  of  the  Sterno-mastoid 
should  be  carefully  examined,  as  the  surgeon  is  sometimes  required  to  divide  one  or  both  portions 
of  the  muscle  in  wryneck.  One  variety  of  this  distortion  is  produced  by  spasmodic  contraction 
or  rigidity  of  the  Sterno-mastoid ;  the  head  being  carried  down  towards  the  shoulder  of  the  same 
side,  and  the  face  turned  to  the  opposite  side,  and  fixed  in  that  position.  When  all  other  reme- 
dies for  the  relief  of  this  disease  have  failed,  subcutaneous  division  of  the  mnscle  is  resorted  to. 
This  is  performed  by  introducing  a  long  narrow  bistoury  beneath  it,  about  half  an  inch  above  its 
origin,  and  dividing  it  from  behind  forwards  whilst  the  muscle  is  put  well  upon  the  stretch. 
There  is  seldom  any  difficulty  in  dividing  the  sternal  portion.  In  dividing  the  clavicular  portion 
care  must  be  taken  to  avoid  wounding  the  external  jugular  vein,  which  runs  parallel  with  the 
posterior  border  of  the  muscle  in  this  situation. 


2.  Infea-hyoid  Eegion  (figs.  153  and  154). 

Depeessors  of  the  Os  Hyoides  and  Laeynx. 

Sterno-hyoid.  Thyro-hyoid. 

Sterno-thyroid.  Omo-hyoid. 

Dissection.  The  muscles  in  this  region  may  be  exposed  by  removing  the  deep  fascia  from  the 
front  of  the  neck.  In  order  to  see  the  entire  extent  of  the  Omo-hyoid,  it  is  necessary  to  divide 
the  Sterno-mastoid  at  its  centre,  and  turn  its  ends  aside,  and  to  detach  the  Trapezius  from  the 
clavicle  and  scapula,  if  this  muscle  has  been  previously  dissected ;  but  not  otherwise. 

The  Sterno-hyoid  is  a  thin,  narrow,  riband-like  muscle,  which  arises  from 
the  inner  extremity  of  the  clavicle,  and  the  upper  and  posterior  part  of  the  first 
piece  of  the  sternum ;  and,  passing  upwards  and  inwards,  is  inserted,  by  short 
tendinous  fibres,  into  the  lower  border  of  the  body  of  the  os  hyoides.     This 


INFRA-HYOID   REGION. 


257 


muscle  is  separated,  below,  from  its  fellow  by  a  considerable  interval ;  but  they 
approach  one  another  in  the  middle  of  their  course,  and  again  diverge  as  they 
ascend.  It  often  presents,  immediately  above  its  origin,  a  transverse  tendinous 
intersection,  analogous  to  those  in  the  Rectus  abdominis. 

Variations.  This  muscle  sometimes  arises  from  the  inner  extremity  of  the  clavicle,  and  the 
posterior  sterno-clavicular  ligament,  or  from  the  sternum  and  this  ligament;  from  either  bone 
alone,  or  from  all  these  parts ;  and  occasionally  has  a  fasciculus  connected  with  the  cartilage  of 
the  first  rib. 

Relations.  By  its  superficial  surface,  below,  with  the  sternum,  sternal  end  of 
the  clavicle,  and  the  Sterno-mastoid ;  and  above,  with  the  Platysma  and  deep 
cervical  fascia.  By  its  deep  surface,  with  the  Sterno-thyroid,  Crico-thyroid,  and 
Thyro-hyoid  muscles,  the  thyroid  gland,  the  superior  thyroid  vessels,  the 
crico-thyroid  and  thyro-hyoid  membranes. 


Fig.  154. — Muscles  of  the  Neck.     Anterior  View. 


The  Slerno-ihyroid  is  situated  beneath  the  preceding  muscle,  but  is  shorter 
and  wider.  It  arises  from  the  posterior  surface  of  the  first  bone  of  the 
sternum,  below  the  origin  of  the  Sterno-hyoid,  and  occasionally  from  the  edge  of 
the  cartilage  of  the  first  rib,  and  is  inserted  into  the  oblique  line  on  the  side 
of  the  ala  of  the  thyroid  cartilage.  This  muscle  is  in  close  contact  with  its 
fellow  at  the  lower  part  of  the  neck ;  and  is  frequently  traversed  by  a  trans- 
verse or  oblique  tendinous  intersection,  analogous  to  those  in  the  Rectus 
abdominis. 

Variations.  This  muscle  is  sometimes  continuous  with  the  Thyro-hyoid  and  Inferior  con- 
strictor of  the  pharynx ;  and  a  lateral  prolongation  from  it  sometimes  passes  as-  far  as  the  o.s 
hyoides. 

17 


258  MUSCLES   AND   FASCIAE. 

Relations.  By  its  anterior  surface,  with  the  Sternohyoid,  Omohyoid,  and 
Sterno-mastoid.  By  its  posterior  surface,  from  below  upwards,  with  the  trachea, 
vena  innominata,  common  carotid  (and  on  the  right  side  the  arteria  innominata), 
the  thyroid  gland  and  its  vessels,  and  the  lower  part  of  the  larynx.  The  middle 
thyroid  vein  lies  along  its  inner  border;  an  important  relation  to  be  remembered  in 
the  operation  of  tracheotomy. 

The  TJiyro-hyoid  is  a  small  quadrilateral  muscle,  appearing  like  a  continuation 
of  the  Sterno-thyroid.  It  arises  from  the  oblique  line  on  the  side  of  the  thyroid 
cartilage,  and  passes  vertically  upwards  to  be  inserted  into  the  lower  border  of 
the  body  and  greater  cornu  of  the  hyoid  bone. 

Relations.  By  its  external  surface,  with  the  Sterno-hyoid  and  Omo-hyoid 
muscles.  By  its  internal  surface,  with  the  thyroid  cartilage,  the  thyro-hyoid 
membrane,  and  the  superior  laryngeal  vessels  and  nerve. 

The  Omo-hyoid  passes  across  the  side  of  the  neck,  from  the  scapula  to  the 
hyoid  bone.  It  consists  of  two  fleshy  bellies,  united  by  a  central  tendon.  It 
arises  from  the  upper  border  of  the  scapula,  and  occasionally  from  the  transverse 
ligament  which  crosses  the  suprascapular  notch ;  its  extent  of  attachment  to  the 
scapula  varying  from  a  few  lines  to  an  inch.  From  this  origin,  the  posterior  belly 
forms  a  flat,  narrow  fasciculus,  which  inclines  forwards  across  the  lower  part  of 
the  neck;  behind  the  Sterno-mastoid  muscle,  where  it  becomes  tendinous,  it  changes 
its  direction,  forming  an  obtuse  angle,  and  ascends  almost  vertically  upwards,  close 
to  the  outer  border  of  the  Sterno-hyoid,  to  be  inserted  into  the  lower  border  of 
the  body  of  the  os  hyoides,  just  external  to  the  insertion  of  the  Sterno-hyoid. 
The  tendon  of  this  muscle,  which  varies  much  in  its  length  and  form  in  different 
subjects,  is  held  in  its  position  by  a  process  of  the  deep  cervical  fascia,  which 
includes  it  in  a  sheath,  and  is  prolonged  down,  to  be  attached  to  the  cartilage 
of  the  first  rib.  It  is  by  this  means  that  the  angular  form  of  the  muscle  is 
maintained. 

This  muscle  subdivides  each  of  the  two  large  triangles  at  the  side  of  the  neck 
into  two  smaller  triangles.  The  two  posterior  ones  are  the  posterior  superior 
or  suboccipital,  and  the  posterior  inferior  or  subclavian;  the  two  anterior,  the 
anterior  superior  or  superior  carotid,  and  the  anterior  inferior  or  inferior  carotid 
triangle. 

Relations.  By  its  superficial  surface,  with  the  Trapezius,  Subclavius,  the 
clavicle,  the  Sterno-mastoid,  deep  cervical  fascia,  Platysma,  and  integument.  By 
its  deep  surface,  with  the  Scaleni,  brachial  plexus,  sheath  of  the  common  carotid 
artery,  and  internal  jugular  vein,  the  descendens  noni  nerve,  Sterno-thyroid  and 
Thyro-hyoid  muscles. 

Nerves.  The  Thyro-hyoid  is  supplied  by  the  hypoglossal ;  the  other  muscles 
of  this  group  by  branches  from  the  loop  of  communication  between  the  descendens 
noni  and  communicans  noni. 

Actions.  These  muscles  depress  the  larynx  and  hyoid  bone,  after  they  have 
been  drawn  up  with  the  pharynx  in  the  act  of  deglutition.  The  Omo-hyoid 
muscles  not  only  depress  the  hyoid  bone,  but  carry  it  backwards,  and  to  one  or 
the  other  side.  These  muscles  are  also  tensors  of  the  cervical  fascia.  The  Thyro- 
hyoid may  act  as  an  elevator  of  the  thyroid  cartilage,  when  the  hyoid  bone  ascends, 
drawing  upwards  the  thyroid  cartilage  behind  the  os  hyoides. 

3.  Supra-hyoid  Begion  (figs.  153  and  154). 

Elevators  of  the  Os  Hyoides  ;  Depressors  of  the  Lower  Jaw. 

Digastric.  Mylo-hyoid. 

Stylo-hyoid.  Genio-hyoid. 

Dissection.  To  dissect  these  muscles,  a  block  should  be  placed  beneath  the  back  of  the  neck, 
and  the  head  drawn  backwards,  and  retained  in  that  position.  On  the  removal  of  the  deep  fascia, 
tho  muscles  are  at  once  exposed. 


SUPRA-HYOID   REGION.  259 

The  Digastric  consists  of  two  fleshy  bellies  united  by  an  intermediate  rounded 
tendon.  It  is  a  small  muscle,  situated  below  the  side  of  the  body  of  the  lower 
jaw,  and  extending,  in  a  curved  form,  from  the  side  of  the  head  to  the  symphysis 
of  the  jaw.  The  posterior  belly,  longer  than  the  anterior,  arises  from  the  di- 
gastric groove  on  the  inner  side  of  the  mastoid  process  of  the  temporal  bone,  and 
passes  downwards,  forwards,  and  inwards.  The  anterior  belly,  being  reflected 
upwards  and  forwards,  is  inserted  into  a  depression  on  the  inner  side  of  the  lower 
border  of  the  jaw,  close  to  the  symphysis.  The  tendon  of  the  muscle  perforates 
the  Stylo-hyoid,  and  is  held  in  connection  with  the  side  of  the  body  of  the  hyoid 
bone  by  an  aponeurotic  loop,  lined  by  a  synovial  membrane.  A  broad  aponeurotic 
layer  is  given  off'  from  the  tendon  of  the  Digastric  on  each  side,  which  is  attached 
to  the  body  and  great  cornu  of  the  hyoid  bone":  this  is  termed  the  supra-hyoid 
aponeurosis.  It  forms  a  strong  layer  of  fascia  between  the  anterior  portion  of  the 
two  muscles,  and  a  firm  investment  for  the  other  muscles  of  the  supra-hyoid  region 
which  lie  beneath  it. 

The  Digastric  muscle  divides  the  anterior  superior  triangle  of  the  neck  into  two 
smaller  triangles.  The  upper  or  submaxillary  triangle  is  bounded,  above,  by  the 
lower  jaw,  and  mastoid  process ;  below,  by  the  two  bellies  of  the  Digastric  muscle: 
the  lower  or  superior  carotid  triangle  being  bounded,  above,  by  the  posterior 
belly  of  the  Digastric ;  behind,  by  the  Sterno-mastoid ;  below,  by  the  Omo-hyoid. 

Relations.  By  its  superficial  surface,  with  the  Platysma,  Sterno-mastoid  and 
Trachelo-mastoid,  part  of  the  Stylo-hyoid  muscle,  and  the  parotid  and  submaxillary 
glands.  By  its  deep  surface,  the  anterior  belly  lies  on  the  Mylo-hyoid  ;  the  pos- 
terior belly  on  the  Stylo-glossus,  Stylo-pharyngeus,  and  Hyo-glossus  muscles,  the 
external  carotid  and  its  lingual  and  facial  branches,  the  internal  carotid,  internal 
jugular  vein,  and  hypoglossal  nerve. 

The  Stylo-hyoid  is  a  small,  slender  muscle,  lying  in  front  of,  and  above,  the 
posterior  belly  of  the  Digastric.  It  arises  from  the  middle  of  the  outer  surface 
of  the  styloid  process ;  and,  passing  downwards  and  forwards,  is  inserted  into  the 
body  of  the  hyoid  bone,  just  at  its  junction  with  the  greater  cornu,  and  immedi- 
ately above  the  Omo-hyoid.  This  muscle  is  perforated,  near  its  insertion,  by  the 
tendou  of  the  Digastric. 

Relations.     The  same  as  the  posterior  belly  of  the  Digastric. 

The  Digastric  and  Stylo-hyoid  should  be  removed,  in  order  to  expose  the  next  muscle. 

The  Mylo-hyoid  is  a  flat  triangular  muscle,  situated  immediately  beneath  the 
anterior  belly  of  the  Digastric,  and  forming,  with  its  fellow  of  the  opposite  side, 
a  muscular  floor  for  the  cavity  of  the  mouth.  It  arises  from  the  whole  length  of 
the  mylo-hyoid  ridge,  from  the  symphysis  in  front,  to  the  last  molar  tooth  behind. 
The  posterior  fibres  pass  obliquely  forwards,  to  be  inserted  into  the  body  of  the 
os  hyoides.  The  middle  and  anterior  fibres  are  inserted  into  a  median  fibrous 
raphe,  where  they  join  at  an  angle  with  the  fibres  of  the  opposite  muscle.  This 
median  raphe  is  sometimes  wanting;  the  muscular  fibres  of  the  two  sides  are  then 
directly  continuous  with  one  another. 

Relations.  By  its  cutaneous  surface,  with  the  Platysma,  the  anterior  belly  .of  the 
Digastric,  the  supra-hyoid  fascia,  the  submaxillary  gland,  and  submental  vessels. 
By  its  deep  or  superior  surface,  with  the  Genio-hyoid,  part  of  the  Hyo-glossus,  and 
Stylo-glossus  muscles,  the  lingual  and  gustatory  nerves,  the  sublingual  gland,  and 
the  buccal  mucous  membrane.  Wharton's  duct  curves  round  its  posterior  border 
in  its  passage  to  the  mouth. 

Dissection.  The  Mylo-hyoid  should  now  be  removed,  in  order  to  expose  the  muscles  which  lie 
beneath;  this  is  effected  by  detaching  it  from  its  attachments  to  the  hyoid  bone  and  jaw,  and 
separating  it  by  a  vertical  incision  from  its  fellow  of  the  opposite  side. 

The  Genio-hyoid 'is  a  narrow  slender  muscle,  situated  immediately  beneath  the 
inner  border  of  the  preceding.  It  arises  from  the  inferior  genial  tubercle  on  the 
inner  side  of  the  symphysis  of  the  jaw,  and  passes  downwards  and  backwards,  to 


260  MUSCLES   AND   FASCIAE. 

be  inserted  into  the  anterior  surface  of  the  body  of  the  os  hyoides.  This  muscle 
lies  in  close  contact  with  its  fellow  of  the  opposite  side,  and  increases  slightly  in 
breadth  as  it  descends. 

Relations.     It  is  covered  by  the  Mylo-hyoid,  and  lies  on  the  Genio-hyo-glossus. 

Nerves.  The  Digastric  is  supplied,  its  anterior  belly  by  the  mylo-hyoid  branch 
of  the  inferior  dental,  its  posterior  belly  by  the  facial ;  the  Stylo-hyoid,  by  the 
facial ;  the  Mylo-hyoid,  by  the  mylo-hyoid  branch  of  the  inferior  dental ;  the 
Genio-hyoid,  by  the  hypoglossal. 

Actions.  This  group  of  muscles  performs  two  very  important  actions ; — they 
raise  the  hyoid  bone,  and  with  it  the  base  of  the  tongue,  during  the  act  of  deglu- 
tition ;  or,  when  the  hyoid  bone  is  fixed  by  its  depressors  and  those  of  the  larynx, 
they  depress  the  lower  jaw.  During  the  first  act  of  deglutition,  when  the  mass 
is  being  driven  from  the  mouth  .into  the  pharynx,  the  hyoid  bone,  and  with  it  the 
tongue,  is  carried  upwards  and  forwards  by  the  anterior  belly  of  the  Digastric, 
the  Mylo-hyoid,  and  Genio-hyoid  muscles.  In  the  second  act,  when  the  mass  is 
passing  through  the  pharynx,  the  direct  elevation  of  the  hyoid  bone  takes  place 
by  the  combined  action  of  all  the  muscles ;  and  after  the  food  has  passed,  the 
hyoid  bone  is  carried  upwards  and  backwards  by  the  posterior  belly  of  the 
Digastric  and  Stylo-hyoid  muscles,  which  assist  in  preventing  the  return  of  the 
morsel  into  the  cavity  of  the  mouth. 

4.  Lingual  Eegion. 

Genio-hyo-glossus.  Lingualis. 

Hyo-glossus.  Stylo-glossus. 

Palato-glossus. 

Dissection.  After  completing'  the  dissection  of  the  preceding  muscles,  saw  through  the  lower 
jaw  just  external  to  the  symphysis.  The  tongue  should  then  be  drawn  forwards  with  a  hook, 
and  its  muscles,  which  are  thus  put  on  the  stretch,  may  be  examined. 

The  Genio-hyo-glossus  has  received  its  name  from  its  triple  attachment  to  the 
chin,  hyoid  bone,  and  tongue;  it  is  a  thin,  flat,  triangular  muscle,  placed  vertically 
in  the  middle  line,  its  apex  corresponding  with  its  point  of  attachment  to  the 
lower  jaw,  its  base  with  its  insertion  into  the  tongue  and  hyoid  bone.  It  arises 
by  a  short  tendon  from  the  superior  genial  tubercle  on  the  inner  side  of  the  sym- 
physis of  the  chin,  immediately  above  the  Genio-hyoid ;  from  this  point,  the  muscle 
spreads  out  in  a  fan-like  form,  the  inferior  fibres  passing  downwards  to  be  inserted 
into  the  upper  part  of  the  body  of  the  hyoid  bone,  a  few  being  continued  into  the 
side  of  the  pharynx ;  the  middle  fibres  passing  backwards,  and  the  superior  ones 
upwards  and  forwards,  to  be  attached  to  the  whole  length  of  the  under  surface  of 
the  tongue,  from  the  base  to  the  apex. 

Relations.  By  its  internal  surface,  it  is  in  contact  with  its  fellow  of  the  opposite 
side,  from  which  it  is  separated,  at  the  back  part  of  the  tongue,  by  a  fibro-cellular 
structure,  which  extends  forwards  through  the  middle  of  the  organ.  By  its 
external  surface,  with  the  Lingualis,  Hyo-glossus,  and  Stylo-glossus,  the  lingual 
artery  and  hypoglossal  nerve,  the  gustatory  nerve,  and  sublingual  gland.  By  its 
upper  border,  with  the  mucous  membrane  of  the  floor  of  the  mouth.  By  its  lower 
border,  with  the  Genio-hyoid. 

The  Hyo-glossus  is  a  thin,  flat,  quadrilateral  muscle,  arising  from  the  side  of 
the  body,  the  lesser  cornu,  and  whole  length  of  the  greater  cornu  of  the  hyoid 
bone,  and,  passing  almost  vertically  upwards,  is  inserted  into  the  side  of  the  tongue, 
between  the  Stylo-glossus  and  Lingualis.  Those  fibres  of  this  muscle  which  arise 
from  the  body  are  directed  upwards  and  backwards,  overlapping  those  from  the 
greater  cornu,  which  are  directed  obliquely  forwards.  Those  from  the  lesser  cornu 
extend  forwards  and  outwards  along  the  side  of  the  tongue,  under  cover  of  the 
portion  arising  from  the  body. 


LINGUAL  REGION. 


261 


The  difference  in  the  direction  of  the  fibres  of  this  muscle,  and  their  separate 
origin  from  different  segments  of  the  hyoid  bone,  led  Albinus  and  other  anato- 
mists to  describe  it  as  three  muscles,  under  the  names  of  the  Basio-glossus,  the 
Cerato-glossus,  and  the  Chondro-glossus. 

Relations.  By  its  external  surface,  with  the  Digastric,  the  Stylo-hyoid,  Stylo- 
glossus, and  Mylo-hyoid  muscles,  the  gustatory  and  hypoglossal  nerves,  Wharton's 
duct,  and  the  sublingual  gland.  By  its  deep  surface,  with  the  Genio-hyo-glossus, 
Lingualis,  and  the  Middle  constrictor,  the  lingual  vessels,  and  the  glosso-pharyn- 
geal  nerve. 

The  Lingualis  is  a  longitudinal  band  of  muscular  fibres,  situated  on  the  under 
surface  of  the  tongue,  lying  in  the  interval  between  the  Hyo-glossus  and  the 
Genio-hyo-glossus,  and  extending  from  the  base  to  the  apex  of  that  organ. 
Posteriorly,  some  of  its  fibres  are  lost  in  the  base  of  the  tongue,  and  others  are 
attached  to  the  hyoid  bone.    It  blends  with  the  fibres  of  the  Stylo-glossus,  in  front 


Fig.  155. — Muscles  of  the  Tongue.     Left  Side. 


of  the  Hyo-glossus,  and  is  continued  forwards  as  far  as  the  apex  of  the  tongue. 
It  is  in  relation,  by  its  under  surface,  with  the  ranine  artery. 

The  Stylo-glossus,  the  shortest  and  smallest  of  the  three  styloid  muscles,  arises 
from  the  anterior  and  outer  side  of  the  styloid  process,  near  its  centre,  and  from 
the  stylo-maxillary  ligament,  to  which  its  fibres,  in  most  cases,  are  attached  by  a 
thin  aponeurosis.  Passing  downwards  and  forwards,  so  as  to  become  nearly  hori- 
zontal in  its  direction,  it  divides  upon  the  side  of  the  tongue  into  two  portions : 
one  longitudinal,  which  is  inserted  along  the  side  of  the  tongue,  blending  with 
the  fibres  of  the  Lingualis,  in  front  of  the  Hyo-glossus ;  the  other,  oblique,  which 
overlaps  the  Hyo-glossus  muscle,  and  decussates  with  its  fibres. 

Relations.  By  its  external  surface,  from  above  downwards,  with  the  parotid 
gland,  the  Internal  pterygoid  muscle,  the  sublingual  gland,  the  gustatory  nerve 


202 


MUSCLES   AND   FASCIA. 


and  the  mucous  membrane  of  the  mouth.  By  its  internal  surface,  with  the  tonsil, 
the  Superior  constrictor,  and  the  Hyo-glossus  muscle. 

The  Palato-glossus  or  Constrictor  Isthmi  Faucium,  although  one  of  the  muscles 
of  the  tongue,  serving  to  draw  its  base  upwards  during  the  act  of  deglutition,  is 
more  nearly  associated  with  the  soft  palate,  both  in  its  situation  and  function ; 
it  will,  consequently,  be  described  with  that  group  of  muscles. 

Nerves.  The  Palato-glossus  is  supplied  by  the  palatine  branches  of  Meckel's 
ganglion ;  the  Lingualis,  by  the  chorda  tympani ;  the  remaining  muscles  of  this 
group,  by  the  hypoglossal. 

Actions.  The  movements  of  the  tongue,  although  numerous  and  complicated, 
may  easily  be  understood  by  carefully  considering  the  direction  of  the  fibres  of  the 
muscles  of  this  organ.  The  Genio-hyo-glossi,  by  means  of  their  posterior  and 
inferior  fibres,  draw  upwards  the  hyoid  bone,  bringing  it  and  the  base  of  the  tongue 
forwards,  so  as  to  protrude  the  apex  from  the  mouth.  The  anterior  fibres  will 
restore  it  to  its  original  position  by  retracting  the  organ  within  the  mouth.  The 
whole  length  of  these  two  muscles  acting  along  the  middle  line  of  the  tongue 
will  draw  it  downwards,  so  as  to  make  it  concave  from  before  backwards,  forming 
a  channel  along  which  fluids  may  pass  towards  the  pharynx,  as  in  sucking.  The 
Hyo-glossi  muscles  draw  down  the  sides  of  the  tongue,  so  as  to  render  it  convex 
from  side  to  side.  The  Linguales,  by  drawing  downwards  the  centre  and  apex 
of  the  tongue,  render  it  convex  from  before  backwards.  The  Palato-glossi  draw 
the  base  of  the  tongue  upwards,  and  the  Stylo-glossi  upwards  and  backwards. 


5.  Phakyngeal  Kegion. 

Constrictor  Inferior.  Constrictor  Superior. 

Constrictor  Medius.  Stylo-pharyngeus. 

Palato-pharyngeus. 

Fig.  156. — Muscles  of  the  Pharynx.     External  View.  Dissection  (fig.  156).  In  order 

to  examine  the  muscles  of  the 
pharynx,  cut  through  the  trachea 
and  oesophagus  just  above  the 
sternum,  and  draw  them  upwards 
by  dividing  the  loose  areolar  tis- 
sue connecting  the  pharynx  with 
the  front  of  the  vertebral  column. 
The  parts  being  drawn  well  for- 
wards, the  edge  of  the  saw  should 
be  applied  immediately  behind 
the  styloid  processes,  and  the 
base  of  the  skull  sawn  through 
from  below  upwards.  The 
pharynx  and  mouth  should  then 
be  stuffed  with  tow,  in  order  to 
distend  its  cavity  and  render  the 
muscles  tense  and  easier  of  dis- 
section. 

The  Inferior  Constrictor, 
the  most  superficial  and 
thickest  of  the  three  con- 
strictors, arises  from  the 
side  of  the  cricoid  and  thy- 
roid cartilages.  To  the 
cricoid  cartilage  it  is  at- 
tached in  the  interval  be- 
tween the  Crico-thyroid,  in 
front,  and  the  articular  facet 
for  the  thyroid  cartilage  be- 
hind. To  the  thyroid  car- 
tilage, it  is  attached  to  the  oblique  line  on  the  side  of  the  great  ala,  the  carti- 


PHARYNGEAL   REGION".  2C3 

laginous  surface  behind  it,  nearly  as  far  as  its  posterior  border,  and  to  the 
inferior  cornu.  From  these  attachments,  the  fibres  spread  backwards  and 
inwards,  to  be  inserted  into  the  fibrous  raphe  in  the  posterior  median  line  of  the 
pharynx.  The  inferior  fibres  are  horizontal,  and  continuous  with  the  fibres  of 
the  oesophagus ;  the  rest  ascend,  increasing  in  obliquity,  and  overlap  the  Middle 
constrictor.  The  superior  laryngeal  nerve  passes  near  the  upper  border,  and  the 
inferior  or  recurrent  laryngeal  beneath  the  lower  border  of  this  muscle,  previous 
to  their  entering  the  larynx. 

Relations.  It  is  covered  by  a  dense  cellular  membrane  which  surrounds  the 
entire  pharynx.  Behind,  it  lies  on  the  vertebral  column  and  the  Longus  colli. 
Laterally,  it  is  in  relation  with  the  thyroid  gland,  the  common  carotid  artery,  and 
the  Sterno-thyroid  muscle.  By  its  internal  surface,  with  the  Middle  constrictor, 
the  Stylo-pharyngeus,  Palato-pharyngeus,  and  the  mucous  membrane  of  the 
pharynx. 

The  Middle  Constrictor  is  a  flattened,  fan-shaped  muscle,  smaller  than  the  pre- 
ceding, and  situated  on  a  plane  anterior  to  it.  It  arises  from  the  whole  length  of 
•the  greater  cornu  of  the  hyoid  bone,  from  the  lesser  cornu,  and  from  the  stylo- 
hyoid ligament.  The  fibres  diverge  from  their  origin ;  the  lower  ones  descending 
beneath  the  Inferior  constrictor,  the  middle  fibres  passing  transversely,  and  the 
upper  fibres  ascending  to  cover  in  the  Superior  constrictor.  It  is  inserted  into 
the  posterior  median  fibrous  raphe,  blending  in  the  middle  line  with  the  fibres  of 
the  opposite  muscle. 

Relations.  This  muscle  is  separated  from  the  Superior  constrictor  by  the  glosso- 
pharyngeal nerve  and  the  Stylo-pharyngeus  muscle ;  and  from  the  Inferior  con- 
strictor, by  the  superior  laryngeal  nerve.  Behind,  it  lies  on  the  vertebral  column, 
the  Longus  colli,  and  the  Rectus  anticus  major.  On  each  side  it  is  in  relation 
with  the  carotid  vessels,  the  pharyngeal  plexus,  and  some  lymphatic  glands.  Near 
its  origin,  it  is  covered  by  the  Hyo-glossus,  from  which  it  is  separated  by  the 
lingual  artery.  It  covers  in  the  Superior  constrictor,  the  Stylo-pharyngeus,  the 
Palato-pharyngeus,  and  the  mucous  membrane. 

The  Superior  Constrictor  is  a  quadrilateral  muscle,  thinner  and  paler  than  the 
other  constrictors,  and  situated  at  the  upper  part  of  the  pharynx.  It  arises  from 
the  lower  third  of  the  margin  of  the  internal  pterygoid  plate  and  its  hamular 
process,  from  the  contiguous  portion  of  the  palate  bone  and  the  reflected  tendon  of 
the  Tensor  palati  muscle,  from  the  ptery go-maxillary  ligament,  from  the  alveolar 
process  above  the  posterior  extremity  of  the  mylo-hyoid  ridge,  and  by  a  few  fibres 
from  the  side  of  the  tongue  in  connection  with  the  Genio-hyo-glossus.  From  these 
points,  the  fibres  curve  backwards,  to  be  inserted  into  the  median  raphe,  being 
also  prolonged  by  means  of  a  fibrous  aponeurosis  to  the  pharyngeal  spine  on  the 
basilar  process  of  the  occipital  bone.  Its  superior  fibres  arch  beneath  the  Levator 
palati  and  the  Eustachian  tube,  the  interval  between  the  upper  border  of  the 
muscle  and  the  basilar  process  being  deficient  in  muscular  fibres,  and  closed  by 
fibrous  membrane. 

Relations.  By  its  outer  surface,  with  the  vertebral  column,  the  carotid  vessels, 
the  internal  jugular  vein,  the  three  divisions  of  the  eighth  and  ninth  nerves,  the 
Middle  constrictor  whioh  overlaps  it,  and  the  Stylo-pharyngeus.  It  covers  the 
Palato-pharyngeus  and  the  tonsil,  and  is  lined  by  mucous  membrane. 

The  Stylo-pharyngeus  is  a  long,  slender  muscle,  round  above,  broad  and  thin 
below.  It  arises  from  the  inner  side  of  the  base  of  the  styloid  process,  passes 
downwards  along  the  side  of  the  pharynx  between  the  Superior  and  Middle  con- 
strictors, and,  spreading  out  beneath  the  mucous  membrane,  some  of  its  fibres  are 
lost  in  the  Constrictor  muscles,  and  others,  joining  with  the  Palato-pharyngeus, 
are  inserted  into  the  upper  border  of  the  thyroid  cartilage.  The  glossopharyngeal 
nerve  runs  on  the  outer  side  of  this  muscle,  and  crosses  over  it  in  passing  forward 
to  the  tongue. 

Relations.  Externally,  with  the  Stylo-glossus  muscle,  the  external  carotid 
artery,  the  parotid  gland,  and  the  Middie  constrictor.    Internally,  with  the  internal 


264 


MUSCLES   AND   FASCIAE. 


carotid,  the  internal  jugular  vein,  the  Superior  constrictor,  Palato-pharyngeus  and 
mucous  membrane. 

Nerves.  The  muscles  of  this  group  are  supplied  by  branches  from  the  pharyn- 
geal plexus  and  glosso-pharyngeal  nerve ;  and  the  Inferior  constrictor,  by  an  addi- 
tional branch  from  the  external  laryngeal  nerve. 

Actions.  When  deglutition  is  about  to  be  performed,  the  pharynx  is  drawn 
upwards  and  dilated  in  different  directions,  to  receive  the  morsel  propelled  into  it 
from  the  mouth.  The  Stylo-pharyngei,  which  are  much  farther  removed  from 
one  another  at  their  origin  than  at  their  insertion,  draw  upwards  and  outwards 
the  sides  of  this  cavity,  the  breadth  of  the  pharynx  in  the  antero-posterior  direction 
being  increased  by  the  larynx  and  tongue  being  carried  forwards  in  their  ascent. 
As  soon  as  the  morsel  is  received  in  the  pharynx,  the  elevator  muscles  relax,  the 
bag  descends,  and  the  Constrictors  contract  upon  the  morsel,  and  convey  it  gradually 
downwards  into  the  oesophagus.  The  pharynx  also  exerts  an  important  influence 
in  the  modulation  of  the  voice,  especially  in  the  production  of  the  higher  tones. 

6.  Palatal  Eegiox. 

Azygos  Uvulae. 


Palato-glossus. 


Levator  Palati. 
Tensor  Palati. 

Palato-pharyngeus. 

Dissection  (fig.  157).  Lay  open  the  pharynx  from  behind,  by  a  vertical  incision  extending 
from  its  upper  to  its  lower  part,  and  partially  divide  the  occipital  attachment  by  a  transverse 
incision  on  each  side  of  the  vertical  one ;  the  posterior  surface  of  the  soft  palate  is  then  exposed. 
Having  fixed  the  uvula  so  as  to  make  it  tense,  the  mucous  membrane  and  glands  should  be  care- 
fully removed  from  the  posterior  surface  of  the  soft  palate,  and  the  muscles  of  this  part  are  at 
once  exposed. 

Fig.  157. — Muscles  of  the  Soft  Palate  ;  the  Pharynx  being  laid  open  from  behiud. 


PALATAL   REGION".  265 

The  Levator  Palati  is  a  long,  thick,  rounded  muscle,  placed  on  the  outer  side 
of  the  posterior  aperture  of  the  nares.  It  arises  from  the  under  surface  of  the 
apex  of  the  petrous  portion  of  the  temporal  bone,  and  from  the  adjoining  carti- 
laginous portion  of  the  Eustachian  tube,  and  after  passing  into  the  pharynx,  above 
the  upper  concave  margin  of  the  Superior  constrictor,  it  descends  obliquely 
downwards  and  inwards,  its  fibres  spreading  out  in  the  posterior  surface  of  the 
soft  palate  as  far  as  the  middle  line,  where  they  blend  with  those  of  the  opposite 
side. 

Relations.  Externally,  with  the  Tensor  palati  and  Superior  constrictor.  Inter- 
nally, it  is  lined  by  the  mucous  membrane  of  the  pharynx.  Posteriorly,  with  the 
mucous  lining  of  the  soft  palate.  This  muscle  must  be  removed  and  the  pterygoid 
attachment  of  the  Superior  constrictor  dissected  away,  in  order  to  expose  the  next 
muscle. 

The  Circumflexus  or  Tensor  Palati  is  a  broad,  thin,  riband-like  muscle,  placed 
on  the  outer  side  of  the  preceding,  and  consisting  of  a  vertical  and  a  horizontal 
portion.  The  vertical  portion  arises  by  a  broad,  thin,  and  fiat  lamella  from  the 
scaphoid  fossa  at  the  base  of  the  internal  pterygoid  plate,  its  origin  extending  as 
far  back  as  the  spine  of  the  sphenoid ;  it  also  arises  from  the  anterior  aspect  of 
the  cartilaginous  portion  of  the  Eustachian  tube ;  descending  vertically  between 
the  internal  pterygoid  plate  and  the  inner  surface  of  the  Internal  pterygoid  muscle, 
it  terminates  in  a  tendon  which  winds  round  the  hamular  process,  being  retained 
in  this  situation  by  a  tendon  of  origin  of  the  Internal  pterygoid  muscle,  and 
lubricated  by  a  bursa.  The  tendon  or  horizontal  portion  then  passes  horizontally 
inwards,  and  expands  into  a  broad  aponeurosis  on  the  anterior  surface  of  the  soft 
palate,  which  unites  in  the  median  line  with  the  aponeurosis  of  the  opposite 
muscle,  the  fibres  being  attached  in  front  to  the  transverse  ridge  on  the  posterior 
border  of  the  horizontal  portion  of  the  palate  bone. 

Relations.  Externally,  with  the  Internal  pterygoid.  Internally,  with  the  Levator 
palati,  from  which  it  is  separated  by  the  Superior  constrictor,  and  the  internal 
pterygoid  plate.  In  the  soft  palate  its  aponeurotic  expansion  is  anterior  to  that 
of  the  Levator  palati,  being  covered  by  mucous  membrane. 

The  Azygos  Uvulse  is  not  a  single  muscle  as  implied  by  its  name,  but  a  pair  of 
narrow  cylindrical  fleshy  fasciculi,  placed  side  by  side  in  the  median  line  of  the 
soft  palate.  Each  muscle  arises  from  the  posterior  nasal  spine  of  the  palate  bone, 
and  from  the  contiguous  tendinous  aponeurosis  of  the  soft  palate,  and  descends  to 
be  inserted  into  the  uvula. 

Relations.  Anteriorly,  with  the  tendinous  expansion  of  the  Levatores  palati ; 
behind,  with  the  mucous  membrane. 

The  two  next  muscles  are  exposed  by  removing  the  mucous  membrane  which  covers  the  pillars 
of  the  soft  palate  throughout  nearly  their  whole  extent. 

The  Palato-glossus  or  Constrictor  Isthmi  Faucium  is  a  small  fleshy  fasciculus, 
narrower  in  the  middle  than  at  either  extremity,  forming,  with  the  mucous  mem- 
brane covering  its  surface,  the  anterior  pillar  of  the  soft  palate.  It  arises  from 
the  anterior  surface  of  the  soft  palate  on  each  side  of  the  uvula,  and,  passing 
forwards  and  outwards  in  front  of  the  tonsil,  is  inserted  into  the  side  and  dorsum 
of  the  tongue,  where  it  blends  with  the  fibres  of  the  Stylo-glossus  muscle.  In  the 
soft  palate,  the  fibres  of  this  muscle  are  continuous  with  those  of  the  opposite  side, 

The  Palato-pharyngeus  is  a  long  fleshy  fasciculus,  narrower  in  the  middle 
than  at  either  extremity,  forming,  with  the  mucous  membrane  covering  its  surface, 
the  posterior  pillar  of  the  soft  palate.  It  is  separated  from  the  preceding  by  an 
angular  interval,  in  which  the  tonsil  is  lodged.  It  arises  from  the  soft  palate  by 
an  expanded  fasciculus,  which  is  divided  into  two  parts  by  the  Levator  palati. 
The  anterior  fasciculus,  the  thickest,  enters  the  soft  palate  between  the  Levator 
palati  and  Tensor  palati,  and  joins  in  the  middle  line  the  corresponding  part  of 
the  opposite  muscle;  the  posterior  fasciculus  lies  in  contact  with  the  mucous  mem- 
brane, and  also  joins  with  the  corresponding  muscle  in  the  middle  line.     Passing 


266  MUSCLES   AND   FASCIAE. 

outwards  and  downwards  behind  the  tonsil,  it  joins  the  Stylo-pharyngeus,  and  is 
inserted  with  it  into  the  posterior  border  of  the  thyroid  cartilage,  some  of  its 
fibres  being  lost  on  the  side  of  the  pharynx,  and  others  passing  across  the  middle 
line  posteriorly,  to  decussate  with  the  muscle  of  the  opposite  side. 

Relations.  In  the  soft  palate,  its  anterior  and  posterior  surfaces  are  covered  by 
mucous  membrane,  from  which  it  is  separated  by  a  layer  of  palatine  glands.  By 
its  superior  border,  it  is  in  relation  with  the  Levator  palati.  Where  it  forms  the 
posterior  pillar  of  the  fauces,  it  is  covered  by  mucous  membrane,  excepting  on  its 
outer  surface.  In  the  pharynx,  it  lies  between  the  mucous  membrane  and  the 
Constrictor  muscles. 

Nerves.  The  Tensor  palati  is  supplied  by  a  branch  from  the  otic  ganglion;  the 
Levator  palati,  and  Azygos  uvulre,  by  the  facial,  through  the  connection  of  its 
trunk,  with  the  Vidian,  by  the  petrosal  nerves ;  the  other  muscles,  by  the  palatine 
branches  of  Meckel's  ganglion. 

Actions.  During  ike  first  act  of  deglutition,  the  morsel  of  food  is  driven  back 
into  the  fauces  by  the  pressure  of  the  tongue  against  the  hard  palate,  the  base  of 
the  tongue  being,  at  the  same  time,  retracted,  and  the  larynx  raised  with  the 
pharynx,  and  carried  forwards  under  it ;  the  epiglottis  is  pressed  over  the  superior 
aperture  of  the  larynx,  and  the  morsel  glides  past  it.  This  constitutes  the  second 
act  of  deglutition ;  then  the  Palato-glossi  muscles,  the  constrictors  of  the  fauces, 
contract  behind  it ;  the  soft  palate  is  slightly  raised  by  the  Levator  palati,  and 
made  tense  by  the  Tensor  palati ;  and  the  Palato-pharyngei  contract,  and  come 
nearly  together,  the  uvula  filling  up  the  slight  interval  between  them.  By  these 
means,  the  food  is  prevented  passing  into  the  upper  part  of  the  pharynx  or  the 
posterior  nares;  at  the  same  time,  the  latter  muscles  form  an  inclined  plane, 
directed  obliquely  downwards  and  backwards,  along  which  the  morsel  descends 
into  the  lower  part  of  the  pharynx. 

Surgical  Anatomy.  The  muscles  of  the  soft  palate  should  be  carefully  dissected,  the  relations 
thej-  bear  to  the  surrounding  parts  especially  examined,  and  their  action  attentively  studied  upon 
the  dead  subject,  as  the  surgeon  is  required  to  divide  one  or  more  of  these  muscles  in  the  opera- 
tion of  staphyloraphy.  Mr.  Fergusson  has  shown,  that  in  the  congenital  deficiency,  called  cleft 
palate,  the  edges  of  the  fissure  are  forcibly  separated  by  the  action  of  the  Levatores  palati  and 
Palato-pharyngei  muscles,  producing  very  considerable  impediment  to  the  healing  process  after 
the  performance  of  the  operation  for  uniting  their  margins  by  adhesion;  he  has,  consequently, 
recommended  the  division  of  these  muscles  as  one  of  the  most  important  steps  in  the  operation : 
by  these  means,  the  flaps  are  relaxed,  lie  perfectly  loose  and  pendulous,  and  are  easily  brought 
and  retained  in  apposition.  The  Palato-pharyngei  may  be  divided  by  cutting  across  the  poste- 
rior pillar  of  the  soft  palate,  just  below  the  tonsil,  with  a  pair  of  blunt-pointed  curved  scissors ; 
and  the  anterior  pillar  may  be  divided  also.  To  divide  the  Levator  palati,  the  plan  recommended 
by  Mr.  Pollock  is  to  be  greatly  preferred.  The  flap  being  put  upon  the  stretch,  a  double-edged 
knife  is  passed  through  the  soft  palate,  just  on  the  inner  side  of  the  hamular  process,  and  above 
the  line  of  the  Levator  palati.  The  handle  being  now  alternately  raised  and  depressed,  a  sweep- 
ing cut  is  made  along  the  posterior  surface  of  the  soft  palate,  and  the  knife  withdrawn,  leaving 
only  a  small  opening  in  the  mucous  membrane  on  the  anterior  surface.  If  this  operation  is  per- 
formed on  the  dead  body,  and  the  parts  afterwards  dissected,  the  Levator  palati  will  be  found 
completely  divided. 

7.  Anterior  Vertebral  Eegion. 

Eectus  Capitis  Anticus  Major.  Eectus  Lateralis. 

Eectus  Capitis  Anticus  Minor.  Longus  Colli. 

The  Rectus  Capitis  Anticus  Major  (fig.  158),  broad  and  thick  above,  narrow 
beiow,  appears  like  a  continuation  upwards  of  the  Scalenus  anticus.  It  arises  by 
four  tendinous  slips  from  the  anterior  tubercles  of  the  transverse  processes  of  the 
third,  fourth,  fifth,  and  sixth  cervical  vertebrae,  and  ascends,  converging  towards 
its  fellow  of  the  opposite  side,  to  be  inserted  into  the  basilar  process  of  the  occi- 
pital bone. 

Relations.  By  its  anterior  surface,  with  the  pharynx,  the  sympathetic  nerve, 
and  the  sheath  inclosing  the  carotid  artery,  internal  jugular  vein,  and  pneumo- 


ANTERIOR  VERTEBRAL  REGION. 


2CT 


gastric  nerve.  By  its  posterior  surface,  with  the  Longus  colli,  the  Rectus  anticus 
minor,  and  the  upper  cervical  vertebrse. 

The  Rectus  Capitis  Anticus  Minor  is  a  short  flat  muscle,  situated  immediately 
beneath  the  upper  part  of  the  preceding.  It  arises  from  the  anterior  surface  of 
the  lateral  mass  of  the  atlas,  and  from  the  root  of  its  transverse  process ;  passing 
obliquely  upwards  and  inwards,  it  is  inserted  into  the  basilar  process  immediately 
behind  the  preceding  muscle. 

Relations.  By  its  anterior  surface,  with  the  Rectus  anticus  major.  By  its 
posterior  surface,  with  the  front  of  the  occipito-atlantal  articulation.  Externally, 
with  the  superior  cervical  ganglion  of  the  sympathetic. 

The  Rectus  Lateralis  is  a  short,  flat  muscle,  situated  between  the  transverse 
process  of  the  atlas  and  the  jugular  process  of  the  occipital  bone.  It  arises  from 
the  upper  surface  of  the  transverse  process  of  the  atlas,  and  is  inserted  into  the 
under  surface  of  the  jugular  process  of  the  occipital  bone. 

Relations.  By  its  anterior  surface,  with  the  internal  jugular  vein.  By  its 
posterior  surface,  with  the  vertebral  artery. 

Fig.  158. — The  Pre-vertebral  Muscles. 


The  Longus  Colli  is  a  long,  flat  muscle,  situated  on  the  anterior  surface  of  the 
spine,  between  the  atlas  and  the  third  dorsal  vertebra,  being  broad  in  the  middle, 
narrow  and  pointed  at  each  extremity.  It  consists  of  three  portions,  a  superior 
oblique,  an  inferior  oblique,  and  a  vertical  portion. 

The  superior  oblique  portion  arises  from  the  anterior  tubercles  of  the  transverse 
processes  of  the  third,  fourth,  and  fifth  cervical  vertebrae ;  and,  ascending  obliquely 
inwards,  is  inserted  by  a  narrow  tendon  into  the  tubercle  on  the  anterior  arch  of 
the  atlas. 

The  inferior  oblique  portion,  the  smallest  part  of  the  muscle,  arises  from  the 


268  MUSCLES   AND   FASCIAE. 

bodies  of  the  first  two  or  three  dorsal  vertebrae ;  and,  passing  obliquely  outwards, 
is  inserted  into  the  transverse  processes  of  the  fifth  and  sixth  cervical  vertebras. 

The  vertical  portion  lies  directly  on  the  front  of  the  spine,  and  is  extended 
between  the  bodies  of  the  lower  three  cervical  and  the  upper  three  dorsal  vertebras 
below,  and  the  bodies  of  the  second,  third,  and  fourth  cervical  vertebras  above. 

Relations.  By  its  anterior  surface,  with  the  pharynx,  the  oesophagus,  sympathetic 
nerve,  the  sheath  of  the  carotid  artery,  internal  jugular  vein,  and  pneumogastric 
nerve,  inferior  thyroid  artery,  and  recurrent  laryngeal  nerve.  By  its  posterior 
surface,  with  the  cervical  and  dorsal  portions  of  the  spine.  Its  inner  border  is 
separated  from  the  opposite  muscle  by  a  considerable  interval  below ;  but  they 
approach  each  other  above. 

8.  Lateral  Vertebral  Eegion. 

Scalenus  Anticus.  Scalenus  Medius. 

Scalenus  Posticus. 

The  Scalenus  Antims  is  a  conical-shaped  muscle,  situated  deeply  at  the  side  of 
the  neck,  behind  the  Sterno-mastoid.  It  arises  by  a  narrow,  flat  tendon  from  the 
tubercle  on  the  inner  border  and  upper  surface  of  the  first  rib ;  and,  ascending 
vertically  upwards,  is  inserted  into  the  anterior  tubercles  of  the  transverse  pro- 
cesses of  the  third,  fourth,  fifth,  and  sixth  cervical  vertebrae.  The  lower  part  of 
this  muscle  separates  the  subclavian  artery  and  vein ;  the  latter  being  in  front, 
and  the  former,  with  the  brachial  plexus,  behind. 

Relations.  It  is  covered  by  the  clavicle,  the  Subclavius,  Sterno-mastoid,  and 
Omo-hyoid  muscles,  the  transversalis  colli,  and  ascending  cervical  arteries,  the 
subclavian  vein,  and  the  phrenic  nerve.  By  its  posterior  surface,  with  the  pleura, 
the  subclavian  artery,  and  brachial  plexus  of  nerves.  It  is  separated  from  the 
Longus  colli,  on  the  inner  side,  by  the  subclavian  artery. 

The  Scalenus  Medius,  the  largest  and  longest  of  the  three  Scaleni,  arises,  by 
a  broad  origin,  from  the  upper  surface  of  the  first  rib,  behind  the  groove  for  the 
subclavian  artery,  as  far  back  as  the  tubercle ;  and,  ascending  along  the  side  of 
the  vertebral  column,  is  inserted,  by  separate  tendinous  slips,  into  the  posterior 
tubercles  of  the  transverse  processes  of  the  lower  six  cervical  vertebrae.  It  is 
separated  from  the  Scalenus  anticus  by  the  subclavian  artery  below,  and  the 
cervical  nerves  above. 

Relations.  By  its  external  surface,  with  the  Sterno-mastoid ;  it  is  crossed  by 
the  clavicle,  and  Omo-hyoid  muscle.  To  its  outer  side,  are  the  Levator  anguli 
scapulae,  and  the  Scalenus  posticus  muscles. 

The  Scalenus  posticus,  the  smallest  of  the  three  Scaleni,  arises  by  a  thin  tendon 
from  the  outer  surface  of  the  second  rib,  behind  the  attachment  of  the  Serratus 
magnus,  and,  enlarging  as  it  ascends,  is  inserted,  by  two  or  three  separate  tendons, 
into  the  posterior  tubercles  of  the  transverse  processes  of  the  lower  two  or  three 
cervical  vertebrae.  This  is  the  most  deeply  placed  of  the  three  Scaleni,  and  is 
occasionally  blended  with  the  Scalenus  medius. 

Nerves.  The  Rectus  capitis  anticus  major  and  Rectus  capitis  anticus  minor  are 
supplied  by  the  suboccipital  and  deep  branches  of  the  cervical  plexus ;  the  Rectus 
lateralis,  by  the  suboccipital ;  and  the  Longus  colli  and  Scaleni,  by  branches  from 
the  lower  cervical  nerves. 

Actions.  The  Rectus  anticus  major  and  Rectus  anticus  minor  are  the  direct 
antagonists  of  those  placed  at  the  back  of  the  neck,  serving  to  restore  the  head  to 
its  natural  position  when  drawn  backwards  by  the  posterior  muscles.  These 
muscles  also  serve  to  flex  the  head,  and,  from  their  obliquity,  rotate  it,  so  as  to 
turn  the  face  to  one  or  the  other  side.  The  Longus  colli  will  flex  and  slightly 
rotate  the  cervical  portion  of  the  spine.  The  Scaleni  muscles,  taking  their  fixed 
point  from  below,  draw  down  the  transverse  processes  of  the  cervical  vertebrae, 
flexing  the  spinal  column  to  one  or  the  other  side.  If  the  muscles  of  both  sides 
act,  the  spine  will  be  kept  erect.  When  taking  their  fixed  point  from  above, 
they  elevate  the  first  and  second  ribs,  and  are,  therefore,  inspiratory  muscles. 


MUSCLES   OF   THE   BACK. 


MUSCLES  AND  FASCIAE  OF  THE  TEUNK. 

The  Muscles  of  the  Trunk  may  be  subdivided  into  four  groups  :— 

1.  Muscles  of  the  Back.  3.  Muscles  of  the  Thorax. 

2.  Muscles  of  the  Abdomen.  4.  Muscles  of  the  Perineum. 

Muscles  of  the  Back. 
The  Muscles  of  the  Back  are  very  numerous,  and  may  be  subdivided  into  five 
layers : — 


First  Layer. 


Cervical  region. 


Trapezius.  „ 

Latissimus  dorsi.  Cervicalis  ascendens. 

Transversahs  colli. 

Second  Layer.  Trachelo-mastoid. 

Levator  anguli  scapulae.  Complexus. 

Ehomboideus  minor.  Jiyenter  ^rvicis. 

Ehomboideus  major.  Spinalis  cervicis. 

Third  Layer. 

Serratus  posticus  superior.  Fifth  Layer. 

Serratus  posticus  inferior. 

Splenius  capitis.  Semi-spinalis  dorsi. 

Splenius  colli.  Semi-spinalis  colli. 

Fourth  Layer.  Multifidus  spina?. 

_,        7       7  7      7  .  Kotatores  spmse. 

sacral  and  lumbar  regions.  Supra-spinales 

Erector  spina?.  Inter-spinales. 

,_.        ,        .  Extensor  coccysris. 

Dorsal  region.  Intertransverses.  _ 

Sacro-lumbalis.  Eectus  posticus  major. 
Musculus  accessorius  ad  sacro-lumbalem.    Eectus  posticus  minor. 

Longissimus  dorsi.  Obliquus  superior. 

Spinalis  dorsi.  Obliquus  inferior. 

First  Layer. 

Trapezius.  Latissimus  Dorsi. 

Dissection  (fig.  159).  The  body  should  be  placed  in  the  prone  position,  with  the  arms  ex- 
tended over  the  sides  of  the  table,  and  the  chest  and  abdomen  supported  by  several  blocks,  so 
as  to  render  the  muscles  tense.  An  incision  should  then  be  made  along  the  middle  line  of  the 
back,  from  the  occipital  protuberance  to  the  coccyx.  From  the  upper  end  of  this,  a  transverse 
incision  should  extend  to  the  mastoid  process ;  and  from  the  lower  end,  a  third  incision  should 
be  made  along  the  crest  of  the  ilium  to  about  its  middle.  This  large  intervening  space,  for  con- 
venience of  dissection,  should  be  subdivided  by  a  fourth  incision,  extending  obliquely  from  the 
spinous  process  of  the  last  dorsal  vertebra,  upwards  and  outwards,  to  the  acromion  process. 
This  incision  corresponds  with  the  lower  border  of  the  Trapezius  muscle.  The  flaps  of  integu. 
ment  should  then  be  removed  in  the  direction  shown  in  the  figure  in  the  next  page. 

The  Trapezius  is  a  broad,  flat,  triangular  muscle,  placed  immediately  beneath 
the  skin,  and  covering  the  upper  and  back  part  of  the  neck  and  shoulders.  It 
arises  from  the  inner  third  of  the  superior  curved  line  of  the  occipital  bone ;  from  the 
ligamentum  nucha?,  the  spinous  process  of  the  seventh  cervical,  and  those  of  all  the 
dorsal  vertebra? ;  and  from  the  corresponding  portion  of  the  supra-spinous  ligament. 
From  this  origin,  the  superior  fibres  proceed  downwards  and  outwards ;  the  inferior 
ones,  upwards  and  outwards ;  and  the  middle  fibres,  horizontally  ;  and  are  inserted, 
the  superior  ones,  into  the  outer  third  of  the  posterior  border  of  the  clavicle ;  the 
middle  fibres,  into  the  upper  margin  of  the  acromion  process,  and  into  the  whole 


270 


MUSCLES   AND   FASCIAE. 


Fig.  159. — Dissection  of  the  Muscles  of  the  Back. 


length  of  the  upper  border  of  the  spine  of  the  scapula;  the  inferior  fibres  converge 
near  the  scapula,  and  are  attached  to  a  triangular  aponeurosis,  which  glides  over 

a  smooth  surface  at  the  inner  extremity  of 
the  spine,  and  is  inserted  into  a  tubercle 
in  immediate  connection  with  its  outer 
part.  The  Trapezius  is  fleshy  in  the 
greater  part  of  its  extent,  but  tendinous 
at  its  origin  and  insertion.  At  its  occipital 
origin,  it  is  connected  to  the  bone  by  a 
thin  fibrous  lamina,  firmly  adherent  to  the 
skin,  and  wanting  the  lustrous,  shining 
appearance  of  aponeurosis.  At  its  origin 
from  the  spines  of  the  vertebrae,  it  is 
connected  by  means  of  a  broad  semi- 
elliptical  aponeurosis,  which  occupies  the 
space  between  the  sixth  cervical  and  the 
third  dorsal  vertebras,  and  forms,  with 
the  aponeurosis  of  the  opposite  muscle,  a 
tendinous  ellipse.  The  remaining  part  of 
the  origin  is  effected  by  numerous  short 
tendinous  fibres.  If  the  Trapezius  is  dis- 
sected on  both  sides,  the  two  muscles 
resemble  a  trapezium,  or  diamond-shaped 
quadrangle ;  two  angles,  corresponding  to 
the  shoulders;  a  third,  to  the  occipital 
protuberance;  and  the  fourth,  to  the 
spinous  process  of  the  last  dorsal  ver- 
tebra. 

The  clavicular  insertion  of  this  muscle 

varies  as  to  the  extent  of  its  attachment; 

it  sometimes  advances  as  far  as  the  middle 

of  the  clavicle,  and  may  even  become  blended  with  the  posterior  edge  of  the 

Sterno-mastoid,  or  overlap  it.     This  should  be  borne  in  mind  in  the  operation  for 

tying  the  third  part  of  the  subclavian  artery. 

Relations.  By  its  superficial  surface,  with  the  integument  to  which  it  is  closely 
adherent  above,  but  separated  below  by  an  aponeurotic  lamina.  By  its  deep  sur- 
face, in  the  neck,  with  the  Complexus,  Splenius,  Levator  anguli  scapulas,  and 
Ehomboideus  minor ;  in  the  back,  with  the  Khomboideus  major,  Supra-spinatus, 
Infra-spinatus,  a  small  portion  of  the  Serratus  posticus  superior,  the  intervertebral 
aponeurosis  which  separates  it  from  the  Erector  spinas,  and  with  the  Latissimus 
dorsi.  The  spinal  accessory  nerve  passes  beneath  the  anterior  border  of  this 
muscle,  near  the  clavicle.  The  outer  margin  of  its  cervical  portion  forms  the 
posterior  boundary  of  the  posterior  triangle  of  the  neck,  the  other  boundaries 
being  the  Sterno-mastoid  in  front,  and  the  clavicle  below. 

The  ligamentum  nuchse  (fig.  160)  is  a  thin  band  of  condensed  cellulo-fibrous 
membrane,  placed  in  the  line  of  union  between  the  two  Trapezii  in  the  neck.  It 
extends  from  the  external  occipital  protuberance  to  the  spinous  process  of  the 
seventh  cervical  vertebra,  where  it  is  continuous  with  the  supra-spinous  ligament. 
From  its  anterior  surface  a  fibrous  slip  is  given  off  to  the  spinous  process  of 
each  of  the  cervical  vertebras,  excepting  the  atlas,  so  as  to  form  a  septum  between 
the  muscles  on  each  side  of  the  neck.  In  man,  it  is  merely  the  rudiment  of  an 
important  elastic  ligament,  which,  in  some  of  the  lower  animals,  serves  to  sustain 
the  weight  of  the  head. 

The  Latissimus  Dorsi  is  a  broad  flat  muscle,  which  covers  the  lumbar  and 
lower  half  of  the  dorsal  regions,  and  is  gradually  contracted  into  a  narrow  fasci- 
culus at  its  insertion  into  the  humerus.  It  arises  by  an  aponeurosis  from  the 
spinous  processes  of  the  sixth  inferior  dorsal,  from  those  of  the  lumbar  and  sacral 


OF   THE   BACK. 


271 


Fig.  160. — Muscles  of  the  Back.     On  the  Left  Side  is  exposed  the  First  Layer ; 
on  the  Right  Side,  the  Second  Layer  and  part  of  the  Third. 


2Y2  MUSCLES   AND   FASCIAE. 

vertebras,  and  from  the  supra-spinous  ligament.  Over  the  sacrum,  the  aponeurosis 
of  this  muscle  blends  with  the  tendon  of  the  Erector  spinas.  It  also  arises  from 
the  external  lip  of  the  crest  of  the  ilium,  behind  the  origin  of  the  External  oblique, 
and  by  fleshy  digitations  from  the  three  or  four  lower  ribs,  being  interposed 
between  similar  processes  of  the  External  oblique  muscle.  From  this  extensive 
origin  the  fibres  pass  in  different  directions,  the  upper  ones  horizontally,  the 
middle  ones  obliquely  upwards,  and  the  lower  ones  vertically  upwards,  so"  as  to 
converge  and  form  a  thick  fasciculus,  which  crosses  the  inferior  angle  of  the 
scapula,  and  occasionally  receives  a  few  fibres  from  it.  The  muscle  then  curves 
around  the  lower  border  of  the  Teres  major,  and  is  twisted  upon  itself,  so  that 
the  superior  fibres  become  at  first  posterior  and  then  inferior,  and  the  vertical 
fibres  at  first  anterior  and  then  superior.  It  then  terminates  in  a  short  quadri- 
lateral tendon,  about  three  inches  in  length,  which,  passing  in  front  of  the  tendon 
of  the  Teres  major,  is  inserted  into  the  bottom  of  the  bicipital  groove  of  the 
humerus,  above  the  insertion  of  the  tendon  of  the  Pectoralis  major.  The  lower 
border  of  the  tendon  of  this  muscle  is  united  with  that  of  the  Teres  major,  the 
surfaces  of  the  two  being  separated  by  a  bursa ;  another  bursa  is  sometimes  inter- 
posed between  the  muscle  and  the  inferior  angle  of  the  scapula. 

A  muscular  slip,  varying  from  3  to  4  inches  in  length,  and  from  |  to  f  of  an  inch  broad,  occa- 
sionally arises  from  the  upper  edge  of  the  Latissimus  dorsi,  about  the  middle  of  the  posterior 
fold  of  the  axilla,  and  crosses  the  axilla  in  front  of  the  axillary  vessels  and  nerves,  to  join  the 
under  surface  of  the  tendon  of  the  Pectoralis  major,  the  Ooraco-brachialis,  or  the  fascia  over  the 
Biceps.  The  position  of  this  abnormal  slip  is  a  point  of  interest  in  its  relation  to  the  axillary 
artery,  as  it  crosses  the  vessel  just  above  the  spot  usually  selected  for  the  application  of  a  liga- 
ture, and  may  mislead  the  surgeon  during  the  operation.  It  may  be  easily  recognized  by  the 
transverse  direction  of  its  fibres.  Dr.  Struthers  found  it  in  8  out  of  105  subjects,  occurring 
7  times  on  both  sides. 

Relations.  Its  superficial  surface  is  subcutaneous,  excepting  at  its  upper  part, 
where  it  is  covered  by  the  Trapezius.  By  its  deep  surface,  it  is  in  relation  with 
the  Erector  spinas,  the  Serratus  posticus  inferior,  lower  Intercostal  muscles  and 
ribs,  the  Serratus  magnus,  inferior  angle  of  the  scapula,  Rhomboideus  major, 
Infra-spinatus,  and  Teres  major.  Its  outer  margin  is  separated,  below,  from  the 
External  oblique,  by  a  smaller  triangular  interval;  and  another  triangular  interval 
exists  between  its  upper  border  and  the  margin  of  the  Trapezius,  in  which  the 
Intercostal  and  Rhomboideus  major  muscles  are  exposed. 

Nerves.  The  Trapezius  is  supplied  by  the  spinal  accessory  and  cervical  plexus; 
the  Latissimus  dorsi,  by  the  subscapular  nerves. 

Second  Layer. 

Levator  Anguli  Scapulas.  Rhomboideus  Minor. 

Rhomboideus  Major. 

Dissection.  The  Trapezius  must  be  removed  in  order  to  expose  the  next  layer ;  to  effect  this, 
the  muscle  must  be  detached  from  its  attachment  to  the  clavicle  and  spine  of  the  scapula,  and 
turned  back  towards  the  spine. 

The  Levator  Anguli  Scapulse  is  situated  at  the  back  part  and  side  of  the  neck. 
It  arises  by  four  tendinous  slips  from  the  posterior  tubercles  of  the  transverse 
processes  of  the  three  or  four  upper  cervical  vertebras ;  these  becoming  fleshy  are 
united  so  as  to  form  a  flat  muscle,  which,  passing  downwards  and  backwards,  is 
inserted  into  the  posterior  border  of  the  scapula,  between  the  superior  angle  and 
the  triangular  smooth  surface  at  the  root  of  the  spine. 

Relations.  By  its  superficial  surface,  with  the  integument,  Trapezius,  and 
Sterno-mastoid.  By  its  deep  surface,  with  the  Splenius  colli,  Transversalis  colli, 
Cervicalis  ascendens,  and  Serratus  posticus  superior,  and  with  the  transverse  cer. 
vical  and  posterior  scapular  arteries. 

The  Rhomboideus  Minor  arises  from  the  ligamentum  nuchas,  and  spinous  pro 
cesses  of  the  seventh  cervical  and  first  dorsal  vertebras.     Passing  downwards  and 


OF   THE   BACK.  273 

outwards,  it  is  inserted  into  the  margin  of  the  triangular  smooth  surface  at  the 
root  of  the  spine  of  the  scapula.  This  small  muscle  is  usually  separated  from  the 
Ehomboideus  major  by  a  slight  cellular  interval. 

The  Ehomboideus  Major  is  situated  immediately  below  the  preceding,  the  adja* 
cent  margins  of  the  two  being  occasionally  united.  It  arises  by  tendinous  fibres 
from  the  spinous  processes  of  the  four  or  five  upper  dorsal  vertebrae  and  the  supra- 
spinous ligament,  and  is  inserted  into  a  narrow,  tendinous  arch,  attached,  above,  to 
the  triangular  surface  near  the  spine ;  below,  to  the  inferior  angle,  the  arch  being 
connected  to  the  border  of  the  scapula  by  a  thin  membrane.  When  the  arch 
extends,  as  it  occasionally  does,  but  a  short  distance,  the  muscular  fibres  are 
inserted  into  the  scapula  itself. 

Relations.  By  their  superficial  surface,  with  the  integument,  and  Trapezius ; 
the  Ehomboideus  major,  with  the  Latissimus  dorsi.  By  their  deep  surface,  with 
the  Serratus  posticus  superior,  posterior  scapular  artery,  part  of  the  Erector  spinae, 
the  Intercostal  muscles  and  ribs. 

Nerves.  These  muscles  are  supplied  by  branches  from  the  fifth  cervical  nerve, 
and  additional  filaments  from  the  deep  branches  of  the  cervical  plexus  are  distrib- 
uted to  the  Levator  anguli  scapulae. 

Actions.  The  movements  effected  by  the  preceding  muscles  are  numerous,  as 
may  be  conceived  from  their  extensive  attachment.  If  the  head  is  fixed,  the  upper 
part  of  the  Trapezius  will  elevate  the  point  of  the  shoulder,  as  in  supporting 
weights ;  when  the  middle  and  lower  fibres  are  brought  into  action,  partial  rotation 
of  the  scapula  upon  the  side  of  the  chest  is  produced.  If  the  shoulders  are  fixed, 
both  Trapezii  acting  together  will  draw  the  head  directly  backwards,  or,  if  only 
one  acts,  the  head  is  drawn  to  the  corresponding  side. 

The  Latissimus  dorsi,  when  it  acts  upon  the  humerus,  draws  it  backwards  and 
downwards,  and  at  the  same  time  rotates  it  inwards.  If  the  arm  is  fixed,  the 
muscle  may  act  in  various  ways  upon  the  trunk ;  thus,  it  may  raise  the  lower  ribs 
and  assist  in  forcible  inspiration,  or,  if  both  arms  are  fixed,  the  two  muscles  may 
conspire  with  the  Abdominal  and  great  Pectoral  muscles  in  drawing  the  whole 
trunk  forwards,  as  in  climbing  or  walking  on  crutches. 

The  Levator  anguli  scapulae  raises  the  superior  angle  of  the  scapula  after  it  has 
been  depressed  by  the  lower  fibres  of  the  Trapezius,  whilst  the  Ehomboid  muscles 
carry  the  inferior  angle  backwards  and  upwards,  thus  producing  a  slight  rotation 
of  the  scapula  upon  the  side  of  the  chest.  If  the  shoulder  be  fixed,  the  Levator 
scapulae  may  incline  the  neck  to  the  corresponding  side.  The  Ehomboid  muscles, 
acting  together  with  the  middle  and  inferior  fibres  of  the  Trapezius,  will  draw  the 
scapula  directly  backwards  towards  the  spine. 

Third  Layer. 

Serratus  Posticus  Superior.  Serratus  Posticus  Inferior. 

c  i     •  (  Splenius  Capitis. 

Splenius      <  Qri     •      n  fr 
^  (  Splenius  Colli. 

Dissection.  The  third  layer  of  muscles  is  brought  into  view  by  the  entire  removal  of  the  pre. 
ceding,  together  with  the  Latissimus  dorsi.  To  effect  this,  the  Levator  anguli  scapulas  and 
Rhomboid  muscles  should  be  detached  near  their  insertion,  and  reflected  upwards,  thus  exposing 
the  Serratus  posticus  superior  ;  the  Latissimus  dorsi  should  then  be  divided  in  the  middle  by  a 
vertical  incision  carried  from  its  upper  to  its  lower  part,  and  the  two  halves  of  the  muscle  reflected. 

The  Serratus  Posticus  Superior  is  a  thin,  flat  muscle,  quadrilateral  in  form, 
situated  at  the  upper  and  back  part  of  the  thorax.  It  arises  by  a  thin  and  broad 
aponeurosis,  from  the  ligamentum  nuchae  and  from  the  spinous  processes  of  the 
last  cervical  and  two  or  three  upper  dorsal  vertebrae.  Inclining  downwards  and 
outwards,  it  becomes  muscular,  and  is  inserted,  by  four  fleshy  digitations,  into 
the  upper  borders  of  the  second,  third,  fourth,  and  fifth  ribs,  a  little  beyond  their 
angles. 

18 


2U  MUSCLES   AND   FASCIAE. 

Relations.  By  its  superficial  surface,  with  the  Trapezius,  Rhomboidei,  and 
Serratus  magnus.  By  its  deep  surface,  with  the  Splenius,  upper  part  of  the 
Erector  spinas,  Intercostal  muscles  and  ribs. 

The  Serratus  Posticus  Inferior  is  situated  opposite  the  junction  of  the  dorsal 
and  lumbar  regions,  is  of  an  irregularly  quadrilateral  form,  broader  than  the  pre- 
ceding, and  separated  from  it  by  a  considerable  interval.  It  arises  by  a  thin 
aponeurosis  from  the  spinous  processes  of  the  last  two  dorsal  and  two  or  three 
upper  lumbar  vertebrae,  and  from  the  interspinous  ligaments.  Passing  obliquely 
upwards  and  outwards,  it  becomes  fleshy,  and  divides  into  four  flat  digitations, 
which  are  inserted  into  the  lower  borders  of.  the  four  lower  ribs,  a  little  beyond 
their  angles. 

Relations.  By  its  superficial  surface,  it  is  covered  by  the  Latissimus  dorsi,  with 
the  aponeurosis  of  which  its  own  aponeurotic  origin  is  inseparably  blended.  By 
its  deep  surface,  with  the  posterior  aponeurosis  of  the  Transversalis,  the  Erector 
spinas,  ribs  and  Intercostal  muscles.  Its  upper  margin  is  continuous  with  the 
vertebral  aponeurosis. 

The  vertebral  ajjoneurosis  is  a  thin  aponeurotic  lamina,  extending  along  the 
whole  length  of  the  back  part  of  the  thoracic  region,  serving  to  bind  down  the 
Erector  spinas,  and  separating  it  from  those  muscles  which  connect  the  spine  to 
the  upper  extremity.  It  consists  of  longitudinal  and  transverse  fibres  blended 
together,  forming  a  thin  lamella,  which  is  attached  in  the  median  line  to  the 
spinous  processes  of  the  dorsal  vertebras  ;  externally,  to  the  angles  of  the  ribs ;  and 
below,  to  the  upper  border  of  the  Inferior  serratus  and  tendon  of  the  Latissimus 
dorsi ;  above,  it  passes  beneath  the  Splenius,  and  blends  with  the  deep  fascia  of 
the  neck. 

The  Serratus  posticus  superior  should  now  be  detached  from  its  origin  and  turned  outwards, 
when  the  Splenius  muscle  will  be  brought  into  view. 

The  Splenius  is  situated  at  the  back  of  the  neck  and  upper  part  of  the  dorsal 
region.  At  its  origin,  it  is  a  single  muscle,  narrow  and  pointed  in  form ;  but  it 
soon  becomes  broader,  and  divides  into  two  portions,  which  have  separate  inser- 
tions. It  arises,  by  tendinous  fibres,  from  the  lower  half  of  the  ligamentum 
nuchas,  from  the  spinous  processes  of  the  last  cervical  and  of  the  six  upper  dorsal 
vertebras,  and  from  the  supra-spinous  ligament.  From  this  origin,  the  fleshy 
fibres  proceed  obliquely  upwards  and  outwards,  forming  a  broad  flat  muscle,  which 
divides  as  it  ascends  into  two  portions,  the  Splenius  capitis  and  Splenius  colli. 

The  splenius  capitis  is  inserted  into  the  mastoid  process  of  the  temporal  bone,  and 
into  the  rough  surface  on  the  occipital  bone  beneath  the  superior  curved  line. 

The  splenius  colli  is  inserted,  by  tendinous  fasciculi,  into  the  posterior  tubercles 
of  the  transverse  processes  of  the  three  or  four  upper  cervical  vertebras. 

The  Splenius  is  separated  from  its  fellow  of  the  opposite  side  by  a  triangular 
interval,  in  which  is  seen  the  Complexus. 

Relations.  By  its  superficial  surface,  with  the  Trapezius,  from  which  it  is  sepa- 
rated below  by  the  Rhomboidei  and  the  Serratus  posticus  superior.  It  is  covered 
at  its  insertion  by  the  Sterno-mastoid.  By  its  deep  surface,  with  the  Spinalis 
dorsi,  Longissimus  dorsi,  Semi-spinalis  colli,  Complexus,  Trachelo-mastoid,  and 
Transversalis  colli. 

Nerves.  The  Splenius  and  Superior  serratus  are  supplied  from  the  externnl 
posterior  branches  of  the  cervical  nerves;  the  Inferior  serratus,  from  the  external 
branches  of  the  dorsal  nerves. 

Actions.  The  Serrati  are  respiratory  muscles  acting  in  antagonism  to  each 
other.  The  Serratus  posticus  superior  elevates  the  ribs  and  is,  therefore,  an  inspi- 
ratory muscle;  while  the  Serratus  inferior  draws  the  lower  ribs  downwards,  and 
is  a  muscle  of  expiration.  This  muscle  is  also  probably  a  tensor  of  the  vertebral 
aponeurosis.  The  Splenii  muscles  of  the  two  sides,  acting  together,  draw  the 
head  directly  backwards,  assisting  the  Trapezius  and  Complexus ;  acting  sepa- 
rately, they  draw  the  head  to  one  or  the  other  side,  and  slightly  rotate  it,  turning 


OF   THE   BACK. 


275 


the  face  to  the  same  side.     They  also  assist  in  supporting  the  head  in  the  erect 
position. 

Fig.  161. — Muscles  of  the  Back.     Deep  Layers. 


:  tit  I      i 


MULTiriDUS    SPINA 


if*  Dorsal 


'   HjZumbar 


ffSacralX. 


£76  MUSCLES   AND   FASCIA. 


Foukth  Layer. 
Sacral  and  Lumbar  Regions.  Cervical  Region. 

Erector  spinae.  Cervicalis  ascendens. 

Dorsal  Region.  Transversalis  colli. 

Sacro-lumbalis.  Trachelo-mastoid. 

Musculus  accessorius  ad  sacro-lumbalem.  Complexus. 

Longissimus  dorsi.  Biventer  cervicis. 

Spinalis  dorsi.  Spinalis  cervicis. 

Dissection.  To  expose  the  muscles  of  the  fourth  layer,  the  Serrati  and  vertebral  aponeurosis 
should  be  entirely  removed.  The  Splenius  may  then  be  detached  by  separating  its  attachments 
to  the  spinous  processes,  and  reflecting  it  outwards. 

The  Erector  Spinse  (fig.  161),  and  its  prolongations  in  the  dorsal  and  cervical 
regions,  fill  up  the  vertebral  groove  on  each  side  of  the  spine.  It  is  covered  in 
the  lumbar  region  by  the  lumbar  aponeurosis;  in  the  dorsal  region,  by  the  Serrati 
muscles  and  the  vertebral  aponeurosis ;  and  in  the  cervical  region,  by  a  layer  of 
cervical  fascia  continued  beneath  the  Trapezius.  This  large  muscular  and  tendinous 
mass  varies  in  size  and  structure  at  different  parts  of  the  spine.  In  the  sacral 
region,  the  Erector  spinae  is  narrow  and  pointed,  and  its  origin  chiefly  tendinous 
in  structure.  In  the  lumbar  region,  it  becomes  enlarged,  and  forms  a  large  fleshy 
mass.  In  the  dorsal  region,  it  subdivides  into  two  parts,  which  gradually 
diminish  in  size  as  they  ascend  to  be  inserted  into  the  vertebras  and  ribs,  and  are 
gradually  lost  in  the  cervical  region,  where  a  number  of  special  muscles  are 
superadded,  which  are  continued  upwards  to  the  head,  which  they  support  upon 
the  spine. 

The  Erector  spinas  arises  from  the  sacro-iliac  groove,  and  from  the  anterior 
surface  of  a  very  broad  and  thick  tendon,  which  is  attached,  internally,  to  the 
spines  of  the  sacrum,  to  the  spinous  processes  of  the  lumbar  and  three  lower 
dorsal  vertebrae,  and  the  supra-spinous  ligament ;  externally,  to  the  back  part  of 
the  inner  lip  of  the  crest  of  the  ilium,  and  to  the  series  of  eminences  on  the  pos- 
terior part  of  the  sacrum,  representing  the  transverse  processes,  where  it  blends 
with  the  great  sacro-sciatic  ligament.  The  muscular  fibres  form  a  single  large 
fleshy  mass,  bounded  in  front  by  the  transverse  processes  of  the  lumbar  vertebrae, 
and  by  the  middle  lamella  of  the  fascia  of  the  Transversalis  muscle.  Opposite  the 
last  rib,  it  divides  into  two  parts,  the  Sacro-lumbalis,  and  the  Longissimus  dorsi. 
*  The  Sacro-lumbalis  (Ilio-costalis),  the  external  and  smaller  portion  of  the 
Erector  spinae,  is  inserted,  by  six  or  seven  flattened  tendons,  into  the  angles 
of  the  six  lower  ribs.  If  this  muscle  is  reflected  outwards,  it  will  be  seen 
to  be  reinforced  by  a  series  of  muscular  slips,  which  arise  from  the  angles  of 
the  ribs;  by  means  of  these  the  Sacro-lumbalis  is  continued  upwards,  to  be 
connected  with  the  upper  ribs,  and  with  the  cervical  portion  of  the  spine, 
forming  two  additional  muscles,  the  Musculus  accessorius  and  the  Cervicalis 
ascendens. 

The  Musculus  accessorius  ad  sacro-lumbalem  arises  by  separate  flattened  tendons, 
from  the  angles  of  the  six  lower  ribs ;  these  become  muscular,  and  are  finally  in- 
serted, by  separate  tendons,  into  the  angles  of  the  six  upper  ribs. 

The  Cervicalis  ascendens  is  the  continuation  of  the  Accessorius  upwards  into  the 
neck:  it  is  situated  on  the  inner  side  of  the  tendons  of  the. Accessorius,  arising 
from  the  angles  of  the  four  or  five  upper  ribs,  and  is  inserted,  by  a  series  of 
slender  tendons,  into  the  posterior  tubercles  of  the  transverse  processes  of  the 
fourth,  fifth,  and  sixth  cervical  vertebrae. 

The  Longissim.us  Dorsi,  the  inner  and  larger  portion  of  the  Erector  spinae, 
arises,  with  the  Sacro-lumbalis,  from  the  common  origin  already  mentioned.  In 
the  lumbar  region,  where  it  is  as  yet  blended  with  the  Sacro-lumbalis,  some  of 
the  fibres  are  attached  to  the  posterior  surface  of  the  transverse  processes  of  the 
lumbar  vertebrae  their  whole  length,  to  the  tubercles  at  the  back  of  the  articular 


OF   THE   BACK.  211 

processes,  and  to  the  layer  of  lumbar  fascia  connected  with  the  apices  of  the 
transverse  processes.  In  the  dorsal  region,  the  Longissimus  dorsi  is  inserted, 
by  long  thin  tendons,  into  the  tips  of  the  transverse  processes  of  all  the  dorsal 
vertebrae,  and  into  from  seven  to  eleven  ribs  between  their  tubercles  and  angles. 
This  muscle  is  continued  upwards  to  the  cranium  and  cervical  portion  of  the 
spine,  by  means  of  two  additional  fasciculi,  the  Transversalis  colli,  and  Trachelo- 
mastoid. 

The  Transversalis  Colli,  placed  on  the  inner  side  of  the  Longissimus  dorsi,  arises, 
by  long  thin  tendons,  from  the  summit  of  the  transverse  processes  of  the  third, 
fourth,  fifth,  and  sixth  dorsal  vertebrae,  and  is  inserted,  by  similar  tendons,  into 
the  posterior  tubercles  of  the  transverse  processes  of  the  five  lower  cervical. 

The  Trachelo-mastoid  lies  on  the  inner  side  of  the  preceding,  between  it  and 
the  Complexus  muscle.  It  arises,  by  four  tendons,  from  the  transverse  processes 
of  the  third,  fourth,  fifth,  and  sixth  dorsal  vertebrae,  and  by  additional  separate 
tendons  from  the  articular  processes  of  the  three  or  four  lower  cervical ;  the  fibres 
form  a  small  muscle,  which  ascends  to  be  inserted  into  the  posterior  margin  of 
the  mastoid  process,  beneath  the  Splenius  and  Sterno-mastoid  muscles.  This 
small  muscle  is  almost  always  crossed  by  a  tendinous  intersection  near  its  inser- 
tion into  the  mastoid  process. 

The  Spinalis  Dorsi  connects  the  spinous  processes  of  the  upper  lumbar  and 
the  dorsal  vertebrae  together  by  a  series  of  muscular  and  tendinous  slips,  which 
are  intimately  blended  with  the  Longissimus  dorsi.  It  is  situated  at  the  inner 
side  of  the  Longissimus  dorsi,  arising,  by  three  or  four  tendons,  from  the  spinous 
processes  of  the  first  two  lumbar  and  the  last  two  dorsal  vertebrae :  these,  uniting, 
form  a  small  muscle,  which  is  inserted,  by  separate  tendons,  into  the  spinous 
processes  of  the  dorsal  vertebrae,  the  number  varying  from  four  to  eight.  It  is 
intimately  united  with  the  Semi-spinalis  dorsi,  which  lies  beneath  it. 

The  Spinalis  Cervicis  is  a  small  muscle,  connecting  together  the  spinous  pro- 
cesses of  the  cervical  vertebrae,  and  analogous  to  the  Spinalis  dorsi  in  the  dorsal 
region.  It  varies  considerably  in  its  size,  and  in  its  extent  of  attachment  to  the 
vertebrae,  not  only  in  different  bodies,  but  on  the  two  sides  of  the  same  body.  It 
usually  arises  by  fleshy  or  tendinous  slips,  varying  from  two  to  four  in  number, 
from  the  spinous  processes  of  the  fifth  and  sixth  cervical  vertebrae,  and  occasionally 
from  the  first  and  second  dorsal,  and  is  inserted  into  the  spinous  process  of  the 
axis,  and  occasionally  into  the  spinous  process  of  the  two  vertebrae  below  it. 
This  muscle  has  been  found  absent  in  five  cases  out  of  twenty -four. 

The  Complexus  is  a  broad  thick  muscle,  situated  at  the  upper  and  back  part  of 
the  neck,  beneath  the  Splenius,  and  internal  to  the  prolongations  from  the 
Longissimus  dorsi.  It  arises,  by  a  series  of  tendons,  about  seven  in  number,  from 
the  tips  of  the  transverse  processes  of  the  upper  three  dorsal  and  seventh  cervical, 
and  from  the  articular  processes  of  the  three  cervical  above  this.  The  tendons 
uniting  form  a  broad  muscle,  which  passes  obliquely  upwards  and  inwards,  and 
is  inserted  into  the  innermost  depression  between  the  two  curved  lines  of  the  occi- 
pital bone.  This  muscle,  about  its  middle,  is  traversed  by  a  transverse  tendinous 
intersection. 

The  Biventer  Cervicis  is  a  small  fasciculus,  situated  on  the  inner  side  of  the 
preceding,  and  in  the  majority  of  cases  blended  with  it ;  it  has  received  its  name 
from  having  a  tendon  intervening  between  two  fleshy  bellies.  It  is  sometimes 
described  as  a  separate  muscle,  arising,  by  from  two  to  four  tendinous  slips,  from 
the  transverse  processes  of  as  many  upper  dorsal  vertebrae,  and  is  inserted,  on 
the  inner  side  of  the  Complexus,  into  the  superior  curved  line  of  the  occipital  bone. 

Relations.  By  their  superficial  surface,  with  the  Trapezius  and  Splenius.  By 
their  deep  surface,  with  the  Semi-spinalis  dorsi  and  Semi-spinalis  colli  and  the 
Recti  and  Obliqui.  The  Biventer  cervicis  is  separated  from  its  fellow  of  the* 
opposite  side  by  the  ligamentum  nuchas,  and  the  Complexus  from  the  Semi- 
spinalis  colli  by  the  profunda  cervicis  artery,  the  princeps  cervicis,  a  branch  of 
the  occipital,  and  by  the  posterior  cervical  plexus  of  nerves. 


2T8  MUSCLES   AND   FASCIJS. 

Nerves.  The  Erector  spinas  and  its  subdivisions  in  the  dorsal  region  are  sup- 
plied by  the  external  posterior  branches  of  the  lumbar  and  dorsal  nerves ;  the 
Cervicalis  ascendens,  Transversalis  colli,  Trachelo-mastoid,  and  Spinalis  cervicis, 
by  the  external  posterior  branches  of  the  cervical  nerves ;  the  Complexus,  by  the 
internal  posterior  branches  of  the  cervical  nerves,  the  suboccipital  and  great 
occipital. 

Fifth  Layer. 

Semi-spinalis  Dorsi.  Extensor  Coccygis. 

Semi-spinalis  Colli.  Inter-transversales. 

Multifidus  Spinas.  Rectus  Capitis  Posticus  Major. 

Rotatores  Spinas.  Rectus  Capitis  Posticus  Minor. 

Supra-spinales.  Obliquus  Superior. 

Inter-spinales.  Obliquus  Inferior. 

Dissection.  The  muscles  of  the  preceding  layer  must  be  removed  by  dividing  and  turning 
aside  the  Complexus;  then  detach  the  Spinalis  and  Longissimus  dorsi  from  their  attachments, 
and  divide  the  Erector  spinae  at  its  connection  below  to  the  sacral  and  lumbar  spines,  and  turn 
it  outward.  The  muscles  filling  up  the  interval  between  the  spinous  and  transverse  processes 
are  then  exposed. 

The  Semi-spinales  muscles  connect  the  transverse  and  articular  processes  to  the 
spinous  processes  of  the  vertebras,  extending  from  the  lower  part  of  the  dorsal 
region  to  the  upper  part  of  the  cervical. 

The  semi-spirialis  dorsi  consists  of  a  thin,  narrow,  fleshy  fasciculus,  interposed 
between  tendons  of  considerable  length.  It  arises  by  a  series  of  small  tendons 
from  the  transverse  processes  of  the  lower  dorsal  vertebras,  from  the  tenth  or 
eleventh  to  the  fifth  or  sixth ;  and  is  inserted,  by  five  or  six  tendons,  into  the 
spinous  processes  of  the  upper  four  dorsal  and  lower  two  cervical  vertebras. 

The  semi-spinalis  colli,  thicker  than  the  preceding,  arises  by  a  series  of  tendinous 
and  fleshy  points  from  the  transverse  processes  of  the  upper  four  dorsal  vertebras, 
and  from  the  articular  processes  of  the  cervical  vertebras  (lower  four) ;  and  is 
inserted  into  the  spinous  processes  of  four  cervical  vertebras,  from  the  axis  to  the 
fifth  cervical.  The  fasciculus  connected  with  the  axis  is  the  largest,  and  chiefly 
muscular  in  structure. 

Relations.  By  their  superficial  surface,  from  below  upwards,  with  the  Longis- 
simus dorsi,  Spinalis  dorsi,  Splenius,  Complexus,  the  profunda  cervicis  and  prin- 
ceps  cervicis  arteries,  and  the  posterior  cervical  plexus  of  nerves.  By  their  deep 
surface,  with  the  Multifidus  spinas. 

The  Multifidus  Spinse  consists  of  a  number  of  fleshy  and  tendinous  fasciculi, 
which  fill  up  the  groove  on  either  side  of  the  spinous  processes  of  the  vertebras, 
from  the  sacrum  to  the  axis.  In  the  sacral  region,  these  fasciculi  arise  from  the 
back  of  the  sacrum,  as  low  as  the  fourth  sacral  foramen ;  and  from  the  aponeurosis 
of  origin  of  the  Erector  spinas.  In  the  iliac  region,  they  arise  from  the  inner 
surface  of  the  posterior  superior  spine,  and  posterior  sacro-iliac  ligaments.  In 
the  lumbar  and  cervical  regions,  they  arise  from  the  articular  processes ;  and  in 
the  dorsal  region,  from  the  transverse  processes.  Each  fasciculus,  ascending 
obliquely  upwards  and  inwards,  is  inserted  into  the  lamina  and  whole  length  of 
the  spinous  process  of  the  vertebra  above.  These  fasciculi  vary  in  length ;  the 
most  superficial,  the  longest,  pass  from  one  vertebra  to  the  third  or  fourth  above ; 
those  next  in  order  pass  from  one  vertebra  to  the  second  or  third  above ;  whilst 
the  deepest  connect  two  contiguous  vertebras. 

Relations.  By  its  superficial  surface,  with  the  Longissimus  dorsi,  Spinalis  dorsi, 
Semi-spinalis  dorsi,  and  Semi-spinalis  colli.  By  its  deep  surface,  with  the  laminas 
and  spinous  processes  of  the  vertebras,  and  with  the  Rotatores  spinas  in  the  dorsal 
region. 

The  Rotatores  Spinse  are  found  only  in  the  dorsal  region  of  the  spine,  beneath 
the  Multifidus  spinas ;  they  are  eleven  in  number  on  each  side.     Each  muscle, 


OF   THE   BACK.  279 

which  is  small  and  somewhat  quadrilateral  in  form,  arises  from  the  upper  and 
back  part  of  the  transverse  process,  and  is  inserted  into  the  lower  border  and 
outer  surface  of  the  lamina  of  the  vertebra  above,  the  fibres  extending  as  far 
inwards  as  the  root  of  the  spinous  process.  The  first  is  found  between  the  first 
and  second  dorsal ;  the  last,  between  the  eleventh  and  twelfth.  Sometimes,  the 
number  of  these  muscles  is  diminished  by  the  absence  of  one  or  more  from  the 
upper  or  lower  end. 

The  Supra-spinales  consist  of  a  series  of  fleshy  bands,  which  lie  on  the  spinous 
processes  in  the  cervical  region  of  the  spine. 

The  Inter-spinales  are  short  muscular  fasciculi,  placed  in  pairs  between  the 
spinous  processes  of  the  contiguous  vertebras. 

In  the  cervical  region,  they  are  most  distinct,  and  consist  of  six  pairs,  the  first 
being  situated  between  the  axis  and  third  vertebra,  and  the  last  between  the  last 
cervical  and  the  first  dorsal.  They  are  small  narrow  bundles,  attached,  above 
and  below,  to  the  apices  of  the  spinous  processes. 

In  the  dorsal  region,  they  are  found  between  the  first  and  second  vertebras,  and 
occasionally  between  the  second  and  third :  and  below,  between  the  eleventh  and 
twelfth. 

In  the  lumbar  region,  there  are  four  pairs  of  these  muscles  in  the  intervals 
between  the  five  lumbar  vertebras.  There  is  also  occasionally  one  in  the  inter- 
spinous  space,  between  the  last  dorsal  and  first  lumbar,  and  between  the  fifth 
lumbar  and  the  sacrum. 

The  Extensor  Coccygis  is  a  slender  muscular  fasciculus,  occasionally  present, 
which  extends  over  the  lower  part  of  the  posterior  surface  of  the  sacrum  and 
coccyx.  It  arises  by  tendinous  fibres  from  the  last  bone  of  the  sacrum,  or  first 
piece  of  the  coccyx,  and  passes  downwards  to  be  inserted  into  the  lower  part  of 
the  coccyx.  It  is  a  rudiment  of  the  Extensor  muscle  of  the  caudal  vertebras 
present  in  some  animals. 

The  Inter-transversaks  are  small  muscles  placed  between  the  transverse  pro- 
cesses of  the  vertebras. 

In  the  cervical  region,  they  are  most  developed,  consisting  of  two  rounded 
muscular  and  tendinous  fasciculi,  which  pass  between  the  anterior  and  posterior 
tubercles  of  the  transverse  processes  of  two  contiguous  vertebras,  being  separated 
from  one  another  by  the  anterior  branch  of  a  cervical  nerve,  which  lies  in  the 
groove  between  them,  and  by  the  vertebral  artery  and  vein.  In  this  region,  there 
are  seven  pairs  of  these  muscles,  the  first  being  between  the  atlas  and  axis,  and 
the  last  between  the  seventh  cervical  and  first  dorsal  vertebra. 

In  the  dorsal  region,  they  are  least  developed,  consisting  chiefly  of  rounded 
tendinous  cords  in  the  inter-transverse  spaces  of  the  upper  dorsal  vertebras ;  but 
between  the  transverse  processes  of  the  lower  three  dorsal  vertebras  and  the  first 
lumbar,  they  are  muscular  in  structure. 

In  the  lumbar  region,  they  are  four  in  number,  and  consist  of  a  single  muscular 
layer,  which  occupies  the  entire  interspace  between  the  transverse  processes  of 
the  lowest  lumbar  vertebras,  whilst  those  between  the  transverse  processes  of  the 
upper  lumbar  are  not  attached  to  more  than  half  the  breadth  of  the  process. 

The  Rectus  Capitis  Posticus  Major,  the  larger  of  the  two  Recti,  arises  by  a 
pointed  tendinous  origin  from  the  spinous  process  of  the  axis,  and,  becoming 
broader  as  it  ascends,  is  inserted  into  the  inferior  curved  line  of  the  occipital  bone 
and  the  surface  of  bone  immediately  below  it.  As  the  muscles  of  the  two  sides 
ascend  upwards  and  outwards,  they  leave  between  them  a  triangular  space,  in 
which  are  seen  the  Recti  capitis  postici  minores  muscles. 

Relations.  By  its  superficial  surface,  with  the  Complexus,  and,  at  its  insertion, 
with  the  Superior  oblique.  By  its  deep  surface,  with  the  posterior  arch  of  the 
atlas,  the  posterior  occipito-atloid  ligament,  and  part  of  the  occipital  bone. 

The  Rectus  Capitis  Posticus  Minor,  the  smallest  of  the  four  muscles  in  this  region, 
is  of  a  triangular  shape ;  it  arises  by  a  narrow,  pointed  tendon  from  the  tubercle 
on  the  posterior  arch  of  the  atlas,  and,  becoming  broader  as  it  ascends,  is  inserted 


280  MUSCLES   AND   FASCIAE. 

into  the  rough  surface  beneath  the  inferior  curved  line,  nearly  as  far  as  the  fora- 
men magnum,  nearer  to  the  middle  line  than  the  preceding. 

Relations.  By  its  superficial  surface,  with  the  Complexus.  By  its  deep  surface, 
with  the  posterior  occipito-atloid  ligament. 

The  Obliquus  Inferior,  the  largest  of  the  two  oblique  muscles,  arises  from  the 
apex  of  the  spinous  process  of  the  axis,  and  passes  almost  horizontally  outwards, 
to  be  inserted  into  the  apex  of  the  transverse  process  of  the  atlas. 

Relations.  By  its  superficial  surface,  with  the  Complexus,  and  is  crossed  by  the 
posterior  branch  of  the  second  cervical  nerve.  By  its  deep  surface,  with  the  ver- 
tebral artery,  and  posterior  occipito-atloid  ligament. 

The  Obliquus  Superior,  narrow  below,  wide  and  expanded  above,  arises  by  ten- 
dinous fibres  from  the  upper  part  of  the  transverse  process  of  the  atlas,  joining 
with  the  insertion  of  the  preceding,  and,  passing  obliquely  upwards  and  inwards, 
is  inserted  into  the  occipital  bone,  between  the  two  curved  lines,  external  to  the 
Complexus.  Between  the  two  oblique  muscles  and  the  Rectus  posticus  major,  a 
triangular  interval  exists,  in  which  are  seen  the  vertebral  artery,  and  the  posterior 
branch  of  the  suboccipital  nerve. 

Relations.  By  its  superficial  surface,  with  the  Complexus  and  Trachelo-mastoid. 
By  its  deep  surface,  with  the  posterior  occipito-atloid  ligament. 

Nerves.  The  Semi-spinalis  dorsi  and  Rotatores  spina?  are  supplied  by  the 
internal  posterior  branches  of  the  dorsal  nerves.  The  Semi-spinalis  colli,  Supra- 
spinales,  and  Inter-spinales,  by  the  internal  posterior  branches  of  the  cervical 
nerves.  The  Inter-transversales,  by  the  internal  posterior  branches  of  the  cervical, 
dorsal,  and  lumbar  nerves.  And  the  Multifidus  spinas,  by  the  same,  with  the 
addition  of  the  internal  posterior  branches  of  the  sacral  nerves.  The  Recti  and 
Obliqui  muscles  are  all  supplied  by  the  suboccipital  and  great  occipital  nerves. 

Actions.  The  Erector  spina?,  comprising  the  Sacro-lumbalis,  with  its  accessory 
muscles,  the  Longissimus  dorsi  and  Spinalis  dorsi,  serves,  as  its  name  implies,  to 
maintain  the  spine  in  the  erect  posture ;  it  also  serves  to  bend  the  trunk  backwards, 
when  it  is  required  to  counterbalance  the  influence  of  any  weight  at  the  front  of 
the  body,  as,  for  instance,  when  a  heavy  weight  is  suspended  from  the  neck,  or 
when  there  is  any  great  abdominal  development,  as  in  pregnant  women  or  in 
abdominal  dropsy ;  the  peculiar  gait  under  such  circumstances  depending  upon 
the  spine  being  drawn  backwards,  by  the  counterbalancing  action  of  the  Erector 
spina?  muscles.  The  continuation  of  these  muscles  upwards  to  the  neck  and  head 
steady  and  preserve  the  upright  position  of  these  several  parts.  If  the  Sacro- 
lumbalis  and  Longissimus  dorsi  of  one  side  act,  they  serve  to  draw  down  the 
chest  and  spine  to  the  corresponding  side.  The  Musculus  accessorius,  taking  its 
fixed  point  from  the  cervical  vertebra?,  elevates  those  ribs  to  which  it  is  attached. 
The  Multifidus  spina?  acts  successively  upon  the  different  segments  of  the  spine ; 
thus,  the  lateral  parts  of  the  sacrum  furnish  a  fixed  point  from  which  the  fasciculi 
of  this  muscle  act  upon  the  lumbar  region ;  these  then  become  the  fixed  points 
for  the  fasciculi  moving  the  dorsal  region,  and  so  on  throughout  the  entire  length 
of  the  spine.  It  is  by  the  successive  contraction  and  relaxation  of  the  separate 
fasciculi  of  this  and  other  muscles,  that  the  spine  preserves  the  erect  posture  with- 
out the  fatigue  that  would  necessarily  have  existed  had  this  movement  been 
accomplished  by  the  action  of  a  single  muscle.  The  Multifidus  spina?,  besides 
preserving  the  erect  position  of  the  spine,  serves  to  rotate  it,  so  that  the  front  of 
the  trunk  is  turned  to  the  side  opposite  to  that  from  which  the  muscle  acts,  this 
muscle  being  assisted  in  its  action  by  the  Obliquus  externus  abdominis.  The 
Complexi,  the  analogues  of  the  Multifidus  spina?  in  the  neck,  draw  the  head 
directly  backwards ;  if  one  muscle  acts,  it  draws  the  head  to  one  side,  and  rotates 
it  so  that  the  face  is  turned  to  the  opposite  side.  The  Rectus  capitis  posticus  minor 
and  the  Superior  oblique  draw  the  head  backwards ;  and  the  latter,  from  the 
obliquity  in  the  direction  of  its  fibres,  may  turn  the  face  to  the  opposite  side. 
The  Rectus  capitis  posticus  major  and  the  Obliquus  inferior  rotate  the  atlas,  and, 
with  it,  the  cranium  round  the  odontoid  process,  and  turn  the  face  to  the  same  side. 


OF   THE   ABDOMEN. 


281 


Muscles  of  the  Abdomen. 


The  muscles  in  this  region  are  the 

Obliquus  Externus. 
Obliquus  Internus. 
Transversalis. 


Eectus. 
Pyramidalis. 
Quadratus  Lumborum. 


Fie.  162. — Dissection  of  Abdomen. 


Dissection  (fig.  162).  To  dissect  the  abdominal  muscles,  a  vertical  incision  should  be  made 
from  the  ensiform  cartilage  to  the  pubes  ;  a  second 
oblique  incision  should  extend  from  the  umbilicus 
upwards  and  outwards  to  the  outer  surface  of  the 
chest,  as  high  as  the  lower  border  of  the  fifth  or 
sixth  rib ;  and  a  third,  commencing  midway  between 
the  umbilicus  and  pubes,  should  pass  transversely 
outwards  to  the  anterior  superior  iliac  spine,  and 
along  the  crest  of  the  ilium  as  far  as  its  posterior 
third.  The  three  flaps  included  between  these 
incisions  should  then  be  reflected  from  within  out- 
wards, in  the  line  of  direction  of  the  muscular 
fibres.  If  necessary,  the  abdominal  muscles  may 
be  made  tense  by  inflating  the  peritoneal  cavity 
through  the  umbilicus. 


The  External  Oblique  Muscle  (fig.  163), 
so  called  from  the  direction  of  its  fibres, 
is  situated  on  the  side  and  fore  part  of 
the  abdomen ;  being  the  largest  and  the 
most  superficial  of  the  three  flat  muscles 
in  this  region.  It  is  broad,  thin,  irregu- 
larly quadrilateral  in  form,  its  muscular 
portion  occupying  the  side,  its  aponeurosis 
the  anterior  wall  of  that  cavity.  It  arises, 
by  eight  fleshy  digitations,  from  the  ex- 
ternal surface  and  lower  borders  of  the 
eight  inferior  ribs;  these  digitations  are 

arranged  in  an  oblique  line  running  downwards  and  backwards,  the  upper  ones 
being  attached  close  to  the  cartilages  of  the  corresponding  ribs,  the  lowest  to  the 
apex  oFIhe  cartilage  of  the  last  rib,  the  intermediate  ones  to  the  ribs  at  some 
distance  from  their  cartilages.  The  five  superior  serrations  increase  in  size  from 
above  downwards,  and  are  received  between  corresponding  processes  of  the  Ser- 
ratus  magnus ;  the  three  lower  ones  diminish  in  size  from  above  downwards, 
receiving  between  them  corresponding  processes  from  the  Latissimus  dorsi. 
From  these  attachments,  the  fleshy  fibres  proceed  in  various  directions.  Those 
from  the  lowest  ribs  pass  nearly  vertically  downwards,  to  be  inserted  into  the 
anterior  half  of  the  outer  lip  of  the  crest  of  the  ilium ;  the  middle  and  upper 
fibres,  directed  downwards  and  forwards,  terminate  in  tendinous  fibres,  which 
spread  out  into  a  broad  aponeurosis.  This  aponeurosis,  joined  with  that  of  the 
opposite  muscle  along  the  median  line,  covers  the  whole  of  the  front  of  the 
abdomen :  above,  it  is  connected  with  the  lower  border  of  the  Pectoralis  major ; 
below,  its  fibres  are  closely  aggregated  together,  and  extend  obliquely  across  from 
the  anterior  superior  spine  of  the  ilium  to  the  spine  of  the  os  pubis  and  the  pec- 
tineal line.  In  the  median  line,  it  interlaces  with  the  aponeurosis  of  the  opposite 
muscle,  forming  the  linea  alba,  and  extends  from  the  ensiform  cartilage  to  the 
symphysis  pubis. 

That  portion  of  the  aponeurosis  which  extends  between  the  anterior  superior 
spine  of  the  ilium  and  the  spine  of  the  os  pubis,  is  a  broad  band,  folded  inwards, 
and  continuous  below  with  the  fascia  lata;  it  is  called  PouparCs  ligament.  The 
portion  which  is  reflected  from  Poupart's  ligament  backwards  and  inwards  into  the 
pectineal  line  is  called  Oimhernais  ligament.     From  the  point  of  attachment  of 


282 


MUSCLES   AND   FASCIAE. 


the  latter  to  the  pectineal  line,  a  few  fibres  pass  upwards  and  inwards  beneath  the 
inner  pillar  of  the  ring,  to  the  linea  alba.  They  diverge  as  they  ascend,  and  form 
a  thin,  triangular,  fibrous  band,  which  is  called  the  triangular  ligament. 

In  the  aponeurosis  of  the  External  oblique,  immediately  above  the  crest  of  the 
os  pubis,  is  a  triangular  opening,  the  external  abdominal  ring,  formed  by  a  sepa- 
ration of  the  fibres  of  the  aponeurosis  in  this  situation ;  it  serves  for  the  trans- 
mission of  the  spermatic  cord  in  the  male,  and  the  round  ligament  in  the  female. 

Fig.  163.— The  External  Oblique  Muscle. 


£  if.  Abdominal  Bitty- 
Cimbcrnal's  Lin^~, 


This  opening  is  directed  obliquely  upwards  and  outwards,  and  'corresponds  with 
the  course  of  the  fibres  of  the  aponeurosis.  It  is  bounded,  below,  by  the  crest  of 
the  os  pubis ;  above,  by  some  curved  fibres,  which  pass  across  the  aponeurosis  at 
the  upper  angle  of  the  ring,  so  as  to  increase  its  strength ;  and,  on  either  side,  by 
the  margins  of  the  aponeurosis,  which  are  called  the  pillars  of  the  ring.  Of 
these,  the  external,  which  is,  at  the  same  time,  inferior,  from  the  obliquity  of  its 
direction,  is  inserted  into  the  spine  of  the  os  pubis.     The  internal  or   superior 


OF   THE   ABDOMEN. 


283 


pillar,  being  attached  to  the  front  of  the  symphysis  pubis,  interlaces  with  the  cor- 
responding fibres  of  the  opposite  muscle,  that  of  the  right  being  superficial.  To 
the  margins  of  the  pillars  of  the  external  abdominal  ring  is  attached  an  exceedingly 
thin  and  delicate  fascia,  which  is  prolonged  down  over  the  outer  surface  of  the 
cord  and  testis.  This  has  received  the  name  of  intercolumnar  fascia,  from  its 
attachment  to  the  pillars  of  the  ring.  It  is  also  called  the  external  spermatic  fascia, 
from  being  the  most  external  of  the  fascise  which  cover  the  spermatic  cord. 

Relations.  By  its  external  surface,  with  the  superficial  fascia,  superficial  epi- 
gastric and  circumflex  iliac  vessels,  and  some  cutaneous  nerves.  By  its  internal 
surface,  with  the  Internal  oblique,  the  lower  part  of  the  eight  inferior  ribs,  and 
Intercostal  muscles,  the  Cremaster,  the  spermatic  cord  in  the  male,  and  round 
ligament  in  the  female.  Its  posterior  border  is  occasionally  overlapped  by  the 
Latissimus  dorsi ;  sometimes  an  interval  exists  between  the  two  muscles,  in  which 
is  seen  a  portion  of  the  Internal  oblique. 

Dissection.  The  External  oblique  should  now  be  detached  by  dividing  it  across,  just  in  front 
of  its  attachment  to  the  ribs,  as  far  as  its  posterior  border,  and  by  separating  it  below  from  the 
crest  of  the  ilium  as  far  as  the  spine ;  the  muscle  should  then  be  carefully  separated  from  the 
Internal  oblique,  which  lies  beneath,  and  turned  towards  the  opposite  side. 

The  Internal  Oblique  Muscle  (fig.  164),  thinner  and  smaller  than  the  preceding, 


Fig.  164. — The  Internal  Oblique  Muscle. 


Conjoined  Tendon 
CREMASTER 


beneath  which  it  lies,  is  of  an  irregularly  quadrilateral  form,  and  situated  at  the 
side  and  fore  part  of  the  abdomen.     It  arises,  by  fleshy  fibres,  from  the  outer  half 


284  MUSCLES   AND   FASCIAE. 

of  Poupart's  ligament,  being  attached  to  the  groove  on  its  upper  surface ;  from  the 
anterior  two-thirds  of  the  middle  lip  of  the  crest  of  the  ilium,  and  from  the  lumbar 
fascia.  From  this  origin,  the  fibres  diverge  in  different  directions.  Those  from 
Poupart's  ligament,  few  in  number  and  paler  in  color  than  the  rest,  arch  down- 
wards and  inwards  across  the  spermatic  cord,  to  be  inserted,  conjointly  with  those 
of  the  Transversalis,  into  the  crest  of  the  os  pubis  and  pectineal  line,  to  the  extent 
of  half  an  inch,  forming  the  conjoined  tendon  of  the  Internal  oblique  and  Trans- 
versalis; those  from  the  anterior  superior  iliac  spine  are  horizontal  in  their 
direction,  whilst  those  which  arise  from  the  fore  part  of  the  crest  of  the  ilium 
pass  obliquely  upwards  and  inwards,  and  terminate  in  an  aponeurosis,  which  is 
continued  forwards  to  the  linea  alba.  The  most  posterior  fibres  ascend  almost 
vertically  upwards,  to  be  inserted  into  the  lower  borders  of  the  cartilages  of  the 
four  lower  ribs,  being  continuous  with  the  Internal  intercostal  muscles. 

The  conjoined  tendon  of  the  Internal  oblique  and  Transversalis  is  inserted  into 
the  crest  of  the  os  pubis  and  pectineal  line  immediately  behind  the  external  abdo- 
minal ring,  serving  to  protect  what  would  otherwise  be  a  weak  point  in  the 
abdomen.  Sometimes  this  tendon  is  insufficient  to  resist  the  pressure  from  within, 
and  is  carried  forward  in  front  of  the  protrusion  through  the  external  ring,  form- 
ing one  of  the  coverings  of  direct  inguinal  herjiia. 

The  aponeurosis  of  the  Internal  oblique  is  continued  forward  to  the  middle  line 
of  the  abdomen,  where  it  joins  with  the  aponeurosis  of  the  opposite  muscle  at  the 
linea  alba,  and  extends  from  the  margin  of  the  thorax  to  the  pubes.  At  the 
outer  margin  of  the  Pectus  muscle,  this  aponeurosis,  for  the  upper  three-fourtli3 
of  its  extent  divides  into  two  lamella?,  which  pass,  one  in  front  and  the  other 
behind  it,  inclosing  it  in  a  kind  of  sheath,  and  reuniting  on  its  inner  border  at 
the  linea  alba :  the  anterior  layer  is  blended  with  the  aponeurosis  of  the  External 
oblique  muscle,  the  posterior  layer  writh  that  of  the  Transversalis.  Along  the 
lower  fourth,  the  aponeurosis  passes  altogether  in  front  of  the  Pectus  without 
any  separation. 

Relations.  By  its  external  surface,  with  the  External  oblique,  Latissimus  dorsi, 
spermatic  cord,  and  external  ring.  By  its  internal  surface,  withr  the  Transversalis 
muscle,  fascia  transversalis,  internal  ring,  and  spermatic  cord.  Its  lower  border 
forms  the  upper  boundary  of  the  spermatic  canal. 

Dissection.  The  Internal  oblique  should  now  be  detached  in  order  to  expose  the  Transver- 
salis beneath.  This  may  be  effected  by  dividing  the  muscle,  above,  at  its  attachment  to  the 
ribs ;  below,  at  its  connection  with  Poupart's  ligament  and  the  crest  of  the  ilium,  and  behind,  by 
a  vertical  incision  extending  from  the  last  rib  to  the  crest  of  the  ilium.  The  muscle  should  pre- 
viously be  made  tense  by  drawing  upon  it  with  the  fingers  of  the  left  hand,  and  if  its  division 
is  carefully  effected,  the  cellular  interval  between  it  and  the  Transversalis,  as  well  as  the  direc- 
tion of  the  fibres  of  the  latter  muscle,  will  afford  a  clear  guide  to  their  separation ;  along  the 
crest  of  the  ilium  the  circumflex  iliac  vessels  are  interposed  between  them,  and  form  an  im- 
portant guide  in  separating  them.  The  muscle  should  then  be  thrown  forwards  towards  the  linea 
alba. 

The  Transversalis  muscle  (fig.  165),  so  called  from  the  direction  of  its  fibres,  is 
the  most  internal  flat  muscle  of  the  abdomen,  being  placed  immediately  beneath 
the  Internal  oblique.  It  arises  by  fleshy  fibres  from  the  outer  third  of  Poupart's 
ligament,  from  the  inner  lip  of  the  crest  of  the  ilium,  its  anterior  two-thirds,  from 
the  inner  surface  of  the  cartilages  of  the  six  lower  ribs,  interdigitating  with  the 
Diaphragm,  and  by  a  broad  aponeurosis  from  the  spinous  and  transverse  processes 
of  the  lumbar  vertebrae.  The  lower  fibres  curve  downwards,  and  are  inserted, 
together  with  those  of  the  Internal  oblique,  into  the  crest  of  the  os  pubis  and 
pectineal  line,  forming  what  was  before  mentioned  as  the  conjoined  tendon  of  these 
muscles.  Throughout  the  rest  of  its  extent  the  fibres  pass  horizontally  inwards, 
and  near  the  outer  margin  of  the  Pectus  terminate  in  an  aponeurosis,  which  is 
inserted  into  the  linea  alba ;  its  upper  three-fourths  passing  behind  the  Rectus 
muscle,  blending  with  the  posterior  lamella  of  the  Internal  oblique,  its  lower 
fourth  passing  in  front  of  the  Rectus. 

Relations.     By  its  external  surface,  writh  the  Internal  obliq  le,  the  inner  surface 


OF   THE   ABDOMEN. 


285 


of  the  lower  ribs,  and  Internal  intercostal  muscles.  Its  inner  surface  is  lined  by 
the  fascia  transversalis,  which  separates  it  from  the  peritoneum.  Its  lower  border 
forms  the  upper  boundary  of  the  spermatic  canal. 

Lumbar  Fascia  (fig.  166).  The  vertebral  aponeurosis  of  the  Transversalis  divides 
into  three  layers,  an  anterior,  very  thin,  which  is  attached  to  the  front  part  of  the 

Fig.  165. — The  Transversalis,  Rectus,  and  Pyranridalis  Muscles. 


Tint 


apices  of  the  transverse  processes  of  the  lumbar  vertebra,  and,  above,  to  the  lower 
margin  of  the  last  rib,  forming  the  ligamentum  arcuatum  externum ;  a  middle 
layer,  much  stronger,  which  is  attached  to  the  apices  of  the  transverse  processes ; 
and  a  posterior  layer,  attached  to  the  apices  of  the  spinous  processes.  Between 
the  anterior  and  middle  layers  is  situated  the  Quadratus  lumborum,  between  the 
middle  and  posterior  the  Erector  spinae.  The  posterior  lamella  of  this  aponeurosis 
receives  the  attachment  of  the  Internal  oblique ;  it  is  also  blended  with  the  apo- 
neurosis of  the  Serratus  posticus  inferior  and  with  that  of  the  Latissimus  dorsi, 
forming  the  lumbar  fascia. 


286 


MUSCLES   AND   FASCIAE. 


Dissection.  To  expose  the  Eectus  muscle,  its  sheath  should  be  opened  by  a  vertical  in- 
cision extending  from  the  margin  of  the  thorax  to  the  pubes,  the  two  portions  should  then  be 
reflected  from  the  surface  of  the  muscle,  which  is  easily  effected,  excepting  at  the  lineae  trans- 
versa?, where  so  close  an  adhesion  exists,  that  the  greatest  care  is  requisite  in  separating  them. 
The  outer  edge  of  the  muscle  should  now  be  raised,  when  the  posterior  layer  of  the  sheath  will 
be  seen.  By  dividing  the  muscle  in  the  centre,  and  turning  its  lower  part  downwards,  the  point 
where  the  posterior  wall  of  the  sheath  terminates  in  a  thin  curved  margin  will  be  seen. 

The  Rectus  Abdominis  is  a  long,  flat  muscle,  which  extends  along  the  whole 
length  of  the  front  of  the  abdomen,  being  separated  from  its  fellow  of  the  opposite 
side  by  the  linea  alba.  It  is  much  broader  above  than  below,  and  arises  by  two 
tendons,  the  external  or  larger  being  attached  to  the  crest  of  the  os  pubis ;  the 
internal  or  smaller  portion,  interlacing  with  its  fellow  of  the  opposite  side,  and  being 
connected  with  the  ligaments  covering  the  symphysis  pubis.  The  fibres  ascend 
vertically  upwards,  and  the  muscle,  becoming  broader  and  thinner  at  its  upper 
part,  is  inserted  by  three  portions  of  unequal  size  into  the  cartilages  of  the  fifth, 
sixth,  and  seventh  ribs.  Some  fibres  are  occasionally  connected  with  the  costo- 
xiphoid  ligaments,  and  side  of  the  ensiform  cartilage. 

i 

Fig.  166. — A  Transverse  Section  of  the  Abdomen  in  the  Lumbar  Region. 


The  Eectus  muscle  is  traversed  by  a  series  of  tendinous  intersections,  which 
vary  from  two  to  five  in  number,  and  have  received  the  name  lineae  transversse. 
One  of  these  is  usually  situated  opposite  the  umbilicus,  and  two  above  that  point ; 
of  the  latter,  one  corresponds  to  the  ensiform  cartilage,  and  the  other  to  the  interval 
between  the  ensiform  cartilage  and  the  umbilicus.  There  is  occasionally  one  below 
the  umbilicus.  These  intersections  pass  transversely  or  obliquely  across  the  muscle 
in  a  zigzag  course ;  they  rarely  extend  completely  through  its  substance,  sometimes 
pass  only  half  way  across  it,  and  are  intimately  adherent  to  the  sheath  in  which  the 
muscle  is  inclosed. 

The  Eectus  is  inclosed  in  a  sheath  (fig.  166)  formed  by  the  aponeuroses  of  the 
Oblique  and  Transversalis  muscles,  which  are  arranged  in  the  following  manner: 
When  the  aponeurosis  of  the  Internal  oblique  arrives  at  the  margin  of  the  Eectus, 
it  divides  into  two  lamellae,  one  of  which  passes  in  front  of  the  Eectus,  blending 
with  the  aponeurosis  of  the  External  oblique,  the  other  behind  it,  blending  with 
the  aponeurosis  of  the  Transversalis ;  and  these,  joining  again  at  its  inner  border, 
are  inserted  into  the  linea  alba.  This  arrangement  of  the  fasciae  exists  along  the 
upper  three-fourths  of  the  muscle  ;  at  the  commencement  of  the  lower  fourth,  the 
posterior  wall  of  the  sheath  terminates  in  a  thin  curved  margin,  the  concavity  of 
which  looks  downwards  towards  the  pubes ;  the  aponeuroses  of  all  three  muscles 
passing  in  front  of  the  Eectus  without  any  separation.     The  Eectus  muscle,  in 


OF   THE   ABDOMEN.  287 

the  situation  where  its  sheath  is  deficient,  is  separated  from  the  peritoneum  by  the 
transversalis  fascia. 

The  Pyramidalis  is  a  small  muscle,  triangular  in  form,  placed  at  the  lower 
part  of  the  abdomen,  in  front  of  the  Rectus,  and  contained  in  the  same  sheath 
with  that  muscle.  It  arises  by  tendinous  fibres  from  the  front  of  the  os  pubis 
and  the  anterior  pubic  ligament ;  the  fleshy  portion  of  the  muscle  passes  upwards, 
diminishing  in  size  as  it  ascends,  and  terminates  by  a  pointed  extremity,  which  is 
inserted  into  the  linea  alba,  midway  between  the  umbilicus  and  the  os  pubis. 
This  muscle  is  sometimes  found  wanting  on  one  or  both  sides.;  the  lower  end  of 
the  Rectus  then  becomes  proportionally  increased  in  size.  Occasionally  it  has 
been  found  double  on  one  side ;  at  times  the  muscles  of  the  two  sides  are  of  unequal 
size.     Sometimes  its  length  ex«eeds  that  stated  above. 

The  Quadratics  Lumborum  is  situated  in  the  lumbar  region,  is  irregularly 
quadrilateral  in  shape,  broader  below  than  above,  and  consists  of  two  portions. 
One  portion  arises  by  aponeurotic  fibres  from  the  ilio-lumbar  ligament,  and  the 
adjacent  portion  of  the  crest  of  the  ilium  for  about  two  inches,  and  is  inserted 
into  the  lower  border  of  the  last  rib,  about  half  its  length,  and,  by  four  small 
tendons,  into  the  apices  of  the  transverse  processes  of  the  third,  fourth,  and  fifth 
lumbar  vertebrae.  The  other  portion  of  the  muscle,  situated  in  front  of  the  pre- 
ceding, arises  from  the  upper  borders  of  the  transverse  processes  of  the  third, 
fourth,  and  fifth  lumbar  vertebrae  and  is  inserted  into  the  lower  margin  of  the 
last  rib.  The  Quadratus  lumborum  is  contained  in  a  sheath  formed  by  the  anterior 
and  middle  lamellae  of  the  vertebral  aponeurosis  of  the  Transversalis. 

Nerves.'  The  abdominal  muscles  are  supplied  by  the  lower  intercostal,  ilio- 
hypogastric, and  ilio-inguinal  nerves.  The  Quadratus  lumborum  receives  filaments 
from  the  anterior  branches  of  the  lumbar  nerves. 

In  the  description  of  the  abdominal  muscles,  mention  has  frequently  been  made 
of  the  linea  alba,  lineae  semilunares,  lineae  transversae ;  when  the  dissection  of 
these  muscles  is  completed,  these  structures  should  be  examined. 

The  linea  alba  is  a  tendinous  raphe  or  cord,  seen  along  the  middle  line  of  the 
abdomen,  extending  from  the  ensiform  cartilage  to  the  pubes.  It  is  placed 
between  the  inner  borders  of  the  Recti  muscles,  and  formed  by  the  blending  of 
the  aponeuroses  of  the  Oblique  and  Transversalis  muscles.  It  is  narrow  below, 
corresponding  to  the  narrow  interval  existing  between  the  Recti,  but  broader 
above,  as  these  muscles  diverge  from  one  another  in  their  ascent,  becoming  of 
considerable  breadth  after  great  distension  of  the  abdomen  from  pregnancy  or 
ascites.  It  presents  numerous  apertures  for  the  passage  of  vessels  and  nerves ; 
the  largest  of  these  is  the  umbilicus,  which  in  the  foetus  transmits  the  umbilical 
vessels,  but  in  the  adult  is  obliterated,  the  cicatrix  being  stronger  than  the  neigh- 
boring parts ;  hence  the  occurrence  of  umbilical  hernia  in  the  adult  above  the 
umbilicus,  whilst  in  the  foetus  it  occurs  at  the  umbilicus.  The  linea  alba  is  in 
relation,  in  front,  with  the  integument  to  which  it  is  adherent,  especially  at  the 
umbilicus ;  behind,  it  is  separated  from  the  peritoneum  by  the  transversalis  fascia ; 
and  below,  by  the  urachus,  and  the  bladder,  when  that  organ  is  distended. 

The  lineae  semilunares  are  two  curved  tendinous  lines,  placed  one  on  each  side 
of  the  linea  alba.  Each  corresponds  with  the  outer  border  of  the  Rectus  muscle, 
extends  from  the  cartilage  of  the  eighth  rib  to  the  pubes,  and  is  formed  by  the 
aponeurosis  of  the  Internal  oblique  at  its  point  of  division  to  inclose  the  Rectus. 

The  lineae  transversa  are  three  or  four  narrow  transverse  lines  which  intersect 
the  Rectus  muscle,  as  already  mentioned,  and  connect  the  lineae  semilunares  with 
the  linea  alba. 

Actiom.     The  abdominal  muscles  perform  a  threefold  action. 

1.  When  the  pelvis  and  thorax  are  fixed,  they  can  compress  the  abdominal 
viscera,  by  constricting  the  cavity  of  the  abdomen,  in  which  action  they  are 
materially  assisted  by  the  descent  of  the  diaphragm.  By  these  means,  the  foetus 
is  expelled  from  the  uterus,  the  faeces  from  the  rectum,  the  urine  from  the  bladder, 
and  the  ingesta  from  the  stomach  in  vomiting. 


288  MUSCLES   AND   FASCIA. 

2.  If  the  spine  is  fixed,  these  muscles  can  compress  the  lower  part  of  the  thorax, 
materially  assisting  in  expiration.  If  the  spine  is  not  fixed,  the  thorax  is  bent 
directly  forward,  if  the  muscles  of  both  sides  act,  or  to  either  side  if  they  act 
alternately,  rotation  of  the  trunk  at  the  same  time  taking  place  to  the  opposite 
side. 

3.  If  the  thorax  is  fixed,  these  muscles,  acting  together,  draw  the  pelvis  upwards, 
as  in  climbing ;  or,  acting  singly,  the  pelvis  is  drawn  upwards,  and  the  vertebral 
column  rotated  to  one  or  the  other  side.  The  Eecti  muscles,  acting  from  below, 
depress  the  thorax,, and  consequently  flex  the  vertebral  column;  when  acting  from 
above,  they  flex  the  pelvis  upon  the  vertebral  column.  The  Pyramidales  are 
tensors  of  the  linea  alba. 

Muscles  and  Fascia  of  the  Thoeax. 

The  muscles  exclusively  connected  with  the  bones  in  this  region  are  few  in 
number.     They  are  the 

Intercostales  Externi.  Infra-costales. 

Intercostales  Interni.  Triangularis  Sterni. 

Levatores  Costarum. 

Intercostal  Fascise.  A  thin  but  firm  layer  of  fascia  covers  the  outer  surface  of 
the  External  intercostal  and  the  inner  surface  of  the  Internal  intercostal  muscles ; 
and  a  third  layer,  more  delicate,  is  interposed  between  the  two  planes  of  muscular 
fibres.  These  are  the  intercostal  fascise ;  they  are  best  marked  in  those  'situations 
where  the  muscular  fibres  are  deficient,  as  between  the  External  intercostal 
muscles  and  sternum,  in  front ;  and  between  the  Internal  intercostals  and  spine, 
behind. 

The  Intercostal  Muscles  are  two  thin  planes  of  muscular  and  tendinous  struc- 
ture, placed  one  over  the  other,  filling  up  the  intercostal  spaces,  and  being  directed 
obliquely  between  the  margins  of  the  adjacent  ribs.  They  have  received  the  names 
"  external"  and  "  internal,"  from  the  position  they  bear  to  one  another. 

The  External  Intercostals  are  eleven  in  number  on  each  side,  being  attached 
to  the  adjacent  margins  of  each  pair  of  ribs,  and  extending  from  the  tubercles  of 
the  ribs,  behind,  to  the  commencement  of  the  cartilages  of  the  ribs,  in  front, 
where  they  terminate  in  a  thin  membranous  aponeurosis,  which  is  continued  for- 
wards to  the  sternum.  They  arise  from  the  outer  lip  of  the  groove  on  the  lower 
border  of  each  rib,  and  are  inserted  into  the  upper  border  of  the  rib  below. 
In  the  two  lowest  spaces  they  extend  to  the  end  of  the  ribs.  Their  fibres  are 
directed  obliquely  downwards  and  forwards,  in  a  similar  direction  with  those  of 
the  External  oblique  muscle.     They  are  thicker  than  the  Internal  intercostals! 

Relations.  By  their  outer  surface,  with  the  muscles  which  immediately  invest 
the  chest,  viz.,  the  Pectoralis  major  and  minor,  Serratus  magnus,  Rhomboideus 
major,  Serratus  posticus  superior  and  inferior,  Scalenus  posticus,  Sacro-lumbalis 
and  Longissimus  dorsi,  Cervicalis  ascendens,  Transversalis  colli,  Levatores  costa- 
rum, and  the  Obliquus  externus  abdominis.  By  their  internal  surface,  with  a  thin 
layer  of  fascia,  which  separates  them  from  the  intercostal  vessels  and  nerve,  the 
Internal  intercostal  muscles,  and,  behind,  from  the  pleura. 

The  Internal  Intercostals,  also  eleven  in  number  on  each  side,  are  placed  on 
the  inner  surface  of  the  preceding,  commencing  anteriorly  at  the  sternum,  in  the 
interspaces  between  the  cartilages  of  the  true  ribs,  and  from  the  anterior  extremi- 
ties of  the  cartilages  of  the  false  ribs;  and  extend  backwards  as  far  as  the  angles 
of  the  ribs,  where  they  are  continued  to  the  vertebral  column  by  a  thin  aponeu- 
rosis. They  arise  from  the  inner  lip  of  the  groove  on  the  lower  border  of  each 
rib,  as  well  as  from  the  corresponding  costal  cartilage,  and  are  inserted  into  the 
upper  border  of  the  rib  below.  Their  fibres  are  directed  obliquely  downwards 
and  backwards,  decussating  with  the  fibres  of  the  preceding. 

Relations.     By  their  external  surface,  with  the  External  intercostals,  and  the 


OF   THE   THORAX.  28!) 

intercostal  vessels  and  nerves.  By  their  internal  surface,  with  the  pleura  costalis. 
Triangularis  sterni,  and  Diaphragm. 

The  Intercostal  muscles  consist  of  muscular  and  tendinous  fibres,  the  latter 
being  longer  and  more  numerous  than  the  former ;  hence  these  spaces  present  very 
considerable  strength,  to  which  their  crossing  materially  contributes. 

The  Infra-costales  consist  of  muscular  and  aponeurotic  fasciculi,  which  vary  in 
number  and  length ;  they  arise  from  the  inner  surface  of  one  rib,  and  are  inserted 
into  the  inner  surface  of  the  first,  second,  or  third  rib  below.  Their  direction 
is  most  usually  oblique,  like  the  Internal  intercostals.  They  are  most  frequent 
between  the  lower  ribs. 

The  Triangularis  Sterni  is  a  thin  plane  of  muscular  and  tendinous  fibres, 
situated  upon  the  inner  wall  of  the  front  of  the  chest.  It  arises  from  the  lower 
part  of  the  side  of  the  sternum,  from  the  inner  surface  of  the  ensiform  cartilage, 
and  from  the  sternal  ends  of  the  costal  cartilages  of  the  three  or  four  lower  true 
ribs.  Its  fibres  diverge  upwards  and  outwards,  to  be  inserted  by  fleshy  digitations 
into  the  lower  border  and  inner  surfaces  of  the  costal  cartilages  of  the  second, 
third,  fourth,  and  fifth  ribs.  The  lowest  fibres  of  this  muscle  are  horizontal  in 
their  direction,  and  are  continuous  with  those  of  the  Transversalis ;  those  which 
succeed  are  oblique,  whilst  the  superior  fibres  are  almost  vertical.  This  muscle 
varies  much  in  its  attachment,  not  only  in  different  bodies,  but  on  opposite  sides 
of  the  same  body. 

Relations.  In  front,  with  the  sternum,  ensiform  cartilage,  the  costal  cartilages, 
the  Internal  intercostal  muscles,  and  internal  mammary  vessels.  Behind,  with 
the  pleura,  pericardium,  and  anterior  mediastinum. 

The  Levatores  Costarum,  twelve  in  number  on  each  side,  are  small  tendinous 
and  fleshy  bundles,  which  arise  from  the  extremities  of  the  transverse  processes 
of  the  dorsal  vertebrae,  and,  passing  obliquely  downwards  and  outwards,  are  in- 
serted into  the  upper  rough  surface  of  the  rib  below  them,  between  the  tubercle 
and  the  angle.  That  for  the  first  rib  arises  from  the  transverse  process  of  the  last 
cervical  vertebra,  and  that  for  the  last  from  the  eleventh  dorsal.  The  inferior 
Levatores  divide  into  two  fasciculi,  one  of  which  is  inserted  as  above  described ;  the 
other  fasciculus  passes  down  to  the  second  rib  below  its  origin :  thus,  each  of  the 
lower  ribs  receives  fibres  from  the  transverse  processes  of  two  vertebrae. 

Nerves.    The  muscles  of  this  group  are  supplied  by  the  intercostal  nerves. 

Actions.  The  Intercostals  are  the  chief  agents  in  the  movement  of  the  ribs  in 
ordinary  respiration.  The  External  intercostals  raise  the  ribs,  especially  their  fore 
part,  and  so  increase  the  capacity  of  the  chest  from  before  backwards ;  at  the  same 
time  they  evert  their  lower  borders,  and  so  enlarge  the  thoracic  cavity  trans- 
versely. The  Internal  intercostals,  at  the  side  of  the  thorax,  depress  the  ribs,  and 
invert  their  lower  borders,  and  so  diminish  the  thoracic  cavity ;  but  at  the  fore 
part  of  the  chest  these  muscles  assist  the  External  intercostals  in  raising  the  car- 
tilages. The  Levatores  Costarum  assist  the  External  intercostals  in  raising  the 
ribs.  The  Triangularis  sterni  draws  down  the  costal  cartilages ;  it  is  therefore  an 
expiratory  muscle. 

Diaphragmatic  Region-. 
Diaphragm.    (Fig.  167.) 

The  Diaphragm  (&ta$pdoea,  to  separate  two  parts),  is  a  thin  musculo-fibrous  sep- 
tum, placed  obliquely  at  the  junction  of  the  upper  with  the  lower  two-thirds  of 
the  trunk,  and  separating  the  thorax  from  the  abdomen,  forming  the  floor  of  the 
former  cavity  and  the  roof  of  the  latter.  It  is  elliptical,  its  longest  diameter  being 
from  side  to  side,  somewhat  fan-shaded,  the  broad  elliptical  portion  being  horizon- 
tal, the  narrow  part,  which  represents  the  handle,  being  vertical,  and  joined  at  right 
angles  with  the  former.  It  is  from  this  circumstance  that  some  anatomists  describe 
it  as  consisting  of  two  portions,  the  upper  or  greater  muscle  of  the  Diaphragm, 
and  the  lower  or  lesser  muscle.  It  arises  from  the  whole  of  the  internal  circum- 
19 


290 


MUSCLES   AND   FASCIAE. 


ference  of  the  thorax,  being  attached,  in  front,  by  fleshy  fibres  to  the  ensiform  car- 
tilage ;  on  each  side,  to  the  inner  surface  of  the  cartilages  and  bony  portions  of 
the  six  or  seven  interior  ribs,  interdigitating  with  the  Transversalis ;  and  behind, 
to  two  aponeurotic  arches,  named  the  ligamentum  arcuatum  externum  and  liga- 
mentum  arcuatum  internum ;  and  to  the  lumbar  vertebra;.  The  fibres  from  these 
sources  vary  in  length ;  those  arising  from  the  ensiform  appendix  are  very  short 
and  occasionally  aponeurotic ;  but  those  from  the  ligamenta  arcuata,  and  more 
especially  those  from  the  ribs  at  the  side  of  the  chest,  are  the  longest,  describe 
well-marked  curves  as  they  ascend,  and  finally  converge,  to  be  inserted  into  the 
circumference  of  the  central  tendon.  Between  the  sides  of  the  muscular  slip 
from  the  ensiform  appendix  and  the  cartilages  of  the  adjoining  ribs,  the  fibres 


Fig.  167.—  The  Diaphragm.     Under  Surface. 


of  the  Diaphragm  are  deficient,  the  interval  being  filled  by  areolar  tissue,  covered 
on  the  thoracic  side  by  the  pleuras ;  on  the  abdominal,  by  the  peritoneum.  This 
is,  consequently,  a  weak  point,  and  a  portion  of  the  contents  of  the  abdomen 
may  protrude  into  the  chest,  forming  phrenic  or  diaphragmatic  hernia,  or  a 
collection  of  pus  in  the  mediastinum  may  descend  through  it,  so  as  to  point  at  the 
epigastrium. 

The  ligamentum  arcuatum  internum  is  a  tendinous  arch,  thrown  across  the 
upper  part  of  the  Psoas  magnus  muscle,  on  each  side  of  the  spine.  It  is  connected, 
by  one  end,  to  the  outer  side  of  the  body  of  the  first,  and  occasionally  the  second, 
lumbar  vertebra,  being  continuous  with  the  outer  side  of  the  tendon  of  the  cor- 
responding crus;  and,  by  the  other  end,  to  the  front  of  the  transverse  process  of 
the  second  lumbar  vertebra. 


DIAPHRAGMATIC   REGION.  291 

The  Ugamentum  arcuatum  externum  is  the  thickened  upper  margin  of  the 
anterior  lamella  of  the  transversalis  fascia ;  it  arches  across  the  upper  part  of  the 
Quadratus  lumborum,  being  attached,  by  one  extremity,  to  the  front  of  the  trans- 
verse process  of  the  second  lumbar  vertebra ;  and,  by  the  other,  to  the  apex  and 
lower  margin  of  the  last  rib. 

To  the  spine,  the  Diaphragm  is  connected  by  two  crura,  which  are  situated  on 
the  bodies  of  the  lumbar  vertebrae,  one  on  each  side  of  the  aorta.  The  crura,  at 
their  origin,  are  tendinous  in  structure ;  the  right  crus,  larger  and  longer  than  the 
left,  arising  from  the  anterior  surface  of  the  bodies  and  intervertebral  substances 
of  the  second,  third,  and  fourth  lumbar  vertebras ;  the  left,  from  the  second  and 
third ;  both  blending  with  the  anterior  common  ligament  of  the  spine.  A  tendi* 
nous  arch  is  thrown  across  the  front  of  the  vertebral  column,  from  the  tendon  of 
one  crus  to  that  of  the  other,  beneath  which  pass  the  aorta,  vena  azygos  major, 
and  thoracic  duct.  The  tendons  terminate  in  two  large  fleshy  bellies,  which,  with 
the  tendinous  portions  above  alluded  to,  are  called  the  crura  or  pillars  of  the  dia- 
phragm. The  outer  fasciculi  of  the  two  crura  are  directed  upwards  and  outwards 
to  the  central  tendon ;  but  the  inner  fasciculi  decussate  in  front  of  the  aorta,  and 
then  diverge,  so  as  to  surround  the  oesophagus  before  ending  in  the  central 
tendon.  The  most  anterior  and  larger  of  these  fasciculi  is  formed  by  the  right 
crus. 

The  Central  or  Cordiform  Tendon  of  the  Diaphragm  is  a  thin  tendinous  apo- 
neurosis, situated  at  the  centre  of  the  vault  of  this  muscle,  immediately  beneath 
the  pericardium,  with  which  its  circumference  is  blended.  It  is  shaped  somewhat 
like  a  trefoil  leaf,  consisting  of  three  divisions  or  leaflets,  separated  from  one 
another  by  slight  indentations.  The  right  leaflet  is  the  largest ;  the  middle  one, 
directed  towards  the  ensiform  cartilage,  the  next  in  size ;  and  the  left,  the  smallest. 
In  structure,  it  is  composed  of  several  planes  of  fibres,  which  intersect  one  another 
at  various  angles,  and  unite  into  straight  or  curved  bundles,  an  arrangement  which 
affords  additional  strength  to  the  tendon. 

The  Openings  connected  with  the  Diaphragm  are  three  large  and  several 
smaller  apertures.  The  former  are  the  aortic,  oesophageal,  and  the  opening  for  the 
vena  cava. 

The  aortic  opening  is  the  lowest  and  the  most  posterior  of  the  three  large  aper- 
tures connected  with  this  muscle.  It  is  situated  in  the  middle  line,  immediately 
in  front  of  the  bodies  of  the  vertebrae ;  and  is,  therefore,  behind  the  Diaphragm, 
not  in  it.  It  is  an  osseo-aponeurotic  aperture,  formed  by  a  tendinous  arch  thrown 
across  the  front  of  the  bodies  of  the  vertebras,  from  the  crus  on  one  side  to  that 
on  the  other,  and  transmits  the  aorta,  vena  azygos  major,  thoracic  duct,  and  occa- 
sionally the  left  sympathetic  nerve. 

The  (Esophageal  opening,  elliptical  in  form,  muscular  in  structure,  and  formed 
by  the  two  crura,  is  placed  above,  and,  at  the  same  time,  anterior  to,  and  a  little  to 
the  left  of,  the  preceding.  It  transmits  the  oesophagus  and  pneumogastric  nerves. 
The  anterior  margin  of  this  aperture  is  occasionally  tendinous,  being  formed  by 
the  margin  of  the  central  tendon. 

The  opening  for  the  vena  cava  is  the  highest ;  it  is  quadrilateral  in  form,  ten- 
dinous in  structure,  and  placed  at  the  junction  of  the  right  and  middle  leaflets  of 
the  central  tendon,  its  margins  being  bounded  by  four  bundles  of  tendinous  fibres, 
which  meet  at  right  angles. 

The  right  crus  transmits  the  sympathetic  and  the  greater  and  lesser  splanchnic 
nerves  of  the  right  side ;  the  left  crus,  the  greater  and  lesser  splanchnic  nerves  of 
the  left  side,  and  the  vena  azygos  minor. 

The  Serous  Membranes  in  relation  with  the  Diaphragm  are  four  in  number ; 
three  lining  its  upper  or  thoracic  surface,  one  its  abdominal.  The  three  serous 
membranes  on  its  upper  surface  are  the  pleura  on  either  side,  and  the  serous  layer 
of  the  pericardium,  which  covers  the  middle  portion  of  the  tendinous  centre. 
The  serous  membrane  covering  its  under  surface  is  a  portion  of  the  general  peri- 
toneal membrane  of  the  abdominal  cavity. 


292  MUSCLES   AND   FASCIAE. 

The  Diaphragm  is  arched,  being  convex  towards  the  chest,  and  concave  to  the 
abdomen.  The  right  portion  forms  a  complete  arch  from  before  backwards,  being 
accurately  moulded  over  the  convex  surface  of  the  liver,  and  having  resting  upon 
it  the  concave  base  of  the  right  lung.  The  left  portion  is  arched  from  before 
backwards  in  a  similar  manner ;  but  the  arch  is  narrower  in  front,  being  encroached 
upon  by  the  pericardium,  and  lower  than  the  right,  at  its  summit,  by  about  three 
quarters  of  an  inch.  It  supports  the  base  of  the  left  lung,  and  covers  the  great 
end  of  the  stomach,  the  spleen,  and  left  kidney.  The  central  portion,  which  sup- 
ports the  heart,  is  higher,  in  front  at  the  sternum,  and  behind  at  the  vertebrae, 
than  the  lateral  portions;  but  deeper,  this  is  reversed. 

The  height  of  the  Diaphragm  is  constantly  varying  during  respiration,  being 
carried  upwards  or  downwards  from  the  average  level ;  its  height  also  varies 
according  to  the  degree  of  distension  of  the  stomach  and  intestines,  and  the  size 
of  the  liver.  After  a  forced  expiration,  the  right  arch  is  on  a  level,  in  front,  with 
the  fourth  costal  cartilage ;  at  the  side,  with  the  fifth,  sixth,  and  seventh  ribs ;  and 
behind,  with  the  eighth  rib :  the  left  arch  being  usually  the  breadth  of  from  one  to 
two  ribs  below  the  level  of  the  right  one.  In  a  forced  inspiration,  it  descends 
from  one  to  two  inches ;  its  slope  would  then  be  represented  by  a  line  drawn  from 
the  ensiform  cartilage  towards  the  tenth  rib. 

Nerves.     The  Diaphragm  is  supplied  by  the  phrenic  nerves. 

Actions.  The  action  of  the  Diaphragm  modifies  considerably  the  size  of  the 
chest,  and  the  position  of  the  thoracic  and  abdominal  viscera.  During  a  forced 
inspiration,  the  cavity  of  the  thorax  is  enlarged  in  the  vertical  direction  from 
two  to  three  inches,  partly  from  the  ascent  of  the  walls  of  the  chest,  partly  from 
the  descent  of  the  Diaphragm.  The  chest,  consequently,  encroaches  upon  the 
abdomen ;  the  lungs  are  expanded,  and  lowered,  in  relation  with  the  ribs,  nearly 
two  inches;  the  heart  being  drawn  down  about  an  inch  and  a  half,  the  descent 
of  the  latter  organ  taking  place  indirectly  through  the  medium  of  its  connec- 
tion with  the  lungs,  as  well  as  directly  by  means  of  the  central  tendon  to  which 
the  pericardium  is  attached.  The  abdominal  viscera  are  also  pushed  down  (the 
liver,  to  the  extent  of  nearly  three  inches),  so  that  these  organs  are  no  longer 
protected  by  the  ribs.  During  expiration,  when  the  Diaphragm  is  passive,  it  is 
pushed  up  by  the  action  of  the  abdominal  muscles ;  the  cavity  of  the  abdomen, 
with  the  organs  contained  in  it,  encroaches  upon  the  chest,  by  which  the  lungs 
and  heart  are  compressed  upwards,  and  the  vertical  diameter  of  the  thoracic  cavity 
diminished.  The  Diaphragm  is  passive  when  raised  or  lowered  by  the  abdominal 
organs,  independently  of  respiration,  in  proportion  as  they  are  large  or  small,  full 
or  empty ;  hence  the  oppression  felt  in  the  chest  after  a  full  meal,  or  from  flatulent 
distension  of  the  stomach  and  intestines. 

In  all  expulsive  acts,  the  Diaphragm  is  called  into  action,  to  give  additional 
power  to  each  expulsive  effort.  Thus,  before  sneezing,  coughing,  laughing,  and 
crying,  before  vomiting,  previous  to  the  expulsion  of  the  urine  and  fasces,  or  of 
the  foetus  from  the  womb,  a  deep  inspiration  takes  place.' 

Muscles  of  the  FEKiNEUir. 
These  muscles  are  described  with  the  anatomy  of  the  Perineum  (p.  778). 

'  For  a  detailed  description  of  the  general  relations  of  the  Diaphragm,  and  its  action,  refer  to 
X)r.  Sibson's  "  Medical  Anatomy." 


UPPER   EXTREMITY. 


293 


MUSCLES  AND  FASCIAE  OF  THE  UPPER  EXTREMITY. 

The  muscles  of  the  Upper  Extremity  are  divisible  into  groups,  corresponding 
with  the  different  regions  of  the  limb. 

Anterior  Thoracic  Region. 
Pectoralis  major. 
Pectoral  is  minor. 
Subclavius. 


Lateral  Tlioracic  Region. 
Serratus  magnus. 


Acromial  Region. 


Deltoid. 


Anterior  Scapular  Region. 
Subscapulars. 

Posterior  Scapular  Region. 
Supra-spinatus. 
Infra-spinatus. 
Teres  minor. 
Teres  major. 

Anterior  Humeral  Region. 
Coraco-brachialis. 
Biceps. 
Brachialis  anticus. 

Posterior  Humeral  Region. 
Triceps. 
Subanconeus. 

Anterior  Brachial  Region. 

1.  Superficial  Layer. 
Pronator  radii  teres. 
Flexor  carpi  radialis. 
Palmaris  longus. 
Flexor  carpi  ulnaris. 
Flexor  sublimis  digitorum. 

2.  Deep  Layer. 
Flexor  profundus  digitorum. 
Flexor  longus  pollicis. 
Pronator  quadratus. 


Radial  Region. 

Supinator  longus. 

Extensor  carpi  radialis  longior. 

Extensor  carpi  radialis  brevior. 

Posterior  Brachial  Region. 

1.  Superficial  Layer. 

Extensor  communis  digitorum. 
Extensor  minimi  digiti. 
Extensor  carpi  ulnaris. 
Anconeus. 

2.  Deep  Layer. 

Supinator  brevis. 
Extensor  ossis  metacarpi  pollicis. 
Extensor  primi  internodii  pollicis. 
Extensor  secundi  internodii  pollicis. 
Extensor  indicis. 


Muscles  of  the  Hand. 

Radial  Region. 
Abductor  pollicis. 

Flexor  ossis  metacarpi  pollicis  (opponens). 
Flexor  brevis  pollicis. 
Adductor  pollicis. 

Ulnar  Region. 
Palmaris  brevis. 
Abductor  minimi  digiti. 
Flexor  brevis  minimi  digiti. 
Flexor  ossis  metacarpi  minimi  digiti. 

Palmar  Region. 
Lumbricales. 
Interossei  palmares. 
Interossei  dorsales. 


Dissection  of  Pectoral  Region  and  Axilla  (fig.  168).  The  arm  being  drawn  away  from  the 
side  nearly  at  right  angles  with  the  trunk,  and  rotated  outwards,  a  vertical  incision  should  be 
made  through  the  integument  in  the  median  line  of  the  chest,  from  the  upper  to  the  lower  part 
of  the  sternum ;  a  second  incision  should  be  carried  along  the  lower  border  of  the  Pectoral  mus- 
cle, from  the  ensiform  cartilage  to  the  outer  side  of  the  axilla  ;  a  third,  from  the  sternum  along 
the  clavicle,  as  far  as  its  centre ;  and  a  fourth,  from  the  middle  of  the  clavicle  obliquely  down- 
wards, along  the  interspace  between  the  Pectoral  and  Deltoid  muscles,  as  low  as  the  fold  of  the 
arm-pit.  The  flap  of  integument  may  then  be  dissected  off  in  the  direction  indicated  in  the 
figure,  but  not  entirely  removed,  as  it  should  be  replaced  on  completing  the  dissection.  If  a 
transverse  incision  is  now  made  from  the  lower  end  of  the  sternum  to  the  side  of  the  chest,  as 
far  as  the  posterior  fold  of  the  arm-pit,  and  the  integument  reflected  outwards,  the  axillary  space 
will  be  more  completely  exposed. 


294 


MUSCLES   AND   FASCIAE. 


3.Dissecti0Ti  erf 
SHOULDER  &  ARM 


Fasciae  of  the  Thorax. 

The  superficial  fascia  of  the  thoracic  region  is  a  loose  cellulo-fibrous  layer,  con- 
tinuous with  the  superficial  fascia  of  the  neck  and  upper  extremity  above,  and 
of  the  abdomen  below.     Opposite  the  mamma,  it  subdivides  into  two  layers,  one 
_     ,  „„     L,  _        _         .  of  which  passes  in  front,  the  other 

behind  this  gland;  and  from  both 
of  these  layers  numerous  septa  pass 
into  its  substance,  supporting  its 
various  lobes;  from  the  anterior 
layer,  fibrous  processes  pass  for- 
ward to  the  integument  and  nipple, 
inclosing  in  their  areolae  masses  of 
fat.  These  processes  were  called, 
by  Sir  A.  Cooper,  the  ligamenta 
suspensoria,  from  the  support  they 
afford  to  the  gland  in  this  situation. 
On  removing  the  superficial  fascia, 
the  deep  fascia  of  the  thoracic  region 
is  exposed ;  it  is  a  thin  aponeurotic 
lamina,  covering  the  surface  of  the 
great  Pectoral  muscle,  and  sending 
numerous  prolongations  between 
its  fasciculi.  It  is  attached,  in  the 
middle  line,  to  the  front  of  the 
sternum,  and,  above,  to  the  clavi- 
cle;  it  is  very  thin  over  the  upper 
part  of  the  muscle,  somewhat  thicker 
in  the  interval  between  the  Pecto- 
ralis  major  and  Latissimus  dorsi, 
where  it  closes  in  the  axillary  space, 
and  divides  at  the  margin  of  the 
latter  muscle  into  two  layers,  one 
of  which  passes  in  front,  and  the 
other  behind  it;  these  proceed  as 
far  as  the  spinous  processes  of  the  dorsal  vertebrae,  to  which  they  are  attached. 
At  the  lower  part  of  the  thoracic  region,  this  fascia  is  well  developed,  and  is  con- 
tinuous with  the  fibrous  sheath  of  the  Eecti  muscles. 


/.  Jilssretiou  of 


2.BCfiDofrZLB0W 


FORE-ARM 


&,  PALM  i?/" HAND 


Anterior  Thoracic  Eegion. 


Pectoralis  Major. 


Pectoralis  Minor. 


Subclavius. 


The  Pectoralis  Major  (fig.  169)  is  a  broad,  thick,  triangular  muscle,  situated  at 
the  upper  and  fore  part  of  the  chest,  in  front  of  the  axilla.  It  arises  from  the 
sternal  half  of  the  clavicle,  its  anterior  surface,  and  from  one  half  the  breadth  of 
the  front  of  the  sternum,  as  low  down  as  the  attachment  of  the  cartilage  of  the 
sixth  or  seventh  rib ;  its  origin  consisting  of  aponeurotic  fibres,  which  intersect 
those  of  the  opposite  muscle.  It  also  arises  from  the  cartilages  of  all  the  true 
ribs,  and  from  the  aponeurosis  of  the  External  oblique  muscle  of  the  abdomen. 
The  fibres  from  this  extensive  origin  converge  towards  its  insertion,  giving  to  the 
muscle  a  radiated  appearance.  Those  fibres  which  arise  from  the  clavicle  pass 
obliquely  doAvnwards  and  outwards,  and  are  usually  separated  from  the  rest  by  a  cel- 
lular interval ;  those  from  the  lower  part  of  the  sternum  and  the  cartilages  of  the  lower 
true  ribs  pass  upwards  and  outwards,  whilst  the  middle  fibres  pass  horizontally. 
As  these  three  sets  of  fibres  converge,  they  are  so  disposed  that  the  upper  overlap 


ANTERIOR   THORACIC   REGION.  295 

the  middle,  and  the  middle  the  lower  portion,  the  fibres  of  the  lower  portion  being 
folded  backwards  upon  themselves ;  so  that  those  fibres  which  are  lowest  in  front, 
become  highest  at  their  point  of  insertion.  They  all  terminate  in  a  flat  tendon, 
about  two  inches  broad,  which  is  inserted  into  the  anterior  bicipital  ridge  of  the 
humerus.  This  tendon  consists  of  two  laminae,  placed  one  in  front  of  the  other, 
and  usually  blended  together  below.  The  anterior,  the  thicker,  receives  the  cla- 
vicular and  upper  half  of  the  sternal  portion  of  the  muscles;  the  posterior  lamina 

Fig.  109. — Muscles  of  the  Chest  and  Front  of  the  Arm.     Superficial  View. 
I       ilk 


receiving  the  attachment  of  the  lower  half  of  the  sternal  portion.  From  this 
arrangement  it  results,  that  the  fibres  of  the  upper  and  middle  portions  of  the 
muscle  are  inserted  into  the  lower  part  of  the  bicipital  ridge ;  those  of  the  lower 
portion,  into  the  upper  part.  The  tendon,  at  its  insertion,  is  connected  with  that 
of  the  Deltoid ;  it  sends  up  an  expansion  over  the  bicipital  groove  to  the  head  of 
the  humerus,  another  backwards,  which  lines  the  groove,  and  a  third  to  the  fascia 
of  the  arm. 


296  MUSCLES   AND   FASCIJE. 

Relations.  By  its  anterior  surface,  with  the  Platysma,  the  mammary  gland,  the 
superficial  fascia,  and  integument.  By  its  posterior  surface:  its  thoracic  portion, 
with  the  sternum,  the  ribs  and  costal  cartilages,  the  Subclavius,  Pectoralis  minor, 
Serratus  magnus,  and  the  Intercostals ;  its  axillary  portion  forms  the  anterior 
wall  of  the  axillary  space,  and  covers  the  axillary  vessels  and  nerves.  Its  upper 
border  lies  parallel  with  the  Deltoid,  from  which  it  is  separated  by  the  cephalic 
vein  and  descending  branch  of  the  thoracico-acromialis  artery.  Its  lower  border 
forms  the  anterior  margin  of  the  axilla,  being  at  first  separated  from  the  Latissimus 
dorsi  by  a  considerable  interval ;  but  both  muscles  gradually  converge  towards  the 
outer  part  of  this  space. 

Peculiarities.  In  muscular  subjects,  the  sternal  origins  of  the  two  Pectoral  muscles  are 
separated  only  by  a  narrow  interval ;  but  this  interval  is  enlarged  where  these  muscles  are  ill- 
developed.  Very  rarely,  the  whole  of  the  sternal  portion  is  deficient.  Occasionally,  one  or  two 
additional  muscular  slips  arise  from  the  aponeurosis  of  the  External  oblique,  and  become  united 
to  the  lower  margin  of  the  Pectoralis  major.  A  slender  muscular  slip  is  occasionally  found 
lying  parallel  with  the  outer  margin  of  the  sternum,  overlapping  the  origin  of  the  Pectoral 
muscle.  It  is  attached,  by  one  end.  to  the  upper  part  of  the  sternum,  near  the  origin  of  the 
Sterno-mastoid ;  and,  by  the  other,  to  the  anterior  wall  of  the  sheath  of  the  Rectus  abdominis. 
It  has  received  the  name  "Rectus  sternalis." 

Dissection.  The  Pectoralis  major  should  now  be  detached  by  dividing  the  muscle  along  its 
attachment  to  the  clavicle,  and  by  making  a  vertical  incision  through  its  substance  a  little  external 
to  its  line  of  attachment  to  the  sternum  and  costal  cartilages.  The  muscle  should  then  be  reflected 
outwards,  and  its  tendon  carefully  examined.  The  Pectoralis  minor  is  now  exposed,  and  imme- 
diately above  it,  in  the  interval  between  its  upper  border  and  the  clavicle,  is  a  strong  fascia,  the 
costo-coracoid  membrane. 

The  costo-coracoid  membrane  protects  the  axillary  vessels  and  nerves,  and  is 
very  thick  and  dense  externally,  where  it  is  attached  to  the  coracoid  process,  and 
is  continuous  with  the  fascia  of  the  arm ;  more  internally,  it  is  connected  with  the 
lower  border  of  the  clavicle,  as  far  as  the  inner  extremity  of  the  first  rib :  traced 
downwards,  it  passes  behind  the  Pectoralis  minor,  surrounding  in  a  more  or  less 
complete  sheath,  the  axillary  vessels  and  nerves ;  and  above,  it  sends  a  prolongation 
behind  the  Subclavius,  which  is  attached  to  the  lower  border  of  the  clavicle,  and 
so  incloses  the  muscle  in  a  kind  of  sheath.  The  costo-coracoid  membrane  is 
pierced  by  the  cephalic  vein,  the  acromial-thoracic  artery  and  vein,  superior 
thoracic  artery,  and  anterior  thoracic  nerve. 

The  Pectoralis  minor  (fig.  170)  is  a  thin,  flat,  triangular  muscle,  situated  at 
the  upper  part  of  the  thorax,  beneath  the  Pectoralis  major.  It  arises,  by  three 
tendinous  digitations,  from  the  upper  margin  and  outer  surface  of  the  third,  fourth, 
and  fifth  ribs,  near  their  cartilages,  and  from  the  aponeurosis  covering  the  Inter- 
costal muscles :  the  fibres  pass  upwards  and  outwards,  and  converge  to  form  a  flat 
tendon,  which  is  inserted  into  the  anterior  border  of  the  coracoid  process  of  the 
scapula. 

Relations.  By  its  anterior  surface,  with  the  Pectoralis  major,  and  the  superior 
thoracic  vessels  and  nerves.  By  its  posterior  surface,  with  the  ribs,  Intercostal 
muscles,  Serratus  magnus,  the  axillary  space,  and  the  axillary  vessels  and  nerves. 
Its  upper  border  is  separated  from  the  clavicle  by  a  triangular  interval,  broad 
internally,  narrow  externally,  bounded  in  front  by  the  costo-coracoid  membrane, 
and  internally  by  the  ribs.     In  this  space  are  seen  the  axillary  vessels  and  nerves. 

The  costo-coracoid  membrane  should  now  be  removed,  when  the  Subclavius  muscle  will  be  seen. 

The  Subclavius  (fig.  170)  is  a  long,  thin,  spindle-shaped  muscle,  placed  in  the 
interval  between  the  clavicle  and  the  first  rib.  It  arises  by  a  short,  thick  tendon, 
from  the  cartilage  of  the  first  rib,  in  front  of  the  rhomboid  ligament ;  the  fleshy 
fibres  proceed  obliquely  outwards  to  be  inserted  into  a  deep  groove  on  the  under 
surface  of  the  middle  third  of  the  clavicle. 

Relations.  By  its  upper  surface,  with  the  clavicle.  By  its  under  surface,  it  is 
separated  from  the  first  rib  by  the  axillary  vessels  and  nerves.     Its  anterior 


ANTERIOR  THORACIC  REGION 


29T 


surface  is  separated  from  the  Pectoralis  major  by  a  strong  aponeurosis,  which, 
with  the  clavicle,  forms  an  osteo-fibrous  sheath  in  which  the  muscle  is  inclosed. 

If  the  costal  attachment  of  the  Pectoralis  minor  is  divided  across,  and  the  muscle  reflected 
outwards,  the  axillary  vessels  and  nerves  are  brought  fully  into  view,  and  should  be  examined. 

Nerves.  The  Pectoral  muscles  are  supplied  by  the  anterior  thoracic  nerves ; 
the  Subclavius,  by  a  filament  from  the  cord  formed  by  the  union  of  the  fifth  and 
sixth  cervical  nerves. 

Actions.  If  the  arm  has  been  raised  by  the  Deltoid,  the  Pectoralis  major  will, 
conjointly  with  the  Latissimus  dorsi  and  Teres  major,  depress  it  to  the  side  of  the 
chest ;  and,  if  acting  singly,  it  will  draw  the  arm  across  the  front  of  the  chest. 


Fig.  170. — Muscles  of  the  Chest  and  Front  of  the  Arm,  with  the  boundaries 

of  the  Axilla. 


The  Pectoralis  minor  depresses  the  point  of  the  shoulder,  drawing  the  scapula 
downwards  and  inwards  to  the  thorax.  The  Subclavius  depresses  the  shoulder, 
drawing  the  clavicle  downwards  and  forwards.  When  the  arms  are  fixed,  all  three 
muscles  act  upon  the  ribs,  drawing  them  upwards  and  expanding  the  chest,  thus 
becoming  very  important  agents  in  forced  inspiration.  Asthmatic  patients  always 
assume  this  attitude,  fixing  the  shoulders,  so  that  all  these  muscles  may  be  brought 
into  action  to  assist  in  dilating  the.  cavity  of  the  chest. 


298  MUSCLES   AND   "PASCIJE. 

Lateral  Thoracic  Eegiox. 

Serratus  Magnus. 

The  Serratus  Magnus  is  a  broad,  thin,  and  irregularly  quadrilateral  muscle, 
situated  at  the  upper  part  and  side  of  the  chest.  It  arises  by  nine  fleshy  digita- 
tions  from  the  outer  surface  and  upper  border  of  the  eight  upper  ribs  (the  second 
rib  having  two),  and  from  the  aponeurosis  covering  the  upper  intercostal  spaces, 
and  is  inserted  into  the  whole  length  of  the  inner  margin  of  the  posterior  border 
of  the  scapula.  This  muscle  has  been  divided  into  three  portions,  a  superior, 
middle,  and  inferior,  on  account  of  the  difference  in  the  direction,  and  in  the  ex- 
tent of  attachment  of  each  part.  The  upper  portion,  separated  from  the  rest  by  a 
cellular  interval,  is  a  narrow,  but  thick  fasciculus,  which  arises  by  two  digitations 
from  the  first  and  second  ribs,  and  from  the  aponeurotic  arch  between  them ;  its 
fibres  proceed  upwards,  outwards  and  backwards,  to  be  inserted  into  the  triangular 
smooth  surface  on  the  inner  side  of  the  superior  angle  of  the  scapula.  The  middle 
portion  of  the  muscle  arises  by  three  digitations  from  the  second,  third  and  fourth 
ribs,  and  forms  a  thin  and  broad  muscular  layer,  which  proceeds  horizontally  back- 
wards, to  be  inserted  into  the  posterior  border  of  the  scapula,  between  the  superior 
and  inferior  angles.  The  lower  portion  arises  from  the  fifth,  sixth,  seventh  and 
eighth  ribs,  by  four  digitations,  in  the  intervals  between  which  are  received  cor- 
responding processes  of  the  External  oblique ;  the  fibres  pass  upwards,  outwards, 
and  backwards,  to  be  inserted  into  the  inner  surface  of  the  inferior  angle  of  the 
scapula,  by  an  attachment  partly  muscular,  partly  tendinous. 

Relations.  This  muscle  is  covered,  in  front,  by  the  Pectoral  muscles ;  behind, 
by  the  Subscapularis ;  above,  by  the  axillary  vessels  and  nerves.  Its  deep  surface 
rests  upon  the  ribs  and  Intercostal  muscles. 

Nerves.     The  Serratus  magnus  is  supplied  by  the  posterior  thoracic  nerve. 

Actions.  The  Serratus  magnus  is  the  most  important  external  inspiratory 
muscle.  When  the  shoulders  are  fixed,  it  elevates  the  ribs,  and  so  dilates  the 
cavity  of  the  chest,  assisting  the  Pectoral  and  Subclavius  muscles.  This  muscle, 
especially  its  middle  and  lower  segments,  draws  the  base  and  inferior  angle  of  the 
scapula  forwards,  and  so  raises  the  point  of  the  shoulder  by  causing  a  rotation  of 
the  bone  on  the  side  of  the  chest ;  assisting  the  Trapezius  muscle  in  supporting 
weights  upon  the  shoulder,  the  thorax  being  at  the  same  time  fixed  by  preventing 
the  escape  of  the  included  air. 

Dissection.  After  completing  the  dissection  of  the  axilla,  if  the  muscles  of  the  back  have 
been  dissected,  the  upper  extremity  should  be  separated  from  the  trunk.  Saw  through  the 
clavicle  at  its  centre,  and  then  cut  through  the  muscles  which  connect  the  scapula  and  arm  with 
the  trunk,  viz.,  the  Pectoralis  minor  in  front,  Serratus  magnus  at  the  side,  and,  behind,  the 
Levator  anguli  scapulae,  the  Ilhomboidei,  Trapezius,  and  Latissimus  dorsi.  These  muscles  should 
be  cleaned  and  traced  to  their  respective  insertions.  An  incision  should  then  be  made  through 
the  integument,  commencing  at  the  outer  third  of  the  clavicle,  and  extending  along  the  margin 
of  this  bone,  the  acromion  process,  and  spine  of  the  scapula ;  the  integument  should  be  dissected 
from  above  downwards  and  outwards,  when  the  fascia  covering  the  Deltoid  is  exposed. 

The  superficial  fascia  of  the  upper  extremity  is  a  thin  cellulo-fibrous  lamina, 
containing  between  its  layers  the  superficial  veins  and  lymphatics,  and  the  cuta- 
neous nerves.  It  is  most  distinct  in  front  of  the  elbow,  and  contains  between 
its  laminas  in  this  situation  the  large  superficial  cutaneous  veins  and  nerves ;  in 
the  hand  it  is  hardly  demonstrable,  the  integument  being  closely  adherent  to  the 
deep  fascia  by  dense  fibrous  bands.  Small  subcutaneous  bursas  are  found  in  this 
fascia,  over  the  acromion,  the  olecranon,  and  the  knuckles.  The  deep  fascia  of 
the  upper  extremity  comprises  the  aponeurosis  of  the  shoulder,  arm,  and  fore- 
arm, the  anterior  and  posterior  annular  ligaments  of  the  carpus,  and  the  palmar 
fascia.  These  will  be  considered  in  the  description  of  the  muscles  of  these  several 
regions. 


ACROMIAL   AND    SCAPULAR   REGIONS.  2G9 

Acromial  Region. 
Deltoid. 

The  deep  fascia  covering  the  Deltoid  (deltoid  aponeurosis)  is  a  thick  and  strong 
fibrous  layer,  which  covers  the  outer  surface  of  the  muscle,  and  sends  down  nume- 
rous prolongations  between  its  fasciculi;  it  is  continuous,  internally,  with  the 
fascia  covering  the  great  Pectoral  muscle ;  behind,  with  that  covering  the  Infra- 
spinatus and  back  of  the  arm ;  above,  it  is  attached  to  the  clavicle,  the  acromion, 
and  spine  of  the  scapula. 

The  Deltoid  is  a  large,  thick,  triangular  muscle,  which  forms  the  convexity  of 
the  shoulder,  and  has  received  its  name  from  its  resemblance  to  the  Greek  letter  a 
reversed.  It  surrounds  the  shoulder-joint  in  the  greater  part  of  its  extent, 
covering  it  on  its  outer  side,  and  in  front  and  behind.  It  arises  from  the  outer 
third  of  the  anterior  border  and  upper  surface  of  the  clavicle;  from  the  outer 
margin  and  upper  surface  of  the  acromion  process ;  and  from  the  whole  length  of 
the  lower  border  of  the  spine  of  the  scapula.  From  this  extensive  origin,  the 
fibres  converge  towards  their  insertion,  the  middle  passing  vertically,  the  anterior 
obliquely  backwards,  the  posterior  obliquely  forwards ;  they  unite  to  form  a  thick 
tendon,  which  is  inserted  into  a  rough  prominence  on  the  middle  of  the  outer  side 
of  the  shaft  of  the  humerus.  This  muscle  is  remarkably  coarse  in  texture,  and 
intersected  by  three  or  four  tendinous  laminae ;  these  are  attached,  at  intervals,  to 
the  clavicle  and  acromion,  extend  into  the  substance  of  the  muscle,  and  give  origin 
to  a  number  of  fleshy  fibres.  The  largest  of  these  laminae  extends  from  the 
summit  of  the  acromion. 

Relations.  By  its  superficial  surface,  with  the  Platysma,  supra-acromial  nerves, 
the  superficial  fascia,  and  integument.  Its  deep  surface  is  separated  from  the 
head  of  the  humerus  by  a  large  sacculated  synovial  bursa,  and  covers  the  coracoid 
process,  coraco-acromial'  ligament,  Pectoralis  minor,  Coraco-brachialis,  both  heads 
of  the  Biceps,  tendon  of  the  Pectoralis  major,  Teres  minor,  scapular  and  external 
heads  of  the  Triceps,  the  circumflex  vessels  and  nerve,  and  the  humerus.  Its 
anterior  border  is  separated  from  the  Pectoralis  major  by  a  cellular  interspace, 
which  lodges  the  cephalic  vein  and  descending  branch  of  the  acromial-thoracic 
artery.     Its  posterior  border  rests  on  the  Infra-spinatus  and  Triceps  muscles. 

Nerves.     The  Deltoid  is  supplied  by  the  circumflex  nerve. 

Actions.  The  Deltoid  raises  the  arm  directly  from  the  side,  so  as  to  bring  it  at 
right  angles  with. the  trunk.  Its  anterior  fibres,  assisted  by  the  Pectoralis  major, 
draw  the  arm  forwards ;  and  its  posterior  fibres,  aided  by  the  Teres  major  and 
Latissimus  dorsi,  draw  it  backwards. 

Dissection.  Divide  the  Deltoid  across,  near  its  upper  part,  by  an  incision  carried  along  the 
margin  of  the  clavicle,  the  acromion  process,  and  spine  of  the  scapula,  and  reflect  it  downwards; 
the  bursa  will  be  seen  on  its  under  surface,  as  well  as  the  circumflex  vessels  and  nerves.  The 
insertion  of  the  muscle  should  be  carefully  examined. 

Anterior  Scapular  Region. 
Subscapularis. 

The  subscapular  aponeurosis  is  a  thin  membrane,  attached  to  the  entire  circum- 
ference of  the  subscapular  fossa,  and  affording  attachment  by  its  inner  surface  to 
some  of  the  fibres  of  the  Subscapularis  muscle :  when  this  is  removed,  the  latter 
is  exposed. 

The  Subscapularis  is  a  large  triangular  muscle,  which  fills  up  the  subscapular 
fossa,  arising  from  its  internal  two-thirds,  with  the  exception  of  a  narrow  margin 
along  the  posterior  border,  and  the  inner  side  of  the  superior  and  inferior  angles, 
which  afford  attachment  to  the  Serratus  magnus.  Some  fibres  arise  from  tendinous 
laminae,  which  intersect  the  muscle,  and  are  attached  to  ridges  on  the  bone ;  and 
others  from  an  aponeurosis,  which  separates  the  muscle  from  the  Teres  major  and 


300  MUSCLES   AND   FASCI.E. 

the  long  head  of  the  Triceps.  The  fibres  pass  outwards,  and,  gradually  converging, 
terminate  in  a  tendon,  which  is  inserted  into  the  lesser  tuberosity  of  the  humerus. 
Those  fibres  which  arise  from  the  axillary  border  of  the  scapula  are  inserted  into 
the  neck  of  the  humerus  to  the  extent  of  an  inch  below  the  tuberosity.  The  tendon 
of  the  muscle  is  in  close  contact  with  the  capsular  ligament  of  the  shoulder-joint, 
and  glides  over  a  large  bursa,  which  separates  it  from  the  base  of  the  coracoid 
process.  This  bursa  communicates  with  the  cavity  of  the  joint  by  an  aperture  in 
the  capsular  ligament.  • 

Relations.  By  its  anterior  surface,  with  the  Serratus  magnus,  Coraco-brachialis, 
and  Biceps,  and  the  axillary  vessels  and  nerves.  By  its  posterior  surface,  with 
the  scapula,  the  subscapular  vessels  and  nerves,  and  the  capsular  ligament  of  the 
shoulder-joint.  Its  lower  border  is  contiguous  with  the  Teres  major  and  Latissi- 
mus  dorsi. 

Nerves.    It  is  supplied  by  the  subscapular  nerves. 

Actions.  The  Subscapularis  rotates  the  head  of  the  humerus  inwards ;  when 
the  arm  is  raised,  it  draws  the  humerus  downwards.  It  is  a  powerful  defence  to 
the  front  of  the  shoulder-joint,  preventing  displacement  of  the  head  of  the  bone 
forwards. 

Posterior  Scapular  Kegion-. 

Supra-spinatus.  Teres  Minor. 

Infra-spinatus.  Teres  Major. 

Dissection.  To  expose  these  muscles,  and  to  examine  their  mode  of  insertion  into  the  hume- 
rus, detach  the  Deltoid  and  Trapezius  from  their  attachment  to  the  spine  of  the  scapula  and  acro- 
mion process.  Remove  the  clavicle  by  dividing  the  ligaments  connecting  it  with  the  coracoid 
process,  and  separate  it  at  its  articulation  with  the  scapula  :  divide  the  acromion  process  near  its 
root  with  a  saw,  and,  the  fragments  being  removed,  the  tendons  of  the  posterior  Scapular  mus- 
cles will  be  fully  exposed,  and  can  be  examined.  A  block  should  be  placed  beneath  the  shoulder- 
joint,  so  as  to  make  the  muscles  tense. 

The  supraspinous  aponeurosis  is  a  thick  and  dense  membranous  layer,  which 
completes  the  osteo-fibrous  case  in  which  the  Supra-spinatus  muscle  is  contained ; 
affording  attachment,  by  its  inner  surface,  to  some  of  the  fibres  of  this  muscle. 
It  is  thick  internally,  but  thinner  externally  under  the  coraco-acromial  ligament. 
When  this  fascia  is  removed,  the  Supra-spinatus  muscle  is  exposed. 

The  Supra-spinatus  muscle  occupies  the  whole  of  the  supra-spinous  fossa,  arising 
from  its  internal  two-thirds,  and  from  a  strong  fascia  which  covers  its  surface. 
The  muscular  fibres  converge  to  a  tendon,  which  passes  across  the  capsular  liga- 
ment of  the  shoulder-joint,  to  which  it  is  intimately  adherent,  and  is  inserted  into 
the  highest  of  the  three  facets  on  the  great  tuberosity  of  the  humerus. 

Relations.  By  its  upper  surface,  with  the  Trapezius,  the  clavicle,  the  acromion, 
the  coraco-acromial  ligament,  and  the  Deltoid.  By  its  under  surface,  with  the 
scapula,  the  supra-scapular  vessels  and  nerve,  and  upper  part  of  the  shoulder- 
joint. 

The  infra-spinous  aponeurosis  is  a  dense  fibrous  membrane,  covering  in  the 
Infra-spinatus  muscle,  and  attached  to  the  circumference  of  the  infra-spinous  fossa ; 
it  affords  attachment,  by  its  inner  surface,  to  some  fibres  of  this  muscle,  is  con- 
tinuous externally  with  the  fascia  of  the  arm,  and  gives  off  from  its  under  surface 
intermuscular  septa,  which  separate  the  Infra-spinatus  from  the  Teres  minor,  and 
the  latter  from  the  Teres  major. 

The  Infra-spinatus  is  a  thick  triangular  muscle,  which  occupies  the  chief  part 
of  the  infra-spinous  fossa,  arising  by  fleshy  fibres,  from  its  internal  two-thirds ; 
and  by  tendinous  fibres,  from  the  ridges  on  its  surface :  it  also  arises  from  a  strong 
fascia  which  covers  it  externally,  and  separates  it  from  the  Teres  major  and  Teres 
minor.  The  fibres  converge  to  a  tendon,  which  glides  over  the  concave  border  of 
the  spine  of  the  scapula,  and,  passing  across  the  capsular  ligament  of  the  shoulder- 
joint,  is  inserted  into  the  middle  facet  on  the  great  tuberosity  of  the  humerus. 


SC4PTJLAR  REGION. 


Wl 


The  tendon  of  tins  muscle  is  occasionally  separated  from  the  spine  of  the  scapula 
by  a  synovial  bursa,  which  communicates  with  the  synovial  membrane  of  the 
shoulder-joint. 

Relations.  By  its  posterior  surface,  with  the  Deltoid,  the  Trapezius,  Latissimus 
dorsi,  and  the  iDtegument.  By  its  anterior  surface,  with  the  scapula,  from  which 
it  is  separated  by  the  superior  and  dorsalis  scapula?  vessels,  and  with  the  capsular 
ligament  of  the  shoulder-joint.  Its  lower  border  is  in  contact  with  the  Teres  minor, 
and  occasionally  united  with  it,  and  with  the  Teres  major. 

The  Teres  Minor  is  a  narrow  elongated  muscle,  which  lies  along  the  inferior 
border  of  the  scapula.  It  arises  from  the  dorsal  surface  of  the  axillary  border  of 
the  scapula  for  the  upper  two-thirds  of  its  extent,  and  from  two  aponeurotic 
laminae,  one  of  which  separates  this  muscle  from  the  Infra-spinatus,  the  other  from 

Fig.  171. — Muscles  on  the  Dorsum  of  the  Scapula  and  the  Triceps. 


the  Teres  major;  its  fibres  pass  obliquely  upwards  and  outwards,  and  terminate 
in  a  tendon,  which  is  inserted  into  the  lowest  of  the  three  facets  on  the  great 
tuberosity  of  the  humerus,  and,  by  fleshy  fibres,  into  the  humerus  immediately 
below  it.  The  tendon  of  this  muscle  passes  across  the  capsular  ligament  of  the 
shoulder -joint. 

Relations.  By  its  posterior  surface,  with  the  Deltoid,  Latissimus  dorsi,  and  in- 
tegument.  By  its  anterior  surface,  with  the  scapula,  the  dorsal  branch  of  the 
subscapular  artery,  the  long  head  of  the  Triceps,  and  the  shoulder-joint.  By  its 
upper  border  with  the  Infra-spinatus.  By  its  lower  border,  with  the  Teres  major, 
from  which  it  is  separated  anteriorly  by  the  long  head  of  the  Triceps. 

The  Teres  Major  is  a  broad  and  somewhat  flattened  muscle,  which  arises  from 
the  dorsal  aspect  of  the  inferior  angle  of  the  scapula,  and  from  the  fibrous  septa 


302  MUSCLES   AND   FASCIA. 

interposed  between  it  and  the  Teres  minor  and  Infra-spinatus ;  the  fibres  are 
directed  upwards  and  outwards,  and  terminate  in  a  flat  tendon,  about  two  inches 
in  length,  which  is  inserted  into  the  posterior  bicipital  ridge  of  the  humerus.  The 
tendon  of  this  muscle,  at  its  insertion  into  the  humerus,  lies  behind  that  of  the 
Latissimus  dorsi,  from  which  it  is  separated  by  a  synovial  bursa. 

Relations.  By  its  posterior  surface,  with  the  integument,  from  which  it  is 
separated,  internally,  by  the  Latissimus  dorsi ;  and  externally,  by  the  long  head  of 
the  Triceps.  By  its  anterior  surface,  with  the  Subscapularis,  Latissimus  dorsi, 
Coraco-brachialis,  short  head  of  the  Bi<?eps,  the  axillary  vessels,  and  brachial 
plexus  of  nerves.  Its  upper  border  is  at  first  in  relation  with  the  Teres  minor, 
from  which  it  is  afterwards  separated  by  the  long  head  of  the  Triceps.  Its 
lower  border  forms,  in  conjunction  with  the  Latissimus  dorsi,  part  of  the  posterior 
boundary  of  the  axilla. 

Nerves.  The  Supra-spinati  and  Infra-spinati  muscles  are  supplied  by  the  supra- 
scapular nerve ;  the  Teres  minor,  by  the  circumflex ;  and  the  Teres  major,  by  the 
subscapular. 

Actions.  The  Supra-spinatus  assists  the  Deltoid  in  raising  the  arm  from  the 
side ;  its  action  must,  however,  be  very  feeble,  from  the  very  disadvantageous 
manner  in  which  the  force  is  applied.  The  Infra-spinatus  and  Teres  minor  rotate 
the  head  of  the  humerus  outwards ;  when  the  arm  is  raised,  they  assist  in  retaining 
it  in  that  position,  and  carrying  it  backwards.  One  of  the  most  important  uses 
of  these  three  muscles  is  the  great  protection  they  afford  to  the  shoulder-joint,  the 
Supra-spinatus  supporting  it  above,  and  preventing  displacement  of  the  head  of 
the  humerus  upwards,  whilst  the  Infra-spinatus  and  Teres  minor  protect  it  behind, 
and  prevent  dislocation  backwards.  The  Teres  major  assists  the  Latissimus  dorsi 
in  drawing  the  humerus  downwards  and  backwards  when  previously  raised,  and 
rotating  it  inwards ;  when  the  arm  is  fixed,  it  may  assist  the  Pectoral  and  Latis* 
simus  dorsi  muscles  in  drawing  the  trunk  forwards. 

Anterior  Humeral  Region. 
Coraco-brachialis.  Biceps.  Brachialis  Anticus. 

Dissection.  The  arm  being  placed  on  the  table,  with  the  front  surface  uppermost,  make  a 
vertical  incision  through  the  integument  along  the  middle  line,  from  the  middle  of  the  interval 
between  the  folds  of  the  axilla,  to  about  two  inches  below  the  elbow-joint,  where  it  should  be 
joined  by  a  transverse  incision,  extending  from  the  inner  to  the  outer  side  of  the  forearm ;  the 
two  flaps  being  reflected  on  either  side,  the  fascia  should  be  examined. 

The  deep  fascia  of  the  arm,  continuous  with  that  covering  the  shoulder  and 
front  of  the  great  Pectoral  muscle,  is  attached,  above,  to  the  clavicle,  acromion, 
and  spine  of  the  scapula ;  it  forms  a  thin,  loose,  membranous  sheath  investing  the 
muscles  of  the  arm,  sending  down  septa  between  them,  and  composed  of  fibres 
disposed  in  a  circular  or  spiral  direction,  these  being  connected  together  by 
vertical  fibres.  It  differs  in  thickness  at  different  parts,  being  thin  over  the  Biceps, 
but  thicker  where  it  covers  the  Triceps,  and  over  the  condyles  of  the  humerus ; 
and  is  strengthened  by  fibrous  aponeuroses,  derived  from  the  Pectoralis  major  and 
Latissimus  dorsi,  on  the  inner  side ;  and  from  the  Deltoid,  externally.  On  either 
side  it  gives  off  a  strong  intermuscular  septum,  which  is  attached  to  the  condyloid 
ridge  and  condyle  of  the  humerus.  These  septa  serve  to  separate  the  muscles  of 
the  anterior  from  those  of  the  posterior  brachial  region.  The  external  inter- 
muscular septum  extends  from  the  lower  part  of  the  anterior  bicipital  ridge,  along 
the  external  condyloid  ridge,  to  the  outer  condyle ;  it  is  blended  with  the  tendon 
of  the  Deltoid,  gives  attachment  to  the  Triceps*  behind,  to  the  Brachialis  anticus, 
Supinator  longus,  and  Extensor  carpi  radialis  longior,  in  front,  and  is  perforated 
by  the  musculo-spiral  nerve,  and  superior  profunda  artery.  The  internal  inter- 
muscular septum,  thicker  than  the  preceding,  extends  from  the  lower  part  of  the 
posterior  bicipital  ridge  below  the  Teres  major,  along  the  internal  condyloid 
ridge  to  the  inner  condyle ;  it  is  blended  with  the  tendon  of  the  Coraco-brachialis, 


ANTERIOR   HUMERAL   REGION.  303 

and  affords  attachment  to  the  Triceps  behind,  and  the  Brachialis  anticus  in  front. 
It  is  perforated  by  the  ulnar  nerve,  and  the  inferior  profunda  and  anastomotic 
arteries.  At  the  elbow,  the  deep  fascia  takes  attachment  to  all  the  prominent 
points  round  this  joint,  and  is  continuous  with  the  fascia  of  the  forearm.  On  the 
removal  of  this  fascia,  the  muscles  of  the  anterior  humeral  region  are  exposed. 

The  Cor aco -brachialis,  the  smallest  of  the  three  muscles  in  this  region,  is  situated 
at  the  upper  and  inner  part  of  the  arm.  It  arises  by  fleshy  fibres  from  the  apex 
of  the  coracoid  process,  in  common  with  the  short  head  of  the  Biceps,  and  from 
the  intermuscular  septum  between  the  two  muscles ;  the  fibres  pass  downwards, 
backwards,  and  a  little  outwards,  to  be  inserted  by  means  of  a  flat  tendon  into  a 
rough  ridge  at  the  middle  of  the  inner  side  of  the  shaft  of  the  humerus.  It  is 
perforated  by  the  musculo-cutaneous-  nerve.  The  inner  border  of  the  muscle 
forms  a  guide  to  the  performance  of  the  operation  of  tying  the  brachial  artery  in 
the  upper  part  of  its  course. 

Relations.  By  its  anterior  surface,  with  the  Deltoid  and  Pectoralis  major  above;  • 
at  its  insertion  it  is  crossed  by  the  brachial  vessels  and  median  nerve.  By  its  ""■»'- 
posterior  surface,  with  the  tendons  of  the  Subscapularis,  Latissimus  dorsi,  and 
Teres  major,  the  short  head  of  the  Triceps,  the  humerus,  and  the  anterior  circumflex 
vessels.  By  its  inner  border,  with  the  brachial  artery,  and  the  median  and  mus- 
culo-cutaneous nerves.  By  its  outer  border,  with  the  short  head  of  the  Biceps 
and  Brachialis  anticus. 

The  Biceps  is  a  long  fusiform  muscle,  situated  along  the  anterior  aspect  of  the 
arm  in  its  entire  length,  and  divided  above  into  two  portions  or  heads,  from  which 
circumstance  it  has  received  its  name.  The  short  head  arises  by  a  thick  flattened 
tendon  from  the  apex  of  the  coracoid  process,  in  common  with  the  Coraco- 
brachialis.  The  long  head  arises  from  the  upper  margin  of  the  glenoid  cavity, 
by  a  long  rounded  tendon,  which  is  continuous  with  the  glenoid  ligament.  This 
tendon  arches  over  the  head  of  the  humerus,  being  inclosed  in  a  special  sheath  of 
the  synovial  membrane  of  the  shoulder -joint ;  it  then  pierces  the  capsular  ligament 
at  its  attachment  to  the  humerus,  and  descends  in  the  bicipital  groove  in  which 
it  is  retained  by  a  fibrous  prolongation  from  the  tendon  of  the  Pectoralis  major. 
The  fibres  from  this  tendon  form  a  rounded  belly,  and,  about  the  middle  of  the 
arm,  join  with  the  short  portion  of  the  muscle.  The  belly  of  the  muscle,  narrow 
and  somewhat  flattened,  terminates  above  the  elbow  in  a  flattened  tendon,  which 
is  inserted  into  the  back  part  of  the  tuberosity  of  the  radius,  a  synovial  bursa 
being  interposed  between  the  tendon  and  the  front  of  the  tuberosity.  The  tendon 
of  the  muscle  is  thin  and  broad ;  as  it  approaches  the  radius  it  becomes  narrow 
and  twisted  upon  itself,  being  applied  by  a  flat  surface  to  the  back  part  of  the 
tuberosity,  and  opposite  the  bend  of  the  elbow  gives  off,  from  its  inner  side,  a 
broad  aponeurosis,  which  passes  obliquely  downwards  and  inwards  across  the 
brachial  artery,  and  is  continuous  with  the  fascia  of  the  forearm.  The  inner 
border  of  this  muscle  forms  a  guide  to  the  performance  of  the  operation  of  tying 
the  brachial  artery  in  the  middle  of  the  arm.1 

Relations.  Its  anterior  surface  is  overlapped  above  by  the  Fectoralis  major  and 
Deltoid ;  in  the  rest  of  its  extent  it  is  covered  by  the  superficial  and  deep  fasciae 
and  the  integument.  Its  posterior  surface  rests  on  the  shoulder-joint  and  humerus, 
from  which  it  is  separated  by  the  Subscapularis,  Teres  major,  Latissimus  dorsi, 
Brachialis  anticus,  and  the  musculo-cutaneous  nerve.  Its  inner  border  is  in  rela- 
tion with  the  Coraco-brachialis,  the  brachial  vessels,  and  median  nerve.  By  its 
outer  border,  with  the  Deltoid  and  Supinator  longus. 

1  A  third  head  to  the  Biceps  is  occasionally  found  (Theile  says  as  often  as  once  in  eight  or 
nine  subjects),  arising  at  the  upper  and  inner  part  of  the  Brachialis  anticus  with  the  fibres  of 
which  it  is  continuous,  and  is  inserted  into  the  bicipital  fascia,  and  inner  side  of  the  tendon  of  the 
Biceps.  In  most  cases  this  additional  slip  passes  behind  the  brachial  artery  in  its  course  down 
the  arm.  Occasionally  the  third  head  consists  of  two  slips,  which  pass  down,  one  in  front,  the 
other  behind  the  artery,  concealing  this  vessel  in  the  lower  half  of  the  arm. 


304  MUSCLES   AND   FASCIA. 

The  Brackialis  Anticus  is  a  broad  muscle,  which  covers  the  elbow-joint  and 
the  lower  half  of  the  front  of  the  humerus.  It  is  somewhat  compressed  from 
before  backward,  and  is  broader  in  the  middle  than  at  either  extremity.  It  arises 
from  the  lower  half  of  the  outer  and  inner  surfaces  of  the  shaft  of  the  humerus, 
commencing  above  at  the  insertion  of  the  Deltoid,  which  it  embraces  by  two 
angular  processes,  and  extending,  below,  to  within  an  inch  of  the  margin  of  the 
articular  surface,  and  being  limited  on  each  side  by  the  external  and  internal 
borders.  It  also  arises  from  the  intermuscular  septa  on  each  side,  but  more 
extensively  from  the  inner  than  the  outer.  Its  fibres  converge  to  a  thick  tendon, 
which  is  inserted  into  a  rough  depression  on  the  under  surface  of  the  coronoid 
process  of  the  ulna,  being  received  into  an  interval  between  two  fleshy  slips  of 
the  Flexor  digitorum  profundus. 

delations.  By  its  anterior  surface,  with  the  Biceps,  the  brachial  vessels,  mus- 
culo-cutaneous  and  median  nerves.  By  its  posterior  surface,  with  the  humerus 
and  front  of  the  elbow-joint.  By  its  inner  border,  with  the  Triceps,  ulnar  nerve, 
and  Pronator  radii  teres,  from  which  it  is  separated  by  the  intermuscular  septum. 
By  its  outer  border,  with  the  musculo-spiral  nerve,  radial  recurrent  artery,  the 
Supinator  longus,  and  Extensor  carpi  radialis  longior. 

Nerves.  The  muscles  of  this  group  are  supplied  by  the  Tnusculo-cutaneous 
nerve.  The  Brachialis  anticus  receives  an  additional  filament  from  the  musculo- 
spiral. 

Actions.  The  Coraco-brachialis  draws  the  humerus  forwards  and  inwards,  and 
at  the  same  time  assists  in  elevating  it  towards  the  scapula.  The  Biceps  and 
Brachialis  anticus  are  flexors  of  the  forearm ;  the  former  muscle  is  also  a  supi- 
nator, and  serves  to  render  tense  the  fascia  of  the  forearm  by  means  of  the  broad 
aponeurosis  given  off  from  its  tendon.  When  the  forearm  is  fixed,  the  Biceps 
and  Brachialis  anticus  flex  the  arm  upon  the  forearm,  as  is  seen  in  efforts  of 
climbing.     The  Brachialis  anticus  forms  an  important  defence  to  the  elbow-joint. 

Posterior  Humeral  Eegion. 
Triceps.  Subanconeus. 

The  Triceps  is  situated  on  the  back  of  the  arm,  extending  the  entire  length  of 
the  posterior  surface  of  the  humerus.  It  is  of  large  size,  and  divided  above  into 
three  parts;  hence  the  name  of  the  muscle.  These  three  portions  have  been 
named,  the  middle  or  long  head,  the  external,  and  the  internal  head. 

The  middle  or  long  head  arises,  by  a  flattened  tendon,  from  a  rough  triangular 
depression,  immediately  below  the  glenoid  cavity,  being  blended  at  its  upper  part 
with  the  capsular  and  glenoid  ligaments ;  the  muscular  fibres  pass  downwards 
between  the  two  other  portions  of  the  muscle,  and  join  with  them  in  the  common 
tendon  of  insertion. 

The  external  head  arises  from  the  posterior  surface  of  the  shaft  of  the  humerus, 
between  the  insertion  of  the  Teres  minor  and  the  upper  part  of  the  musculo-spiral 
groove,  from  the  external  border  of  the  humerus  and  external  intermuscular 
septum ;  the  fibres  from  this  origin  converging  towards  the  common  tendon  of 
insertion. 

The  internal  head  arises  from  the  posterior  surface  of  the  shaft  of  the 
humerus,  below  the  groove  for  the  musculo-spiral  nerve,  commencing  above, 
narrow  and  pointed,  below  the  insertion  of  the  Teres  major,  and  extending  to 
within  an  inch  of  the  trochlear  surface ;  it  also  arises  from  the  internal  border 
and  internal  intermuscular  septum.  The  fibres  of  this  portion  of  the  muscle  are 
directed,  some  downwards  to  the  olecranon,  whilst  others  converge  to  the  common 
tendon  of  insertion. 

The  common  tendon  of  the  Triceps  commences  about  the  middle  of  the  back 
part  of  the  muscle ;  it  consists  of  two  aponeurotic  laminae,  one  of  which  is  sub- 
cutaneous, and  covers  the  posterior  surface  of  the  muscle  for  the  lower  half  of  its 
extent,  the  other  is  more  deeply  seated  in  the  substance  of  the  muscle.     After 


POSTERIOR   HUMERAL   REGION.  305 

receiving  the  attachment  of  the  muscular  fibres,  they  join  together  above  the 
elbow,  and  are  inserted  into  the  back  part  of  the  upper  surface  of  the  olecranon 
process,  a  small  bursa,  occasionally  multilocular,  being  interposed  between  the 
tendon  and  the  front  of  this  surface. 

The  long  head  of  the  Triceps  descends  between  the  Teres  minor  and  Teres 
major,  dividing  the  triangular  space  between  these  two  muscles  and  the  humerus 
into  two  smaller  spaces,  one  triangular,  the  other  quadrangular  (fig.  171).  The 
triangular  space  transmits  the  dorsalis  scapulae  vessels ;  it  is  bounded  by  the  Teres 
minor  above,  the  Teres  major  below,  and  the  scapular  head  of  the  Triceps,  ex- 
ternally :  the  quadrangular  space  transmits  the  posterior  circumflex  vessels  and 
nerve;  it  is  bounded  by  the  Teres  minor  above,  the  Teres  major  below,  the 
scapular  head  of  the  Triceps  internally,  and  the  humerus  externally. 

Relations.  Its  posterior  surface  is  overlapped  by  the  Deltoid  above,  superficial 
in  the  rest  of  its  extent.  By  its  anterior  surface,  with  the  humerus,  musculo-spiral 
nerve,  superior  profunda  vessels,  and  back  part  of  the  elbow-joint.  Its  middle  or 
long  head  is  in  relation,  behind,  with  the  Deltoid  and  Teres  minor ;  in  front,  with 
the  Subscapularis,  Latissimus  dorsi,  and  Teres  major. 

The  Subanconeus  is  a  small  muscle,  distinct  from  the  Triceps,  and  analogous  to 
the  Subcrureus  in  the  lower  limb.  It  may  be  exposed  by  removing  the  Triceps 
from  the  lower  part  of  the  humerus.  It  consists  of  one  or  two  slender  fasciculi, 
which  arise  from  the  humerus,  immediately  above  the  olecranon  fossa,  and  are 
inserted  into  the  posterior  ligament  of  the  elbow-joint. 

Nerves.  The  Triceps  and  Subanconeus  are  supplied  by  the  musculo-spiral 
nerve. 

Actions.  The  Triceps  is  the  great  Extensor  muscle  of  the  forearm ;  when  the 
forearm  is  flexed,  it  serves  to  draw  it  into  a  right  line  with  the  arm.  It  is  the 
direct  antagonist  of  the  Biceps  and  Brachialis  anticus.  When  the  arm  is  extended, 
the  long  head  of  the  muscle  may  assist  the  Teres  major  and  Latissimus  dorsi  in 
drawing  the  humerus  backwards.  The  long  head  of  the  Triceps  protects  the 
under  part  of  the  shoulder-joint,  and  prevents  displacement  of  the  head  of  the 
humerus  downwards  and  backwards. 

Muscles  of  the  Forearm. 

Dissection.  To  dissect  the  forearm,  place  the  limb  in  the  position  indicated  in  fig.  168 ;  make 
a  vertical  incision  along  the  middle  line  from  the  elbow  to  the  wrist,  and  connect  each  extremity 
with  a  transverse  incision;  the  .flaps  of  integument  being  removed,  the  fascia  of  the  forearm  is 
exposed. 

The  deep  fascia  of  the  forearm,  continuous  above  with  that  inclosing  the  arm, 
is  a  dense  highly  glistening  aponeurotic  investment,  which  forms  a  general  sheath 
inclosing  the  muscles  in  this  region ;  it  is  attached  behind  to  the  olecranon  and 
posterior  border  of  the  ulna,  and  gives  off  from  its  inner  surface  numerous  inter- 
muscular septa,  which  inclose  each  muscle  separately.  It  consists  of  circular  and 
oblique  fibres,  connected  together  at  right  angles  by  numerous  vertical  fibres.  It 
is  much  thicker  on  the  dorsal  than  on  the  palmar  surface,  and  at  the  lower  than 
at  the  upper  part  of  the  forearm,  and  is  strengthened  by  tendinous  fibres,  derived 
from  the  Brachialis  anticus  and  Biceps  in  front,  and  from  the  Triceps  behind. 
Its  inner  surface  gives  origin  to  muscular  fibres,  especially  at  the  upper  part  of 
the  inner  and  outer  sides  of  the  forearm,  and  forms  the  boundaries  of  a  series  of 
conical-shaped  fibrous  cavities,  in  which  the  muscles  in  this  region  are  contained. 
Besides  the  vertical  septa  separating  each  muscle,  transverse  septa  are  given  off 
both  on  the  anterior  and  posterior  surfaces  of  the  forearm,  separating  the  deep 
from  the  superficial  layer  of  muscles.  Numerous  apertures  exist  in  the  fascia  for 
the  passage  of  vessels  and  nerves ;  one  of  these,  of  large  size,  situated  at  the  front 
of  the  elbow,  serves  for  the  passage  of  a  communicating  branch  between  the 
superficial  and  deep  veins. 

The  muscles  of  the  forearm  may  be  subdivided  into  groups  corresponding  to 
20 


306  MUSCLES  AND   FASCIJE. 

the  region  they  occupy.  One  group  occupies  the  inner  and  anterior  aspect  of  the 
forearm,  and  comprises  the  Flexor  and  Pronator  muscles.  Another  group  oc- 
cupies the  outer  side  of  the  forearm ;  and  a  third,  its  posterior  aspect.  The  two 
latter  groups  include  all  the  Extensor  and  Supinator  muscles. 


Anterior  Brachial  Begion. 


Fig.  172.. 
arm. 


-Front  of  the  Left  Fore- 
Superficial  Muscles. 


Superficial  Layer. 

Pronator  radii  teres. 
Flexor  carpi  radialis. 
Palmaris  longus. 
Flexor  carpi  ulnaris. 
Flexor  sublimis  digitorum. 

These  muscles  take  origin  from 
the  internal  condyle  by  a  common 
tendon. 

The  Pronator  Radii  Teres  arises  by 
two  heads.  One,  the  largest  and  most 
superficial,  arises  from  the  humerus, 
immediately  above  the  internal  condyle, 
and  from  the  tendon  common  to  the 
origin  of  the  other  muscles;  also  from 
the  fascia  of  the  forearm,  and  inter- 
muscular septum  between  it  and  the 
Flexor  carpi  radialis.  The  other  head 
is  a  thin  fasciculus,  which  arises  from 
the  inner  side  of  the  coronoid  process 
of  the  ulna,  joining  the  preceding  at  an 
acute  angle.  Between  the  two  heads 
passes  the  median  nerve.  The  muscle 
passes  obliquely  across  the  forearm 
from  the  inner  to  the  outer  side,  and 
terminates  in  a  flat  tendon,  which 
turns  over  the  outer  margin  of  the 
radius,  and  is  inserted  into  a  rough 
ridge  at  the  middle  of  the  outer  surface 
of  the  shaft  of  that  bone. 

Relations.  By  its  anterior  surface, 
with  the  deep  fascia,  the  Supinator 
longus,  and  the  radial  vessels  and 
nerve.  By  its  posterior  surface,  with 
the  Brachialis  anticus,  Flexor  sublimis 
digitorum,  the  median  nerve,  and  ulnar 
artery.  Its  outer  border  forms  the 
inner  boundary  of  a  triangular  space, 
in  which  are  placed  the  brachial  artery, 
median  nerve,  and  tendon  of  the 
Biceps  muscle.  Its  inner  border  is 
in  contact  with  the  Flexor  carpi 
radialis. 
The  Flexor  Carpi  Radialis  lies  on  the  inner  side  of  the  preceding  muscle. 
It  arises  from  the  internal  condyle  by  the  common  tendon,  from  the  fascia  of  the 
forearm,  and  from  the  intermuscular  septa  between  it  and  the  Pronator  radii  teres, 
on  the  inside;  the  Palmaris  longus,  externally;  and  the  Flexor  sublimis  digitorum, 
beneath.     Slender  and  aponeurotic  in  structure  at  its  commencement,  it  increases 


ANTERIOR  BRACHIAL   REGION.  307 

in  size,  and  terminates  in  a  tendon  which  forms  the  lower  two-thirds  of  its  struc- 
ture. This  tendon  passes  through  a  canal  on  the  outer  side  of  the  annular  liga- 
ment, runs  through  a  groove  in  the  os  trapezium,  converted  into  a  canal  by  a 
fibrous  sheath  lined  by  a  synovial  membrane,  and  is  inserted  into  the  base  of 
the  metacarpal  bone  of  the  index-finger.  The  radial  artery  lies  between  the 
tendon  of  this  muscle  and  the  Supinator  longus,  and  may  easily  be  secured  in 
this  situation. 

Relations.  By  its  superficial  surface,  with  the  deep  fascia  and  the  integument. 
By  its  deep  surface,  with  the  Flexor  sublimis  digitorum,  Flexor  longus  pollicis, 
and  wrist-joint.  By  its  outer  border,  with  the  Pronator  radii  teres,  and  the  radial 
vessels.  By  its  inner  border,  with  the  Palmaris  longus  above,  the  median  nerve 
below. 

The  Palmaris  Longus  is  a  slender  fusiform  muscle,  lying  on  the  inner  side  of 
the  preceding.  It  arises  from  the  inner  condyle  of  the  humerus  by  the  common 
tendon,  from  the  deep  fascia,  and  intermuscular  septa  between  it  and  the  adjacent 
muscles.  It  terminates  in  a  slender  flattened  tendon,  which  is  inserted  into  the 
annular  ligament,  expanding  to  end  in  the  palmar  fascia. 

Variation!1;.  This  muscle  is  often  absent;  when  present,  it  exhibits  many  varieties.  Its  fleshy 
belly  is  sometimes  very  long,  or  it  may  occupy  the  middle  of  the  muscle,  which  is  tendinous  at 
either  extremity ;  or  it  may  be  muscular  at  its  lower  extremity,  its  upper  part  being  tendinous. 
Occasionally  there  is  a  second  Palmaris  longus  placed  on  the  inner  side  of  the  preceding,  termi- 
nating, below,  partly  in  the  annular  ligament  or  fascia,  and  partly  in  the  small  muscles  of  the 
little  finger. 

Relations.  By  its  anterior  surface,  with  the  deep  fascia.  By  its  posterior  surface, 
with  the  Flexor  sublimis  digitorum.  Internally,  with  the  Flexor  carpi  ulnarisi 
Externally,  with  the  Flexor  carpi  radialis. 

The  Flexor  Carpi  Ulnaris  lies  along  the  ulnar  side  of  the  forearm.  It  arises  by 
two  heads,  separated  by  a  tendinous  arch,  beneath  which  passes  the  ulnar  nerve, 
and  posterior  ulnar  recurrent  artery.  One  head  arises  from  the  inner  condyle  of 
the  humerus,  by  the  common  tendon ;  the  other,  from  the  inner  margin  of  the 
olecranon,  by  an  aponeurosis  from  the  upper  two-thirds  of  the  posterior  border  of 
the  ulna,  and  from  the  intermuscular  septum  between  it  and  the  Flexor  sublimis 
digitorum.  The  fibres  terminate  in  a  tendon,  which  occupies  the  anterior  part  of 
the  lower  half  of  the  muscle,  and  is  inserted  into  the  pisiform  bone,  some  fibres 
being  prolonged  to  the  annular  ligament  and  base  of  the  metacarpal  bone  of  the 
little  finger.  The  ulnar  artery  lies  on  the  outer  side  of  the  tendon  of  this  muscle, 
in  the  lower  two-thirds  of  the  forearm ;  the  tendon  forming  a  guide  to  the  opera- 
tion of  including  this  vessel  in  a  ligature  in  this  situation. 

Relations.  By  its  anterior  surface,  with  the  deep  fascia,  with  which  it  is 
intimately  connected  for  a  considerable  extent.  By  its  posterior  surface,  with  the 
Flexor  sublimis,  the  Flexor  profundus,  the  Pronator  quadratus,  and  the  ulnar 
vessels  and  nerve.  By  its  outer  or  radial  border,  with  the  Palmaris  longus,  above; 
with  the  ulnar  vessels  and  nerve,  below. 

The  Flexor  Digitorum  Sublimis  is  placed  beneath  the  preceding  muscles ;  these 
therefore  require  to  be  removed  before  its  attachment  is  brought  into  view.  It 
is  the  largest  of  the  muscles  of  the  superficial  layer,  and  arises  by  three  heads. 
One  from  the  internal  condyle  of  the  humerus  by  the  common  tendon,  from  the 
internal  lateral  ligament  of  the  elbow-joint,  and  from  the  intermuscular  septum 
common  to  it  and  the  preceding  muscles.  The  second  head  arises  from  the  inner 
side  of  the  coronoid  process  of  the  ulna,  above  the  ulnar  origin  of  the  Pronator 
radii  teres.  The  third  head  arises  from  the  oblique  line  of  the  radius,  extending 
from  the  tubercle  to  the  insertion  of  the  Pronator  radii  teres.  The  fibres  pass 
vertically  downwards,  forming  a  broad  and  thick  muscle,  which  divides  into  four 
tendons  about  the  middle  of  the  forearm;  as  these  tendons  pass  beneath  the 
annular  ligament  into  the  palm  of  the  hand,  they  are  arranged  in  pairs,  the  anterior 
pair  corresponding  to  the  middle  and  ring  fingers;  the  posterior  pair  to  the  index 


308  MUSCLES   AND   FASCIAE. 

and  little  fingers.  The  tendons  diverge  from  one  another  as  thej  pass  onwards, 
and  are  finally  inserted  into  the  lateral  margins  of  the  second  phalanges,  about 
their  centre.  Opposite  the  base  of  the  first  phalanges,  each  tendon  divides,  so  as 
to  leave  a  fissured  interval,  between  which  passes  one  of  the  tendons  of  the  Flexor 
profundus,  and  they  both  enter  an  osseo-aponeurotic  canal,  formed  by  a  strong 
fibrous  band  which  arches  across  them,  and  is  attached  on  each  side  to  the  margins 
of  the  phalanges.  The  two  portions  into  which  the  tendon  of  the  Flexor  sublimis 
divides,  so  as  to  admit  of  the  passage  of  the  deep  flexor,  expand  somewhat,  and 
form  a  grooved  channel,  into  which  the  accompanying  deep  flexor  tendon  is 
received ;  the  two  divisions  then  unite,  and  finally  subdivide  a  second  time  to  be 
inserted  into  the  fore  part  and  sides  of  the  second  phalanges.  The  tendons,  whilst 
contained  in  the  fibro-osseous  canals,  are  connected  to  the  phalanges  by  slender 
tendinous  filaments,  called  vincula  accessoria  tendinum.  A  synovial  sheath  invests 
the  tendons  as  they  pass  beneath  the  annular  ligament ;  a  prolongation  from  which 
surrounds  each  tendon  as  it  passes  along  the  phalanges. 

Relations.  In  the  Forearm.  By  its  anterior  surface,  with  the  deep  fascia  and 
all  the  preceding  superficial  muscles.  By  its  posterior  surface,  with  the  Flexor 
profundus  digitorum,  Flexor  longus  pollicis,  the  ulnar  vessels  and  nerve,  and  the 
median  nerve.  In  the  Hand,  its  tendons  are  in  relation,  in  front,  with  the  palmar 
fascia,  superficial  palmar  arch,  and  the  branches  of  the  median  nerve;  behind, 
with  the  tendons  of  the  deep  Flexor  and  the  Lumbricales. 


Anterior  Brachial  Eegiox. 

Deep  Layer. 

Flexor  Profundus  Digitorum.  Flexor  Longus  Pollicis. 

Pronator  Quadratus. 

Dissection.  Divide  each  of  the  superficial  muscles  at  its  centre,  and  turn  either  end  aside ;  the 
deep  layer  of  muscles,  together  with  the  median  nerve  and  ulnar  vessels,  will  then  be  exposed: 

The  Flexor  Profundus  Digitorum  (perforans)  is  situated  on  the  ulnar  side  of  the 
forearm,  immediately  beneath  the  superficial  Flexors.  It  arises  from  the  upper 
two-thirds  of  the  anterior  and  inner  surfaces  of  the  shaft  of  the  ulna,  embracing, 
above,  the  insertion  of  the  Brachialis  anticus,  and  extending,  below,  to  within  a 
short  distance  of  the  Pronator  quadratus.  It  also  arises  from  a  depression  on  the 
inner  side  of  the  coronoid  process,  by  an  aponeurosis  from  the  upper  two-thirds 
of  the  posterior  border  of  the  ulna,  and  from  the  ulnar  half  of  the  interosseous 
membrane.  The  fibres  form  a  fleshy  belly  of  considerable  size,  which  divides 
into  four  tendons,  which  pass  under  the  annular  ligament  beneath  the  tendons 
of  the  Flexor  sublimis.  Opposite  the  first  phalanges,  the  tendons  pass  between 
the  two  slips  of  the  tendons  of  the  Flexor  sublimis,  and  are  finally  inserted  into 
the  bases  of  the  last  phalanges.  The  tendon  of  the  index  finger  is  distinct ;  the 
rest  are  connected  together  by  cellular  tissue  and  tendinous  slips,  as  far  as  the 
palm  of  the  hand. 

Four  small  muscles,*  the  Lumbricales,  are  connected  with  the  tendons  of  the 
Flexor  profundus  in  the  palm.  They  will  be  described  with  the  muscles  in  that 
region. 

Relations.  By  its  anterior  surface,  in  the  forearm,  with  the  Flexor  sublimis 
digitorum,  the  Flexor  carpi  ulnaris,  the  ulnar  vessels  and  nerve,  and  the  median 
nerve;  and  in  the  hand,  with  the  tendons  of  the  superficial  Flexor.  By  its 
posterior  surface,  in  the  forearm,  with  the  ulna,  the  interosseous  membrane,  the 
Pronator  quadratus ;  and  in  the  hand,  with  the  Interossei,  Adductor  pollicis,  and 
deep  palmar  arch.  By  its  ulnar  border,  with  the  Flexor  carpi  ulnaris.  By  its 
radial  border,  with  the  Flexor  longus  pollicis,  the  anterior  interosseous  vessels  and 
nerve  being  interposed. 


ANTERIOR   BRACHIAL   REGION. 


309 


The  Flexor  Longus  Polli- 
cis  is  situated  on  the  radial 
side  of  the  forearm,  lying  on 
the  same  plane  as  the  preced- 
ing. It  arises  from  the  up- 
per two-thirds  of  the  grooved 
anterior  surface  of  the  shaft 
of  the  radius;  commencing, 
above,  immediately  below  the 
tuberosity  and  oblique  line, 
and  extending,  below,  to  with- 
in a  short  distance  of  the 
Pronator  quadratus.  It  also 
arises  from  the  adjacent  part 
of  the  interosseous  membrane, 
and  occasionally  by  a  fleshy 
slip  from  the  inner  side  of  the 
base  of  the  coronoid  process. 
The  fibres  pass  downwards 
and  terminate  in  a  flattened 
tendon,  which  passes  beneath 
the  annular  ligament,  is  then 
lodged  in  the  interspace  be- 
tween the  two  heads  of  the 
Flexor  brevis  pollicis,  and 
entering  a  tendino-osseous  ca- 
nal, similar  to  those  for  the 
other  flexor  tendons,  is  in- 
serted into  the  base  of  the  last 
phalanx  of  the  thumb. 

Relations.  By  its  anterior 
surface,  with  the  Flexor  sub- 
limis  digitorum,  Flexor  carpi 
radialis,  Supinator  longus,  and 
radial  vessels.  By  its  poste- 
rior surface,  with  the  radius, 
interosseous  membrane,  and 
Pronator  quadratus.  By  its 
ulnar  border,  with  the  Flexor 
profundus  digitorum,  from 
which  it  is  separated  by  the 
anterior  interosseous  vessels 
and  nerve. 

The  Pronator  Quadratus 
is  a  small,  flat  muscle,  quadri- 
lateral in  form,  extending 
transversely  across  the  front 
of  the  radius  and  ulna,  above 
their  carpal  extremities.  It 
arises  from  the  oblique  line 
on  the  lower  fourth  of  the 
anterior  surface  of  the  shaft 
of  the  ulna,  and  the  surface  of 
bone  immediately  below  it; 
from  the  internal  body  of  the 
ulna;  and  from  a  strong  apo- 
neurosis    which    covers    the 


Fig.  173. — Front  of  the  Left  Forearm.     Deep  Muscles. 


310  MUSCLES   AND   FASCIAE. 

inner  third  of  the  muscle.  The  fibres  pass  horizontally  outwards,  to  be  inserted 
into  the  lower  fourth  of  the  anterior  surface  and  external  border  of  the  shaft  of 
the  radius. 

Relations.  By  its  anterior  surface,  with  the  Flexor  profundus  digitorum,  the 
Flexor  longus  pollicis,  Flexor  carpi  radialis,  and  the  radial  vessels.  By  its  poste- 
rior surface,  with  the  radius,  ulna,  and  interosseous  membrane. 

Nerves.  All  the  muscles  of  the  superficial  layer  are  supplied  by  the  median 
nerve,  excepting  the  Flexor  carpi  ulnaris,  which  is  supplied  by  the  ulnar.  Of  the 
deep  layer,  the  Flexor  profundus  digitorum  is  supplied  conjointly  by  the  ulnar 
and  anterior  interosseous  nerves,  the  Flexor  longus  pollicis  and  Pronator  quadratus 
by  the  anterior  interosseous  nerve. 

Actions.  These  muscles  act  upon  the  forearm,  the  wrist,  and  hand.  Those 
acting  on  the  forearm  are  the  Pronator  radii  teres  and  Pronator  quadratus,  which 
rotate  the  radius  upon  the  ulna,  rendering  the  hand  prone ;  when  pronation  has 
been  fully  effected,  the  Pronator  radii  teres  assists  the  other  muscles  in  flexing  the 
forearm.  The  flexors  of  the  wrist  are  the  Flexor  carpi  ulnaris  and  radialis,  and 
the  flexors  of  the  phalanges  are  the  Flexor  sublimis  and  Profundus  digitorum ; 
the  former  flexing  the  second  phalanges,  and  the  latter  the  last.  The  Flexor  longus 
pollicis  flexes  the  last  phalanx  of  the  thumb.  The  three  latter  muscles,  after  flex- 
ing the  phalanges,  by  continuing  their  action,  act  upon  the  wrist,  assisting  the 
ordinary  flexors  of  this  joint ;  and  all  assist  in  flexing  the  forearm  upon  the  arm. 
The  Palmaris  longus  is  a  tensor  of  the  palmar  fascia ;  when  this  action  has  been 
fully  effected,  it  flexes  the  hand  upon  the  forearm. 

Badial  Begiox. 

Supinator  Longus.  Extensor  Carpi  Badialis  Longior. 

Extensor  Carpi  Badialis  Brevior. 

Dissection.  Divide  the  internment  in  the  same  manner  as  in  the  dissection  of  the  anterior 
brachial  region  ;  and  after  having  examined  the  cutaneous  vessels  and  nerves  and  deep  fascia, 
they  should  be  removed,  when  the  muscles  of  this  region  will  be  exposed.  The  removal  of  the 
fascia  will  be  considerably  facilitated  by  detaching  it  from  below  upwards.  Great  care  should  be 
taken  to  avoid  cutting  across  the  tendons  of  the  muscles  of  the  thumb. 

The  Supinator  Longus  is  the  most  superficial  muscle  on  the  radial  side  of  the 
forearm,  fleshy  for  the  upper  two-thirds  of  its  extent,  tendinous  below.  It  arises 
from  the  upper  two-thirds  of  the  external  condyloid  ridge  of  the  humerus,  and 
from  the  external  intermuscular  septum,  being  limited  above  by  the  musculo-spiral 
groove.  The  fibres  terminate  above  the  middle  of  the  forearm  in  a  flat  tendon, 
which  is  inserted  into  the  base  of  the  styloid  process  of  the  radius. 

Relations.  By  its  superficial  surface,  with  the  integument  and  fascia  for  the 
greater  part  of  its  extent ;  near  its  insertion  it  is  crossed  by  the  Extensor  ossis--  - 
metacarpi  pollicis  and  the  Extensor  primi  internodii  pollicis.  By  its  deep  surface, 
with  the  humerus,  the  Extensor  carpi  radialis  longior  and  brevior,  the  insertion  of 
the  Pronator  radii  teres,  and  the  Supinator  brevis.  By  its  inner  border,  above  the 
elbow,  with  the  Brachialis  anticus,  the  musculo-spiral  nerve,  and  radial  recurrent 
artery ;  and  in  the  forearm,  with  the  radial  vessels  and  nerve. 

The  Hlxtensor  Carpi  Radialis  Longior  is  placed  partly  beneath  the  preceding 
muscle.  It  arises  from  the  lower  third  of  the  external  condyloid  ridge  of  the 
humerus,  and  from  the  external  intermuscular  septum.  The  fibres  terminate  at 
the  upper  third  of  the  forearm  in  a  flat  tendon,  which  runs  along  the  outer  border 
of  the  radius,  beneath  the  extensor  tendons  of  the  thumb ;  it  then  passes  through 
a  groove  common  to  it  and  the  Extensor  carpi  radialis  brevior,  immediately  behind 
the  styloid  process ;  and  is  inserted  into  the  base  of  the  metacarpal  bone  of  the 
index-finger,  its  radial  side. 

Relations^  By  its  superficial  surface,  with  the  Supinator  longus,  and  fascia 
of  the  forearm.     Its  outer  side  is  crossed  obliquely  by  the  extensor  tendons  of 


RADIAL   REGIOX. 


311 


the  thumb.  By  its  deep 
surface,  with  the  elbow-joint, 
the  Extensor  carpi  radialis 
brevior,  and  back  part  of  the 
wrist. 

The  Extensor  Carpi  Ra- 
dialis Brevior  is  shorter,  as 
its  name  implies,  and  thicker 
than  the  preceding  muscle, 
beneath  which  it  is  placed. 
It  arises  from  the  external 
condyle  of  the  humerus  by  a 
tendon  common  to  it  and  the 
three  muscles  next  to  be  de- 
scribed ;  from  the  external  late- 
ral ligament  of  the  elbow-joint; 
from  a  strong  aponeurosis 
which  covers  its  surface;  and 
from  the  intermuscular  septa 
between  it  and  the  adjacent 
muscles.  The  fibres  terminate 
about  the  middle  of  the  forearm 
in  a  flat  tendon,  which  is  closely 
connected  with  that  of  the 
preceding  muscle,  accompanies 
it  to  the  wrist,  lying  in  the 
same  groove  on  the  posterior 
surface  of  the  radius;  passes 
beneath  the  annular  ligament, 
and,  diverging  somewhat  from 
its  fellow,  is  inserted  into  the 
base  of  the  metacarpal  bone 
of  the  middle  finger,  its  radial 
side. 

The  tendons  of  the  two  pre- 
ceding muscles  pass  through 
the  same  compartment  of  the 
annular  ligament,  are  lubri- 
cated by  a  single  synovial 
membrane,  but  separated  from 
each  other  by  a  small  vertical 
ridge  of  bone,  as  they  lie  in 
the  groove  at  the  back  of  the 
radius. 

Relations.  By  its  super- 
ficial surface,  with  the  Ex- 
tensor carpi  radialis  longior, 
and  crossed  by  the  Extensor 
muscles  of  the  thumb.  By 
its  deep  surface,  with  the 
Supinator  brevis,  tendon  of 
the  Pronator  radii  teres, 
radius,  and  wrist-joint.  By 
its  ulnar  border,  with  the 
Extensor  communis  digito- 
rum. 


Fig.  174.— Posterior  Surface  of  Forearm.   Superficial  Muscles. 


312  MUSCLES   AND   FASCIA. 

Posterior  Brachial  Eegion-. 

Superficial  Layer. 

Extensor  Communis  Digitorum.  Extensor  Carpi  Ulnaris. 

Extensor  Minimi  Digiti.  Anconeus. 

The  Extensor  Communis  Digitorum  is  situated  at  the  "back  part  of  the  forearm. 
It  arises  from  the  external  condyle  of  the  humerus  by  the  common  tendon,  from 
the  deep  fascia,  and  the  intermuscular  septa  between  it  and  the  adjacent  muscles. 
Just  below  the  middle  of  the  forearm  it  divides  into  three  tendons,  which  pass, 
together  with  the  Extensor  indicis,  through  a  separate  compartment  of  the  annular 
ligament,  lubricated  by  a  synovial  membrane.  The  tendons  then  diverge,  the 
innermost  one  dividing  into  two ;  and  all,  after  passing  across  the  back  of  the  hand, 
are  inserted  into  the  second  and  third  phalanges  of  the  fingers  in  the  following 
manner :  Each  tendon,  opposite  its  corresponding  metacarpo-phalangeal  articula- 
tion, becomes  narrow  and  thickened,  gives  off  a  thin  fasciculus  upon  each  side  of 
the  joint,  and  spreads  out  into  a  broad  aponeurosis,  which  covers  the  whole  of  the 
dorsal  surface  of  the  first  phalanx;  being  reinforced,  in  this  situation,  by  the  ten- 
dons of  the  Interossei  and  Lumbricales,  Opposite  the  first  phalangeal  joint,  this 
aponeurosis  divides  into  three  slips,  a  middle,  and  two  lateral ;  the  former  is  in- 
serted into  the  base  of  the  second  phalanx ;  and  the  two  lateral,  which  are  continued 
onwards  along  the  sides  of  the  second  phalanx,  unite  by  their  contiguous  margins, 
and  are  inserted  into  the  upper  surface  of  the  last  phalanx.  The  tendons  of  the 
middle,  ring,  and  little  fingers  are  connected  together,  as  they  cross  the  hand,  by 
small  oblique  tendinous  slips.  The  tendons  of  the  index  and  little  fingers  also 
receive,  before  their  division,  the  special  extensor  tendons  belonging  to  them. 

Relations.  By  its  superficial  surface,  with  the  fascia  of  the  forearm  and  hand, 
the  posterior  annular  ligament,  and  integument.  By  its  deep  surface,  with  the 
Supinator  brevis,  the  Extensor  muscles  of  the  thumb  and  index-finger,  posterior 
interosseous  vessels  and  nerve,  the  wrist-joint,  carpus,  metacarpus,  and  phalanges. 
By  its  radial  border,  with  the  Extensor  carpi  radialis  brevior.  By  its  ulnar 
border,  with  the  Extensor  minimi  digiti,  and  Extensor  carpi  ulnaris. 

The  Extensor  Minimi  Digiti  is  a  slender  muscle,  placed  on  the  inner  side  of 
the  Extensor  communis,  with  which  it  is  generally  connected.  It  arises  from  the 
common  tendon  by  a  thin  tendinous  slip ;  and  from  the  intermuscular  septa  between 
it  and  the  adjacent  muscles.  Its  tendon  runs  through  a  separate  compartment  in 
the  annular  ligament  behind  the  inferior  radio-ulnar  joint,  subdivides  into  two 
as  it  crosses  the  hand,  and,  at  the  metacarpo-phalangeal  articulation,  unites  with 
the  tendon  derived  from  the  long  Extensor.  The  common  tendon  then  spreads 
into  a  broad  aponeurosis,  which  is  inserted  into  the  second  and  third  phalanges  of 
the  little  finger  in  a  similar  manner  to  the  common  extensor  tendons  of  the  other 
fingers. 

The  Extensor  Carpi  Ulnaris  is  the  most  superficial  muscle  on  the  ulnar  side  of 
the  forearm.  It  arises  from  the  external  condyle  of  the  humerus,  by  the  common 
tendon ;  from  the  middle  third  of  the  posterior  border  of  the  ulna  below  the  An- 
coneus, and  from  the  fascia  of  the  forearm.  This  muscle  terminates  in  a  tendon, 
which  runs  through  a  groove  behind  the  styloid  process  of  the  ulna,  passes  through 
a  separate  compartment  in  the  annular  ligament,  and  is  inserted  into  the  base  of 
the  metacarpal  bone  of  the  little  finger. 

Relations.  By  its  superficial  surface,  with  the  fascia  of  the  forearm.  By  its 
deep  surface,  with  the  ulna,  and  the  muscles  of  the  deep  layer. 

The  Anconeus  is  a  small  triangular  muscle,  placed  behind  and  below  the  elbow- 
joint,  and  appears  to  be  a  continuation  of  the  external  portion  of  the  Triceps.  It 
arises  by  a  separate  tendon  from  the  back  part  of  the  outer  condyle  of  the  humerus; 
and  is  inserted  into  the  side  of  the  olecranon,  and  upper  third  of  the  posterior 
surface  of  the  shaft  of  the  ulna ;  its  fibres  diverge  from  their  origin,  the  upper 
ones  being  directed  transversely,  the  lower  obliquely  inwards. 


POSTERIOR  BRACHIAL   REGION".  313 

Relations.  By  its  superficial  surface,  with  a  strong  fascia  derived  from  the 
Triceps.  By  its  deep  surface,  with  the  elbow-joint,  the  orbicular  ligament,  the 
ulna,  and  a  small  portion  of  the  Supinator  brevis. 

Posterior  Brachial  Region". 
Deep  Layer. 
Supinator  Brevis.  Extensor  Primi  Internodii  Pollicis. 

Extensor  Ossis  Metacarpi  Pollicis.  Extensor  Secundi  Internodii  Pollicis. 

Extensor  Indicis. 

The  Supinator  Brevis  is  a  broad  muscle,  of  a  hollow  cylindrical  form,  curved 
round  the  upper  third  of  the  radius.  It  arises  from  the  external  condyle  of  the 
humerus,  from  the  external  lateral  ligament  of  the  elbow-joint,  and  the  orbicular 
ligament  of  the  radius,  from  an  oblique  ridge  on  the  ulna,  extending  down  from 
the  posterior  extremity  of  the  lesser  sigmoid  cavity,  and  from  the  triangular 
depression  in  front  of  it ;  and  it  also  arises  from  a  tendinous  expansion  which  covers 
its  surface.  The  muscle  surrounds  the  upper  part  of  the  radius ;  the  upper  fibres 
forming  a  sling-like  fasciculus,  which  encircles  the  neck  of  the  radius  above  the 
tuberosity,  to  be  attached  to  the  back  part  of  its  inner  surface ;  the  middle  fibres 
are  attached  to  the  outer  edge  of  the  bicipital  tuberosity ;  the  lower  fibres  to  the 
oblique  line,  as  low  down  as  the  insertion  of  the  Pronator  radii  teres.  This 
muscle  is  pierced  by  the  posterior  interosseous  nerve. 

Relations.  By  its  superficial  surface,  with  the  superficial  Extensor  and  Supi- 
nator muscles,  and  the  radial  vessels  and  nerve.  By  its  deep  surface,  with  the 
elbow-joint,  the  interosseous  membrane,  and  the  radius. 

The  Extensor  Ossis  Metacarpi  Pollicis  is  the  most  external  and  the  largest  of 
the  deep  Extensor  muscles,  lying  immediately  below  the  Supinator  brevis,  with 
which  it  is  sometimes  united.  It  arises  from  the  posterior  surface  of  the  shaft  of 
the  ulna  below  the  origin  of  the  Anconeus,  from  the  interosseous  ligament,  and 
from  the  middle  third  of  the  posterior  surface  of  the  shaft  of  the  radius.  Passing 
obliquely  downwards  and  outwards,  it  terminates  in  a  tendon  which  runs  through 
a  groove  on  the  outer  side  of  the  styloid  process  of  the  radius,  accompanied  by 
the  tendon  of  the  Extensor  primi  internodii  pollicis,  and  is  inserted  into  the  base 
of  the  metacarpal  bone  of  the  thumb. 

Relations.  By  its  superficial  surface,  with  the  Extensor  communis  digitorum, 
Extensor  minimi  digiti,  and  fascia  of  the  forearm ;  being  crossed  by  the  branches 
of  the  posterior  interosseous  artery  and  nerve.  By  its  deep  surface,  with  the  ulna, 
interosseous  membrane,  radius,  the  tendons  of  the  Extensor  carpi  radialis  longior 
and  brevior ;  and,  at  the  outer  side  of  the  wrist,  with  the  radial  vessels.  By  its 
upper  border,  with  the  Supinator  brevis.  By  its  lower  border,  with  the  Extensor 
primi  internodii  pollicis. 

The  Extensor  Primi  Internodii  Pollicis,  the  smallest  muscle  of  this  group,  lies 
on  the  inner  side  of  the  preceding.  It  arises  from  the  posterior  surface  of  the 
shaft  of  the  radius,  below  the  Extensor  ossis  metacarpi,  and  from  the  interosseous 
membrane.  Its  direction  is  similar  to  that  of  the  Extensor  ossis  metacarpi,  its 
tendon  passing  through  the  same  groove  on  the  outer  side  of  the  styloid  process, 
to  be  inserted  into  the  base  of  the  first  phalanx  of  the  thumb. 

Relations.     The  same  as  those  of  the  Extensor  ossis  metacarpi  pollicis. 

The  Extensor  Secundi  Internodii  Pollicis  is  much  larger  than  the  preceding 
muscle,  the  origin  of  which  it  partly  covers  in.  It  arises  from  the  posterior  surface 
of  the  shaft  of  the  ulna,  below  the  origin  of  the  Extensor  ossis  metacarpi  pollicis, 
and  from  the  interosseous  membrane.  It  terminates  in  a  tendon  which  passes 
through  a  separate  compartment  in  the  annular  ligament,  lying  in  a  narrow  oblique 
groove  at  the  back  part  of  the  lower  end  of  the  radius.  It  then  crosses  obliquely 
the  Extensor  tendons  of  the  carpus,  being  separated  from  the  other  Extensor 
tendons  of  the  thumb  by  a  triangular  interval,  in  which  the  radial  artery  is  found ; 
and  is  finally  inserted  into  the  base  of  the  last  phalanx  of  the  thumb. 


314 


MUSCLES   AND   FASCIA. 


Relations.  By  its  superficial  surface,  with  the  same  parts  as  the  Extensor  ossis 
metacarpi  pollicis.  By  its  deep  surface,  with  the  ulna,  interosseous  membrane, 
radius,  the  wrist,  the  radial  vessels,  and  metacarpal  bone  of  the  thumb. 

The  HJxtensor  Indicis  is  a  narrow  elongated  muscle,  placed  on  the  inner  side  of, 
and  parallel  with,  the  preceding.     It  arises  from  the  posterior  surface  of  the  shaft 

of  the  ulna,  below  the  origin 
Fig.  375. — Posterior  Surface  of  the  Forearm.    Deep  Muscles.     Gf  the  Extensor  secundi  inter- 

nodii  pollicis,  and  from  the 
interosseous  membrane.  Its 
tendon  passes  with  the  Ex- 
tensor communis  digitorum 
through  the  same  canal  in  the 
annular  ligament,  and  subse- 
quently joins  that  tendon  of 
the  Extensor  communis  which 
belongs  to  the  index-finger, 
opposite  the  lower  end  of 
the  corresponding  metacarpal 
bone.  It  is  finally  inserted 
into  the  second  and  third  pha- 
langes of  the  index-finger,  in 
the  manner  already  described. 

Relations,  They  are  simi- 
lar to  those  of  the  preceding 
muscles. 

Nerves.  The  Supinator  lon- 
gus,  Extensor  carpi  radialis 
longior,  and  Anconeus,  are 
supplied  by  branches  from  the 
musculo- spiral  nerve;  the  re- 
maining muscles  of  the  ra- 
dial and  posterior  brachial 
regions,  by  the  posterior  inter- 
osseous nerve. 

Actions.  The  muscles  of 
the  radial  and  posterior  bra- 
chial regions,  which  comprise 
all  the  Extensor  and  Supinator 
muscles,  act  upon  the  fore- 
arm, wrist,  and  hand;  they 
are  the  direct  antagonists  of 
the  Pronator  and  Flexor 
muscles.  The  Anconeus  as- 
sists the  Triceps  in  extending 
the  forearm.  The  Supinator 
longus  and  brevis  are  the 
supinators  of  the  forearm  and 
hand ;  the  former  muscle  more 
especially  acting  as  a  supina- 
tor when  the  limb  is  pronated. 
When  supination  has  been 
produced,  the  Supinator  lon- 
gus, if  still  continuing  to  act, 
flexes  the  forearm.  The  Ex- 
tensor carpi  radialis  longior 
and  brevior,  and  Extensor 
carpi  ulnaris  muscles,  are  the 


OF   THE   HAXD. 


315 


Extensors  of  the  wrist ;  continuing  their  action,  they  serve  to  extend  the  forearm 
upon  the  arm ;  they  are  the  direct  antagonists  of  the  Flexor  carpi  radialis  and 
ulnaris.  The  common  Extensor  of  the  fingers,  the  Extensors  of  the  thumb,  and 
the  Extensors  of  the  index  and  little  fingers,  serve  to  extend  the  phalanges  into 
which  they  are  inserted ;  and  are  the  direct  antagonists  of  the  Flexors.  By  con- 
tinuing their  action,  they  assist  in  extending  the  forearm.  The  Extensors  of  the 
thumb  may  assist  in  supinating  the  forearm,  when  this  part  of  the  hand  has  been 
drawn  inwards  towards  the  palm,  on  account  of  the  oblique  direction  of  the  tendons 
of  these  muscles. 


Muscles  and  Fasciae  of  the  Hand. 

Dissection  (fig.  168).  Make  a  transverse  incision  across  the  front  of  the  wrist,  and  a  second 
across  the  heads  of  the  metacarpal  bones,  connect  the  two  by  a  vertical  incision  in  the  middle 
line,  and  continue  it  through  the  centre  of  the  middle  finger.  The  anterior  and  posterior  annular 
ligaments,  and  the  palmar  fascia,  should  first  be  dissected. 

The  Anterior  Annular  Ligament  is  a  strong  fibrous  band,  which  arches  over 
the  carpus,  converting  the  deep  groove  on  the  front  of  these  bones  into  a  canal, 
beneath  which  pass  the  flexor  tendons  of  the  fingers.  It  is  attached,  internally, 
to  the  pisiform  bone,  and  unciform  process  of  the  unciform ;  and  externally,  to  the 
tuberosity  of  the  scaphoid,  and  ridge  on  the  trapezium.  It  is  continuous,  above, 
with  the  deep  fascia  of  the  forearm,  and,  below,  with  the  palmar  fascia.  It  is 
crossed  by  the  tendon  of  the  Palmaris  longus,  by  the  ulnar  vessels  and  nerve,  and 
the  cutaneous  branches  of  the  median  and  ulnar  nerves.  It  has  inserted  into  its 
upper  and  inner  part,  the  tendon  of  the  Flexor  carpi  ulnaris ;  and  has,  arising 
from  it  below,  the  small  muscles  of  the  thumb  and  little  finger.  It  is  pierced  by 
the  tendon  of  the  Flexor  carpi  radialis ;  and,  beneath  it,  pass  the  tendons  of  the 
Flexor  sublimis  and  Flexor  profundus  digitorum,  the  Flexor  longus  pollicis,  and 
the  median  nerve.  There  are  two  synovial  membranes  beneath  this  ligament ;  one 
of  large  size,  inclosing  the  tendons  of  the  Flexor  sublimis  and  Flexor  profundus ; 
and  a  separate  one  for  the  tendon  of  the  Flexor  longus  pollicis ;  the  latter  is  also 
large  and  very  extensive,  reaching  from  above  the  wrist  to  the  extremity  of  the 
last  phalanx  of  the  thumb. 

The  Posterior  Annular  Liga- 
ment is  a  strong  fibrous  band, 
extending  transversely  across 
the  back  of  the  wrist,  and  con- 
tinuous with  the  fascia  of  the 
forearm.  It  forms  a  sheath  for 
the  Extensor  tendons  in  their 
passage  to  the  fingers,  being 
attached,  internally,  to  the  ulna, 
the  cuneiform  and  pisiform 
bones,  and  palmar  fascia;  ex- 
ternally, to  the  margin  of  the 
radius ;  and  in  its  passage  across 
the  wrist,  to  the  elevated  ridges 
on  the  posterior  surface  of  the 
radius.  It  presents  six  com- 
partments for  the  passage  of 
tendons,  each,  of  which  is.  lined 
by  a  separate  synovial  mem- 
brane. These  are,  from  without  inwards — 1.  On  the  outer  side  of  the  styloid  pro- 
cess for  the  tendons  of  the  Extensor  ossis  metacarpi  pollicis,  and  Extensor  primi 
internodii  pollicis.  2.  Behind  the  styloid  process,  for  the  tendons  of  the  Extensor 
carpi  radialis  longior  and  brevior.  3.  Opposite  the  outer  side  of  the  posterior 
surface  of  the  radius,  for  the  tendon  of  the  Extensor  secundi  internodii  pollicis. 


Fig.  176. — Transverse  section  through  the  Wrist,  show- 
ing the  Posterior  Annular  Ligament,  and  the  canals 
for  the  passage  of  the  Extensor  Tendons. 


^iwt,  nxj- c""  "' o. 


*yt  COM.  DlC 
"T-   INDlCli. 


•HUK.*.** 


316  MUSCLES   AND   FASCIAE. 

4.  To  the  inner  side  of  the  latter,  for  the  tendons  of  the  Extensor  communis 
digitorum,  and  Extensor  indicis.  5.  For  the  Extensor  minimi  digiti,  opposite  the 
interval  between  the  radius  and  ulna.  6.  For  the  tendon  of  the  Extensor  carpi 
ulnaris,  grooving  the  back  of  the  ulna.  The  synovial  membranes  lining  these 
sheaths  are  usually  very  extensive,  reaching  from  above  the  annular  ligament 
down  upon  the  tendons,  almost  to  their  insertion. 

The  palmar  fascia  forms  a  common  sheath  which  invests  the  muscles  of  the 
hand.     It  consists  of  a  central  and  two  lateral  portions. 

The  central  -portion  occupies  the  middle  of  the  palm,  is  triangular  in  shape,  of 
great  strength  and  thickness,  and  binds  down  the  tendons  in  this  situation.  It  is 
narrow  above,  being  attached  to  the  lower,  margin  of  the  annular  ligament,  and 
receives  the  expanded  tendon  of  the  Palmaris  longus  muscle.  Below,  it  is  broad 
and  expanded,  and  opposite  the  heads  of  the  metacarpal  bones  divides  into  four 
slips,  for  the  four  fingers.  Each  slip  subdivides  into  two  processes,  which  inclose 
the  tendons  of  the  Flexor  muscles,  and  are  attached  to  the  sides  of  the  first  pha- 
lanx, and  to  the  glenoid  ligament ;  by  this  arrangement,  four  arches  are  formed, 
under  which  the  Flexor  tendons  pass.  The  intervals  left  in  the  fascia  between 
the  four  fibrous  slips  transmit  the  digital  vessels  and  nerves,  and  the  tendons  of 
the  Lumbricales.  At  the  point  of  division  of  the  palmar  fascia  into  the  slips  above 
mentioned,  numerous  strong  transverse  fibres  bind  the  separate  processes  together. 
The  palmar  fascia  is  intimately  adherent  to  the  integument  by  numerous  fibrous 
bands,  and  gives  origin  by  its  inner  margin  to  the  Palmaris  brevis ;  it  covers  the 
superficial  palmar  arch,  the  tendons  of  the  'Flexor  muscles,  and  the  branches  of  the 
median  and  ulnar  nerves;  and  on  each  side  it  gives  off  a  vertical  septum,  which 
is  continuous  with  the  interosseous  aponeurosis,  and  separates  the  lateral  from  the 
middle  palmar  group  of  muscles. 

The  lateral  portions  of  the  palmar  fascia  are  thin  fibrous  layers,  which  cover, 
on  the  radial  side,  the  muscles  of  the  ball  of  the  thumb ;  and,  on  the  ulnar  side, 
the  muscles  of  the  little  finger ;  they  are  continuous  with  the  dorsal  fascia,  and  in 
the  palm,  with  the  middle  portion  of  the  palmar  fascia. 

Muscles  of  the  Hand. 

The  muscles  of  the  hand  are  subdivided  into  three  groups. — 1.  Those  of  the 
thumb,  which  occupy  the  radial  side.  2.  Those  of  the  little  finger,  which  occupy 
the  ulnar  side.  3.  Those  in  the  middle  of  the  palm  and  between  the  interosseous 
spaces. 

Radial  Region". 

Muscles  of  the  Thumb. 

Abductor  Pollicis. 

Opponens  Pollicis  or  Flexor  Ossis  Metacarpi. 

Flexor  Brevis  Pollicis. 

Adductor  Pollicis. 

The  Abductor  Pollicis  is  a  thin,  flat  muscle,  placed  immediately  beneath  the 
integument.  It  arises  from  the  ridge  of  the  os  trapezium  and  annular  ligament ; 
and,  passing  outwards  and  downwards,  is  inserted  by  a  thin,  flat  tendon  into  the 
radial  side  of  the  base  of  the  first  phalanx  of  the  thumb. 

Relations.  By  its  superficial  surface,  with  the  palmar  fascia.  By  its  deep  sur- 
face, with  the  Opponens  pollicis,  from  which  it  is  separated  by  a  thin  aponeurosis. 
Its  inner  border  is  separated  from  the  Flexor  brevis  pollicis  by  a  narrow  cellular 
interval. 

The  Opponens  Pollicis  is  a  small  triangular  muscle,  placed  beneath  the  pre- 
ceding. It  arises  from  the  palmar  surface  of  the  trapezium  and  annular  ligament: 
passing  downwards  and  outwards,  it  is  inserted  into  the  whole  length  of  the  meta- 
carpal bone  of  the  thumb  on  its  radial  side. 

Relations.     By  its  superficial  surface,  with  the  Abductor  pollicis.     By  its  deep 


OF   THE   HAND. 


31T 


surface,  with  the  trapezio-metacarpal  articulation.     By  its  inner  border,  with  the 
Flexor  brevis  pollicis. 

The  Flexor  Brevis  Pollicis  is  much  larger  than  either  of  the  two  preceding 
muscles,  beneath  which  it  is  placed.  It  consists  of  two  portions,  in  the  interval 
between  which  lies  the  tendon  of  the  Flexor  longus  pollicis.     The  anterior  and 

Fig.  177. — Muscles  of  the  Left  Hand.     Palmar  Surface. 


more  superficial  portion  arises  from  the  trapezium  and  outer  two-thirds  of  .the 
annular  ligament;  the  deeper  portion  from  the  trapezoides,  os  magnum,  base 
of  the  third  metacarpal  bone,  and  sheath  of  the  tendon  of  the  Flexor  carpi  radialis. 
The  fleshy  fibres  unite  to  form  a  single  muscle ;  this  divides  into  two  portions, 


318  MUSCLES   AND   FASCIAE. 

winch  are  inserted  one  on  either  side  of  the  base  of  the  first  phalanx  of  the  thumb, 
the  outer  portion  being  joined  with  the  Abductor,  and  the  inner  with  the  Adductor. 
A  sesamoid  bone  is  developed  in  each  tendon  as  it  passes  across  the  metacarpo- 
phalangeal joint. 

Relations.  By  its  superficial  surface,  with  the  palmar  fascia.  By  its  deep  sur- 
face, with  the  Adductor  pollicis,  and  tendon  of  the  Flexor  carpi  radialis.  By  its 
external  surface,  with  the  Opponens  pollicis.  By  its  internal  surface,  with  the 
tendon  of  the  Flexor  longus  pollicis. 

The  Adductor  Pollicis  (fig.  173)  is  the  most  deeply  seated  of  this  group  of 
muscles.  It  is  of  a  triangular  form,  arising,  by  its  broad  base,  from  the  whole 
length  of  the  metacarpal  bone  of  the  middle  finger  on  its  palmar  surface ;  the 
fibres,  proceeding  outwards,  converge,  to  be  inserted  with  the  innermost  tendon  of 
the  Flexor  brevis  pollicis,  into  the  ulnar  side  of  the  base  of  the  first  phalanx  of 
the  thumb,  and  into  the  internal  sesamoid  bone. 

Relations.  By  its  superficial  surf  ace,  with  the  Flexor  brevis  pollicis,  the  tendons 
of  the  Flexor  profundus  and  Lumbricales.  Its  deep  surface  covers  the  first  two 
interosseous  spaces,  from  which  it  is  separated  by  a  strong  aponeurosis. 

Nerves.  The  Abductor,  Opponens,  and  outer  head  of  the  Flexor  brevis  pollicis, 
are  supplied  by  the  median  nerve;  the  inner  head  of  the  Flexor  brevis,  and  the 
Adductor  pollicis,  by  the  ulnar  nerve. 

Actions.  The  actions  of  the  muscles  of  the  thumb  are  almost  sufficiently  indi- 
cated by  their  names.  This  segment  of  the  hand  is  provided  with  three  Extensors, 
an  Extensor  of  the  metacarpal  bone,  an  Extensor  of  the  first,  and  an  Extensor  of 
the  second  phalanx ;  these  occupy  the  dorsal  surface  of  the  forearm  and  hand. 
There  are,  also,  three  Flexors  on  the  palmar  surface,  a  Flexor  of  the  metacarpal 
bone,  the  Flexor  ossis  metacarpi  or  Opponens  pollicis,  the  Flexor  brevis  pollicis, 
and  the  Flexor  longus  pollicis;  there  is  also  an  Abductor  and  an  Adductor. 
These  muscles  give  to  the  thumb  that  extensive  range  of  motion  which  it  pos- 
sesses in  an  eminent  degree. 

Ulnar  Region. 

Muscles  of  the  Little  Finger. 

Palmaris  Brevis.  Flexor  Brevis  Minimi  Digiti. 

Abductor  Minimi  Digiti.  Opponens  Minimi  Digiti. 

The  Palmaris  Brevis  is  a  thin  quadrilateral  muscle,  placed  beneath  the  integu- 
ment on  the  ulnar  side  of  the  hand.  It  arises  by  tendinous  fasciculi,  from  the 
annular  ligament  and  palmar  fascia ;  the  fleshy  fibres  pass  horizontally  inwards, 
to  be  inserted  into  the  skin  on  the  inner  border  of  the  palm  of  the  hand. 

Relations.  By  its  superficial  surface,  with  the  integument  to  which  it  is  inti- 
mately adherent,  especially  by  its  inner  extremity.  By  its  deep  surface,  with  the 
inner  portion  of  the  palmar  fascia,  which  separates  it  from  the  ulnar  vessels  and 
nerve,  and  from  the  muscles  of  the  ulnar  side  of  the  hand. 

The  Abductor  Minimi  Digiti  is  situated  on  the  ulnar  border  of  the  palm  of  the 
hand.  It  arises  from  the  pisiform  bone,  and  from  an  expansion  of  the  tendon  of 
the  Flexor  carpi  ulnaris ;  and  terminates  in  a  flat  tendon,  which  is  inserted  into 
the  ulnar  side  of  the  base  of  the  first  phalanx  of  the  little  finger. 

Relations.  By  its  superficial  surface,  with  the  inner  portion  of  the  palmar 
fascia,  and  the  Palmaris  brevis.  By  its  deep  surface,  with  the  Flexor  ossis  meta- 
carpi.    By  its  inner  border,  with  the  Flexor  brevis  minimi  digiti. 

The  Flexor  Brevis  Minimi  Digiti  lies  on  the  same  plane  as  the  preceding  muscle, 
on  its  radial  side.  It  arises  from  the  tip  of  the  unciform  process  of  the  unciform 
bone,  and  anterior  surface  of  the  annular  ligament,  and  is  inserted  into  the  base  of 
the  first  phalanx  of  the  little  finger,  with  the  preceding.  It  is  separated  from  the 
Abductor  at  its  origin,  by  the  deep  branches  of  the  ulnar  artery  and  nerve.  This 
muscle  is  sometimes  wanting ;  the  Abductor  is  then,  usually,  of  large  size. 


OF   THE   HAND. 


319 


Relations.  By  its  superficial  surface,  with  the  internal  portion  of  the  palmar 
fascia,  and  the  Palmaris  brevis.  By  its  deep  surface,  with  the  Flexor  ossis  meta- 
carpi. 

The  Opponens  Minimi  Digiti  (fig.  173),  is  of  a  triangular  form,  and  placed  im- 
mediately beneath  the  preceding  muscles.  It  arises  from  the  unciform  process  of 
the  unciform  bone,  and  contiguous  portion  of  the  annular  ligament ;  its  fibres  pass 
downwards  and  inwards,  to  be  inserted  into  the  whole  length  of  the  metacarpal 
bone  of  the  little  finger,  along  its  ulnar  margin. 

Relations.  By  its  superficial  surface,  with  the  Flexor  brevis,  and  Abductor 
minimi  digiti.  By  its  deep  surface,  with  the  Interossei  muscles  in  the  fifth 
metacarpal  space,  the  metacarpal  bone,  and  the  Flexor  tendons  of  the  little 
finger. 

Nerves.     All  the  muscles  of  this  group  are  supplied  by  the  ulnar  nerve. 

Actions.  The  actions  of  the  muscles  of  the  little  finger  are  expressed  in  their 
names.  The  Palmaris  brevis  corrugates  the  skin  on  the  inner  side  of  the  palm 
of  the  hand. 


Middle  Palmar  Eegion". 

Lumbricales.  Interossei  Palmares. 

Interossei  Dorsales. 

The  Lumbricales  are  four  small  fleshy  fasciculi,  accessories  to  the  deep  Flexor 
muscle.  They  arise  by  fleshy  fibres  from  the  tendons  of  the  deep  Flexor :  the  first 
and  second,  from  the  radial  side  and  palmar  surface  of  the  tendons  of  the  index 
and  middle  fingers ;  the  third,  from  the  contiguous  sides  of  the  tendons  of  the 
middle  and  ring  fingers ;  and  the  fourth,  from  the  contiguous  sides  of  the  tendons 
of  the  ring  and  little  fingers.  They  pass  forwards  to  the  radial  side  of  the  corre- 
sponding fingers,  and  opposite  the  metacarpophalangeal  articulations  each  tendon 

terminates  in  a  broad  aponeurosis,  which 

,    j   •    ,      ,  r      .      j  •  •         Fig.  178. — The  Dorsal  Interossei  of  Left  Hand, 

is  inserted  into  the  tendinous  expansion 

from  the  Extensor  communis  digitorum, 

which  covers  the  dorsal  aspect  of  each 

finger. 

The  Interossei  Muscles  are  so  named 
from  occupying  the  intervals  between  the 
metacarpal  bones.  They  are  divided  into 
two  sets,  a  dorsal  and  palmar ;  the  former 
are  four  in  number,  one  in  each  meta- 
carpal space ;  the  latter,  three  in  number, 
lie  upon  the  metacarpal  bones. 

The  Dorsal  Interossei  are  four  in 
number,  larger  than  the  palmar,  and 
occupy  the  intervals  between  the  meta- 
carpal bones.  They  are  bipenniform 
muscles,  arising  by  two  heads  from  the 
adjacent  sides  of  the  metacarpal  bones, 
but  more  extensively  from  that  side  of 
the  metacarpal  bone,  which  corresponds 
to  the  side  of  the  finger  in  which  the 
muscle  is  inserted.  They  are  inserted 
into  the  base  of  the  first  phalanges,  and 
into  the  aponeurosis  of  the  common 
Extensor  tendon.  Between  the  double  origin  of  each  of  these  muscles  is  a 
narrow  triangular  interval,  through  which  passes  a  perforating  branch  from  the 
deep  palmar  arch. 

The  First  Dorsal  Interosseous  muscle  or  Abductor  indicis  is  larger  than  the 
others,  and  lies  in  the  interval  between  the  thumb  and  index-finger.     It  is  flat, 


320 


SURGICAL   ANATOMY. 


Fig.  179. — The  Palmar  Interossei  of  Left  Hand. 


triangular  in  form,  and  arises  by  two  heads,  separated  by  a  fibrous  arch,  for  the 
passage  of  the  radial  artery  into  the  deep  part  of  the  palm  of  the  hand.  The 
outer  head  arises  from  the  upper  half  of  the  ulnar  border  of  the  first  metacarpal 
bone ;  the  inner  head,  from  the  entire  length  of  the  radial  border  of  the  second 
metacarpal  bone ;  the  tendon  is  inserted  into  the  radial  side  of  the  index-finger. 
The  second  and  third  are  inserted  into  the  middle  finger,  the  former  into  its 
radial,  the  latter  into  its  ulnar  side.  The  fourth  is  inserted  in  the  ulnar  side  of 
the  ring-finger. 

The  Palmar  Interossei,  three  in  number,  are  smaller  than  the  Dorsal,  and  placed 
upon  the  palmar  surface  of  the  metacarpal  bones,  rather  than  between  them. 

They  arise  from  the  entire  length  of  the 
metacarpal  bone  of  one  finger,  and  are 
inserted  into  the  side  of  the  base  of  the 
first  phalanx  and  aponeurotic  expansion 
of  the  common  Extensor  tendon  of  the 
same  finger. 

The  first  arises  from  the  ulnar  side  of 
the  second  metacarpal  bone,  and  is  in- 
serted into  the  same  side  of  the  index- 
finger.  The  second  arises  from  the  radial 
side  of  the  fourth  metacarpal  bone,  and 
is  inserted  into  the  same  side  of  the  ring- 
finger.  The  third  arises  from  the  radial 
side  of  the  fifth  metacarpal  bone,  and  is 
inserted  into  the  same  side  of  the  little 
finger.  From  this  account  it  may  be  seen, 
that  each  finger  is  provided  with  two  In- 
terossei muscles,  with  the  exception  of  the 
little  finger. 

Nerves.  The  two  outer  Lumbricales 
are  supplied  by  the  median  nerve;  the 
rest  of  the  muscles  of  this  group,  by  the 
ulnar. 

Actions.  The  Dorsal  interossei  muscles 
abduct  the  fingers  from  an  imaginary  line  drawn  longitudinally  through  the  centre 
of  the  middle  finger ;  and  the  Palmar  interossei  adduct  the  fingers  towards  the 
same  line.  .  They  usually  assist  the  Extensor  muscles ;  but  when  the  fingers  are 
slightly  bent,  they  assist  in  flexing  the  fingers. 


SURGICAL  ANATOMY. 


The  Student,  having  completed  the  dissection  of  the  muscles  of  the  upper  extremity,  should 
consider  the  effects  likely  to  be  produced  by  the  action  of  the  various  muscles  in  fracture  of  the 
bones ;  the  causes  of  displacement  are  thus  easily  recognized,  and  a  suitable  treatment  in  each 
case  may  be  readily  adopted. 

In  considering  the  actions  of  the  various  muscles  upon  fractures  of  the  upper  extremity,  the 
most  common  forms  of  injury  have  been  selected,  both  for  illustration  and  description. 

Fracture  of  the  clavicle  is  an  exceedingly  common  accident,  and  is  usually  caused  by  indirect 
violence,  as  a  fall  upon  the  shoulder ;  it  occasionally,  however,  occurs  from  direct  force.  Its  most 
usual  situation  is  just  external  to  the  centre  of  the  bone,  but  it  may  occur  at  the  sternal  or  acro- 
mial ends. 

Fracture  of  the  middle  of  the  clavicle  (fig.  180)  is  always  attended  with  considerable  displace- 
ment, the  outer  fragment  being  drawn  downwards,  forwards,  and  inwards ;  the  inner  fragment 
slightly  upwards.  The  outer  fragment  is  drawn  down  by  the  weight  of  the  arm,  and  the  action 
of  the  Deltoid,  and  forwards  and  inwards  by  the  Pectoralis  minor  and  Subclavius  muscles;  the 
inner  fragment  is  slightly  raised  by  the  Sterno-cleido-mastoid,  but  only  to  a  very  limited  extent, 
as  the  attachment  of  the  costo-clavicular  ligament  and  Pectoralis  major  below  and  in  front  would 
prevent  any  very  great  displacement  upwards.  The  causes  of  displacement  having  been  ascer- 
tained, it  is  easy  to  apply  the  appropriate  treatment.     The  outer  fragment  is  to  be  drawn  out- 


OF   THE   MUSCLES   OF   THE   UPPER   EXTREMITY.       321 


wards,  and,  together  with  the  scapula,  raised  upwards  to  a  level  with  the  inner  fragment,  and 
retained  in  that  position. 


Fig.  ISO.— Fracture  of  the  Middle  of  the 
Clavicle. 


In  fracture  of  the  acromial  end  of  the  cla- 
vicle between  the  conoid  and  trapezoid  liga- 
ments, only  slight  displacement  occurs,  as 
these  ligaments,  from  their  oblique  insertion, 
serve  to  hold  both  portions  of  the  bone  in 
apposition.  Fracture,  also,  of  the  sternal  end, 
internal  to  the  costoclavicular  ligament,  is 
attended  with  only  slight  displacement,  this 
ligament  serving  to  retain  the  fragments  in 
close  apposition. 

Fracture  of  the  acromion  process  usually 
arises  from  violence  applied  to  the  upper  and 
outer  part  of  the  shoulder;  it  is  generally 
known  by  the  rotundity  of  tho  shoulder  being 
lost,  from  the  Deltoid  drawing  downwards  and 
forwards  the  fractured  portion ;  and  the  dis- 
placement may  easily  be  discovered  by  tracing 
the  margin  of  the  clavicle  outwards,  when  the 
fragment  will  be  found  resting  on  the  front 
and  upper  part  of  the  head  of  the  humerus. 
In  order  to  relax  the  anterior  and  outer  fibres 
of  the  Deltoid  (the  opposing  muscle),  the  arm 
should  be  drawn  forwards  across  the  chest, 
and  the  elbow  well  raised,  so  that  the  head 
of  the  bone  may  press  upwards  the  acromion 
process,  and  retain  it  in  its  position. 

Fracture  of  the  coracoid  process  is  an  ex- 
tremely rare  accident,  and  is  usually  caused 
by  a  sharp  blow  on  the  point  of  the  shoulder. 
Displacement  is  here  produced  by  the  com- 
bined actions  of  the  Pectoralis  minor,  short 

head  of  the  Biceps,  and  Coraco-brachialis,  the  former  muscle  drawing  the  fragment  inwards,  the 
latter  directly  downwards,  the  amount  of  displacement  being  limited  by  the  connection  of  this 
process  to  the  acromion  by  means  of  the  coraco-acromial  ligament.  In  order  to  relax  these 
muscles,  and  replace  the  fragments  in  close  apposition,  the  forearm  should  be  flexed  so  as  to 
relax  the  Biceps,  and  the  arm  drawn  forwards  and  inwards  across  the  chest  so  as  to  relax  the 
Coraco-brachialis  ;  tne  humerus  should  then  be  pushed  upwards  against  the  coraco-acromial 
ligament,  and  the  arm  retained  in  this  position. 

,  Fracture  of  the  anatomical  neck  of  the  humerus  within  the  capsular  ligament  is  a  rare  accident, 
attended  with  very  slight  displacement,  an  impaired  condition  of  the  motions  of  the  joint,  and 
crepitus. 

Fracture  of  the  surgical  neck  (fig.  181)  is  very  common,  is  attended  with  considerable  displace- 
ment, and  its  appearances  correspond  somewhat  with  those  of  dislocation  of  the  head  of  the 
humerus  into  the  axilla.   The  upper  fragment 


is  slightly  elevated  under  the  coraco-acromial 
ligament  by  the  muscles  attached  to  the 
greater  and  lesser  tuberosities ;  the  lower 
fragment  is  drawn  inwards  by  the  Pectoralis 
major,  Latissimus  dorsi,  and  Teres  major; 
and  the  humerus  is  thrown  obliquely  outwards 
from  the  side  by  the  Deltoid,  and  occasionally 
elevated  so  as  to  project  beneath  and  in  front 
of  the  coracoid  process.  By  fixing  the  shoul- 
der, and  drawing  the  arm  outwards  and 
downwards,  the  deformity  is  at  once  reduced. 
To  counteract  the  action  of  the  opposing 
muscles,  and  to  keep  the  fragments  in  posi- 
tion, the  arm  should  be  drawn  from  the  side, 
and  pasteboard  splints  applied  on  its  four 
sides ;  a  large  conical-shaped  pad  should  be 
placed  in  the  axilla  with  the  base  turned 
upwards,  and  the  elbow  approximated  to  the 
side,  and  retained  there  by  a  broad  roller 
passed  round  the  chest ;  the  forearm  should 
then  be  flexed,  and  the  hand  supported  in  a 
sling,  care  being  taken  not  to  raise  the  elbow, 
otherwise  the  lower  fragment  may  be  displaced 
upwards. 

21 


Fig.  181. — Fracture  of  the  Surgical  Neck 
of  the  Humerus. 


322 


SURGICAL   ANATOMY. 


In  fracture  of  the  shaft  of  the  humerus,  below  the  insertion  of  the  Pectoralis  major,  Latissimus 
dorsi,  and  Teres  major,  and  above  the  insertion  of  the  Deltoid,  there  is  also  considerable  deformity, 
the  upper  fragment  being  drawn  inwards  by  the  first-mentioned  muscles,  and  the  lower  fragment 
drawn  upwards  and  outwards  by  the  Deltoid,  producing  shortening  of  the  limb,  and  a  considerable 
prominence  at  the  seat  of  fracture,  from  the  fractured  ends  of  the  bone  riding  over  one  another, 
especially  if  the  fracture  takes  place  in  an  oblique  direction.  The  fragments  may  be  readily 
brought  into  apposition  by  extension  from  the  elbow,  and  retained  in  that  position  by  adopting 
■  the  same  means  as  in  the  preceding  injury. 

In  fracture  of  the  shaft  of  the  humerus  immediately  below  the  insertion  of  the  Deltoid,  the 
amount  of  deformity  depends  greatly  upon  the  direction  of  the  fracture.  If  the  fracture  occurs 
in  a  transverse  direction,  only  slight  displacement  occurs,  the  upper  fragment  being  drawn  a 
little  forwards ;  but  in  oblique  fracture,  the  combined  actions  of  the  Biceps  and  Brachialis  anticus 
muscles  in  front,  and  the  Triceps  behind,  draw  upwards  the  lower  fragment,  causing  it  to  glide 
over  the  upper  fragment,  either  backwards  or  forwards,  according  to  the  direction  of  the  fracture. 
Simple  extension  reduces  the  deformity,  and  the  application  of  splints  on  the  four  sides  of  the 
arm  retains  the  fragments  in  apposition.  Care  should  be  taken  not  to  raise  the  elbow,  but  the 
forearm  and  hand  may  be  supported  in  a  sling. 

Fracture  of  the  humerus  (fig.  182)  immediately  above  the  condyles  deserves  very  attentive 

consideration,  as  the  general  appearances  cor- 


Fig.  182.— Fracture  of  the  Humerus  above  the 
Condyles. 


respond  somewhat  with  those  produced  by 
separation  of  the  epiphysis  of  the  humerus, 
and  with  those  of  dislocation  of  the  radius 
and  ulna  backwards.  If  the  direction  of  the 
fracture  is  oblique  from  above,  downwards, 
and  forwards,  the  lower  fragment  is  drawn 
upwards  and  backwards  by  the  Brachialis 
anticus  and  Biceps  in  front,  and  the  Triceps 
behind.  This  injury  may  be  diagnosticated  from 
dislocation,  by  the  increased  mobility  in  frac- 
ture, the  existence  of  crepitus,  and  the  de- 
formity being  remedied  by  extension,  by  the 
discontinuance  of  which  it  is  again  reproduced. 
The  age  of  the  patient  is  of  importance  in 
distinguishing  this  form  of  injury  from  sepa- 
ration of  the  epiphysis.  If  fracture  occurs 
in  the  opposite  direction  to  that  shown  in 
the  accompanying  figure,  the  lower  fragment 
is  drawn  upwards  and  forwards,  causing  a 
considerable  prominence  in  front;  and  the 
upper  fragment  projects  backwards  beneath 
the  tendon  of  the  Triceps  muscle. 

Fracture  of  the  coronoid  process  of  the  ulna 
is   an   accident   of   rare    occurrence,   and  is 
usually  caused  by  violent  action  of  the  Bra- 
chialis anticus  muscle.     The  amount  of  dis- 
placement varies  according  to  the  extent  of  the  fracture.     If  the  tip  of  the  process  only  is 
broken   off,   the   fragment  is   drawn  upwards   by  the  Brachialis  anticus  on  a  level  with  the 

coronoid  depression  of  the  humerus,  and 
Fig.  183.— Fracture  of  the  Olecranon.  tne  power  of  flexion  is  partially  lost.     If 

the  process  is  broken  off  near  its  root,  the 
fragment  is  still  displaced  by  the  same 
muscle ;  at  the  same  time,  on  extending 
the  forearm,  partial  dislocation  backwards 
of  the  ulna  occurs  from  the  action  of  the 
Triceps  muscle.  The  appropriate  treat- 
ment would  be  to  relax  the  Brachialis  an- 
ticus by  flexing  the  forearm,  and  to  retain 
the  fragments  irt  apposition  by  keeping 
the  arm  in  this  position.  Union  is  generally 
ligamentous. 

Fracture  of  the  olecranon  process  (fig. 
183)  is  a  more  frequent  accident,  and  is 
caused  either  by  violent  action  of  the 
Triceps  muscle,  or  by  a  fall  or  blow  upon 
the  point  of  the  elbow.  The  detached 
fragment  is  displaced  upwards,  by  the 
action  of  the  Triceps  muscle,  from  half  an 
inch  to  two  inches;  the  prominence  of  the 
elbow  is  consequently  lost,  and  a  deep 
hollow  is  felt  at  the  back  part  of  the  joint,  which  is  much  increased  on  flexing  the  limb.     The 


OF   THE   MUSCLES   OF   THE   UPPER  EXTREMITY.        323 

patient  at  the  same  time  loses  the  power  of  extending  the  forearm.  The  treatment  consists  in 
relaxing  the  Triceps  by  extending  the  forearm,  and  retaining  it  in  this  position  by  means  of  a 
long  straight  splint  applied  to  the  front  of  the  arm  ;  the  fragments  are  thus  brought  into  closer 
apposition,  and  may  be  further  approximated  by  drawing  down  the  upper  fragment.  Union  is 
generally  ligamentous. 

Fracture  of  the  neck  of  the  radius  is  an  exceedingly  rare  accident,  and  is  generally  caused  by 
direct  violence.  Its  diagnosis  is  somewhat  obscure,  on  account  of  the  slight  deformity  visible 
from  the  large  number  of  muscles  which  surround  it ;  but  the  movements  of  pronation  and  supi- 
nation are  entirely  lost.  The  upper  fragment  is  drawn  outwards  by  the  Supinator  brevis,  iis 
extent  of  displacement  being  limited  by  the  attachment  of  the  orbicular  ligament.  The  lower 
fragment  is  drawn  forwards  and  slightly  upwards  by  the  Biceps,  and  inwards  by  the  Pronator 
radii  teres,  its  displacement  forwards  and  upwards  being  counteracted  in  some  degree  by  the 
Supinator  brevis.  The  treatment  essentially  consists  in  relaxing  the  Biceps,  Supinator  brevis, 
and  Pronator  radii  teres  muscles,  by  flexing  the  forearm,  and  placing  it  in  a  position  midway 
between  pronation  and  supination,  extension  having  been  previously  made  so  as  to  bring  the 
parts  in  apposition. 

Fracture  of  the  radius  (fig.  184)  is  more  common  than  fracture  of  the  ulna,  on  account  of  the 
connection  of  the  former  with  the  wrist.    Fracture  of  the  shaft  of  the  radius  near  its  centre  may 
occur  from  direct  violence,  but  more  fre- 
quently from  a  fall  forwards,  the  entire  weight 

of  the  body  being  received  on  the  wrist  and  Fig.  184.— Fracture  of  the  Shaft  of  the  Radius. 

hand.  The  upper  fragment  is  drawn  up- 
wards by  the  Biceps,  and  inwards  by  the 
Pronator  radii  teres,  holding  a  position  mid- 
way between  pronation  and  supination,  and 
a  degree  of  fulness  in  the  upper  half  of  the 
forearm  is  thus  produced ;  the  lower  frag- 
ment is  drawn  downwards  and  inwards 
towards  the  ulna  by  the  Pronator  quadratus, 
and  thrown  into  a  state  of  pronation  by  the 
same  muscle ;  at  the  same  time,  the  Supi- 
nator longus,  by  elevating  the  styloid  pro- 
cess, into  which  it  is  inserted,  will  serve  to 
depress  still  more  the  upper  end  of  the  lower 

fragment  towards  the  ulna.  In  order  to  relax  the  opposing  muscles  the  forearm  should  be 
bent,  and  the  limb  placed  in  a  position  midway  between  pronation  and  supination ;  the  fracture 
is  then  easily  reduced  by  extension  from  the  wrist  and  elbow.  Well-padded  splints  should  then  be 
applied  on  both  sides  of  the  forearm  from  the  elbow  to  the  wrist;  the  hand  being  allowed  to  fall 
will,  by  its  own  weight,  counteract  the  action  of  the  Pronator  quadratus  and  Supinator  longus, 
and  elevate  the  lower  fragment  to  the  level  of  the  upper  one. 

Fracture  of  the  shaft  of  the  ulna  is  not  a  common  accident;  it  is  usually  caused  by  direct  vio- 
lence. Its  more  protected  position  on  the  inner  side  of  the  limb,  the  greater  strength  of  its  shaft, 
and  its  indirect  connection  with  the  wrist,  render  it  less  liable  to  injury  than  the  radius.  It  usu- 
ally occurs  a  little  below  the  centre,  which  is  the  weakest  part  of  the  bone.  The  upper  fragment 
retains  it3  usual  position ;  but  the  lower  fragment  is  drawn  outwards  towards  the  radius  by  the 
Pronator  quadratus,  producing  a  well-marked  depression  at  the  seat  of  fracture,  and  some  fulness 
on  the  dorsal  and  palmar  surfaces  of  the  forearm.  The  fracture  is  easily  reduced  by  extension 
from  the  wrist  and  forearm.  The  forearm  should  be  flexed,  and  placed  in  a  position  midway 
between  pronation  and  supination,  and  well-padded  splints  applied  from  the  elbow  to  the  ends  of 
the  fingers. 

Fracture  of  the  shafts  of  the  radius  and  ulna  together  is  not  a  common  accident ;  it  may  arise 
from  a  direct  blow,  or  from  indirect  violence.  The  lower  fragments  are  drawn  upwards,  some- 
times forwards,  sometimes  backwards,  according  to  the  direction  of  the  fracture,  by  the  combined 
actions  of  the  Flexor  and  Extensor  muscles,  producing  a  degree  of  fulness  on  the  dorsal  or  pal- 
mar surface  of  the  forearm;  at  the  same  time  the  two  fragments  are  drawn  into  contact  by  the 
Pronator  quadratus,  the  radius  in  a  state  of  pronation  :  the  upper  fragment  of  the  radius  is  drawn 
upwards  and  inwards  by  the  Biceps  and  Pronator  radii  teres  to  a  higher  level  than  the  ulna;  the 
upper  portion  of  the  ulna  is  slightly  elevated  by  the  Brachialis  anticus.  The  fracture  may  be 
reduced  by  extension  from  the  wrist  and  elbow,  and  the  forearm  should  be  placed  in  the  same 
position  as  in  fracture  of  the  ulna. 

In  the  treatment  of  all  cases  of  fracture  of  the  bones  of  the  forearm,  the  greatest  care  is  requi- 
site to  prevent  the  ends  of  the  bones  from  being  drawn  inwards  towards  the  interosseous  space : 
if  this  is  not  carefully  attended  to,  the  radius  and  ulna  may  become  anchylosed,  and  the  move- 
ments of  pronation  and  supination  entirely  lost.  To  obviate  this,  the  splints  applied  to  the  limb 
should  be  well  padded,  so  as  to  press  the  muscles  down  into  their  normal  situation  in  the  interos- 
seous space,  and  so  prevent  the  approximation  of  the  fragments. 

Fracture  of  the  lower  end  of  the  radius  (fig.  185)  is  usually  called  Colles's  fracture,  from  the 
name  of  the  eminent  Dublin  surgeon  who  first  accurately  described  it.  It  is  generally  produced 
from  the  patient  falling  from  a  height,  and  alighting  upon  the  hand,  which  receives  the  entire 
weight  of  the  body.     This  fracture  usually  takes  place  from  half  an  inch  to  an  inch  above  the 


324 


MUSCLES   AND   FASCIAE 


articular  surface  if  it  occurs  in  the  adult;  but  in  the  child,  before  the  age  of  sixteen,  it  is  more 
frequently  a  separation  of  the  epiphysis  from  the  apophysis.  The  displacement  which  is  produced 
is  very  considerable,  and  bears  some  resemblance  to  dislocation  of  the  carpus  backwards,  from 
which  it  should  be  carefully  distinguished.    The  lower  fragment  is  drawn  upwards  and  backwards 


Fig.  185. — Fracture  of  the  Lower  End  of  the  Radius. 


behind  the  upper  fragment  by  the  combined  actions  of  the  Supinator  longus  and  the  Flexors  and 
the  Extensors  of  the  thumb  and  carpus,  producing  a  well-marked  prominence  on  the  back  of  the 
wrist,  with  a  deep  depression  behind.  The  upper  fragment  projects  forwards,  often  lacerating 
the  substance  of  the  Pronator  quadratus,  and  is  drawn  by  this  muscle  into  close  contact  with  the 
lower  end  of  the  ulna,  causing  a  projection  on  the  anterior  surface  of  the  forearm,  immediately 
above  the  carpus,  from  the  flexor  tendons  being  thrust  forwards.  This  fracture  may  be  dis- 
tinguished from  dislocation  by  the  deformity  being  removed  on  making  sufficient  extension,  when 
crepitus  may  be  occasionally  detected ;  at  the  same  time,  on  extension  being  discontinued,  the 
parts  immediately  resume  their  deformed  appearance.  The  age  of  the  patient  will  also  assist  in 
determining  whether  the  injury  is  fracture  or  separation  of  the  epiphysis.  The  treatment  consists 
in  flexing  the  forearm;  and  making  powerful  extension  from  the  wrist  and  elbow,  depressing  at 
the  same  time  the  radial  side  of  the  hand,  and  retaining  the  parts  in  this  position  by  well-padded 
pistol-shaped  splints. 


MUSCLES  AND  FASCIA  OF  THE  LOWER  EXTREMITY. 


The  Muscles  of  the  Lower  Extremity  are 
ing  with  the  different  regions  of  the  limb. 


Iliac 


region. 


Psoas  magnus. 
Psoas  parvus. 
Iliacus. 

Thigh. 
Anterior  femoral  region. 
Tensor  vaginae  femoris. 
Sartorius. 
Rectus. 

Vastus  externus. 
Vastus  internus. 
Crureus. 
Subcrureus. 

Internal  femoral  region. 

Gracilis. 
Pectineus. 
Adductor  longus. 


subdivided  into  groups,  correspond- 

Adductor  brevis. 
Adductor  magnus. 

Hip. 
Gluteal  region. 
Gluteus  maximus. 
Gluteus  medius. 
Gluteus  minimus. 
Pyriformis. 
Gemellus  superior. 
Obturator  internus. 
Gemellus  inferior. 
Obturator  externus. 
Quadratus  femoris. 

Posterior  femoral  region. 

Biceps. 

Semi-tendinosus. 

Semi-membranosus. 


OF   TIIE   LOWER  EXTREMITY.  325 

Leg.  Foot. 

Anterior  tibio-fibular  region.  Dorsal  region. 

Tibialis  anticus.  Extensor  brevis  digitorum. 

Extensor  longus  digitorum.  Interossei  dorsales. 
Extensor  proprius  pollicis.  Plantar  region. 

Peroneus  tertius.  First  layer. 

Posterior  tibio-fibular  region.  Abductor  pollicis. 

Superficial  layer.  Flexor  brevis  digitorum. 

Gastrocnemius  Abductor  minimi  digiti. 
Plantaris.  Second  layer. 

Musculus  accessorius. 

Deep  layer.  Lumbricales. 
Popliteus.  Third  layer. 

Flexor  longus  pollicis.  Flexor  brevis  pollicis. 

Flexor  longus  digitorum.  Adductor  pollicis. 

Tibialis  posticus.  Flexor  brevis  minimi  digiti. 

Fibular  region.  Transversus  pedis. 
Peroneus  longus.  Fourth  layer. 

Peroneus  brevis.  Interossei  plantares. 

Iliac  Region, 

Psoas  Magnus.  Psoas  Parvus.  Iliacus. 

Dissection.  No  detailed  description  is  required  for  the  dissection  of  these  muscles.  They  are 
exposed  after  the  removal  of  the  viscera  from  the  abdomen,  covered  by  the  peritoneum  and  a 
t!.in  layer  of  fascia,  the  fascia  iliaca. 

The  iliac  fascia  is  the  aponeurotic  layer  which  lines  the  back  part  of  the 
abdominal  cavity,  and  incloses  the  Psoas  and  Iliacus  muscles  throughout  their 
whole  extent.  It  is  thin  above;  and  becomes  gradually  thicker  below,  as  it 
approaches  the  femoral  arch. 

The  portion  investing  the  Psoas  is  attached,  above,  to  the  ligamentum  arcuatum 
internum ;  internally,  to  the  sacrum ;  and  by  a  series  of  arched  processes  to  the 
intervertebral  substances,  and  prominent  margins  of  the  bodies  of  the  vertebrae ; 
the  intervals  left  opposite  the  constricted  portions  of  the  bodies  transmitting  the 
lumbar  arteries  and  sympathetic  filaments  of  nerves.  Externally,  it  is  continuous 
with  the  fascia  lumborum. 

The  portion  investing  the  Iliacus  is  connected,  externall}'-,  to  the  whole  length 
of  the  inner  border  of  the  crest  of  the  ilium ;  internally,  to  the  brim  of  the  true 
pelvis,  where  it  is  continuous  with  the  periosteum,  and  receives  the  tendon  of 
insertion  of  the  Psoas  parvus.  External  to  the  femoral  vessels,  this  fascia  is 
intimately  connected  with  Poupart's  ligament,  and  is  continuous  with  the  fascia 
transversalis ;  but,  corresponding  to  the  point  where  the  femoral  vessels  pass  down 
into  the  thigh,  it  is  prolonged  down  behind  them,  forming  the  posterior  wall  of  the 
femoral  sheath.  Below  this  point,  the  iliac  fascia  surrounds  the  Psoas  and  Iliacus 
muscles  to  their  termination,  and  becomes  continuous  with  the  iliac  portion  of  the 
fascia  lata.  Internal  to  the  femoral  vessels  the  iliac  fascia  is  connected  to  the  ilio- 
pectineal  line,  and  is  continuous  with  the  pubic  portion  of  the  fascia  lata.  The 
iliac  vessels  lie  in  front  of  the  iliac  fascia,  but  all  the  branches  of  the  lumbar 
plexus  behind  it;  it  is  separated  from  the  peritoneum  by  a  quantity  of  loose  areolar 
tissue.  In  abscess  accompanying  caries  of  the  lower  part  of  the  spine,  the  matter 
makes  its  way  to  the  femoral  arch,  distending  the  sheath  of  the  Psoas ;  and  when 
it  accumulates  in  considerable  quantity,  this  muscle  becomes  absorbed,  and  the 
nervous  cords  contained  in  it  are  dissected  out,  and  lie  exposed  in  the  cavity  of 
the  abscess ;  the  femoral  vessels,  however,  remain  intact,  and  the  peritoneum  seldom 
becomes  implicated  notwithstanding  the  extreme  thinness  of  the  membrane. 


326  MUSCLES   AND   FASCIAE. 

Remove  this  fascia,  and  the  muscles  of  the  iliac  region  will  be  exposed. 
The  Psoas  Magnus  (fig.  187)  is  a  long  fusiform  muscle,  placed  on  the  side  of 
the  lumbar  region  of  the  spine  and  margin  of  the  pelvis.  It  arises  from  the  sides  of 
the  bodies,  from  the  corresponding  intervertebral  substances,  and  from  the  front 
of  the  bases  of  the  transverse  processes  of  the  last  dorsal  and  all  the  lumbar  ver- 
tebras. The  muscle  is  connected  to  the  bodies  of  the  vertebras  by  five  slips ;  each 
slip  is  attached  to  the  upper  and  lower  margins  of  the  two  vertebras,  and  to  the 
intervertebral  substance  between  them,  the  slips  themselves  being  connected  by 
tendinous  arches  extending  across  the  constricted  part  of  the  bodies,  beneath  which 
pass  the  lumbar  arteries  and  sympathetic  nervous  filaments.  These  tendinous  arches 
also  give  origin  to  muscular  fibres  and  protect  the  bloodvessels  and  nerves 
from  pressure  during  the  action  of  the  muscle.  The  first  slip  is  attached  to  the 
contiguous  margins  of  the  last  dorsal  and  first  lumbar  vertebras ;  the  last,  to  the 
contiguous  margins  of  the  fourth  and  fifth  lumbar,  and  intervertebral  substance. 
From  these  points,  the  muscle  passes  down  across  the  brim  of  the  pelvis,  and, 
diminishing  gradually  in  size,  passes  beneath  Poupart's  ligament,  and  terminates 
in  a  tendon,  which,  after  receiving  the  fibres  of  the  Iliacus,  is  inserted  into  the 
I  lesser  trochanter  of  the  femur. 

Relations.  In  the  Lumbar  Region.  By  its  anterior  surface,  which  is  placed 
behind  the  peritoneum,  with  the  ligamentum  arcuatum  internum,  the  kidney,  Psoas 
parvus,  renal  vessels,  ureter,  spermatic  vessels,  genito-crural  nerve,  the  colon,  and, 
along  its  pelvic  border,  with  the  common  and  external  iliac  artery  and  vein.  By 
its  posterior  surface,  with  the  transverse  processes  of  the  lumbar  vertebras  and  the 
Quadratus  lumborum,  from  which  it  is  separated  by  the  anterior  lamella  of  the 
aponeurosis  of  the  Transversalis ;  the  anterior  crural  nerve  is  at  first  situated  in 
the  substance  of  the  muscle,  and  emerges  from  its  outer  border  at  its  lower  part. 
The  lumbar  plexus  is  situated  in  the  posterior  part  of  the  substance  of  the  muscle. 
By  its  inner  side,  with  the  bodies  of  the  lumbar  vertebras,  the  lumbar  arteries,  the 
sympathetic  ganglia,  and  its  communicating  branches  with  the  spinal  nerves ;  the 
lumbar  glands,  with  the  vena  cava  on  the  right,  and  the  aorta  on  the  left  side.  In 
the  thigh,  it  is  in  relation,  in  front,  with  the  fascia  lata ;  behind,  with  the  capsular 
ligament  of  the  hip,  from  which  it  is  separated  by  a  synovial  bursa,  which  some- 
times communicates  with  the  cavity  of  the  joint  through  an  opening  of  variable 
size.  By  its  inner  border,  with  the  Pectineus  and  the  femoral  artery,  which 
slightly  overlaps  it.     By  its  outer  border  with  the  crural  nerve  and  Iliacus  muscle. 

The  Psoas  parvus  is  a  long  slender  muscle,  placed  in  front  of  the  preceding. 
It  arises  from  the  sides  of  the  bodies  of  the  last  dorsal  and  first  lumbar  vertebras, 
and  from  the  intervertebral  substance  between  them.  It  forms  a  small  flat 
muscular  bundle,  which  terminates  in  a  long,  flat  tendon,  which  is  inserted  into 
the  ilio-pectineal  eminence,  being  continuous,  by  its  outer  border,  with  the  iliac 
fascia.  This  muscle  is  present,  according  to  M.  Theile,  in  one  out  of  every  twenty 
subjects  examined. 

Relations.  It  is  covered  by  the  peritoneum,  and  at  its  origin  by  the  ligamentum 
arcuatum  internum ;  it  rests  on  the  Psoas  magnus. 

The  Iliacus  is  a  flat  radiated  muscle,  which  fills  up  the  whole  of  the  internal 
iliac  fossa.  It  arises  from  the  iliac  fossa,  and  inner  margin  of  the  crest  of  the 
ilium ;  behind,  from  the  ilio-lumbar  ligament,  and  base  of  the  sacrum ;  in  front, 
from  the  anterior  superior  and  anterior  inferior  spinous  processes  of  the  ilium,  the 
notch  between  them,  and  by  a  few  fibres  from  the  capsule  of  the  hip-joint.  The 
fibres  converge  to  be  inserted  into  the  outer  side  of  the  tendon  of  the  Psoas,  some 
of  them  being  prolonged  into  the  oblique  line  which  extends  from  the  lesser  tro- 
chanter to  the  linea  aspera. 

Relations.  Within  the  Pelvis:  by  its  anterior  surface,  with  the  iliac  fascia, 
which  separates  the  muscle  from  the  peritoneum,  and  with  the  external  cutaneous 
nerve ;  on  the  right  side,  with  the  cascum ;  on  the  left  side,  with  the  sigmoid 
flexure  of  the  colon.  By  its  postenor  surface,  with  the  iliac  fossa.  By  its  inner 
border,  with  the  Psoas  magnus,  and  anterior  crural  nerve. — In  the  Hugh,  it  is  in 


ANTERIOR   FEMORAL   REGION 


327 


relation,  by  its  anterior  surface,  with  the  fascia  lata,  Rectus  and  Sartorius ;  behind, 
with  the  capsule  of  the  hip-joint,  a  synovial  bursa  common  to  it  and  the  Psoas 
magnus  being  interposed. 

Nerves.  The  Psose  muscles  are  supplied  by  the  anterior  branches  of  the  lumbar 
nerves.     The  Iliacus  from  the  anterior  crural. 

Actions.  The  Psoas  and  Iliacus  muscles,  acting  from  above,  flex  the  thigh  upon 
the  pelvis,  and,  at  the  same  time,  rotate  the  femur  outwards,  from  the  obliquity 
of  their  insertion  into  the  inner  and  back  part  of  that  bone.  Acting  from  below, 
the  femur  being  fixed,  the  muscles  of  both  sides  bend  the  lumbar  portion  of  the 
spine  and  pelvis  forwards.  They  also  serve  to  maintain  the  erect  position,  by 
supporting  the  spine  and  pelvis  upon  the  femur,  and  assist  in  raising  the  trunk 
when  the  body  is  in  the  recumbent  posture. 

The  Psoas  parvus  is  a  tensor  of  the  iliac  fascia. 


Anterior  Femoral  Region. 


Tensor  Vaginae  Femoris. 


Sartorius. 
Rectus. 


Vastus  Externus. 
Vastus  Internus. 
Crureus. 


Subcrureus. 


Dissection.    To  expose  the  muscles  and  fasciae  in  this  region,  an  incision  should  be  made 
along  Poupart's  ligament,  from  the  spine  of  the  Ilium  to  the  pubes,  from  the  centre  of  which  a 
vertical  incision  must  be  carried  along  the  middle      Fi     186._Dissection  of  Lower  Extremitv. 
line  ot  the  thigh  to  below  the  knee-joint,  and  con-  Front  View. 

nected  with  a  transverse  incision,  carried  from 
the  inner  to  the  outer  side  of  the  leg.  The  flaps 
of  integument  having  been  removed,  the  super- 
ficial and  deep  fasciae  should  be  examined.  The 
more  advanced  student  would  commence  the 
study  of  this  region  by  an  examination  of  the 
anatomy  of  femoral  hernia,  and  Scarpa's  triangle, 
the  incisions  for  the  dissection  of  which  are 
marked  out  in  the  accompanying  figure. 


Fascijs  of  the  Thigh. 

The  superficial  fascia  forms  a  continu- 
ous layer  over  the  whole  of  the  lower 
extremity,  and  consists  of  areolar  tissue, 
containing  in  its  meshes  much  adipose 
matter,  and  capable  of  being  separated 
into  two  or  more  layers,  between  which 
are  found  the  superficial  vessels  and 
nerves.  It  varies  in  thickness  in  differ- 
ent parts  of  the  limb ;  in  the  sole  of  the 
foot  it  is  so  thin  as  to  be  scarcely  demon- 
strable, the  integument  being  closely  ad- 
herent to  the  deep  fascia  beneath,  but  in 
the  groin  it  is  thicker,  and  the  two  layers 
are  separated  from  one  another  by  the 
superficial  inguinal  glands,  the  internal 
saphenous  vein,  and  several  smaller  ves- 
sels. Of  these  two  layers,  the  most 
superficial  is  continuous  above  with  the 
superficial  fascia  of  the  abdomen,  the  deep 
layer  becoming  blended  with  the  fascia 
lata,  a  little  below  Poupart's  ligament. 
The  deep  layer  of  superficial  fascia  is  in- 
timately adherent  to  the  margins  of  the 


4    4 


I 


/ .  Dissection 

°f 
FEMORAL  HERNIA, 

fc 
SCARPAS  TRIANGLE 


Z\Z     \     2-  FRONTjf  THIGH 


3  .  FRONTrf   LEO 


/f.  .  DORSUMgf  FOOT 


328 


MUSCLES   AND   FASCIA. 


Fig.  187.—: 


the  Iliac  and  Anterior 
.  Regions. 


««?°/!l 


saphenous  opening  in  the  fascia  lata,  and 
pierced  in  this  situation  by  numerous 
small  bloodvessels  and  lymphatics,  hence 
the  name  cribriform  fascia,  which  has  been 
applied  to  it.  Subcutaneous  bursse  are 
found  in  the  superficial  fascia  over  the 
patella,  point  of  the  heel,  and  phalangeal 
articulations  of  the  toes. 

The  deep  fascia  of  the  thigh  is  exposed 
on  the  removal  of  the  superficial  fascia, 
and  is  named,  from  its  great  extent,  the 
fascia  lata ;  it  forms  a  uniform  investment 
for  the  whole  of  this  region  of  the  limb, 
but  varies  in  thickness  in  different  parts ; 
thus,  it  is  thickest  in  the  upper  and  outer 
side  of  the  thigh,  where  it  receives  a 
fibrous  expansion  from  the  Gluteus  maxi- 
mus  muscle,  and  the  Tensor  vaginae  femoris 
is  inserted  between  its  layers ;  it  is  very 
thin  behind,  and  at  the  upper  and  inner 
side,  where  it  covers  the  Adductor  muscles, 
and  again  becomes  stronger  around  the 
knee,  receiving  fibrous  expansions  from 
the  tendon  of  the  Biceps  externally,  and 
from  the  Sartor  ius,  Gracilis,  Semi-tendi- 
nosus,  and  Quadriceps  extensor  cruris  in 
front.  The  fascia  lata  is  attached,  above, 
to  Poupart's  ligament,  and  crest  of  the 
ilium;  behind,  to  the  margin  of  the  sa- 
crum and  coccyx ;  internally,  to  the  pubic 
arch  and  pectineal  line ;  and  below,  to  all 
the  prominent  points  around  the  knee- 
joint,  the  condyles  of  the  femur,  tuberosi- 
ties of  the  tibia,  and  head  of  the  fibula. 
That  portion  which  invests  the  Gluteus 
medius  (the  Gluteal  aponeurosis)  is  very 
thick  and  strong,  and  gives  origin  by  its 
inner  surface,  to  some  of  the  fibres  of 
that  muscle ;  at  the  upper  border  of  the 
Gluteus  maximus,  it  divides  into  two 
layers,  the  most  superficial,  very  thin, 
covering  the  surface  of  the  Gluteus  maxi- 
mus, and  is  continuous  below  with  the 
fascia  lata;  the  deep  layer  being  thick  above, 
and  blending  with  the  great  sacro-sciatic 
ligament,  thin  below,  where  it  separates 
the  Gluteus  maximus  from  the  deeper 
muscles.  From  the  inner  surface  of  the 
fascia  lata,  are  given  off  two  strong  inter- 
muscular septa,  which  are  attached  to 
the  whole  length  of  the  linea  aspera :  the 
external  and  stronger  one,  which  extends 
from  the  insertion  of  the  Gluteus  maximus, 
to  the  outer  condyle,  separates  the  Vastus 
externus  in  front  from  the  short  head  of 
the  Biceps  behind,  and  gives  partial  origin 
to    these    muscles ;    the    inner    one,    the 


ANTERIOR   FEMORAL   REGION.  S29 

thinner  of  the  two,  separates  the  Vastus  internus  from  the  Adductor  muscles. 
Besides  these,  there  are  numerous  smaller  septa,  separating  the  individual  muscles, 
and  inclosing  each  in  a  distinct  sheath.  At  the  upper  and  inner  part  of  the  thigh, 
a  little  below  Poupart's  ligament,  a  large  oval-shaped  aperture  is  observed :  it 
transmits  the  internal  saphenous  vein,  and  other  smaller  vessels,  and  is  termed 
the  saphenous  opening.  In  order  more  correctly  to  consider  the  mode  of  forma- 
tion of  this  aperture,  the  fascia  lata  is  described  as  consisting,  in  this  part  of  the 
thigh,  of  two  portions,  an  iliac  portion,  and  a  pubic  portion. 

The  iliac  portion  is  all  that  part  of  the  fascia  lata  placed  on  the  outer  side  of 
the  saphenous  opening.  It  is  attached,  externally,  to  the  crest  of  the  ilium,  and 
its  anterior  superior  spine,  to  the  whole  length  of  Poupart's  ligament,  as  far  inter- 
nally as  the  spine  of  the  pubes,  and  to  the  pectineal  line  in  conjunction  with  Gim- 
bernat's  ligament.  From  the  spine  of  the  pubes,  it  is  reflected  downwards  and 
outwards,  forming  an  arched  margin,  the  superior  cornu  or  outer  boundary  of  the 
saphenous  opening ;  this  margin  overlies,  and  is  adherent  to,  the  anterior  layer  of 
the  sheath  of  the  femoral  vessels ;  to  its  edge  is  attached  the  cribriform  fascia,  and, 
below,  it  is  continuous  with  the  pubic  portion  of  the  fascia  lata. 

The  pubic  portion  is  situated  at  the  inner  side  of  the  saphenous  opening ;  at  the 
lower  margin  of  this  aperture  it  is  continuous  with  the  iliac  portion ;  traced  up- 
wards, it  is  seen  to  cover  the  surface  of  the  Pectin  eus  muscle,  and  passing  behind 
the  sheath  of  the  femoral  vessels,  to  which  it  is  closely  united,  is  continuous  with 
the  sheath  of  the  Psoas  and  Iliacus  muscles,  and  is  finally  lost  in  the  fibrous  cap- 
sule of  the  hip-joint.  This  fascia  is  attached  above  to  the  pectineal  line  in  front 
of  the  insertion  of  the  aponeurosis  of  the  External  oblique,  and  internally  to  the 
margin  of  the  pubic  arch.  From  this  description  it  may  be  observed,  that  the 
iliac  portion  of  the  fascia  lata  passes  in  front  of  the  femoral  vessels,  the  pubic  por- 
tion behind  them,  an  apparent  aperture  consequently  existing  between  the  two, 
through  which  the  internal  saphenous  joins  the  femoral  vein. 

The  fascia  should  now  be  removed  from  the  surface  of  the  muscles.  This  may  be  effected  by 
pinching  it  up  between  the  forceps,  dividing  it,  and  separating  it  from  each  muscle  in  the  course 
of  its  fibres. 

The  Tensor  Vaginse  Femoris  is  a  short  flat  muscle,  situated  at  the  upper  and 
outer  side  of  the  thigh.  It  arises  from  the  anterior  part  of  the  outer  lip  of  the 
crest  of  the  ilium,  and  from  the  outer  surface  of  the  anterior  superior  spinous 
process,  between  the  Gluteus  medius  and  Sartorius.  The  muscle  passes  obliquely 
downwards,  and  a  little  backwards,  to  be  inserted  into  the  fascia  lata,  about  one- 
fourth  down  the  outer  side  of  the  thigh. 

Relations.  By  its  superficial  surface,  with  the  fascia  lata  and  the  integument. 
By  its  deep  surface,  with  the  Gluteus  medius,  Rectus  femoris,  Vastus  externus, 
and  the  ascending  branches  of  the  external  circumflex  artery.  By  its  anterior 
border,  with  the  Sartorius,  from  which  it  is  separated  below  by  a  triangular  space, 
in  which  is  seen  the  Rectus  femoris.  By  its  posterior  border,  with  the  Gluteus 
medius. 

The  Sartorius,  the  longest  muscle  in  the  body,  is  a  flat,  narrow,  riband-like 
muscle,  which  arises  by  tendinous  fibres  from  the  anterior  superior  spinous  process 
of  the  ilium  and  upper  half  of  the  notch  below  it ;  it  passes  obliquely  across  the 
upper  and  anterior  part  of  the  thigh,  from  the  outer  to  the  inner  side  of  the 
limb,  then  descends  vertically,  as  far  as  the  inner  side  of  the  knee,  passing  behind 
the  inner  condyle  of  the  femur,  and  terminates  in  a  tendon,  which  curving  ob- 
liquely forwards,  expands  into  a  broad  aponeurosis,  which  is  inserted  into  the 
upper  part  of  the  inner  surface  of  the  shaft  of  the  tibia,  nearly  as  far  forwards  as 
the  crest.  This  expansion  covers  the  insertion  of  the  tendons  of  the  Gracilis  and 
Semi-tendinosus,  with  which  it  is  partially  united,  a  synovial  bursa  being  inter- 
posed between  them.  An  offset  is  derived  from  this  aponeurosis,  which  blends 
with  the  fibrous  capsule  of  the  knee-joint,  and  another,  given  off*  from  its  lower 
border  blends  with  the  fascia  on  the  inner  side  of  the  leg.     The  relations  of  this 


330  MUSCLES   AND   FASCIA. 

muscle  to  the  femoral  artery  should  be  carefully  examined,  as  its  inner  border 
forms  the  chief  guide  in  the  operation  of  including  this  vessel  in  a  ligature.  In 
the  upper  third  of  the  thigh,  it  forms,  with  the  Adductor  longus,  the  side  of  a 
triangular  space,  Scarpa's  triangle,  the  base  of  which,  turned  upwards,  is  formed 
by  Poupart's  ligament :  the  femoral  artery  passes  perpendicularly  through  the 
centre  of  this  space  from  its  base  to  its  apex.  In  the  middle  third  of  the  thigh, 
the  femoral  artery  lies  first  along  the  inner  border,  and  then  beneath  the  Sar- 
torius. 

Relations.  By  its  superficial  surface,  with  the  fascia  lata  and  integument.  By 
its  deep  surface,  with  the  Iliacus,  Psoas,  Kectus,  Vastus  internus,  anterior  crural 
nerve,  sheath  of  the  femoral  vessels,  Adductor  longus,  Adductor  magnus,  Graci- 
lis, long  saphenous  nerve,  and  internal  lateral  ligament  of  the  knee-joint. 

The  Quadriceps  extensor  includes  the  four  remaining  muscles  on  the  front  of 
the  thigh.  It  is  the  great  Extensor  muscle  of  the  leg,  forming  a  large  fleshy  mass, 
which  covers  the  front  and  sides  of  the  femur,  being  united  below  into  a  single 
tendon,  attached  to  the  tibia,  and,  above,  subdividing  into  separate  portions,  which 
have  received  separate  names.  Of  these,  one  occupying  the  middle  of  the  thigh, 
connected  above  with  the  ilium,  is  called  the  Rectus  femoris,  from  its  straight 
course.  The  other  divisions  lie  in  immediate  connection  with  the  shaft  of  the 
femur,  which  they  cover  from  the  condyles  to  the  trochanters.  The  portion  on 
the  outer  side  of  the  femur  is  termed  the  Vastus  externus;  that  covering  the  inner 
side,  the  Vastus  internus ;  and  that  covering  the  front  of  the  femur,  the  Crureus. 
The  two  latter  j)ortions  are,  however,  so  intimately  blended,  as  to  form  but  one 
muscle. 

The  Rectus  femoris  is  situated  in  the  middle  of  the  anterior  region  of  the  thigh ; 
it  is  fusiform  in.  shape,  and  its  fibres  are  arranged  in  a  bipenniform  manner.  It 
arises  by  two  tendons ;  one,  the  straight  tendon,  from  the  anterior  inferior  spinous 
process  of  the  ilium ;  the  other  is  flattened,  and  curves  outwards,  to  be  attached 
to  a  groove  above  the  brim  of  the  acetabulum ;  this  is  the  reflected  tendon  of  the 
Rectus,  uniting  with  the  straight  tendon  at  an  acute  angle,  and  then  spreading  into 
an  aponeurosis,  from  which  the  muscular  fibres  arise.  The  muscle  terminates  in 
a  broad  and  thick  aponeurosis,  which  occupies  the  lower  two-thirds  of  its  poste- 
rior surface,  and,  gradually  becoming  narrowed  into  a  flattened  tendon,  is  inserted 
into  the  patella  in  common  with  the  Vasti  and  Crureus. 

Relations.  By  its  superficial  surface,  with  the  anterior  fibres  of  the  Gluteus 
medius,  the  Tensor  vaginas  femoris,  Sartorius,  and  the  Psoas  and  Iliacus ;  by  its 
lower  three-fourths,  with  the  fascia  lata.  By  its  posterior  surface,  with  the  hip- 
joint,  the  external  circumflex  vessels,  and  the  Crureus  and  Vasti  muscles. 

The  three  remaining  muscles  have  been  described  collectively  by  some  anato- 
mists, separate  from  the  Eectus,  under  the  name  of  the  Triceps  extensor  cruris ;  in 
order  to  expose  them,  divide  the  Sartorius  and  Rectus  muscles  across  the  middle, 
and  turn  them  aside,  when  they  will  be  fully  brought  into  view. 

The  Vastus  externus  is  the  largest  part  of  the  Quadriceps  extensor.  It  arises 
by  a  broad  aponeurosis,  which  is  attached  to  the  anterior  border  of  the  great  tro- 
chanter, to  a  horizontal  ridge  on  its  outer  surface,  to  a  rough  line,  leading  from 
the  trochanter  major  to  the  linea  aspera,  and  to  the  whole  length  of  the  outer  lip 
of  the  linea  aspera ;  this  aponeurosis  covers  the  upper  three-fourths  of  the  muscle, 
and  from  its  inner  surface  many  fibres  arise.  A  few  additional  fibres  come  from 
the  tendon  of  the  Gluteus  maximus,  and  from  the  external  intermuscular  septum 
between  the  Vastus  externus  and  short  head  of  the  Biceps.  These  fibres  form  a 
large  fleshy  mass,  which  is  attached  to  a  strong  aponeurosis,  placed  on  the  under 
surface  of  the  muscle  at  its  lowest  part;  this  becomes  contracted  and  thickened 
into  a  flat  tendon,  which  is  inserted  into  the  outer  part  of  the  upper  border  of  the 
patella,  blending  with  the  great  Extensor  tendon. 

Relations.  By  its  superficial  surface,  with  the  Rectus,  the  Tensor  vaginas 
femoris,  the  fascia  lata,  and  the  Gluteus  maximus,  from  which  it  is  separated  by  a 


ANTERIOR   FEMORAL  REGION.  331 

synovial  bursa.  By  its  deep  surface,  with  the  Crureus,  some  large  branches  of 
the  external  circumflex  artery  and  anterior  crural  nerve  being  interposed. 

The  Vastus  interims  and  Crureus  are  so  inseparably  connected  together,  as  to 
form  but  one  muscle.  It  is  the  smallest  portion  of  the  Quadriceps  extensor.  The 
anterior  portion  of  it,  which  is  covered  by  the  Rectus,  being  called  the  Crureus ; 
the  internal  portion,  which  lies  immediately  beneath  the  fascia  lata,  is  called  the 
Vastus  Internus.  It  arises  by  an  aponeurosis,  which  is  attached  to  the  lower  part 
of  the  line  that  extends  from  the  inner  side  of  the  neck  of  the  femur  to  the  linea 
aspera,  from  the  whole  length  of  the  inner  lip  of  the  linea  aspera,  and  internal 
intermuscular  septum.  It  also  arises  from  nearly-  the  whole  of  the  internal, 
anterior,  and  external  surfaces  of  the  shaft  of  the  femur,  limited,  above,  by  the  line 
between  the  two  trochanters,  and  extending,  below,  to  within  the  lower  fourth  of 
the  bone.  From  these  different  origins,  the  fibres  converge  to  a  broad  aponeurosis, 
which  covers  the  anterior  surface  of  the  middle  portion  of  the  muscle  (the  Crureus), 
and  the  deep  surface  of  the  inner  division  of  the  muscle  (the  Vastus  internus) ; 
becoming  joined  and  gradually  narrowing,  it  is  inserted  into  the  patella,  blending 
with  the  other  portions  of  the  Quadriceps  extensor. 

Relations.  By  their  superficial  surface,  with  the  Psoas  and  Iliacus,  the  Rectus, 
Sartorius,  Pectineus,  Adductors,  and  fascia  lata,  femoral  vessels,  and  saphenous 
nerve.  By  its  deep  surface,  with  the  femur,  Subcrureus,  and  synovial  membrane 
of  the  knee-joint. 

The  student  will  observe  the  striking  analogy  that  exists  between  the  Quadri- 
ceps extensor,  and  the  Triceps  brachialis  in  the  upper  extremity.  So  close  is  this 
similarity,  that  M.  Cruveilhier  has  described  it  under  the  name  of  the  Triceps 
femoralis.  Like  the  Triceps  brachialis,  it  consists  of  three  distinct  divisions 
or  heads;  a  middle  or  long  head,  analogous  to  the  long  head  of  the  Triceps, 
attached  to  the  ilium,  and  of  two  other  portions  which  have  respectively  received 
the  names  of  the  external  and  internal  heads  of  the  muscle.  These,  it  will 
be  noticed,  are  strictly  analogous  to  the  outer  and  inner  heads  of  the  Triceps 
brachialis. 

The  tendons  of  the  different  portions  of  the  Quadriceps  extensor  unite  at  the 
lower  part  of  the  thigh,  so  as  to  form  a  single  strong  tendon,  which  is  inserted 
into  the  upper  part  of  the  patella.  More  properly  speaking,  the  patella  may  be 
regarded  as  a  sesamoid  bone,  developed  in  the  tendon  of  the  Quadriceps ;  and  the 
ligamentum  patellae,  which  is  continued  from  the  lower  part  of  the  patella  to  the 
tuberosity  of  the  tibia,  as  the  proper  tendon  of  insertion  of  this  muscle.  A  syno- 
vial bursa  is  interposed  between  the  tendon  and  the  upper  part  of  the  tuberosity 
of  the  tibia.  From  the  tendons  corresponding  to  the  Vasti,  a  fibrous  prolongation 
is  derived,  which  is  attached  below  to  the  upper  extremities  of  the  tibia  and  fibula. 
It  serves  to  protect  the  knee-joint,  which  is  strengthened  on  its  outer  side  by  the 
fascia  lata. 

The  Subcrureus  is  a  small  muscle,  usually  distinct  from  the  superficial  muscle, 
which  arises  from  the  anterior  surface  of  the  lower  part  of  the  shaft  of  the  femur, 
and  is  inserted  into  the  upper  part  of  the  synovial  pouch  that  extends  upwards 
from  the  knee-joint  behind  the  patella.  This  fasciculus  is  occasionally  united  with 
the  Crureus.     It  sometimes  consists  of  two  separate  muscular  bundles. 

Nerves.  The  Tensor  vaginse  femoris  is  supplied  by  the  superior  gluteal  nerve ; 
the  other  muscles  of  this  region,  by  branches  from  the  anterior  crural. 

Actions.  The  Tensor  vaginse  femoris  is  a  tensor  of  the  fascia  lata ;  continuing 
its  action,  the  oblique  direction  of  its  fibres  enables  it  to  rotate  the  thigh  inwards. 
In  the  erect  posture,  acting  from  below,  it  will  serve  to  steady  the  pelvis  upon  the 
head  of  the  femur.  The  Sartorius  flexes  the  leg  upon  the  thigh,  and,  continuing 
to  act,  the  thigh  upon  the  pelvis,  at  the  same  time  drawing  the  limb  inwards,  so 
as  to  cross  one  leg  over  the  other.  Taking  its  fixed  point  from  the  leg,  it  flexes 
the  pelvis  upon  the  thigh,  and,  if  one  muscle  acts,  assists  in  rotating  it.  The 
Quadriceps  extensor  extends  the  leg  upon  the  thigh.  Taking  its  fixed  point  from 
the  leg,  as  in  standing,  this  muscle  will  act  upon  the  femur,  supporting  it  perpen- 


332 


MUSCLES   AND   FASCIJE. 


dicularly  upon  the  head  of  the  tibia,  thus  maintaining  the  entire  weight  of  the 
body.  The  Eectus  muscle  assists  the  Psoas  and  Iliacus  in  supporting  the  pelvis 
and  trunk  upon  the  femur,  or  in  bending  it  forwards. 


Fig.  188. — Muscles  of  the  Internal  Femoral 
Region.  I 


Internal  Femoral  Region. 

Gracilis. 
Pectineus. 
Adductor  Longus. 
Adductor  Brevis. 
Adductor  Magnus. 

Dissection.  These  muscles  are  at  once  ex- 
posed by  removing  the  fascia  from  the  fore  part 
and  inner  side  of  the  thigh.  The  limb  should 
be  abducted,  so  as  to  render  the  muscles  tense, 
and  easier  of  dissection. 

The  Gracilis  is  the  most  superficial 
muscle  on  the  inner  side  of  the  thigh.  It 
is  thin  and  flattened,  broad  above,  narrow 
and  tapering  below.  It  arises  by  a  thin 
aponeurosis  between  two  and  three  inches 
in  breadth,  from  the  inner  margin  of  the 
ramus  of  the  pubes  and  ischium.  The 
fibres  pass  vertically  downwards,  and 
terminate  in  a  rounded  tendon  which 
passes  behind  the  internal  condyle  of  the 
femur ;  curving  round  the  inner  tubero- 
sity of  the  tibia,  it  becomes  flattened, 
and  is  inserted  into  the  upper  part  of  the 
inner  surface  of  the  shaft  of  the  tibia, 
below  the  tuberosity.  The  tendon  of 
this  muscle  is  situated  immediately  above 
that  of  the  Semi-tendinosus,  and  beneath 
the  aponeurosis  of  the  Sartorius,  with 
which  it  is  in  part  blended.  As  it  passes 
across  the  internal  lateral  ligament  of  the 
knee-joint,  it  is  separated  from  it  by  a 
synovial  bursa  common  to  it  and  the  Semi- 
tendinosus  muscle. 

Relations.  By  its  superficial  surface, 
with  the  fascia  lata  and  the  Sartorius 
below ;  the  internal  saphenous  vein  crosses 
it  obliquely  near  its  lower  part,  lying 
superficial  to  the  fascia  lata.  By  its  deep 
surface,  with  the  three  Adductors,  'and 
the  internal  lateral  ligament  of  the  knee- 
joint. 

The  Pectineus  is  a  flat  quadrangular 
muscle,  situated  at  the  anterior  part  of 
the  upper  and  inner  aspect  of  the  thigh. 
It  arises  from  the  linea  ilio-pectinea,  from 
the  surface  of  bone  in  front  of  it,  between 
the  pectineal  eminence  and  spine  of  the 
pubes,  and  from  a  tendinous  prolongation 
of  Gimbernat's  ligament,  which  is  attached 


INTERNAL    FEMORAL   REGION.  333 

to  the  crest  of  the  pubes,  and  is  continuous  with  the  fascia  covering  the  outer 
surface  of  the  muscle;  the  fibres  pass  downwards,  backwards,  and  outwards, 
to  be  inserted  into  a  rough  line  leading  from  the  trochanter  minor  to  the  linea 

aspera.  .  . 

Relations.  By  its  anterior  surface,  with  the  pubic  portion  of  the  fascia  lata, 
which  separates  it  from  the  femoral  vessels  and  internal  saphenous  vein.  By  its 
posterior  surface,  with  the  hip-joint,  the  Adductor  brevis  and  Obturator  externus 
muscles,  the  obturator  vessels  and  nerve  being  interposed.  By  its  outer  border, 
with  the  Psoas,  a  cellular  interval  separating  them,  upon  which  lies  the  femoral 
artery.     By  its  inner  border,  with  the  margin  of  the  Adductor  longus. 

The  Adductor  Longus,  the  most  superficial  of  the  three  Adductors,  _  is  a  flat 
triangular  muscle,  lying  on  the  same  plane  as  the  Pectineus,  with  which  it  is  often 
blended  above.  It  arises,  by  a  flat  narrow  tendon,  from  the  front  of  the  pubes,  at 
the  angle  of  junction  of  the  crest  with  the  symphysis ;  it  soon  expands  into  a  broad 
fleshy  belly,  which,  passing  downwards,  backwards,  and  outwards,  is  inserted,  by 
an  aponeurosis,  into  the  middle  third  of  the  linea  aspera,  between  the  Vastus 
internus  and  the  Adductor  magnus. 

Relations.  By  its  anterior  surface,  with  the  fascia  lata,  and,  near  its  insertion, 
with  the  femoral  artery  and  vein.  By  its  posterior  surface,  with  the  Adductor 
brevis  and  Adductor  magnus,  the  anterior  branches  of  the  obturator  vessels  and 
nerve,  and  with  the  profunda  artery  and  vein  near  its  insertion.  By  its  outer 
border,  with  the  Pectineus.     By  its  inner  border,  with  the  Gracilis. 

The  Pectineus  and  Adductor  longus  should  now  be  divided  near  their  origin,  and  turned  down- 
wards, when  the  Adductor  brevis  and  Obturator  externus  will  be  exposed. 

The  Adductor  Brevis  is  situated  immediately  beneath  the  two  preceding  muscles. 
It  is  somewhat  triangular  in  form,  and  arises  by  a  narrow  origin  from  the  outer 
surface  of  the  descending  ramus  of  the  pubes,  between  the  Gracilis  and  Obturator 
externus.  Its  fibres,  passing  backwards,  outwards,  and  downwards,  are  inserted, 
by  an  aponeurosis,  into  the  upper  part  of  the  linea  aspera,  immediately  behind  the 
Pectineus  and  upper  part  of  the  Adductor  longus. 

Relations.  By  its  anterior  surface,  with  the  Pectineus,  Adductor  longus,  and 
anterior  branches  of  the  obturator  vessels  and  nerve.  By  its  posterior  surface, 
with  the  Adductor  magnus,  and  posterior  branches  of  the  obturator  vessels  and 
nerve.  By  its  outer  border,  with  the  Obturator  externus,  and  conjoined  tendon 
of  the  Psoas  and  Iliacus.  By  its  inner  border,  with  the  Gracilis  and  Adductor 
magnus.  This  muscle  is  pierced,  near  its  insertion,  by  the  middle  perforating 
branch  of  the  profunda  artery. 

The  Adductor  brevis  should  now  be  cut  away  near  its  origin,  and  turned  outwards,  when  the 
entire  extent  of  the  Adductor  magnus  will  be  exposed. 

The  Adductor  Magnus  is  a  large  triangular  muscle,  forming  a  septum  between 
the  muscles  on  the  inner  part  and  those  on  the  back  of  the  thigh.  It  arises  from 
a  small  part  of  the  descending  ramus  of  the  pubes,  from  the  ascending  ramus  of 
the  ischium,  and  from  the  outer  margin  and  under  surface  of  the  tuberosity  of  the 
ischium.  Those  fibres  which  arise  from  the  ramus  of  the  pubes  are  very  short, 
horizontal  in  direction,  and  are  inserted  into  the  rough  line  leading  from  the  great 
trochanter  to  the  linea  aspera,  internal  to  the  Gluteus  maximus ;  those  from  the 
ramus  of  the  ischium  are  directed  downwards  and  outwards  with  different  degrees 
of  obliquity,  to  be  inserted,  by  means  of  a  broad  aponeurosis,  into  the  whole  length 
of  the  linea  aspera  and  upper  part  of  its  internal  bifurcation  below.  The  internal 
portion  of  the  muscle,  consisting  principally  of  those  fibres  which  arise  from  the 
tuberosity  of  the  ischium,  forms  a  thick  fleshy  mass  consisting  of  coarse  bundles 
which  descend  almost  vertically,  and  terminate  about  the  lower  third  of  the  thigh 
in  a  rounded  tendon,  which  is  inserted  into  the  tubercle  above  the  inner  condyle 
of  the  femur,  being  connected  by  a  fibrous  expansion  to  the  line  leading  upwards 
from  the  tubercle  to  the  linea  aspera.     Between  the  two  portions  of  the  muscle, 


334  MUSCLES   AND   FASCIAE. 

an  angular  interval  is  left,  tendinous  in  front,  fleshy  behind,  for  the  passage  of 
the  femoral  vessels  into  the  popliteal  space.  The  external  portion  of  the  muscle 
is  pierced  by  four  apertures ;  the  three  superior,  for  the  three  superior  perforating 
arteries,  the  fourth  for  the  passage  of  the  profunda.  This  muscle  gives  off  an 
aponeurosis,  which  passes  in  front  of  the  femoral  vessels,  and  joins  with  the  Vastus 
internus. 

Relations.  By  its  anterior  surface,  with  the  Pectineus,  Adductor  brevis,  Adduc- 
tor longus  and  the  femoral  vessels.  By  its  posterior  surface,  with  the  great 
sciatic  nerve,  the  Gluteus  maximus,  Biceps,  Semi-tendinosus,  and  Semi-membra- 
nosus.  By  its  superior  or  shortest  border,  it  lies  parallel  with  the  Quadratus 
femoris.  By  its  internal  or  longest  border,  with  the  Gracilis,  Sartorius,  and  fascia 
lata.  By  its  external  or  attached  border,  it  is  inserted  into  the  femur  behind  the 
Adductor  brevis  and  Adductor  longus,  which  separate  it,  in  front,  from  the  Vastus 
internus,  and  in  front  of  the  Gluteus  maximus  and  short  head  of  the  Biceps,  which 
separate  it  from  the  Vastus  externus. 

Nerves.  All  the  muscles  of  this  group  are  supplied  by  the  obturator  nerve. 
The  Pectineus  receives  additional  branches  from  the  accessory  obturator  and  ante- 
rior crural ;  and  the  Adductor  magnus  an  additional  branch  from  the  great  sciatic. 

Actions.  The  Pectineus  and  three  Adductors  adduct  the  thigh  powerfully ;  they 
are  especially  used  in  horse-exercise,  the  flanks  of  the  horse  being  firmly  grasped 
between  the  knees  by  the  action  of  these  muscles.  From  their  oblique  insertion 
into  the  linea  aspera,  they  rotate  the  thigh  outwards,  assisting  the  external  Eotators, 
and  when  the  limb  has  been  abducted,  they  draw  it  inwards,  carrying  the  thigh 
across  that  of  the  opposite  side.  The  Pectineus  and  Adductor  brevis  and  Adduc- 
tor longus  assist  the  Psoas  and  Iliacus  in  flexing  the  thigh  upon  the  pelvis.  In 
progression,  also,  all  these  muscles  assist  in  drawing  forwards  the  hinder  limb. 
The  Gracilis  assists  the  Sartorius  in  flexing  the  leg  and  drawing  it  inwards ;  it  is 
also  an  Adductor  of  the  thigh.  If  the  lower  extremities  are  fixed,  these  muscles 
may  take  their  fixed  point  from  below  and  act  upon  the  pelvis,  serving  to  maintain 
the  body  in  the  erect  posture ;  or,  if  their  action  is  continued,  to  flex  the  pelvis 
forwards  upon  the  femur. 


Gluteal  Kegion-. 

Gluteus  Maximus.     .  Gemellus  Superior. 

Gluteus  Medius.  Obturator  Internus. 

Gluteus  Minimus.  Gemellus  Inferior. 

Pyriformis.  Obturator  Externus. 

Quadratus  Femoris. 

Dissection  (fig.  189).  The  subject  should  be  turned  on  its  face,  a  block  placed  beneath  the 
pelvis  to  make  the  buttocks  tense,  and  the  limbs  allowed  to  hang  over  the  end  of  the  table,  the 
foot  inverted,  and  the  limb  abducted.  An  incision  should  be  made  through  the  integument  along 
the  back  part  of  the  crest  of  the  ilium  and  margin  of  the  sacrum  to  the  tip  of  the  coccj'x,  from 
which  point  a  second  incision  should  be  carried  obliquely  downwards  and  outwards  to  the  outer 
side  of  the  thigh,  four  inches  below  the  great  trochanter.  The  portion  of  integument  included 
between  these  incisions,  together  with  the  superficial  fascia,  should  be  removed  in  the  direction 
shown  in  the  figure,  when  the  Gluteus  maximus  and  the  dense  fascia  covering  the  Gluteus  medius 
will  be  exposed. 

The  Gluteus  Maximus,  the  most  superficial  muscle  in  the  gluteal  region,  is  a 
very  broad  and  thick  fleshy  mass,  of  a  quadrilateral  shape,  which  forms  the  pro- 
minence of  the  nates.  Its  large  size  is  one  of  the  most  characteristic  points  in 
the  muscular  system  in  man,  connected  as  it  is  with  the  power  he  has  of  main- 
taining the  trunk  in  the  erect  posture.  In  structure  it  is  remarkably  coarse,  being 
made  up  of  muscular  fasciculi  lying  parallel  with  one  another,  and  collected 
together  into  large  bundles,  separated  by  deep  cellular  intervals.  It  arises  from 
the  superior  curved  line  of  the  ilium,  and  the  portion  of  bone,  including  the  crest, 


GLUTEAL   KEGIOX. 


335 


Fig. 


189. — Dissection  of  the  Lower  Ex- 
tremity.    Posterior  View. 


/  i  Dissection  of 

CLUTEAL    REGIOIJ 


immediately  behind  it ;  from  the  posterior  surface  of  the  last  piece  of  the  sacrum, 
the  side  of  the    coccyx,   and  posterior  surface  of  the  great   sacro-sciatic  and 
posterior  sacro-iliac  ligaments.     The  fibres  are  directed  obliquely  downwards  and 
outwards ;  those  forming  the  upper  and  larger 
portion  of  the  muscle  (after  converging  some- 
what) terminate  in  a  thick  tendinous  lamina, 
which  passes  across  the  great  trochanter,  and 
is  inserted  into  the  fascia  lata  covering  the 
outer  side  of  the  thigh,  the  lower  portion  of 
the  muscle  being  inserted  into  the  rough  line 
leading  from  the  great  trochanter  to  the  linea 
aspera,  between  the  Vastus  externus  and  Ad- 
ductor magnus. 

Three  synovial  bursse  are  usually  found  se- 
parating the  under  surface  of  this  muscle  from 
the  eminences  which  it  covers.  One  of  these, 
of  large  size,  and  generally  multilocular,  sepa- 
rates it  from  the  great  trochanter.  A  second, 
often  wanting,  is  situated  on  the  tuberosity  of 
the  ischium.  A  third,  between  the  tendon  of 
this  muscle  and  the  Vastus  externus. 

Relations.  By  its  superficial  surface,  with 
a  thin  fascia,  which  separates  it  from  cellular 
membrane,  fat,  and  the  integument.  By  its 
deep  surface,  from  above  downwards,  with 
the  ilium,  sacrum,  coccyx,  and  great  sacro- 
sciatic  ligament,  part  of  the  Gluteus  medius, 
Pyriformis,  Gemelli,  Obturator  internus, 
Quadratus  femoris,  the  tuberosity  of  the 
ischium,  great  trochanter,  the  origin  of  the 
Biceps,  Semi-tendinosus,  Semi-membranosus, 
and  Adductor  magnus  muscles.  The  gluteal 
vessels  and  nerve  are  seen  issuing  from  the 
pelvis  above  the  Pyriformis  muscle,  the 
ischiatic  and  internal  pudic  vessels  and  nerves, 
and  the  nerve  to  the  Obturator  internus 
muscle  below  it.  Its  upper  border  is  thin, 
and  connected  with  the  Gluteus  medius  by 
the  fascia  lata.  Its  lower  border,  free  and 
prominent,  forms  the  fold  of  the  nates,  and  is 
directed  towards  the  perineum. 


BACK   of  THICB 


POPLITEAL  SPACE 


BACK  of     LEG 


SOLE   of    FOOT 


Dissection.  The  Gluteus  maxiraus  should  now  be  divided  near  its  origin  by  a  vertical  incision 
carried  from  its  upper  to  its  lower  border :  a  cellular  interval  will  be  exposed,  separating  it  from 
the  Gluteus  medius  and  external  Rotator  muscles  beneath.  The  upper  portion  of  the  muscle 
should  be  altogether  detached,  and  the  lower  portion  turned  outwards ;  the  loose  areolar  tissue 
filling  up  the  interspace  between  the  trochanter  major  and  tuberosity  of  the  ischium  being  re- 
moved, the  parts  already  enumerated  as  exposed  by  the  removal  of  this  muscle  will  be  seen. 


The  Gluteus  Medius  is  a  broad,  thick,  radiated  muscle,  situated  on  the  outer 
surface  of  the  pelvis.  Its  posterior  third  is  covered  by  the  Gluteus  maximus ;  its 
anterior  two-thirds  are  covered  by  the  fascia  lata,  which  separates  it  from  %he 
integument.  It  arises  from  the  outer  surface  of  the  ilium,  between  the  superior 
and  middle  curved  lines,  and  from  the  outer  lip  of  that  portion  of  the  crest  which 
is  between  them ;  it  also  arises  from  the  dense  fascia  covering  its  anterior  part. 
The  fibres  converge  to  a  strong  flattened  tendon,  which  is  inserted  into  the  oblique 
line  which  traverses  the  outer  surface  of  the  great  trochanter.     A  synovial  bursa 


336 


MUSCLES   AND    FASCI.E, 


Fig.  190. — Muscles  of  the  Hip  and  Thigh. 


TT-irm  atriny 


separates  the  tendon  of  the 
muscle  from  the  surface  of 
the  trochanter  in  front  of  its 
insertion. 

Relations.  By  its  superfi- 
cial surface,  with  the  Gluteus 
maximus  behind,  the  Tensor 
vaginae  femoris  and  deep  fas- 
cia in  front.  By  its  deep 
surface,  with  the  Gluteus  mi- 
nimus and  the  gluteal  vessels 
and  nerve.  Its  anterior  bor- 
der is  blended  with  the  Glu- 
teus minimus.  Its  posterior 
border  lies  parallel  with  the 
Pyriformis,  the  gluteal  vessels 
intervening. 

This  muscle  should  now  be  divided 
near  its  insertion  and  turned  up- 
wards, when  the  Gluteus  minimus 
will  be  exposed. 

The  Gluteus  Minimus,  the 
smallest  of  the  three  glutei, 
is  placed  immediately  beneath 
the  preceding.  It  is  fan- 
shaped,  arising  from  the  outer 
surface  of  the  ilium,  between 
the  middle  and  inferior  curved 
lines,  and  behind,  from  the 
margin  of  the  great  sacro- 
sciatic  notch;  the  fibres  con- 
verge to  the  deep  surface  of 
a  radiated  aponeurosis,  which, 
terminating  in  a  tendon,  is 
inserted  into  an  impression 
on  the  anterior  border  of  the 
great  trochanter.  A  synovial 
bursa  is  interposed  between 
the  tendon  and  the  great  tro- 
chanter. 

Relations.  By  its  superfi- 
cial surface,  with  the  Gluteus 
medius,  and  the  gluteal  vessels 
and  nerve.  By  its  deep  sur- 
face, with  the  ilium,  the  re- 
flected tendon  of  the  Eectus 
femoris,  and  capsular  liga- 
ment of  the  hip-joint.  Its 
anterior  margin  is  blended 
with  the  Gluteus  medius.  Its 
posterior  margin  is  often 
joined  with  the  tendon  of  the 
Pyriformis. 

The  Pyriformis  is  a  flat 
muscle,  pyramidal  in  shape, 
lying    almost    parallel    with 


GLUTEAL   REGION.  337 

the  lower  margin  of  the  Gluteus  minimus.  It  is  situated  partly  within  the  pelvis 
at  its  posterior  part,  and  partly  at  the  back  of  the  hip-joint.  It  arises  from  the 
front  of  the  sacrum  by  three  fleshy  digitations,  attached  to  the  portions  of  bone 
interposed  between  the  second,  third,  and  fourth  anterior  sacral  foramina,  and 
also  from  the  grooves  leading  from  the  foramina ;  a  few  fibres  also  arise  from  the 
margin  of  the  great  sacro-sciatic  foramen,  and  from  the  anterior  surface  of  the 
great  sacro-sciatic  ligament.  The  muscle  passes  out  of  the  pelvis  through  the 
great  sacro-sciatic  foramen,  the  upper  part  of  which  it  fills,  and  is  inserted,  by  a 
rounded  tendon,  into  the  upper  border  of  the  great  trochanter,  being  generally 
blended  with  the  tendon  of  the  Obturator  internus. 

Relations.  By  its  anterior  surface,  within  the  pelvis,  with  the  Rectum  (especially 
on  the  left  side),  the  sacral  plexus  of  nerves,  and  the  internal  iliac  vessels ;  external 
to  the  pelvis,  with  the  os  innominatum  and  capsular  ligament  of  the  hip-joint.  By 
its  posterior  surface,  within  the  pelvis,  with  the  sacrum  ;  and  external  to  it,  with  the 
Gluteus  maximus.  By  its  upper  border,  with  the  Gluteus  medius,  from  which  it 
is  separated  by  the  gluteal  vessels  and  nerves.  By  its  lower  border,  with  the 
Gemellus  superior ;'  the  ischiatic  vessels  and  nerves,  the  internal  pudic  vessels  and 
nerve,  and  the  nerve  to  the  Obturator  internus,  passing  from  the  pelvis  in  the 
interval  between  them. 

Dissection.  The  next  muscle,  as  well  as  the  origin  of  the  Pyriformis,  can  only  be  seen  when 
the  pelvis  is  divided,  and  the  viscera  contained  in  this  cavity  removed. 

The  Obturator  Internus,  like  the  preceding  muscle,  is  situated  partly  within  the 
cavity  of  the  pelvis,  partly  at  the  back  of  the  hip-joint.  It  arises  from  the  inner 
surface  of  the  anterior  and  external  wall  of  the  pelvis,  being  attached  to  the 
margin  of  bone  around  the  inner  side  of  the  obturator  foramen ;  viz.,  from  the 
descending  ramus  of  the  pubes,  and  the  ascending  ramus  of  the  ischium ;  and 
laterally,  from  the  inner  surface  of  the  body  of  the  ischium,  between  the  margin 
of  the  obturator  foramen  in  front,  the  great  sacro-sciatic  notch  behind,  and  the 
brim  of  the  true  pelvis  above.  It  also  arises  from  the  inner  surface  of  the  obturator 
membrane  and  from  the  tendinous  arch  which  completes  the  canal  for  the  passage 
of  the  obturator  vessels  and  nerve.  The  fibres  are  directed  backwards  and  down- 
wards, and  terminate  in  four  or  five  tendinous  bands,  which  are  found  on  its  deep 
surface ;  these  bands  are  reflected  at  a  right  angle  over  the  inner  surface  of  the 
tuberosity  of  the  ischium,  which  is  covered  with  cartilage,  grooved  for  their 
reception,  and  lined  with"  a  synovial  bursa.  The  muscle  leaves  the  pelvis  by  the 
lesser  sacro-sciatic  notch ;  and  the  tendinous  bands  unite  into  a  single  flattened 
tendon,  which  passes  horizontally  outwards,  and,  after  receiving  the  attachment 
of  the  Gemelli,  is  inserted  into  the  upper  border  of  the  great  trochanter  in  front 
of  the  Pyriformis.  A  synovial  bursa,  narrow  and  elongated  in  form,  is  usually 
found  between  the  tendon  of  this  muscle  and  the  capsular  ligament  of  the  hip 
It  occasionally  communicates  with  that  between  the  tendon  and  the  tuberosity  of 
the  ischium,  the  two  forming  a  single  sac. 

In  order  to  display  the  peculiar  appearances  presented  by  the  tendon  of  this  muscle,  it  should 
be  divided  near  its  insertion  and  reflected  outwards. 

Relations.  Within  the  pelvis,  this  muscle  is  in  relation,  by  its  anterior  surface, 
with  the  obturator  membrane  and  inner  surface  of  the  anterior  wall  of  the  pelvis ; 
by  its  posterior  surface,  with  the  pelvic  and  obturator  fasciae,  which  separate  it 
from  the  Levator  ani ;  and  it  is  crossed  by  the  internal  pudic  vessels  and  nerve. 
This  surface  forms  the  outer  boundary  of  the  ischio-rectal  fossa.  External  to  the 
pelvis,  it  is  covered  by  the  great  sciatic  nerve  and  Gluteus  maxjmus,  and  rests 
on  the  back  part  of  the  hip-joint. 

The  Gemelli  are  two  small  muscular  fasciculi,  accessories  to  the  tendon  of  the 
Obturator  internus,  which  is  received  into  a  groove  between  them.  They  have 
received  the  names  stqierior  and  inferior  from  the  position  they  occupy. 

The  Gemellus  Superior,  the  smaller  of  the  two,  arises  from  the  outer  surface  of 
the  spine  of  the  ischium,  and,  passing  horizontally  outwards,  becomes  blended 
22 


338  MUSCLES   AND   FASCI.E. 

with  the  upper  part  of  the  tendon  of  the  Obturator  internus,  and  is  inserted  with 
it  into  the  upper  border  of  the  great  trochanter.  This  muscle  is  sometimes 
wanting. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  maximus  and  the  ischiatic 
vessels  and  nerves.  By  its  deep  surface,  with  the  capsule  of  the  hip-joint.  By  its 
upper  border,  with  the  lower  margin  of  the  Pyriformis.  By  its  lower  border,  with 
the  tendon  of  the  Obturator  internus. 

The  Gemellus  Inferior  arises  from  the  upper  part  of  the  outer  border  of  the 
tuberosity  of  the  ischium,  and,  passing  horizontally  outwards,  is  blended  with  the 
lower  part  of  the  tendon  of  the  Obturator  internus,  and  inserted  with  it  into  the 
upper  border  of  the  great  trochanter. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  maximus,  and  the 
ischiatic  vessels  and  nerves.  By  its  deep  surface,  it  covers  the  capsular  ligament 
of  the  hip-joint.  By  its  upper  border,  with  the  tendon  of  the  Obturator  internus. 
By  its  lower  border,  with  the  tendon  of  the  Obturator  externus  and  Quadratus 
fern  oris. 

The  Quadratus  Femoris  is  a  short,  flat  muscle,  quadrilateral  in  shape  (hence  its 
name),  situated  between  the  Gemellus  inferior  and  the  upper  margin  of  the 
Adductor  magnus.  It  arises  from  the  outer  border  of  the  tuberosity  of  the 
ischium,  and,  proceeding  horizontally  outwards,  is  inserted  into  the  upper  part  of 
the  linea  quadrati,  on  the  posterior  surface  of  the  trochanter  major.  A  synovial 
bursa  is  often  found  between  the  under  surface  of  this  muscle  and  the  lesser  tro- 
chanter, which  it  covers. 

Relations.  By  its  posterior  surface,  with  the  Gluteus  maximus  and  the  sciatic 
vessels  and  nerves.  By  its  anterior  surface,  with  the  tendon  of  the  Obturator 
externus  and  trochanter  minor.  By  its  upper  border,  with  the  Gemellus  inferior. 
Its  lower  border  is  separated  from  the  Adductor  magnus  by  the  terminal  branches 
of  the  internal  circumflex  vessels. 

Dissection.  In  order  to  expose  the  nest  muscle  (the  Obturator  externus),  it  is  necessary  to 
remove  the  Psoas,  Iliacus,  Pectineus,  and  Adductor  brevis  and  Adductor  longus  muscles,  from  the 
front  and  inner  side  of  the  thigh ;  and  the  Gluteus  maximus  and  Quadratus  femoris,  from  the  back 
part.  Its  dissection  should  consequently  be  postponed  until  the  muscles  of  the  anterior  and 
internal  femoral  regions  have  been  examined. 

The  Obturator  Externus  is  a  flat  triangular  muscle,  which  covers  the  outer  sur- 
face of  the  anterior  wall  of  the  pelvis.  It  arises  from  the  margin  of  bone  imme- 
diately around  the  inner  side  of  the  obturator  foramen,  viz.,  from  the  body  and 
ramus  of  the  pubes,  and  the  ramus  of  the  ischium ;  it  also  arises  from  the  inner 
two-thirds  of  the  outer  surface  of  the  obturator  membrane,  and  from  the  tendinous 
arch  which  completes  the  canal  for  the  passage  of  the  obturator  vessels  and  nerves. 
The  fibres  converging  pass  outwards  and  backwards,  and  terminate  in  a  tendon 
which  runs  across  the  back  part  of  the  hip-joint,  and  is  inserted  into  the  digital  fossa 
of  the  femur. 

Relations.  By  its  anterior  surface,  with  the  Psoas,  Iliacus,  Pectineus,  Adductor 
longus,  Adductor  brevis,  and  Gracilis ;  and  more  externally,  with  the  neck  of  the 
femur  and  capsule  of  the  hip-joint.  By  its  posterior  surface,  with  the  obturator 
membrane  and  Quadratus  femoris. 

Nerves.  The  Gluteus  maximus  is  supplied  by  the  inferior  gluteal  nerve  and  a 
branch  from  the  sacral  plexus.  The  Gluteus  medius  and  Gluteus  minimus,  by  the 
superior  gluteal.  The  Pyriformis,  Gemelli,  Obturator  internus,  and  Quadratus 
femoris,  by  branches  from  the  sacral  plexus ;  and  the  Obturator  externus,  by  the 
obturator  nerve. 

Actions.  The  Glutei  muscles,  Avhen  they  take  their  fixed  point  from  the  pelvis, 
are  all  abductors  of  the  thigh.  The  Gluteus  maximus  and  the  posterior  fibres  of 
the  Gluteus  medius  rotate  the  thigh  outwards ;  the  anterior  fibres  of  the  Gluteus 
medius  and  the  Gluteus  minimus  rotate  it  inwards.  The  Gluteus  maximus  serves 
to  extend  the  femur,  and  the  Gluteus  medius  and  Gluteus  minimus  draw  it  forwards. 
The  Gluteus  maximus  is  also  a  tensor  of  the  fascia  lata.     Taking  their  fixed  point 


POSTERIOR   FEMORAL   REGION.  339 

from  the  femur,  the  Glutei  muscles  act  upon  the  pelvis,  supporting  it  and  the  whole 
trunk  upon  the  head  of  the  femur :  this  is  especially  obvious  in  standing  on  one 
leg.  In  order  to  gain  the  erect  posture  after  the  effort  of  stooping,  these  muscles 
draw  the  pelvis  backwards,  assisted  by  the  Biceps,  Semi-tendinosus,  and  Semi- 
membranosus muscles.  The  remaining  muscles  are  powerful  rotators  of  the  thigh 
outwards.  In  the  sitting  posture,  when  the  thigh  is  flexed  upon  the  pelvis,  their 
action  as  rotators  ceases,  and  they  become  abductors,  with  the  exception  of  the 
Obturator  externus,  which  still  rotates  the  femur  outwards.  When  the  femur  is 
fixed,  the  Pyriformis  and  Obturator  muscles  serve  to  draw  the  pelvis  forwards  if 
it  has  been  inclined  backwards,  and  assist  in  steadying  it  upon  the  head  of  the 
femur. 


Posterior  Femoral  Region. 

Biceps.  Semi-tendinosus.  Semi-membranosus. 

Dissection  (fig.  189).  Make  a  vertical  incision  along  the  middle  of  the  thigh,  from  the  lower 
fold  of  the  nates  to  about  three  inches  below  the  back  of  the  knee-joint,  and  there  connect  it 
with  a  transverse  incision,  carried  from  the  inner  to  the  outer  side  of  the  leg.  A  third  incision 
should  then  be  made  transversely  at  the  junction  of  the  middle  with  the  lower  third  of  the  thigh. 
The  integument  having  been  removed  from  the  back  of  the  knee,  and  the  boundaries  of  the  pop- 
liteal space  examined,  the  removal  of  the  integument  from  the  remaining  part  of  the  thigh 
should  be  continued,  when  the  fascia  and  muscles  of  this  region  will  be  exposed. 

The  Biceps  is  a  large  muscle,  of  considerable  length,  situated  on  the  posterior 
and  outer  aspect  of  the  thigh.  It  arises  by  two  heads :  one,  the  long  head,  from 
an  impression  at  the  upper  and  back  part  of  the  tuberosity  of  the  ischium,  by  a 
tendon  common  to  it  and  the  Semi-tendinosus ;  the  femoral  or  short  head,  from 
the  outer  lip  of  the  linea  aspera,  between  the  Adductor  magnus  and  Vastus  ex- 
ternus, extending  from  two  inches  below  the  insertion  of  the  Gluteus  maximus, 
to  within  two  inches  of  the  outer  condyle ;  it  also  arises  from  the  external  inter- 
muscular septum.  The  fibres  of  the  long  head  form  a  fusiform  belly,  which, 
passing  obliquely  downwards  and  a  little  outwards,  terminates  in  an  aponeurosis 
which  covers  the  posterior  surface  of  the  muscle,  and  receives  the  fibres  of  the 
short  head ;  this  aponeurosis  becomes  gradually  contracted  into  a  tendon,  which  is 
inserted  into  the  outer  side  of  the  head  of  the  fibula.  At  its  insertion,  the  tendon 
divides  into  two  portions,  which  embrace  the  external  lateral  ligament  of  the 
knee-joint,  a  strong  prolongation  being  sent  forwards  to  the  outer  tuberosity  of 
the  tibia,  which  gives  off  an  expansion  to  the  fascia  of  the  leg.  The  tendon  of 
this  muscle  forms  the  outer  ham-string. 

Relations.  By  its  superficial  surface,  with  the  Gluteus  maximus  above,  the 
fascia  lata  and  integument  in  the  rest  of  its  extent.  By  its  deep  surface,  with  the 
Semi-membranosus,  Adductor  magnus,  and  Vastus  externus,  the  great  sciatic 
nerve,  popliteal  artery  and  vein,  and,  near  its  insertion,  with  the  external  head  of 
the  Gastrocnemius,  Plantaris,  and  superior  external  articular  artery. 

The  Semi-tendinosus,  remarkable  for  the  great  length  of  its  tendon,  is  situated 
at  the  posterior  and  inner  aspect  of  the  thigh.  It  arises  from  the  tuberosity  of 
the  ischium  by  a  tendon  common  to  it  and  the  long  head  of  the  Biceps ;  it  also 
arises  from  an  aponeurosis  which  connects  the  adjacent  surfaces  of  the  two  muscles 
to  the  extent  of  about  three  inches  from  their  origin.  It  forms  a  fusiform  muscle, 
which,  passing  downwards  and  inwards,  terminates  a  little  below  the  middle  of 
the  thigh  in  a  long  round  tendon,  which  lies  along  the  inner  side  of  the  popliteal 
space ;  curving  around  the  inner  tuberosity  of  the  tibia,  it  is  inserted  into  the 
upper  part  of  the  inner  surface  of  the  shaft  of  that  bone,  nearly  as  far  forwards 
as  its  anterior  border.  This  tendon  lies  beneath  the  expansion  of  the  Sartorius, 
and  below  that  of  the  Gracilis,  to  which  it  is  united.  A  tendinous  intersection  is 
usually  observed  about  the  middle  of  the  muscle. 

Relations.     By  its  superficial  surface,  with  the  Gluteus  maximus  and  fascia  lata. 


340  MUSCLES   AND   FASCIAE. 

By  its  deep  surface,  with  the  Semi-membranosus,  Adductor  magnus,  inner  head  of 
the  Gastrocnemius,  and  internal  lateral  ligament  of  the  knee-joint. 

The  Semi-membranosus,  so  called  from  the  membranous  expansion  on  its  anterior 
and  posterior  surfaces,  is  situated  at  the  back  part  and  inner  side  of  the  thigh. 
It  arises  by  a  thick  tendon  from  the  upper  and  outer  part  of  the  tuberosity  of  the 
ischium,  above  and  to  the  outer  side  of  the  Biceps  and  Semi-tendinosus,  and  is 
inserted  into  the  inner  and  back  part  of  the  inner  tuberosity  of  the  tibia,  beneath 
the  internal  lateral  ligament.  The  tendon  of  the  muscle  at  its  origin  expands 
into  an  aponeurosis,  which  covers  the  upper  part  of  its  anterior  surface ;  from  this 
aponeurosis  muscular  fibres  arise,  and  converge  to  another  aponeurosis,  which 
covers  the  lower  part  of  its  posterior  surface,  and  this  contracts  into  the  tendon  of 
insertion.  The  tendon  of  the  muscle  at  its  insertion  divides  into  three  portions ; 
the  middle  portion  is  the  fasciculus  of  insertion  into  the  back  part  of  the  inner 
tuberosity,  sending  down  an  expansion  to  cover  the  Popliteus  muscle.  The 
internal  portion  is  horizontal,  passing  forwards  beneath  the  internal  lateral  liga- 
ment, to  be  inserted  into  a  groove  along  the  inner  side  of  the  internal  tuberosity. 
The  posterior  division  passes  upwards  and  backwards,  to  be  inserted  into  the  back 
part  of  the  outer  condyle  of  the  femur,  forming  the  chief  part  of  the  posterior 
ligament  of  the  knee-joint. 

The  tendons  of  the  two  preceding  muscles,  with  those  of  the  Gracilis  and 
Sartorius,  form  the  inner  ham-string. 

Relations.  By  its  superficial  surface,  with  the  Semi-tendinosus,  Biceps,  and 
fascia  lata.  By  its  deep  surface,  with  the  popliteal  vessels,  Adductor  magnus; 
and  the  inner  head  of  the  Gastrocnemius,  from  which  it  is  separated  by  a  synovial 
bursa.  By  its  inner  border,  with  the  Gracilis.  By  its  outer  border,  with  the  great 
sciatic  nerve,  and  its  internal  popliteal  branch. 

Nerves.     The  muscles  of  this  region  are  supplied  by  the  great  sciatic  nerve. 

Actions.  The  three  ham-string  muscles  flex  the  leg  upon  the  thigh.  When  the 
knee  is  semi-flexed,  the  Biceps,  from  its  oblique  direction  downwards  and  outwards, 
rotates  the  leg  slightly  outwards ;  and  the  Semi-membranosus,  in  consequence  of 
its  oblique  direction,  rotates  the  leg  inwards,  assisting  the  Popliteus.  Taking 
their  fixed  point  from  below,  these  muscles  serve  to  support  the  pelvis  upon  the 
head  of  the  femur,  and  to  draw  the  trunk  directly  backwards,  as  is  seen  in  feats 
of  strength,  when  the  body  is  thrown  backwards  in  the  form  of  an  arch. 

Surgical  Anatomy.  The  tendons  of  these  muscles  occasionally  require  subcutaneous  division 
in  some  forms  of  spurious  anchylosis  of  the  knee-joint,  dependent  upon  permanent  contraction 
and  rigidity  of  the  Flexor  muscles,  or  from  stiffening  of  the  ligamentous  and  other  tissues  sur- 
rounding the  joint,  the  result  of  disease.  This  is  easily  effected  by  putting  the  tendon  upon  the 
stretch,  and  inserting  a  narrow  sharp-pointed  knife  between  it  and  the  skin ;  the  cutting  edge 
being  then  turned  towards  the  tendon,  it  should  be  divided,  taking  care  that  the  wound  in  the 
skin  is  not  at  the  same  time  enlarged.  This  operation  has  been  attended  with  considerable  suc- 
cess in  some  cases  of  stiffened  knee  from  rheumatism,  gradual  extension  being  kept  up  for  some 
time  after  the  operation. 

Muscles  and  Fascia  of  the  Leg. 

Dissection  (fig.  186).  The  knee  should  be  bent,  a  block  placed  beneath  it,  and  the  foot  kept 
in  an  extended  position  ;  an  incision  should  then  be  made  through  the  integument  in  the  middle 
line  of  the  leg  to  the  ankle,  and  continued  along  the  dorsum  of  the  foot  to  the  toes.  A  second 
incision  should  be  made  transversely  across  the  ankle,  and  a  third  in  the  same  direction  across 
the  bases  of  the  toes :  the  flaps  of  integument  included  between  these  incisions  should  be 
removed,  and  the  deep  fascia  of  the  leg  examined. 

The  fascia  of  the  leg  forms  a  complete  investment  to  the  whole  of  this  region 
of  the  limb,  excepting  to  the  inner  surface  of  the  tibia,  to  which  it  is  unattached. 
It  is  continuous  above  with  the  fascia  lata,  receiving  an  expansion  from  the 
tendon  of  the  Biceps  on  the  outer  side,  and  from  the  tendons  of  the  Sartorius, 
Gracilis,  and  Semi-tendinosus  on  the  inner  side;  in  front  it  blends  with  the 
periosteum  covering  the  tibia  and  fibula ;  below,  it  is  continuous  with  the  annular 
ligaments  of  the  ankle.     It  is  thick  and  dense  in  the  upper  and  anterior  part  of 


ANTERIOR   TIBIO-FIBTJLAR   REGION. 


341 


the  leg,  and  gives  attachment,  by  its  inner  sur- 
face, to  the  Tibialis  anticus  and  Extensor 
longus  digitorum  muscles;  but  thinner  behind, 
where  it  covers  the  Gastrocnemius  and  Soleus 
muscles.  Its  inner  surface  gives  off,  on  the 
outer  side  of  the  leg,  two  strong  intermuscular 
septa,  which  inclose  the  Peronei  muscles,  and 
separate  them  from  the  muscles  on  the  anterior 
and  posterior  tibial  regions,  and  several  smaller 
and  more  slender  processes  inclose  the  indi- 
vidual muscles  in  each  region;  at  the  same 
time,  a  broad  transverse  intermuscular  septum 
intervenes  between  the  superficial  and  deep 
muscles  in  the  posterior  tibio-fibular  region. 

The  fascia  should  now  be  removed  by  dividing  it  in 
the  same  direction  as  the  integument,  excepting  oppo- 
site the  ankle,  wnere  it  should  be  left  entire.  The  re- 
moval of  the  fascia  should  be  commenced  from  below, 
opposite  the  tendons,  and  detached  in  the  line  of  direc- 
tion of  the  muscular  fibres. 

Muscles  of  the  Leg. 

These  may  be  subdivided  into  three  groups : 
those  on  the  anterior,  those  on  the  posterior, 
and  those  on  the  outer  side. 

Anterior  Tibio-fibular  Region. 

Tibialis  Anticus. 
Extensor  Proprius  Pollicis. 
Extensor  Longus  Digitorum. 
Peroneus  Tertius. 

The  Tibialis  Anticus  is  situated  on  the  outer 
side  of  the  tibia ;  it  is  thick  and  fleshy  at  its 
upper  part,  tendinous  below.  It  arises  from 
the  outer  tuberosity  and  upper  two-thirds  of 
the  external  surface  of  the  shaft  of  the  tibia ; 
from  the  adjoining  part  of  the  interosseous 
membrane ;  from  the  deep  fascia  of  the  leg ;  and 
from  the  intermuscular  septum  between  it  and 
the  Extensor  communis  digitorum ;  the  fibres 
pass  vertically  downwards,  and  terminate  in  a 
tendon,  which  is  apparent  on  the  anterior  sur- 
face of  the  muscle  at  the  lower  third  of  the  leg. 
After  passing  through  the  innermost  compart- 
ment of  the  anterior  annular  ligament,  it  is 
inserted  into  the  inner  and  under  surface  of 
the  internal  cuneiform  bone,  and  base  of  the 
metatarsal  bone  of  the  great  toe. 

Relations.  By  its  anterior  surface,  with  the 
deep  fascia,  and  with  the  annular  ligament.  By 
its  posterior  surface,  with  the  interosseous  mem- 
brane, tibia,  ankle-joint,  and  inner  side  of  the 
tarsus.  By  its  inner  surface,  with  the  tibia. 
By  its  outer  surface,  with  the  Extensor  longus 
digitorum.  and  Extensor  proprius  pollicis,  the 
anterior  tibial  vessels  and  nerve  lying  between 
it  and  the  last  mentioned  muscle. 


•Fiff.  191. — Muscles  of  the  Front  of 


"  *L 


\Ti6i. 


^N 


-  A 


342  MUSCLES   AXD   FASCIA, 

_  The  Extensor  Proprius  Pollicis  is  a  thin,  elongated,  and  flattened  muscle, 
situated  between  the  Tibialis  anticus  and  Extensor  longus  digitorum.  It  arises 
from  the  anterior  surface  of  the  fibula  for  about  the  middle  two-fourths  of  its 
extent,  its  origin  being  internal  to  the  Extensor  longus  digitorum ;  it  also  arises 
from  the  interosseous  membrane  to  a  similar  extent.  The  fibres  pass  downwards, 
and  terminate  in  a  tendon,  which  occupies  the  anterior  border  of  the  muscle, 
passes  through  a  distinct  compartment  in  the  annular  ligament,  and  is  inserted  into 
the  base  of  the  last  phalanx  of  the  great  toe.  Opposite  the  metatarso-phalangeal 
articulation,  the  tendon  gives  off  a  thin  prolongation  on  each  side,  which  covers 
its  surface. 

Relations.  By  its  anterior  border,  with  the  deep  fascia,  and  the  anterior  annular 
ligament.  By  its  posterior  border,  with  the  interosseous  membrane,  fibula,  tibia, 
ankle-joint,  and  Extensor  brevis  digitorum.  By  its  outer  side,  with  the  Extensor 
longus  digitorum  above,  the  dorsalis  pedis  vessels  and  anterior  tibial  nerve 
below.  By  its  inner  side,  with  the  Tibialis  anticus,  and  the  anterior  tibial  vessels 
above. 

The  Extensor  Longus  Digitorum  is  an  elongated,  flattened,  semi-penniform 
muscle,  situated  the  most  externally  of  all  the  muscles  on  the  fore  part  of  the  leg. 
It  arises  from  the  outer  tuberosity  of  the  tibia ;  from  the  upper  three-fourths  of 
the  anterior  surface  of  the  shaft  of  the  fibula ;  from  the  interosseous  membrane,  and 
deep  fascia ;  and  from  the  intermuscular  septa  between  it  and  the  Tibialis  anticus 
on  the  inner,  and  the  Peronei  on  the  outer  side.  The  muscle  terminates  in  three 
tendons,  which  pass  through  a  canal  in  the  annular  ligament,  with  the  Peroneus 
tertius,  run  across  the  dorsum  of  the  foot,  and,  the  innermost  tendon  having  sub- 
divided into  two,  are  inserted  into  the  second  and  third  phalanges  of  the  four 
lesser  toes.  The  mode  in  which  the  tendons  are  inserted  is  the  following ;  each 
tendon  opposite  the  metatarso-phalangeal  articulation  is  joined,  on  its  outer  side, 
by  the  tendon  of  the  Extensor  brevis  digitorum  (except  the  fourth),  and  receives 
a  fibrous  expansion  from  the  Interossei  and  Lumbricales,  which  then  spreads 
into  a  broad  aponeurosis,  covering  the  dorsal  surface  of  the  first  phalanx ;  this 
aponeurosis,  at  the  articulation  of  the  first  with  the  second  phalanx,  divides  into 
three  slips,  a  middle  one,  which  is  inserted  into  the  base  of  the  second  phalanx ; 
and  two  lateral  slips,  which,  after  uniting  on  the  dorsal  surface  of  the  second 
phalanx,  are  continued  onwards,  to  be  inserted  into  the  base  of  the  third. 

Relations.  By  its  anterior  surface,  with  the  deep  fascia,  and  the  annular  liga- 
ment. By  its  posterior  surface,  with  the  fibula,  interosseous  membrane,  ankle- 
joint,  and  Extensor  brevis  digitorum.  By  its  inner  side,  with  the  Tibialis  anticus, 
Extensor  proprius  pollicis,  and  anterior  tibial  vessels  and  nerve.  By  its  outer  side, 
with  the  Peroneus  longus  and  Peroneus  brevis. 

The  Peroneus  Tertius  may  be  considered  as  part  of  the  Extensor  longus  digi- 
torum, being  almost  always  intimately  united  with  it.  It  arises  from  the  lower 
fourth  of  the  anterior  surface  of  the  fibula,  on  its  outer  side ;  from  the  lower  part 
of  the  interosseous  membrane ;  and  from  an  intermuscular  septum  between  it  and 
the  Peroneus  brevis.  Its  tendon,  after  passing  through  the  same  canal  in  the 
annular  ligament  as  the  Extensor  longus  digitorum,  is  inserted  into  the  base  of  the 
metatarsal  bone  of  the  little  toe,  on  its  dorsal  surface.  This  muscle  is  sometimes 
wanting. 

Nerves.     These  muscles  are  supplied  by  the  anterior  tibial  nerve. 

Actions.  The  Tibialis  anticus  and  Peroneus  tertius  are  the  direct  flexors  of  the 
tarsus  upon  the  leg ;  the  former  muscle,  from  the  obliquity  in  the  direction  of  its 
tendon,  raises  the  inner  border  of  the  foot,  and  the  latter,  acting  with  the  Peroneus 
brevis  and  Peroneus  longus,  will  draw  the  outer  border  of  the  foot  upwards,  and 
the  sole  outwards.  The  Extensor  longus  digitorum  and  Extensor  proprius  pollicis 
extend  the  phalanges  of  the  toes,  and,  continuing  their  action,  flex  the  tarsus  upon 
the  leg.  Taking  their  origin  from  below,  in  the  erect  posture,  all  these  muscles 
serve  to  fix  the  bones  of  the  leg  in  a  perpendicular  direction,  and  give  increased 
strength  to  the  ankle-joint. 


POSTERIOR   TIBIO-FIBULAR   REGION. 


343 


Fig.  192. 


-Muscles  of  the  Back  of  the  Leg. 
Superficial  Layer. 


Posterior  Tibio-fibular  Region. 

Dissection  (fig.  189).  Make  a  vertical  incision  along  the  middle  line  of  the  back  of  the  leg, 
from  the  lower  part  of  the  popliteal  space  to  the  heel,  connecting  it  below  by  a  transverse  incision 
extending  between  the  two  malleoli;  the  flaps  of  integument  being  removed,  the  fascia  and  muscles 
should  be  examined. 

The  muscles  in  this  region  of  the  leg  are  subdivided  into  two  layers,  superficial 
and  deep.  The  superficial  layer  constitutes  a  powerful  muscular  mass,  forming 
what  is  called  "the  calf  of  the  leg.  Its 
large  size  is  one  of  the  most  characteristic 
features  of  the  muscular  apparatus  in 
man,  and  bears  a  direct  connection  with 
his  ordinary  attitude  and  mode  of  pro- 
gression. 

Superficial  Layer. 

Gastrocnemius.  Soleus. 

Plantaris. 

The  Gastrocnemius  is  the  most  super- 
ficial muscle,  and  forms  the  greater  part 
of  the  calf.  It  arises  by  two  heads,  which 
are  connected  to  the  condyles  of  the  femur 
by  two  strong  flat  tendons.  The  inner 
head,  the  larger,  and  a  little  the  most 
posterior,  is  attached  to  a  depression  at 
the  upper  and  back  part  of  the  inner 
condyle;  the  outer  head,  to  the  upper 
and  back  part  of  the  external  condyle, 
immediately  above  the  origin  of  the 
Popliteus.  Both  heads,  also,  arise  by  a 
few  tendinous  and  fleshy  fibres  from  the 
ridges  which  are  continued  upwards  from 
the  condyles  to  the  linea  aspera.  Each 
tendon  spreads  into  an  aponeurosis,  which 
covers  the  posterior  surface  of  that  por- 
tion of  the  muscle  to  which  it  belongs ; 
that  covering  the  inner  head  being  longer 
and  thicker  than  the  outer.  From  the 
anterior  surface  of  these  tendinous  ex- 
pansions, muscular  fibres  are  given  off; 
those  in  the  median  line,  which  cor- 
respond to  the  accessory  portions  of  the 
muscle  derived  from  the  bifurcations  of 
the  linea  aspera,  unite  at  an  angle  upon 
a  median  tendinous  raphe  below.  The 
remaining  fibres  converge  to  the  posterior 
surface  of  an  aponeurosis  which  covers 
the  front  of  the  muscle,  and  this,  gradu- 
ally contracting,  unites  with  the  tendon 
of  the  Soleus,  and  forms  with  it  the  tendo 
Achillis. 

Relations.  By  its  superficial  surface, 
with  the  fascia  of  the  leg,  which  sepa- 
rates it  from  the  external  saphenous  vein 
and  nerve.     By  its  deep  surface,  with  the 


344  MUSCLES   AND   FASCIA. 

posterior  ligament  of  the  knee-joint, -the  Popliteus,  Soleus,  Plantaris,  popliteal 
vessels,  and  internal  popliteal  nerve.  The  tendon  of  the  inner  head  corresponds 
with  the  back  part  of  the  inner  condyle,  from  which  it  is  separated  by  a  synovial 
bursa,  which,  in  some  cases,  communicates  with  the  cavity  of  the  knee-joint.  The 
tendon  of  the  outer  head  contains  a  sesamoid  fibro-cartilage,  rarely  osseous,  where 
it  plays  over  the  corresponding  outer  condyle ;  and  one  is  occasionally  found  in 
the  tendon  of  the  inner  head. 

The  Gastrocnemius  should  be  divided  across,  just  below  its  origin,  and  turned  downwards,  in 
order  to  expose  the  next  muscles. 

The  Soleus  is  a  broad  flat  muscle,  situated  immediately  beneath  the  preceding. 
It  has  received  its  name  from  the  fancied  resemblance  it  bears  to  a  sole-fish.  It 
arises  by  tendinous  fibres  from  the  back  part  of  the  head,  and  from  the  upper 
half  of  the  posterior  surface  of  the  shaft  of  the  fibula,  from  the  oblique  line  of 
the  tibia,  and  from  the  middle  third  of  its  internal  border ;  some  fibres  also  arise 
from  a  tendinous  arch  placed  between  the  tibial  and  fibular  origins  of  the  muscle, 
and  beneath  which  the  posterior  tibial  vessels  and  nerve  pass  into  the  leg.  The 
fibres  pass  backwards  to  an  aponeurosis  which  covers  the  posterior  surface  of  the 
muscle,  and  this,  gradually  becoming  thicker  and  narrower,  joins  with  the  tendon 
of  the  Gastrocnemius,  and  forms  with  it  the  tendo  Achillis. 

delations.  By  its  superficial  surface,  with  the  Gastrocnemius  and  Plantaris.  By 
its  deep  surface,  with  the  Flexor  longus  digitorum,  Flexor  longus  pollicis,  Tibialis 
posticus,  and  posterior  tibial  vessels  and  nerve,  from  which  it  is  separated  by  the 
transverse  intermuscular  septum. 

The  tendo  Achillis,  the  common  tendon  of  the  Gastrocnemius  and  Soleus,  is 
the  thickest  and  strongest  tendon  in  the  body.  It  is  about  six  inches  in  length, 
and  formed  by  the  junction  of  the  aponeuroses  of  the  two  preceding  muscles.  It 
commences  about  the  middle  of  the  leg,  but  receives  fleshy  fibres  on  its  anterior 
surface,  nearly  to  its  lower  end.  Gradually  becoming  contracted  below,  it  is 
inserted  into  the  lower  part  of  the  posterior  tuberosity  of  the  os  calcis,  a  synovial 
bursa  being  interposed  between  the  tendon  and  the  upper  part  of  the  tuberosity. 
The  tendon  is  covered  by  the  fascia  and  the  integument,  and  is  separated  from  the 
deep  muscles  and  vessels,  by  a  considerable  interval  filled  up  with  areolar  and 
adipose  tissue.  Along  its  outer  side,  but  superficial  to  it,  is  the  external  saphe- 
nous vein. 

The  Plantaris  is  an  extremely  diminutive  muscle,  placed  between  the  Gastroc- 
nemius and  Soleus,  and  remarkable  for  its  long  and  delicate  tendon.  It  arises 
from  the  lower  part  of  the  outer  bifurcation  of  the  linea  aspera,  and  from  the 
posterior  ligament  of  "the  knee-joint.  It  forms  a  small  fusiform  belly,  about  two 
inches  in  length,  terminating  in  a  long  slender  tendon,  which  crosses  obliquely 
between  the  two  muscles  of  the  calf,  and,  running  along  the  inner  border  of  the 
tendo  Achillis,  is  inserted  with  it  into  the  posterior  part  of  the  os  calcis.  This 
muscle  is  occasionally  double,  and  is  sometimes  wanting.  At  times,  its  tendon 
is  lost  in  the  internal  annular  ligament,  or  in  the  fascia  of  the  leg. 

Nerves.     These  muscles  are  supplied  by  the  internal  popliteal  nerve. 

Actions.  The  muscles  of  the  calf  possess  considerable  power,  and  are  con- 
stantly called  into  use  in  standing,  walking,  dancing,  and  leaping ;  hence  the  large 
size  they  usually  present.  In  walking,  these  muscles  draw  powerfully  upon  the 
os  calcis,  raising  the  heel,  and,  with  it,  the  entire  body,  from  the  ground ;  the  body 
being  thus  supported  on  the  raised  foot,  the  opposite  limb  can  be  carried  forwards. 
In  standing,  the  Soleus,  taking  its  fixed  point  from  below,  steadies  the  leg  upon 
the  foot,  and  prevents  the  body  from  falling  forwards,  to  which  there  is  a  constant 
tendency  from  the  superincumbent  weight.  The  Gastrocnemius,  acting  from 
below,  serves  to  flex  the  femur  upon  the  tibia,  assisted  by  the  Popliteus.  The 
Plantaris  is  the  rudiment  of  a  large  muscle  which  exists  in  some  of  the  lower 
animals,  and  serves  as  a  tensor  of  the  plantar  fascia. 


POSTERIOR   TIBIO-FIBULAR   REGION. 


345 


Posterior  Tibio-fibular  region. 


Popliteus. 

Flexor  Longus  Pollicis. 

Dissection.     Detach  the  Soleus  from  its  attachment 
downwards,  when  the  deep  layer  of  muscles 
exposed,  covered  by  the  deep  fascia  of  the  leg 


Deep  Layer. 

Flexor  Longus  Digitorum. 
Tibialis  Posticus. 

to  the  fibula  and  tibia,  and  turn  It 


The  deep  fascia  of  the  leg  is  a  broad, 
transverse,  intermuscular  septum,  inter- 
posed between  the  superficial  and  deep 
muscles  in  the  posterior  tibio-fibular  re- 
gion. On  each  side  it  is  connected  to  the 
margins  of  the  tibia  and  fibula.  Above, 
where  it  covers  the  Popliteus,  it  is  thick 
and  dense,  and  receives  an  expansion  from 
the  tendon  of  the  Semi-membranosus;  it 
is  thinner  in  the  middle  of  the  leg,  but, 
below,  where  it  covers  the  tendons  passing 
behind  the  malleoli,  it  is  thickened.  It 
is  continued  onwards  in  the  interval 
between  the  ankle  and  the  heel,  where  it 
covers  the  vessels,  and  is  blended  with 
the  internal  annular  ligament. 

This  fascia  should  now  be  removed,  commenc- 
ing from  below  opposite  the  tendons,  and  detach- 
ing it  from  the  muscles  in  the  direction  of  their 
fibres. 

The  Popliteus  is  a  thin,  flat,  triangular 
muscle,  which  forms  the  floor  of  the 
popliteal  space,  and  is  covered  by  a 
tendinous  expansion,  derived  from  the 
Semi-membranosus  muscle.  It  arises  by 
a  strong  flat  tendon,  about  an  inch  in 
length,  from  a  deep  depression  on  the 
outer  side  of  the  external  condyle  of  the 
femur ;  and  from  the  posterior  ligament  of 
the  knee-joint;  and  is  inserted  into  the 
inner  two-thirds  of  the  triangular  surface 
above  the  oblique  line  on  the  posterior 
surface  of  the  shaft  of  the  tibia,  and  into 
the  tendinous  expansion  covering  the  sur- 
face of  the  muscle.  The  tendon  of  the 
muscle  is  covered  by  that  of  the  Biceps 
and  the  external  lateral  ligament  of  the 
knee-joint;  it  grooves  the  outer  surface 
of  the  external  semilunar  cartilage,  and 
is  invested  by  the  synovial  membrane  of 
the  knee-joint. 

Relations.  By  its  superficial  surface, 
with  the  fascia  above  mentioned,  which 
separates  ,  it  from  the  Gastrocnemius, 
Plantaris,  popliteal  vessels,  and  internal 
popliteal  nerve.  By  its  deep  surface,  with 
the  superior  tibio-fibular  articulation,  and 
back  of  the  tibia. 


Fig. 


193. — Muscles  of  the  Back  of  the  Leg. 
Deep  Layers. 


346  MUSCLES   AND   FASCIA. 

The  Flexor  Longus  Pollicis  is  situated  on  the  fibular  side  of  the  leg,  and  is  the  most 
superficial,  and  largest  of  the  three  next  muscles.  It  arises  from  the  lower  two- 
thirds  of  the  internal  surface  of  the  shaft  of  the  fibula,  with  the  exception  of  an 
inch  below ;  from  the  lower  part  of  the  interosseous  membrane ;  from  an  inter- 
muscular septum  between  it  and  the  Peronei,  externally ;  and  from  the  fascia 
covering  the  Tibialis  posticus.  The  fibres  pass  obliquely  downwards  and  back- 
wards, and  terminate  round  a  tendon  which  occupies  nearly  the  whole  length  of 
the  posterior  surface  of  the  muscle.  This  tendon  passes  through  a  groove  on  the 
posterior  surface  of  the  tibia,  external  to  that  for  the  Tibialis  posticus  and  Flexor 
longus  digitorum ;  it  then  passes  through  another  groove  on  the  posterior  extremity 
of  the  astragalus,  and  along  a  third  groove,  beneath  the  tubercle  of  the  os  calcis, 
into  the  sole  of  the  foot,  where  it  runs  forwards  between  the  two  heads  of  the 
Flexor  brevis  pollicis,  and  is  inserted  into  the  base  of  the  last  phalanx  of  the  great 
toe.  The  grooves  in  the  astragalus  and  os  calcis  which  contain  the  tendon  of  the 
muscle  are  converted  by  tendinous  fibres  into  distinct  canals,  lined  by  synovial 
membrane ;  and  as  the  tendon  crosses  the  sole  of  the  foot,  it  is  connected  to  the 
common  flexor  by  a  tendinous  slip. 

Relations.  By  its  superficial  surface,  with  the  Soleus  and  tendo  Achillis,  from 
which  it  is  separated  by  the  deep  fascia.  By  its  deep  surface,  with  the  fibula, 
Tibialis  posticus,  the  peroneal  vessels,  the  lower  part  of  the  interosseous  mem- 
brane, and  the  ankle-joint.  By  its  outer  border,  with  the  Peronei.  By  its  inner 
border,  with  the  Tibialis  posticus,  and  Flexor  longus  digitorum. 

The  Flexor  Longus  Digitorum  is  situated  on  the  tibial  side  of  the  leg.  At  its 
origin,  it  is  thin  and  pointed,  but  gradually  increases  in  size  as  it  descends.  It 
arises  from  the  posterior  surface  of  the  shaft  of  the  tibia,  immediately  below  the 
oblique  line,  to  within  three  inches  of  its  extremity,  internal  to  the  tibial  origin 
of  the  Tibialis  posticus ;  some  fibres  also  arise  from  the  intermuscular  septum, 
between  it  and  the  Tibialis  posticus.  The  fibres  terminate  in  a  tendon,  which 
runs  nearly  the  whole  length  of  the  posterior  surface  of  the  muscle.  This  tendon 
passes,  behind  the  inner  malleolus,  in  a  groove,  common  to  it  and  the  Tibialis 
posticus,  but  separated  from  the  latter  by  a  fibrous  septum ;  each  tendon  being 
contained  in  a  special  sheath  lined  by  a  separate  synovial  membrane.  It  then 
passes,  obliquely,  forwards  and  outwards,  beneath  the  arch  of  the  os  calcis,  into  the 
sole  of  the  foot,  where,  crossing  beneath  the  tendon  of  the  Flexor  longus  pollicis, 
to  which  it  is  connected  by  a  strong  tendinous  slip,  it  becomes  expanded,  is  joined 
by  the  Flexor  accessorius,  and  finally  divides  into  four  tendons,  which  are  in- 
serted into  the  bases  of  the  last  phalanges  of  the  four  lesser  toes,  each  tendon  pass- 
ing through  a  fissure  in  the  tendon  of  the  Flexor  brevis  digitorum,  opposite  the 
middle  of  the  first  phalanges. 

Relations.  In  the  leg.  By  its  superficial  surface,  with  the  Soleus,  and  the  pos- 
terior vessels  and  nerve,  from  which  it  is  separated  by  the  deep  fascia.  By 
its  deep  surface,  with  the  tibia  and  Tibialis  posticus.  In  the  foot,  it  is  covered  by 
the  Abductor  pollicis,  and  Flexor  brevis  digitorum,  and  crosses  beneath  the 
Flexor  longus  pollicis. 

The  Tibialis  Posticus  lies  between  the  two  preceding  muscles,  and  is  the  most 
deeply  seated  of  all  the  muscles  in  the  leg.  It  commences  above,  by  two  pointed 
processes,  separated  by  an  angular  interval,  through  which  the  anterior  tibial 
vessels  pass  forwards  to  the  front  of  the  leg.  It  arises  from  the  posterior  surface  of 
the  interosseous  membrane,  its  whole  length,  excepting  its  lowest  part,  from  the 
posterior  surface  of  the  shaft  of  the  tibia,  external  to  the  Flexor  longus  digitorum, 
between  the  commencement  of  the  oblique  line  above,  and  the  middle  of  the 
external  border  of  the  bone  below,  and  from  the  upper  two-thirds  of  the  inner 
surface  of  the  shaft  of  the'fibula ;  some  fibres  also  arise  from  the  deep  fascia,  and 
from  the  intermuscular  septa,  separating  it  from  the  adjacent  muscles  on  each 
side.  This  muscle,  in  the  lower  fourth  of  the  leg,  passes  in  front  of  the  Flexor 
longus  digitorum,  terminates  in  a  tendon,  which  passes  through  a  groove  with  it 
behind  the  inner  malleolus,  but  inclosed  in  a  separate  sheath,  then  passes  through 


FIBULAR   REGIOX.  347 

another  sheath,  over  the  internal  lateral  ligament,  and  beneath  the  calcaneo- 
scaphoid  articulation,  and  is  inserted  into  the  tuberosity  of  the  scaphoid,  and 
internal  cuneiform  bones.  The  tendon  of  this  muscle  contains  a  sesamoid  bone, 
near  its  insertion,  and  gives  off  fibrous  expansions,  one  of  which  passes  back- 
wards to  the  os  calcis,  some  outwards  to  the  middle  and  external  cuneiform,  and 
others  forwards  to  the  bases  of  the  third  and  fourth  metatarsal  bones. 

Relations.  By  its  superficial  surface,  with  the  Soleus  and  Flexor  longus 
digitorum,  the  posterior  tibial  vessels  and  nerve,  and  the  peroneal  vessels,  from 
which  it  is  separated  by  the  deep  fascia.  By  its  deep  surface,  with  the  interosseous 
ligament,  the  tibia,  fibula,  and  ankle-joint. 

Nerves.  The  Popliteus  is  supplied  by  the  internal  popliteal  nerve,  the  remaining 
muscles  of  this  group  by  the  posterior  tibial  nerve. 

Actions.  The  Popliteus  assists  in  flexing  the  leg  upon  the  thigh ;  when  the  leg 
is  flexed,  it  may  rotate  the  tibia  inwards.  The  Tibialis  posticus  is  a  direct  extensor 
of  the  tarsus  upon  the  leg ;  acting  in  conjunction  with  the  Tibialis  anticus,  it 
turns  the  sole  of  the  foot  inwards,  antagonizing  the  Peroneus  longus  which 
turns  it  outwards.  The  Flexor  longus  digitorum  and  Flexor  longus  pollicis  are 
the  direct  Flexors  of  the  phalanges,  and,  continuing  their  action,  extend  the  foot 
upon  the  leg ;  they  assist  the  Gastrocnemius  and  Soleus  in  extending  the  foot, 
as  in  the  act  of  walking,  or  in  standing  on  tiptoe.  In  consequence  of  the  oblique 
direction  of  the  tendon  of  the  long  extensor,  the  toes  would  be  drawn  inwards, 
were  it  not  for  the  Flexor  accessorius  muscle,  which  is  inserted  into  the  outer  side 
of  that  tendon,  and  draws  it  to  the  middle  line  of  the  foot,  during  its  action.  Taking 
their  fixed  point  from  the  foot,  these  muscles  serve  to  maintain  the  upright 
posture,  by  steadying  the  tibia  and  fibula,  perpendicularly,  upon  the  ankle-joint. 
They  also  serve  to  raise  these  bones  from  the  oblique  position  they  assume  in  the 
stooping  posture. 

I 
Fibulae  Region. 

Peroneus  Longus.  Peroneus  Brevis. 

Dissection.  These  muscles  are  readily  exposed,  by  removing  the  fascia  covering  their  surface, 
from  below  upwards,  in  the  line  of  direction  of  their  fibres. 

The  Peroneus  Longus  is  situated  at  the  upper  part  of  the  outer  side  of  the 
leg,  and  is  the  more  superficial  of  the  two  muscles.  It  arises  from  the  head  and 
upper  two-thirds  of  the  outer  surface  of  the  shaft  of  the  fibula,  from  the  deep 
fascia,  and  from  the  intermuscular  septa  between  it  and  the  muscles  on  the  front, 
and  those  on  the  back  of  the  leg.  It  terminates  in  a  long  tendon,  which  passes 
behind  the  outer  malleolus,  in  a  groove,  common  to  it  and  the  Peroneus  brevis, 
the  groove  being  converted  into  a  canal  by  a  fibrous  band,  and  the  tendons 
invested  by  a  common  synovial  membrane ;  it  is  then  reflected,  obliquely  forwards, 
across  the  outer  side  of  the  os  calcis,  being  contained  in  a  separate  fibrous  sheath, 
lined  by  a  prolongation  of  the  synovial  membrane,  from  the  groove  behind 
the  malleolus.  Having  reached  the  outer  side  of  the  cuboid  bone,  it  runs,  in  a 
groove,  on  its  under  surface,  which  is  converted  into  a  canal  by  the  long  calcaneo- 
cuboid ligament,  lined  by  a  synovial  membrane,  and  crossing,  obliquely,  the  sole 
of  the  foot,  is  inserted  into  the  outer  side  of  the  base  of  the  metatarsal  bone  of 
the  great  toe.  The  tendon  of  the  muscle  has  a  double  reflection,  first,  behind  the 
external  malleolus,  secondly,  on  the  outer  side  of  the  cuboid  bone ;  in  both  of 
these  situations,  the  tendon  is  thickened,  and,  in  the  latter,  a  sesamoid  bone  is 
usually  developed  in  its  substance. 

Relations.  By  its  superficial  surface,  with  the  fascia  and  integument.  By  its 
deep  surface,  with  the  fibula,  the  Peroneus  brevis,  os  calcis,  and  cuboid  bone. 
By  its  anterior  border,  an  intermuscular  septum  intervenes  between  it  and  the 
Extensor  longus  digitorum.  By  its  posterior  border,  an  intermuscular  septum 
separates  it  from  the  Soleus  above,  and  the  Flexor  longus  pollicis  below. 


348  MUSCLES   AND   FASCIA. 

The  Peroneus  Brevis  lies  beneath  the  Peroneus  longus,  and  is  shorter  and 
smaller  than  it.  It  arises  from  the  middle  third  of  the  external  surface  of  the 
shaft  of  the  fibula,  internal  to  the  Peroneus  longus ;  from  the  anterior  and  posterior 
borders  of  the  bone ;  and  from  the  intermuscular  septa  separating  it  from  the 
adjacent  muscles  on  the  front  and  back  part  of  the  leg.  The  fibres  pass  vertically 
downwards,  and  terminate  in  a  tendon,  which  runs  through  the  same  groove  as 
the  preceding  muscle,  behind  the  external  malleolus,  being  contained  in  the  same 
fibrous  sheath,  and  lubricated  by  the  same  synovial  membrane;  it  then  passes 
through  a  separate  sheath  on  the  outer  side  of  the  os  calcis,  above  that  for  the 
tendon  of  the  Peroneus  longus,  and  is  finally  inserted  into  the  base  of  the  meta- 
tarsal bone  of  the  little  toe,  on  its  dorsal  surface. 

Relations.  By  its  superficial  surface,  with  the  Peroneus  longus  and  the  fascia 
of  the  leg  and  foot.  By  its  deep  surface,  with  the  fibula  and  outer  side  of  the 
os  calcis. 

Nerves.  The  Peroneus  longus  and  Peroneus  brevis  are  supplied  by  the  musculo- 
cutaneous branch  of  the  external  popliteal  nerve. 

Actions.  The  Peroneus  longus  and  Peroneus  brevis  extend  the  foot  upon  the  leg, 
in  conjunction  with  the  Tibialis  posticus,  antagonizing  the  Tibialis  anticus  and  Pero- 
neus tertius,  which  are  flexors  of  the  foot.  The  Peroneus  longus  also  everts  the  sole 
of  the  foot ;  hence  the  extreme  e version  observed  in  fracture  of  the  lower  end  of 
the  fibula,  where  that  bone  offers  no  resistance  to  the  action  of  this  muscle. 
Taking  their  fixed  point  below,  they  serve  to  steady  the  leg  upon  the  foot.  This 
is  especially  the  case  in  standing  upon  one  leg,  when  the  tendency  of  the  superin- 
cumbent weight  is  to  throw  the  leg  inwards ;  and  the  Peroneus  longus  overcomes 
this  by  drawing  on  the  outer  side  of  the  leg,  and  thus  maintains  the  perpendicular 
direction  of  the  limb. 

Surgical  Anatomy.  The  student  should  now  consider  the  position  of  the  tendons  of  the  various 
muscles  of  the  leg,  their  relation  with  the  ankle-joint  and  surrounding  bloodvessels,  and  especially 
their  action  upon  the  foot,  as  their  rigidity  and  contraction  give  rise  to  one  or  the  other  forms 
of  deformity  known  as  club-foot.  The  most  simple  and  common  deformity,  and  one  that  is  rarely 
if  ever  congenital,  is  the  talipes  equinus,  the  heel  being  raised  by  rigidity  and  contraction  of  the 
Gastrocnemius  muscle,  and  the  patient  walking  upon  the  ball  of  the  foot.  In  the  talipes  varus, 
which  is  the  more  common  congenital  form,  the  heel  is  raised  by  the  tendo  Achillis,  the  inner 
border  of  the  foot  drawn  upwards  by  the  Tibialis  anticus,  and  the  anterior  two-thirds  of  the  foot 
twisted  inwards  by  the  Tibialis  posticus  and  Flexor  longus  digitorum,  the  patient  walking  upon 
the  outer  edge  of  the  foot,  and  in  severe  cases  upon  the  dorsum  and  outer  ankle.  In  the  talipes 
valgus,  the  outer  edge  of  the  foot  is  raised  by  the  Peronei  muscles,  and  the  patient  walks  on  the 
inner  ankle.  In  the  talipes  calcaneus,  the  toes  are  raised  by  the  Extensor  muscles,  the  heel  is 
depressed,  and  the  patient  walks  upon  it.  Other  varieties  of  deformity  are  met  with,  as  the 
talipes  equino-varus,  equino-valgus,  and  calcaneo-valgus,  whose  names  sufficiently  indicate  their 
nature.  Each  of  these  deformities  may  be  successfully  relieved  (after  other  remedies  fail)  by 
division  of  the  opposing  tendons  and  fascia;  by  this  means,  the  foot  regains  its  proper  position, 
and  the  tendons  heal  by  the  organization  of  lymph  thrown  out  between  the  divided  ends.  The 
operation  is  easily  performed  by  putting  the  contracted  tendon  upon  the  stretch,  and  dividing  it 
by  means  of  a  narrow  sharp-pointed  knife  inserted  between  it  and  the  skin. 


Muscles  and  Fasciae  of  the  Foot. 

The  fibrous  bands  which  bind  down  the  tendons  in  front  of  and  behind  the  ankle  in  their  passage 
to  the  foot,  should  now  be  examined ;  they  are  termed  the  annular  ligaments,  and  are  three  in 
number,  the  anterior,  internal,  and  external. 

The  Anterior  Annular  Ligament  consists  of  a  superior  or  vertical  portion, 
which  binds  down  the  Extensor  tendons  as  they  descend  on  the  front  of  the  tibia 
and  fibula,  and  an  inferior  or  horizontal  portion,  which  retains  them  in  connection 
with  the  tarsus,  the  two  portions  being  connected  by  a  thin  intervening  layer  of 
fascia.  The  vertical  portion  is  attached  externally  to  the  lower  end  of  the  fibula, 
internally  to  the  tibia,  and  above  is  continuous  with  the  fascia  of  the  leg ;  it 
contains  two  separate  sheaths,  one  internally  for  the  tendon  of  the  Tibialis  anti- 


OF   THE    FOOT.  349 

eus ;  one  externally,  for  the  tendons  of  the  Extensor  longus  digitorum  and  Pero- 
neus  tertius,  and  the  tendon  of  the  Extensor  proprius  pollicis,  and  the  anterior  tibial 
vessels  and  nerve  pass  beneath  it.  The  horizontal  portion  is  attached  externally 
to  the  upper  surface  of  the  os  calcis,  in  front  of  the  depression  for  the  interosseous 
ligament,  and  internally  to  the  inner  malleolus  and  plantar  fascia :  it  contains 
three  sheaths,  the  most  internal  for  the  tendon  of  the  Tibialis  anticus,  the  next 
in  order  for  the  tendon  of  the  Extensor  proprius  pollicis,  and  the  most  external  for 
the  Extensor  communis  digitorum  and  Peroneus  tertius :  the  anterior  tibial  ves- 
sels and  nerve  lie  altogether  beneath  it.  These  sheaths  are  lined  by  separate 
synovial  membranes. 

The  Internal  Annular  Ligament  is  a  strong  fibrous  band,  which  extends  from 
the  inner  malleolus  above,  to  the  internal  margin  of  the  os  calcis  below,  converting 
a  series  of  bony  grooves  in  this  situation  into  osteo-fibrous  canals,  for  the  passage 
of  the  tendons  of  the  Flexor  muscles  and  vessels  into  the  sole  of  the  foot.  It  is 
continuous  above  with  the  deep  fascia  of  the  leg,  below  with  the  plantar  fascia 
and  the  fibres  of  origin  of  the  Abductor  pollicis  muscle.  The  three  canals  which 
it  forms  transmit  from  within  outwards,  first,  the  tendon  of  the  Tibialis  posticus ; 
secondly,  the  tendon  of  the  Flexor  longus  digitorum,  then  the  posterior  tibial  vessels 
and  nerve,  which  run  through  a  broad  space  beneath  the  ligament ;  lastly,  in  a 
canal  formed  partly  by  the  astragalus,  the  tendon  of  the  Flexor  longus  pollicis. 
Each  of  these  canals  is  lined  by  a  separate  synovial  membrane. 

The  External  Annular  Ligament  extends  from  the  extremity  of  the  outer 
malleolus  to  the  outer  surface  of  the  os  calcis,  and  binds  down  the  tendons  of  the 
Peronei  muscles  in  their  passage  beneath  the  outer  ankle.  The  two  tendons  are 
inclosed  in  one  synovial  sac. 

Dissection  of  the  Sole  of  the  Foot.  The  foot  should  be  placed  on  a  high  block  with  the  sole 
uppermost,  and  firmly  secured  in  that  position.  Carry  an  incision  round  the  heel  and  along  the 
inner  and  outer  borders  of  the  foot  to  the  great  and  little  toes.  This  incision  should  divide  the 
integument  and  thick  layer  of  granular  fat  beneath,  until  the  fascia  is  visible ;  it  should  then  be 
removed  from  the  fascia  in  a  direction  from  behind  forwards,  as  seen  in  fig.  189. 

The  Plantar  Fascia,  the  densest  of  all  the  fibrous  membranes,  is  of  great 
strength,  and  consists  of  dense  pearly -white  glistening  fibres,  disposed,  for  the 
most  part,  longitudinally ;  it  is  divided  into  a  central  and  two  lateral  portions. 

The  central  portion,  the  thickest,  is  narrow  behind  and  attached  to  the  inner 
tuberosity  of  the  os  calcis,  behind  the  origin  of  the  Flexor  brevis  digitorum,  and, 
becoming  broader  and  thinner  in  front,  divides  opposite  the  middle  of  the  meta- 
tarsal bones  into  five  processes,  one  for  each  of  the  toes.  Each  of  these  processes 
divides  opposite  the  metatarso-phalangeal  articulation  into  two  slips,  which  em- 
brace the  sides  of  the  Flexor  tendons  of  the  toes,  and  are  inserted  into  the  sides 
of  the  metatarsal  bones,  and  into  the  transverse  metatarsal  ligament,  thus  forming 
a  series  of  arches  through  which  the  tendons  of  the  short  and  long  Flexors  pass  to 
the  toes.  The  intervals  left  between  the  five  processes  allow  the  digital  vessels 
and  nerves,  and  the  tendons  of  the  Lumbricales  and  Interossei  muscles  to  become 
superficial.  At  the  point  of  division  of  the  fascia  into  processes  and  slips, 
numerous  transverse  fibres  are  superadded,  which  serve  to  increase  the  strength 
of  the  fascia  at  this  part,  by  binding  the  processes  together  and  connecting  them 
with  the  integument.  The  central  portion  of  the  plantar  fascia  is  continuous  with 
the  lateral  portions  at  each  side,  and  sends  upwards  into  the  foot,  at  their  point 
of  junction,  two  strong  vertical  intermuscular  septa,  broader  in  front  than  behind, 
which  separate  the  middle  from  the  external  and  internal  plantar  group  of  muscles ; 
from  these,  again,  thinner  transverse  septa  are  derived,  which  separate  the  various 
layers  of  muscles  in  this  region.  The  upper  surface  of  this  fascia  gives  attach- 
ment behind  to  the  Flexor  brevis  digitorum  muscle. 

The  lateral  portions  of  the  plantar  fascia  are  thinner  than  the  central  piece  and 
cover  the  sides  of  the  foot. 

The  outer  portion  covers  the  under  surface  of  the  Abductor  minimi  digiti ;  it  is 


350  MUSCLES   AND   FASCIAE. 

thick  behind,  thin  in  front,  and  extends  from  the  os  calcis  forwards  to  the  base  of 
the  fifth  metatarsal  bone,  into  the  outer  side  of  which  it  is  attached ;  it  is  con- 
tinuous internally  with  the  middle  portion  of  the  plantar  fascia,  and  externally 
with  the  dorsal  fascia. 

The  inner  portion  is  very  thin,  and  covers  the  Abductor  pollicis  muscle ;  it  is 
attached  behind  to  the  internal  annular  ligament,  is  continuous  around  the  side 
of  the  foot  with  the  dorsal  fascia,  and  externally  with  the  middle  portion  of  the 
plantar  fascia. 

Muscles  of  the  Foot. 

These  are  divided  into  two  groups :  1.  Those  on  the  dorsum ;  2.  Those  on  the 
plantar  surface. 

1.  Dorsal  Kegiost. 
Extensor  Brevis  Digitorum. 

The  Fascia  on  the  dorsum  of  the  foot  is  a  thin  membranous  layer,  continuous 
above  with  the  anterior  margin  of  the  annular  ligament ;  it  becomes  gradually 
lost  opposite  the  heads  of  the  metatarsal  bones,  and  on  each  side  blends  with  the 
lateral  portions  of  the  plantar  fascia.  It  forms  a  sheath  for  the  tendons  placed  on 
the  dorsum  of  the  foot.  On  the  removal  of  this  fascia,  the  muscles  of  the  dorsal 
region  of  the  foot  are  exposed. 

The  Extensor  Brevis  Digitorum  is  a  broad  thin  muscle,  which  arises  from  the 
outer  side  of  the  os  calcis,  in  front  of  the  groove  for  the  Peroneus  brevis ;  from 
the  astragalo-calcanean  ligament ;  and  from  the  horizontal  portion  of  the  anterior 
annular  ligament ;  passing  obliquely  across  the  dorsum  of  the  foot,  it  terminates 
in  four  tendons.  The  innermost,  which  is  the  largest,  is  inserted  into  the  first 
phalanx  of  the  great  toe ;  the  other  three,  into  the  outer  sides  of  the  long  Extensor 
tendons  of  the  second,  third,  and  fourth  toes. 

delations.  By  its  superficial  surface,  with  the  fascia  of  the  foot,  the  tendons  of 
the  Extensor  longus  digitorum,  and  Extensor  proprius  pollicis.  By  its  deep  sur- 
face, with  the  tarsal  and  metatarsal  bones,  and  the  Dorsal  interossei  muscles. 

Nerves.     It  is  supplied  by  the  anterior  tibial  nerve. 

Actions.  The  Extensor  brevis  digitorum  is  an  accessory  to  the  long  Extensor, 
extending  the  phalanges  of  the  four  inner  toes,  but  acting  only  on  the  first  phalanx 
of  the  great  toe.  The  obliquity  of  its  direction  counteracts  the  oblique  movement 
given  to  the  toes  by  the  long  Extensor,  so  that,  both  muscles  acting  together,  the 
toes  are  evenly  extended. 

2.  Plantar  Eegion.  * 

The  muscles  in  the  plantar  region  of  the  foot  may  be  divided  into  three  groups, 
in  a  similar  manner  to  those  in  the  hand.  Those  of  the  internal  plantar  region 
are  connected  with  the  great  toe,  and  correspond  with  those  of  the  thumb ;  those 
of  the  external  plantar  region  are  connected  with  the  little  toe,  and  correspond 
with  those  of  the  little  finger ;  and  those  of  the  middle  plantar  region  are  con- 
nected with  the  tendons  intervening  between  the  two  former  groups.  In  order  to 
facilitate  the  dissection  of  these  muscles,  it  will  be  found  more  convenient  to  divide 
them  into  three  layers,  as  they  present  themselves,  in  the  order  in  which  they  are 
successively  exposed. 

First  Layer. 

Abductor  Pollicis.  Flexor  Brevis  Digitorum. 

Abductor  Minimi  Digiti. 

Dissection.  Remove  the  fascia  on  the  inner  and  outer  sides  of  the  foot,  commencing  in  front 
over  the  tendons,  and  proceeding  backwards.  The  central  portion  should  be  divided  transversely 
in  the  middle  of  the  foot,  and  the  two  flaps  dissected  forwards  and  backwards. 


OF   TIIE    SOLE    OF   THE   FOOT.     FIRST   LAYER. 


351 


The  Abductor  Pollicis  lies  along  the  inner  border  of  the  foot.  It  arises  from 
the  inner  tuberosity  on  the  under  surface  of  the  os  calcis ;  from  the  internal  annular 
ligament;  from  the  plantar  fascia; "and  from  the  intermuscular  septum  between  it 
and  the  Flexor  brevis  digitorum.  The  fibres  terminate  in  a  tendon,  which  is 
inserted,  together  with  the  innermost  tendon  of  the  Flexor  brevis  pollicis,  into  the 
inner  side  of  the  base  of  the  first  phalanx  of  the  great  toe. 

Relations.  By  its  superficial  surface,  with  the  plantar  fascia.  By  its  deep 
surface,  with  the  Flexor  brevis  polli- 


Fig.  194.— Muscles  of  the  Sole  of  the  Foot. 
First  Layer. 


cis,  the  Flexor  accessorius,  and  the 
tendons  of  the  Flexor  longus  digitorum 
and  Flexor  longus  pollicis,  the  Tibialis 
anticus  and  posticus,  the  plantar  ves- 
sels and  nerves,  and  the  articulations 
of  the  tarsus. 

The  Flexor  Brevis  Digitorum  lies 
in  the  middle  line  of  the  sole  of  the 
foot,  immediately  beneath  the  plantar 
fascia,  with  which  it  is  firmly  united. 
It  arises,  by  a  narrow  tendinous  pro- 
cess, from  the  inner  tuberosity  of  the 
os  calcis ;  from  the  central  part  of  the 
plantar  fascia ;  and  from  the  intermus- 
cular septa  between  it  and  the  adjacent 
muscles.  It  passes  forwards,  and 
divides  into  four  tendons.  Opposite 
the  middle  of  the  first  phalanges,  each 
tendon  presents  a  longitudinal  slit,  to 
allow  of  the  passage  of  the  correspond- 
ing tendon  of  the  Flexor  longus  digi- 
torum, the  two  portions  forming  a 
groove  for  its  reception,  and,  after  re- 
uniting, divides  a  second  time  into  two 
processes,  which  are  inserted  into 
the  sides  of  the  second  phalanges. 
The  mode  of  division  of  the  tendons 
of  the  Flexor  brevis  digitorum,  and 
of  their  insertion  into  the  phalanges,  is 
analogous  to  that  of  the  Flexor  sublimis 
in  the  hand. 

Relations.  By  its  superficial  surface, 
with  the  plantar  fascia.  By  its  deep 
surface,  with  the  Flexor  accessorius, 
the  Lumbricales,  the  tendons  of  the 
Flexor  longus  digitorum,  and  the  ex- 
ternal plantar  vessels  and  nerve,  from 
which  it  is  separated  by  a  thin  layer  of 
fascia.  The  outer  and  inner  borders  are 
separated  from  the  adjacent  muscles 
by  means  of  vertical  prolongations  of 
the  plantar  fascia. 

The  Abductor  Minimi  Digiti  lies  along  the  outer  border  of  the  foot.  It  arises. 
by  a  very  broad  origin,  from  the  outer  tuberosity  of  the  os  calcis,  from  the  under 
surface  of  the%  os  calcis  in  front  of  both  tubercles,  from  the  plantar  fascia,  and  the 
intermuscular  septum  between  it  and  the  Flexor  brevis  digitorum.  Its  tendon, 
after  gliding  over  a  smooth  facet  on  the  under  surface  of  the  base  of  the  fifth 
metatarsal  bone,  is  inserted  with  the  short  Flexor  of  the  little  toe  into  the  outer 
side  of  the  base  of  the  first  phalanx  of  the  little  toe. 


352 


MUSCLES   AND    FASCIAE. 


Relations.  By  its  superficial  surface,  with,  the  plantar  fascia.  By  its  deep 
surface,  with  the  Flexor  accessorius,  the  Flexor  brevis  minimi  digiti,  the  long 
plantar  ligament,  and  Peroneus  longus.  On  its  inner  side  are  the  external  plantar 
vessels  and  nerve,  and  it  is  separated  from  the  Flexor  brevis  digitorum  by  a  ver- 
tical septum  of  fascia. 

Dissection.  The  muscles  of  the  superficial  layer  should  be  divided  at  their  origin,  by  inserting 
the  knife  beneath  each,  and  cutting  obliquely  backwards,  so  as  to  detach  them  from  the  bone  ; 

.    they  should  then  be  drawn  forwards,  in  order 


Fig.  195.— Muscles  of  the  Sole  of  the  Foot. 
Second  Layer. 


to  expose  the  second  layer,  but  not  separated 
at  their  insertion.  The  two  layers  are  sepa- 
rated by  a  thin  membrane,  the  deep  plantar 
fascia,  on  the  removal  of  which  are  seen  the 
tendon  of  the  Flexor  longus  digitorum,  with 
its  accessory  muscle,  the  Flexor  longus  pol- 
licis,  and  the  Lumbricales.  The  long  flexor 
tendons  cross  each  other  at  an  acute  angle, 
the  Flexor  longus  pollicis  running  along  the 
inner  side  of  the  foot,  on  a  plane  superior  to 
that  of  the  Flexor  longus  digitorum.  the  di- 
rection of  which  is  obliquely  outwards. 


Second  Layer. 

Flexor  Accessorius. 
Lumbricales. 


The  Flexor  Accessorius  arises  by  two 
heads :  the  inner  or  larger,  which  is 
muscular,  being  attached  to  the  inner 
concave  surface  of  the  os  calcis,  and 
to  the  calcaneo- scaphoid  ligament;  the 
outer  head,  flat  and  tendinous,  to  the 
under  surface  of  the  os  calcis,  in  front 
of  its  outer  tuberosity,  and  to  the  long 
plantar  ligament.  The  two  portions 
become  united  at  an  acute  angle,  and 
are  inserted  into  the  outer  margin  and 
upper  and  under  surfaces  of  the  tendon 
of  the  Flexor  longus  digitorum,  form- 
ing a  kind  of  groove,  in  which  the 
tendon  is  lodged. 

Relations.  By  its  superficial  surf  ace, 
with  the  muscles  of  the  superficial 
layer,  from  which  it  is  separated  by 
the  external  plantar  vessels  and  nerves. 
By  its  deep  surface,  with  the  os  calcis 
and  long  calcaneo-cuboid  ligament. 

The  Lumbricales  are  four  small 
muscles,  accessory  to  the  tendons  of  the 
Flexor  longus  digitorum:  they  arise 
from  the  tendons  of  the  long  Flexor,  as  far  back  as  their  angle  of  division,  each 
arising  from  two  tendons,  except  the  internal  one.  Each  muscle  terminates  in  a 
tendon,  which  passes  forwards  on  the  inner  side  of  each  of  the  lesser  toes,  and  is 
inserted  into  the  expansion  of  the  long  Extensor  and  base  of  the  second  phalanx 
of  the  corresponding  toe. 


Dissection.    The  Flexor  tendons  should  be  divided  at  the  back  part  of  the  foot,  and  the  Flexor 
accessorius  at  its  origin,  and  drawn  forwards,  in  order  to  expose  the  third  layer. 


OF  THE   SOLE   OF   THE   FOOT— THIRD   LAYER. 


353 


Third  Layer. 


Flexor  Brevis  Pollicis. 
Adductor  Pollicis. 


Flexor  Brevis  Minimi  Digiti. 
Transversus  Pedis. 


Fig.  196.— Muscles  of  the  Sole  of  the  Foot. 
Third  Layer. 


The  Flexor  Brevis  Pollicis  arises,  by  a  pointed  tendinous  process,  from  the 
inner  border  of  the  cuboid  bone,  from  the  contiguous  portion  of  the  external 
cuneiform,  and  from  the  prolongation  of  the  tendon  of  the  Tibialis  posticus,  which 
is  attached  to  that  bone.  The  muscle 
divides,  in  front,  into  two  portions, 
which  are  inserted  into  the  inner  and 
outer  sides  of  the  base  of  the  first 
phalanx  of  the  great  toe,  a  sesamoid 
bone  being  developed  in  each  tendon 
at  its  insertion.  The  inner  head  of 
this  muscle  is  blended  with  the  Ab- 
ductor pollicis  previous  to  its  insertion ; 
the  outer  head,  with  the  Adductor 
pollicis;  and  the  tendon  of  the  Flexor 
longus  pollicis  lies  in  a  groove  between 
them. 

Relations.  By  its  superficial  surface, 
with  the  Abductor  pollicis,  the  tendon 
of  the  Flexor  longus  pollicis  and  plantar 
fascia.  By  its  deep  surface,  with  the 
tendon  of  the  Peroneus  longus,  and 
metatarsal  bone  of  the  great  toe.  By  its 
inner  border,  with  the  Abductor  pollicis. 
By  its  outer  border,  with  the  Adductor 
pollicis. 

The  Adductor  Pollicis  is  a  large,  thick, 
fleshy  mass,  passing  obliquely  across 
the  foot,  and  occupying  the  hollow  space 
between  the  four  outer  metatarsal  bones. 
It  arises  from  the  tarsal  extremities  of 
the  second,  third,  and  fourth  metatarsal 
bones,  and  from  the  sheath  of  the  tendon 
of  the  Peroneus  longus,  and  is  inserted, 
together  with  the  outer  head  of  the 
Flexor  brevis,  pollicis,  into  the  outer 
side  of  the  base  of  the  first  phalanx  of 
the  great  toe. 

The  Flexor  Brevis  Minimi  Digiti  lies 
on  the  metatarsal  bone  of  the  little  toe. 
It  arises  from  the  base  of  the  metatarsal 
bone  of  the  little  toe,  and  from  the 
sheath  of  the  Peroneus  longus;  its 
tendon  is  inserted  into  the  base"  of  the 
first  phalanx  of  the  little  toe,  on  its 
outer  side. 

Relations.     By  its  superficial  surface,  with  the  plantar  fascia  and  tendon  of  the 
Abductor  minimi  digiti.     By  its  deep  surface,  with  the  fifth  metatarsal  bone. 

The  Transversus  Pedis  is  a  narrow,  flat,  muscular  fasciculus,  stretched  trans- 
versely across  the  heads  of  the  metatarsal  bones,  between  them  and  the  flexor 
tendons.  It  arises  from  the  under  surface  of  the  head  of  the  fifth  metatarsal 
bone,  and  from  the  transverse  ligament  of  the  metatarsus,  and  is  inserted  into 
the  outer  side  of  the  first  phalanx  of  the  great  toe ;  its  fibres  being  blended  with 
the  tendon  of  insertion  of  the  Adductor  pollicis. 
23 


554 


SURGICAL   ANATOMY. 


Relations.      By  its  under  surface,  with  the  tendons  of   the  long  and  short 
Flexors  and  Lumbricales.     By  its  upper  surface,  with  the  Interossei. 


Fig.  197. — The  Dorsal  Interossei. 
Left  Foot. 


Fig.  19S.— The  Plantar  Interossei. 
Left  Foot. 


The  Interossei. 

The  Interossei  muscles  in  the  foot  are  simi- 
lar to  those  in  the  hand.  They  are  seven  in 
number,  and  consist  of  two  groups,  dorsal,  and 
plantar. 

The  Dorsal  Interossei,  four  in  number,  are 
situated  between  the  metatarsal  bones.  They 
are  bipenniform  muscles,  arising  by  two  heads 
from  the  adjacent  sides  of  the  metatarsal  bones 
between  which  they  are  placed,  their  tendons 
being  inserted  into,  the  bases  of  the  first  pha- 
langes, and  into  the  aponeurosis  of  the  common 
Extensor  tendon.  In  the  angular  interval  left 
between  each  muscle  at  its  posterior  extremity, 
the  perforating  arteries  pass  to  the  dorsum  of 
the  foot,  except  in  the  first  Interosseous  muscle, 
where  the  interval  allows  the  passage  of  the 
communicating  branch  of  the  dorsalis  pedis 
artery.  The  first  Dorsal  interosseous  muscle 
is  inserted  into  the  inner  side  of  the  second  toe ; 
the  other  three  are  inserted  into  the  outer  sides 
of  the  second,  third,  and  fourth  toes.  They 
are  all  abductors  from  an  imaginary  line  or 
axis  drawn  through  the  second  toe. 

The  Plantar  Interossei,  three  in  number,  lie 
beneath,  rather  than  between,  the  metatarsal 
bones.  They  are  single  muscles,  and  are  each 
connected  with  but  one  metatarsal  bone.  They 
arise  from  the  base  and  inner  sides  of  the  shaft 
of  the  third,  fourth,  and  fifth  metatarsal  bones, 
and  are  inserted  into  the  inner  sides  of  the 
bases  of  the  first  phalanges  of  the  same  toes, 
and  into  the  aponeurosis  of  the  common 
Extensor  tendon.  These  muscles  are  all 
adductors  towards  an  imaginary  line,  extend- 
ing through  the  second  toe. 

Nerves.  The  internal  plantar  nerve  supplies 
the  Abductor  pollicis,  Flexor  brevis  digitorum, 
Flexor  brevis  pollicis,  and  the  first  and  second 
Lumbricales.  The  external  plantar  nerve  sup- 
plies the  Abductor  minimi  digiti,  Flexor 
accessorius,  third  and  fourth  Lumbricales,  Ad- 
ductor pollicis,  Flexor  brevis  minimi  digiti, 
Transversus  pedis,  and  all  the  Interossei. 


SURGICAL  ANATOMY. 

The  student  should  now  consider  the  effects  produced 
by  the  action  of  the  various  muscles  in  fractures  of 
the  bones  of  the  lower  extremity.  The  more  common 
forms  of  fracture  may  be  especially  selected  for 
illustration  and  description. 


OF  THE  MUSCLES  OF  THE  LOWER  EXTREMITY. 


355 


Fracture  of  the  neck  of 
the  femur  within  the  cap- 
sular ligament  (fig.  199) 
is  a  very  common  accident, 
and  is  most  frequently 
caused  by  indirect  vio- 
lence, such  as  slipping  off 
the  edge  of  the  curbstone, 
the  impetus  and  weight 
of  the  body  falling  upon 
the  neck  of  the  bone.  It 
usually  occurs  in  females, 
and  seldom  under  fifty 
years  of  age.  At  this 
period  of  life,  the  cancel- 
lous tissue  of  the  neck  of 
the  bone  not  unfrequently 
is  atrophied,  becoming  soft 
and  infiltrated  with  fatty 
matter,  and  the  compact  tis- 
sue is  partially  absorbed ; 
hence  the  bone  is  more 
brittle,  and  more  liable  to 
fracture.  The  characteris- 
tic marks  of  this  accident 
are  slight  shortening  of  the 
limb,  and  eversion  of 
the  foot,  neither  of  which 
symptoms  occur,  however, 
in  some  cases  until  some 
time  after  the  injury.  The 
eversion  is  caused  by  the  combined  action  of  the  external 
rotator  muscles,  as  well  as  by  the  Psoas  and  Iliacus,  Pec- 
tineus, Adductors,  and  Glutei  muscles.  The  shortening 
and  retraction  is  produced  by  the  action  of  the  Glutei,  and 
by  the  Rectus  femoris  in  front,  and  the  Biceps,  Semi-tendi- 
nosus,  and  Semi-membranosus  behind. 

Fracture  of  the  femur  just  below  the  trochanters  (fig.  200) 
is  an  accident  of  not  unfrequent  occurrence,  and  is  at- 
tended with  great  displacement  producing  considerable 
deformity.  The  upper  fragment,  the  portion  chiefly  dis- 
placed, is  tilted  forwards  almost  at  right  angles  with  the 
pelvis,  by  the  combined  action  of  the  Psoas  and  Iliacus ; 
and,  at  the  same  time,  everted  and  drawn  outwards  by  the 
external  rotator  and  Glutei  muscles,  causing  a  marked 
prominence  at  the  upper  and  outer  side  of  the  thigh,  and 
much  pain  from  the  bruising  and  laceration  of  the  muscles. 
The  limb  is  shortened,  from  the  lower  fragment  being 
drawn  upwards  by  the  Rectus  in  front,  and  the  Biceps, 
Semi-membranosus,  and  Semi-tendinosus  behind ;  and,  at 
the  same  time,  everted,  and  the  upper  end  thrown  out- 
wards, the  lower  inwards,  by  the  Pectineus  and  Adductor 
muscles.  This  fracture  may  be  reduced  in  two  different 
methods;  either  by  direct  relaxation  of  all  the  opposing 
muscles,  to  effect  which,  the  limb  should  be  placed  on  a 
double  inclined  plane;  or,  by  overcoming  the  contraction 
of  the  muscle  by  continued  extension,  which  may  be 
effected  by  means  of  the  long  splint. 

Oblique  fracture  of  the  femur  immediately  above  the  con- 
dyles (fig.  201)  is  a  formidable  injury,  and  attended  with 
considerable  displacement.  On  examination  of  the  limb, 
the  lower  fragment  may  be  felt  deep  in  the  popliteal 
space,  being  drawn  backwards  by  the  Gastrocnemius, 
SSoleus,  and  Plantaris  muscles ;  and  upwards  by  the  poste- 
rior femoral,  and  Rectus  muscles.  The  pointed  end  of  the 
upper  fragment  is  drawn  inwards  by  the  Pectineus  and 
Adductor  muscles,  and  tilted  forwards  by  the  Psoas  and 
Biacus,  piercing  the  Rectus  muscle,  and,  occasionally,  the 
integument.  Relaxation  of  these  muscles  and  direct 
approximation  of  the  broken  fragments  are  effected  by 
placing  the  limb  on  a  double  inclined  plane.    The  greatest 


Fig.  199. — Fracture  of  the  Neck  of  the  Femur  within  the 
Capsular  Ligament. 


PTRiro«MI  j 
CCMCI.LUS     SHrnitn 


OBTURATOR 


■TURATOM     CXTERNUI 
UAORATWS     FCKORif 


Fig.  200. — Fracture  of  the  Femur 
below  the  Trochanters. 


rtMI-MCMI.ARV 


I1MI-  II  HOIK. 


35  C 


SURGICAL   ANATOMY. 


care  is  requisite  in  keeping  the  pointed  extremity  of  the  upper  fragment  in  proper  apposition ; 
otherwise,  after  union  of  the  fracture,  extension  of  the  limb  is  partially  destroyed  from  the  Kec- 
tus  muscle  being  held  down  by  the  fractured  end  of  the  bone,  and  from  the  patella,  when  elevated, 
being  drawn  upwards  against  it. 


Fig.  201. — Fracture  of  the  Femur  above  the  Condyles. 


Fig.  202.— Fracture  of  the  Patella. 


Fig.  203. 


-Oblique  Fracture  of  the  Shaft 
of  the  Tibia. 


Fracture  of  the  patella  (fig.  202)  may  be  produced  by  muscular  action,  or  by  direct  violence. 
When  produced  by  muscular  action,  it  occurs  thus :  a  person  in  danger  of  falling  forwards, 
attempts  to  recover  himself  by  throwing  the  body  backwards,  and  the  violent  action  of  the 

Quadriceps  extensor  upon  the  patella  snaps 
that  bone  transversely  across.  The  upper  frag- 
ment is  drawn  up  the  thigh  by  the  Quadriceps 
extensor,  the  lower  fragment  being  retained  in 
its  position  by  the  ligamentum  patellae ;  the 
extent  of  separation  of  the  two  fragments  de- 
pending upon  the  degree  of  laceration  of  the 
ligamentous  structures  around  the  bone.  The 
patient  is  totally  unable  to  straighten  the 
limb,  the  prominence  of  the  patella  is  lost, 
and  a  marked  but  varying  interval  can  be  felt 
between  the  fragments.  The  treatment  consists 
in  relaxing  the  opposing  muscles,  which  maybe 
effected  by  raising  the  trunk,  and  slightly  elevat- 
ing the  limb,  which  should  be  kept  in  a  straight 
position.  Union  is  usually  ligamentous.  In 
fracture  from  direct  violence,  the  bone  is  gene- 
rally comminuted,  or  fractured  obliquely  or  per- 
pendicularly. 

Oblique  fracture  of  the  shaft  of  the  tibia 
(fig.  203)  usually  occurs  at  the  lower  fourth  of 
the  bone,  this  being  the  narrowest  and  weakest 
part,  and  is  usually  accompanied  with  fracture 
of  the  fibula.  If  the  fracture  has  taken  place 
obliquely  from  above,  downwards  and  forwards. 
the  fragments  ride  over  one  another,  the  lower 
fragment  being  drawn  backwards  and  upwards 
by  the  powerful  action  of  the  muscles  of  the  calf; 
the  pointed  extremity  of  the  upper  fragment 
projects  forwards  immediately  beneath  the  in- 
tegument, often  protruding  through  it,  and  ren- 
dering the  fracture  a  compound  one.  If  the 
direction  of  the  fracture  is  the  reverse  of  that 
shown  in  the  figure,  the  pointed  extremity  of  the 
lower  fragment  projects  forwards,  riding  upon 
the  lower  end  of  the  upper  one.  By  bending  the 
knee,  which  relaxes  the  opposing  muscles,  and 


OF  THE  MUSCLES  OF  THE  LOWER  EXTREMITY 


357 


making  extension  from  the  knee  and  ankle,  the  fragments  may  be  brought  into  apposition.     It 
is  often  necessary,  however,  in  compound  fracture,  to  remove  a  portion  of  the  projecting  bone 
with  the  saw  before  complete  adapta- 
tion can  be  effected.  Fig.  204.— Fracture  of  the  Fibula,  with  Displacement 

Fracture  of  the  fibula,  with  displace-  of  the  Tibia. — "  Pott's  Fracture.  " 

merit  of  the  tibia  (fig.  204),  commonly 
known  as  "  Pott's  Fracture,"  is  one  of 
the  most  frequent  injuries  of  the  ankle- 
joint.  The  end  of  the  tibia  is  displaced 
from  the  corresponding  surface  of  the 
astragalus,  the  internal  lateral  ligament 
is  ruptured,  and  the  iiiner  malleolus 
projects  inwards  beneath  the  integu- 
ment, which  is  tightly  stretched  over 
it,  and  in  danger  of  bursting.  The 
fibula  is  broken,  usually  from  two  to 
three  inches  above  the  ankle,  and  oc- 
casionally that  portion  of  the  tibia 
with  which  it  is  more  directly  connected 
below;  the  foot  is  everted  by  the  action 
of  the  Peroneus  longus,  its  inner  border 
resting  upon  the  ground,  and,  at  the 
same  time,  the  heel  is  drawn  up  by  the 
muscles  of  the  calf.  This  injury  may 
be  at  once  reduced  by  flexing  the  leg 
at  right  angles  with  the  thigh,  which 
relaxes  all  the  opposing  muscles,  and 
by  making  slight  extension  from  the 
knee  and  ankle. 


For  a  detailed  account  of  the  Minute  Anatomy  of  Muscle,  reference  should  be  made  to  the 
following  sources  of  information  :  Quain's  "  Elements  of  Anatomy." — Kolliker's  "  Handbook  of 
Human  Microscopic  Anatomy,"  before  alluded  to. — Todd' and  Bowman's  "  Physiological  Ana- 
tomy."— To  the  article,  "  Muscle  and  Muscular  Motion,"  by  W.  Bowman,  in  the  Cyclopedia  of 
Anatomy ;  and  "  On  the  Minute  Structure  of  Voluntary  Muscle,"  by  the  same  author,  in  the 
Phil.  Trans.  1840,  1841. 

On  the  Descriptive  Anatomy  of  the  Muscles,  refer  to  Cruveilhier's  "Anatomie  Descriptive." — 
"Traite  de  Myologie  et  d'Angeiologie,"  by  F.  G.  Theile,  "  1'ncyclopedie  Anatomique,"  Paris,  1843 ; 
and  Henle's  "Handbuch  der  Systematischen  Anatomic,"  before  alluded  to. 


Of  the  Arteries. 

The  Arteries  are  cylindrical  tubular  vessels,  which  serve  to  convey  blood  from 
both  ventricles  of  the  heart  to  every  part  of  the  body.  These  vessels  were  named 
arteries  (<%  trjnv,  to  contain  air),  from  the  belief  entertained  by  the  ancients  that 
they  contained  air.  To  Galen  is  due  the  honor  of  refuting  this  opinion ;  he  showed 
that  these  vessels,  though  for  the  most  part  empty  after  death,  contained  blood  in 
the  living  body. 

The  pulmonary  artery,  which  arises  from  the  right  ventricle  of  the  heart,  carries 
venous  blood  directly  into  the  lungs,  from  whence  it  is  returned  by  the  pulmonary 
veins  into  the  left  auricle.  This  constitutes  the  lesser  or  pulmonic  circulation. 
The  great  artery,  the  aorta,  which  arises  from  the  left  ventricle,  conveys  arterial 
blood  to  the  body  generally ;  from  whence  it  is  brought  back  to  the  right  side  of 
the  heart  by  means  of  the  veins.  This  constitutes  the  greater  or  systemic  cir- 
culation. 

The  distribution  of  the  systemic  arteries  is  like  a  highly  ramified  tree,  the  com- 
mon trunk  of  which,  formed  by  the  aorta,  commences  at  the  left  ventricle  of  the 
heart,  the  smallest  ramifications  corresponding  to  the  circumference  of  the  body 
and  the  contained  organs.  The  arteries  are  found  in  nearly  every  part  of  the 
animal  body,  with  the  exception  of  the  hairs,  nails,  epidermis,  cartilages,  and 
cornea ;  and  the  larger  trunks  usually  occupy  the  most  protected  situations,  run- 
ning, in  the  limbs,  along  the  flexor  side,  where  they  are  less  exposed  to  injury. 

There  is  considerable  variation  in  the  mode  of  division  of  the  arteries ;  occa- 
sionally a  short  trunk  subdivides  into  several  branches  at  the  same  point,  as  we 
observe  in  the  cceliac  and  thyroid  axes ;  or  the  vessel  may  give  off  several  branches 
in  succession,  and  still  continue  as  the  main  trunk,  as  is  seen  in  the  arteries  of  the 
limbs ;  but  the  usual  division  is  dichotomous,  as,  for  instance,  the  aorta  dividing 
into  the  two  common  iliacs ;  and  the  common  carotid,  into  the  external  and  internal 
carotids. 

The  branches  of  arteries  arise  at  very  variable  angles ;  some,  as  the  superior 
intercostal  arteries,  arise  from  the  aorta  at  an  obtuse  angle  ;  others,  as  the  lumbar 
arteries,  at  a  right  angle ;  or,  as  the  spermatic,  at  an  acute  angle.  An  artery  from 
which  a  branch  is  given  off*  is  smaller  in  size,  but  retains  a  uniform  diameter  until 
a  second  branch  is  derived  from  it.  A  branch  of  an  artery  is  smaller  than  the 
trunk  from  which  it  arises,  but  if  an  artery  divides  into  two  branches,  the  com- 
bined area  of  the  two  vessels  is,  in  nearly  every  instance,  somewhat  greater  than 
that  of  the  trunk,  and  the  combined  area  of  all  the  arterial  branches  greatly 
exceeds  the  area  of  the  aorta ;  so  that  the  arteries  collectively  may  be  regarded 
as  a  cone,  the  apex  of  which  corresponds  to  the  aorta ;  the  base  to  the  capillary 
system. 

The  arteries,  in  their  distribution,  communicate  freely  with  one  another,  forming 
what  is  called  an  anastomosis  (avo,  between ;  ar6fia,  mouth),  or  inosculation ;  and  this 
communication  is  very  free  between  the  large,  as  well  as  between  the  smaller 
branches.  The  anastomoses  between  trunks  of  equal  size  is  found  where  great 
freedom  and  activity  of  the  circulation  is  requisite,  as  in  the  brain ;  here,  the  two 
vertebral  arteries  unite  to  form  the  basilar,  and  the  two  internal  carotid  arteries  are 
connected  by  a  short  inter-communicating  trunk ;  it  is  also  found  in  the  abdomen, 
the  intestinal  arteries  having  very  free  anastomoses  between  their  larger  branches. 
In  the  limbs,  the  anastomoses  are  most  frequent  and  of  largest  size  around  the 
joints ;  the  branches  of  an  artery  above,  freely  inosculating  with  branches  from 
the  vessel  below.  These  anastomoses  are  of  considerable  interest  to  the  surgeon, 
as  it  is  by  their  enlargement  that  a  collateral  circulation  is  established  after  the 
application  of  a  ligature  to  an  artery  for  the  cure  of  aneurism.  The  smaller  branches 
of  arteries  anastomose  more  frequently  than  the  larger ;  and  between  the  smallest 
358 


GENERAL   ANATOMY.  359 

twigs,  these  inosculations  become  so  numerous  as  to  constitute  a  close  network 
that  pervades  nearly  every  tissue  of  the  body. 

Throughout  the  body  generally,  the  larger  arterial  branches  pursue  a  perfectly 
straight  course,  but  in  certain  situations  they  are  tortuous :  thus,  the  facial  artery 
in  its  course  over  the  face,  and  the  labial  arteries  of  the  lips,  are  extremely  tor- 
tuous in  their  course,  to  accommodate  themselves  to  the  movements  of  these  parts. 
The  uterine  arteries  are  also  tortuous,  to  accommodate  themselves  to  the  increase 
of  size  which  this  organ  undergoes  during  pregnancy.  Again,  the  internal  carotid 
and  vertebral  arteries,  previous  to  their  entering  the  cavity  of  the  skull,  describe 
a  series  of  curves,  which  are  evidently  intended  to  diminish  the  velocity  of  the 
current  of  blood,  by  increasing  the  extent  of  surface  over  which  it  moves,  and 
adding  to  the  amount  of  impediment  which  is  produced  from  friction. 

The  arteries  are  dense  in  structure,  of  considerable  strength,  highly  elastic,  and, 
when  divided,  they  preserve,  although  empty,  'their  cylindrical  form. 

The  arteries  are  composed  of  three  coats — internal,  middle,  and  external. 

The  internal,  the  thinnest,  consists  usually  of  two  layers,  an  inner  or  epithelial,  and 
an  outer  or  elastic  coat.  The  former  consists  of  a  single  layer  of  fusiform-shaped 
epithelial  cells  with  round  or  oval  nuclei.  The  latter  is  a  transparent,  colorless, 
shining  membrane,  perforated  with  small  elongated  apertures  (hence  the  name, 
fenestrated),  and  marked  with  numerous  reticulations.  This  layer  is  perfectly 
smooth  when  the  artery  is  distended ;  but  when  empty  presents  numerous  longi- 
tudinal and  transverse  folds. 

In  arteries  above  the  size  of  the  capillaries,  the  elastic  layer  is  very  delicate, 
and  the  epithelium  clearly  demonstrable. 

In  arteries  of  less  than  a  line  in  diameter,  the  internal  coat  consists  of  two  layers, 
as  above  described ;  but  in  medium-sized  arteries,  several  lamellae,  composed  of 
elastic  fibres  and  connective  tissue,  are  interposed  between  the  epithelial  and  elastic 
coats.  In  the  largest  arteries,  the  inner  coat  is  usually  much  thickened,  especially 
in  the  aorta ;  and  consists  of  a  homogeneous  substance,  occasionally  striated  or 
fibrillated,  traversed  by  longitudinal  elastic  networks,  which  are  very  fine  in  the 
lamellae  immediately  beneath  the  epithelium,  but  increase  in  thickness  from  within 
outwards.  The  internal  and  middle  coats  are  separated,  by  either  a  dense  elastic 
reticulated  coat  or  a  true  fenestrated  membrane. 

The  middle  coat,  thicker  than  the  preceding,  consists  of  muscular  and  elastic 
fibres,  and  connective  tissue,  disposed  chiefly  in  the  transverse  direction.  In  the 
largest  arteries,  this  coat  is  of  great  thickness,  of  a  yellow  color,  and  highly 
elastic ;  it  diminishes  in  thickness,  and  becomes  redder  in  color  as  the  arteries 
become  smaller,  becomes  very  thin,  and  finally  disappears.  In  small  arteries,  this 
coat  is  purely  muscular,  consisting  of  muscular  fibre-cells  united  to  form  lamellae, 
which  vary  in  number  according  to  the  size  of  the  arteries,  the  very  small  arteries 
having  only  a  single  layer,  and  those  not  larger  than  the  T'0th  of  a  line  three  or 
four  layers.  In  arteries  of  medium  size,  this  coat  becomes  thicker  in  proportion 
with  the  size  of  the  vessel ;  its  layers  of  muscular  tissue  are  more  numerous,  and 
intermixed  with  numerous  fine  elastic  fibres  which  unite  to  form  broad-meshed 
networks.  In  the  larger  vessels  of  this  class,  as  the  femoral,  superior  mesenteric, 
coeliac,  external  iliac,  brachial,  and  popliteal  arteries,  the  elastic  fibres  unite  to  form 
lamellae,  which  alternate  with  the  layers  of  muscular  fibre.  In  the  largest  arteries, 
the  muscular  tissue  is  only  slightly  developed,  and  forms  about  one-third  or  one- 
fourth  of  the  whole  substance  of  the  middle  coat.  This  is  especially  the  case  in  the 
aorta,  and  trunk  of  the  pulmonary  artery,  in  which  the  individual  cells  of  the 
muscular  layer  are  imperfectly  formed ;  while,  in  the  carotid,  axillary,  iliac,  and 
subclavian  arteries,  the  muscular  tissue  of  the  middle  coat  is  more  developed. 
The  elastic  lamellae  are  well  marked,  may  amount  to  fifty  or  sixty  in  number,  and 
alternate  regularly  with  the  layers  of  muscular  fibre.  They  are  most  distinct,  and 
arranged  with  most  regularity,  in  the  abdominal  aorta,  innominate  artery,  and 
common  carotid. 

The  external,  or  areolar  and  elastic  coat,  the  thickest  of  the  three,  consists  of 


360  ARTERIES. 

connective  tissue  and  elastic  fibres.  It  is  very  thin  in  the  largest  arteries ;  hut  in 
those  of  medium  size,  and  in  small  arteries,  is  as  thick  as,  or  thicker  than  the  middle 
coat.  In  small  arteries,  this  coat  consists  of  connective  tissue  and  fine  elastic  fibres. 
In  arteries  rather  larger  than  the  capillaries,  the  elastic  fibres  are  wanting ;  the 
connective  tissue  composing  the  coat  becoming,  the  nearer  it  approaches  the  capil- 
laries, more  homogeneous,  being  gradually  reduced  to  a  thin  membranous  envelope 
which  finally  disappears.  In  articles  of  medium  size,  this  coat  is  composed  of 
two  distinct  layers,  an  inner  composed  of  elastic  tissue ;  an  outer,  composed  of 
connective  tissue,  containing  elastic  networks  irregularly  connected  with  each 
other.  The  inner  elastic  layer  is  very  distinct  in  the  carotid,  femoral,  brachial, 
profunda,  mesenteric,  and  cceliac  arteries,  the  elastic  fibres  being  often  arranged 
in  lamellae.  .  . 

Some  arteries  have  extremely  thin  coats  in  proportion  to  their  size ;  this  is 
especially  the  case  in  those  situated  in  the  cavity  of  the  cranium  and  spinal  canal, 
the  difference  depending  upon  the  greater  thinness  of  the  external  and  middle 
coats. 

The  arteries,  in  their  distribution  throughout  the  body,  are  included  in  a  thin 
areolo-fibrous  investment,  which  forms  what  is  called  their  sheath.  In  the  limbs, 
this  is  usually  formed  by  a  prolongation  of  the  deep  fascia ;  in  the  upper  part  of 
the  thigh,  it  consists  of  a  continuation  downwards  of  the  transversalis  and  iliac 
fasciae  of  the  abdomen ;  in  the  neck,  of  a  prolongation  of  the  deep  cervical  fascia. 
The  included  vessel  is  loosely  connected  with  its  sheath  by  a  delicate  areolar 
tissue,  and  the  sheath  usually  incloses  the  accompanying  veins,  and  sometimes  a 
nerve.     Some  arteries,  as  those  in  the  cranium,  are  not  included  in  sheaths. 

All  the  larger  arteries  are  supplied  with  bloodvessels  like  the  other  organs  of 
the  body ;  they  are  called  vasa  vasorum.  These  nutrient  vessels  arise  from  a 
branch  of  the  artery  or  from  a  neighboring  vessel,  at  some  considerable  distance 
from  the  point  at  which  they  are  distributed ;  they  ramify  in  the  loose  areolar 
tissue  connecting  the  artery  with  its  sheath,  and  are  distributed  to  the  external 
and  middle  coats,  and,  according  to  Arnold  and  others,  supply  the  internal  coat. 
Minute  veins  serve  to  return  the  blood  from  these  vessels ;  they  empty  themselves 
into  the  venae  comites  in  connection  with  the  artery.  Arteries  are  also  provided 
with  nerves ;  they  are  derived  chiefly  from  the  sympathetic,  but  partly  from  the 
cerebro-spinal  system.  They  form  intricate  plexuses  upon  the  surface  of  the  larger 
trunks,  the  smaller  branches  being  usually  accompanied  by  single  filaments ;  their 
exact  mode  of  distribution  is  unknown.  According  to  Kolliker,  the  majority  of 
the  arteries  of  the  brain  and  spinal  cord,  those  of  the  choroid,  of  the  placenta,  as  well 
as  many  arteries  of  muscles,  glands,  and  membranes,  are  unprovided  with  them. 

The  smaller  arterial  branches,  excepting  those  of  the  cavernous  structures  of 
the  sexual  organs,  and  in  the  uterine  placenta,  terminate  in  a  network  of  vessels 
which  pervade  nearly  every  tissue  of  the  body.  These  vessels,  from  their  minute 
size,  are  termed  capillaries  {capillus,  "  a  hair").  They  are  interposed  between  the 
smallest  branches  of  the  arteries  and  the  commencing  veins,  constituting  a  net- 
work, the  branches  of  which  maintain  the  same  diameter  throughout,  the  meshes 
of  the  network  being  more  uniform  in  shape  and  size  than  those  formed  by  the 
anastomoses  of  the  small  arteries  and  veins. 

The  diameter  of  the  capillaries  varies  in  the  different  tissues  of  the  body,  their 
usual  size  being  about  ^Vtrth  part  of  an  inch.  The  smallest  are  those  of  the 
brain,  and  the  mucous  membrane  of  the  intestines ;  the  largest,  those  of  the  skin, 
and  the  marrow  of  bones. 

The  form  of  the  capillary  net  varies  in  the  different  tissues,  being  modifications 
chiefly  of  rounded  or  elongated  meshes.  The  rounded  form  of  mesh  is  most 
common,  and  prevails  where  there  is  a  dense  network,  as  in  the  lungs,  in  most 
glands  and  mucous  membranes,  and  in  the  cutis ;  the  meshes  being  more  or  less 
angular,  sometimes  nearly  quadrangular,  or  polygonal ;  more  frequently,  irregular. 
Elongated  meshes  are  observed  in  the  bundles  of  fibres  and  tubes  composing 
muscles  and  nerves,  the  meshes  being  usually  of  a  parallelogram  form,  the  long 


GENERAL   ANATOMY.  361 

axis  of  the  mesh  running  parallel  with  the  long  axis  of  the  nerve  or  fibre.  Some- 
times the  capillaries  have  a  looped  arrangement,  a  single  vessel  projecting  from 
the  common  network,  and  returning  after  forming  one  or  more  loops,  as  in  the 
papillae  of  the  tongue  and  skin. 

The  number  of  the  capillaries,  and  the  size  of  the  meshes,  determine  the  degree 
of  vascularity  of  a  part.  The  closest  network,  and  the  smallest  interspaces,  are 
found  in  the  lungs  and  in  the  choroid  coat  of  the  eye.  In  the  liver  and  lung,  the 
interspaces  are  smaller  than  the  capillary  vessels  themselves.  In  the  kidney,  in 
the  conjunctiva,  and  in  the  cutis,  the  interspaces  are  from  three  to  four  times  as 
large  as  the  capillaries  which  form  them ;  and  from  eight  to  ten  times  as  large  as 
the  capillaries  of  the  brain  in  their  long  diameter,  and  from  four  to  six  times  as 
large  in  their  transverse  diameter.  In  the  cellular  coat  of  the  arteries,  the  width. 
of  the  meshes  is  ten  times  that  of  the  capillary  vessels.  As  a  general  rule,  the 
more  active  the  function  of  an  organ  is,  the  closer  is  its  capillary  net,  and  the 
larger  its  supply  of  blood ;  the  network  being  very  narrow  in  all  growing  parts, 
in  the  glands,  and  in  the  mucous  membranes ;  wider  in  bones  and  ligaments,  which 
are  comparatively  inactive ;  and  nearly  altogether  absent  in  tendons  and  cartilages, 
in  which  very  little  organic  change  occurs  after  their  formation. 

Structure.  The  walls  of  the  capillaries  consist  of  a  fine,  transparent,  homoge- 
neous membrane,  in  which  are  imbedded,  at  intervals,  minute  oval  corpuscles, 
probably  the  remains  of  the  nuclei  of  the  cells  from  which  the  vessel  was  origi- 
nally formed.  The  largest  capillaries  have  a  trace  of  an  epithelial  lining,  and  a 
few  filaments  circularly  dispersed. 

In  the  description  of  the  arteries,  we  shall  first  consider  the  efferent  trunk  of 
the  systemic  circulation,  the  aorta,  and  its  branches ;  and  then  the  efferent  trunk 
of  the  pulmonic  circulation,  the  pulmonary  artery. 

The  Aorta. 

The  aorta  (aoprr;,  arteria  magna)  is  the  main  trunk  of  a  series  of  vessels,  which, 
arising  from  the  heart,  conveys  the  red  oxygenated  blood  to  every  part  of  the 
body  for  its  nutrition.  This  vessel  commences  at  the  upper  part  of  the  left  ven- 
tricle, and,  after  ascending  for  a  short  distance,  arches  backwards  to  the  left  side, 
over  the  root  of  the  left  lung,  descends  within  the  thorax  on  the  left  side  of  the 
vertebral  column,  passes  through  the  aortic  opening  in  the  Diaphragm,  and  enter- 
ing the  abdominal  cavity  terminates,  considerably  diminished  in  size,  opposite 
the  fourth  lumbar  vertebra,  where  it  divides  into  the  right  and  left  common  iliac 
arteries.  Ilence  its  subdivision  into  the  arch  of  the  aorta,  the  thoracic  aorta  and 
the  abdominal  aorta,  from  the  direction  or  position  peculiar  to  each  part. 

Arch  of  the  Aorta. 

Dif  section.  In  order  to  examine  the  arch  of  the  aorta,  the  thorax  should  be  opened,  by  divid- 
ing the  cartilages  of  the  ribs  on  each  side  of  the  sternum,  and  raising  this  bone  from  below  up- 
wards, and  then  sawing  through  the  sternum  on  a  level  with  its  articulation  with  the  clavicle. 
By  this  means,  the  relations  of  the  large  vessels  to  the  upper  border  of  the  sternum  and  root  of 
the  neck  are  kept  in  view. 

The  arch  of  the  aorta  extends  from  the  origin  of  the  vessel  at  the  upper  part 
of  the  left  ventricle,  to  the  lower  border  of  the  body  of  the  third  dorsal  vertebra. 
At  its  commencement,  it  ascends  behind  the  sternum,  obliquely  upwards  and 
forwards  towards  the  right  side,  and  opposite  the  upper  border  of  the  second 
costal  cartilage  of  the  right  side,  passes  transversely  from  right  to  left,  and  from 
before  backwards  to  the  left  side  of  the  second  dorsal  vertebra ;  it  then  descends 
upon  the  left  side  of  the  body  of  the  third  dorsal  vertebra,  at  the  lower  border  of 
which  it  becomes  the  thoracic  aorta.  Hence  this  portion  of  the  vessel  is  divided 
into  an  ascending,  a  transverse,  and  a  descending  portion.  The  artery  in  its  course 
describes  a  curve,  the  convexity  of  which  is  directed  upwards  and  to  the  right 
side,  the  concavity  in  the  opposite  direction. 


362 


ARTERIES. 


Ascending  Part  of  the  Arch. 

The  ascending  portion  of  the  arch  of  the  aorta  is  about  two  inches  in  length. 
It  commences  at  the  upper  part  of  the  left  ventricle,  in  front  of  the  left  auriculo- 
ventricular  orifice,  and  opposite  the  middle  of  the  sternum  on  a  line  with  its 
junction  to  the  third  costal  cartilage ;  it  passes  obliquely  upwards  in  the  direction 
of  the  heart's  axis,  to  the  right  side,  as  high  as  the  upper  border  of  the  second 
costal  cartilage,  describing  a  slight  curve  in  its  course,  and  being  situated,  when 


SfVagu. 
Reeurrmt  laryngeal 


Fig.  205. — The  Arch  of  the  Aorta  and  its  Branches. 

I 

Left  Vagus 

Left  Phrenic 

—  ThoracicDuct 


Fig.  206.  Flan  rftluBranJm 


Itfl  Crmmrj 


distended,  about  a  quarter  of  an  inch  behind  the  posterior  surface  of  the  sternum. 
A  little  above  its  commencement,  it  is  somewhat  enlarged,  and  presents  three  small 
dilatations,  called  the  sinuses  of  the  aorta  (sinuses  of  Valsalva)  opposite  to  which 
are  attached  the  three  semilunar  valves,  which  serve  the  purpose  of  preventing 
any  regurgitation  of  blood  into  the  cavity  of  the  ventricle.  A  section  of  the  aorta 
opposite  this  part  has  a  somewhat  triangular  figure ;  but  below  the  attachment  of 
the  valves  it  is  circular.  This  portion  of  the  arch  is  contained  in  the  cavity  of 
the  pericardium,  and,  together  with  the  pulmonary  artery,  is  invested  in  a  tube 
of  serous  membrane,  continued  on  to  them  from  the  surface  of  the  heart. 


ARCH   OF   AORTA.  363 

Relations.  The  ascending  part  of  the  arch  is  covered  at  its  commencement  by 
the  trunk  of  the  pulmonary  artery  and  the  right  auricular  appendage,  and,  higher 
up,  is  separated  from  the  sternum  by  the  pericardium,  some  loose  areolar  tissue, 
and  the  remains  of  the  thymus  gland ;  behind,  it  rests  upon  the  right  pulmonary 
vessels  and  root  of  the  right  lung.  On  the  right  side,  it  is  in  relation  with  the 
superior  vena  cava  and  right  auricle ;  on  the  left  side,  with  the  pulmonary  artery. 

Plan  of  the  Relations  of  the  Ascending  Pakt  of  the  Arch. 

In  front. 
Pulmonary  artery. 
,  Eight  auricular  appendage. 

Pericardium. 
Remains  of  thymus  gland. 

Right  side.  f  \  heft  side. 

Superior  vena  cava.  (      ^orta f      *  Pulmonary  artery. 

Eight  auricle. 


Behind. 
Right  pulmonary  vessels. 
Eoot  of  right  lung. 

Transverse  Part  of  the  Arch. 

The  second  or  transverse  portion  of  the  arch  commences  at  the  upper  border  of 
the  second  costo-sternal  articulation  of  the  right  side  in  front,  and  passes  from 
right  to  left,  and  from  before  backwards,  to  the  left  side  of  the  second  dorsal 
vertebra  behind.  Its  upper  border  is  usually  about  an  inch  below  the  upper 
margin  of  the  sternum. 

Relations.  Its  anterior  surface  is  covered  by  the  left  pleura  and  lung,  and 
crossed  towards  the  left  side  by  the  left  pneumogastric  and  phrenic  nerves,  and 
cardiac  branches  of  the  sympathetic.  Its  posterior  surface  lies  on  the  trachea, 
just  above  its  bifurcation,  on  the  great  cardiac  plexus,  the  oesophagus,  thoracic 
duct,  and  left  recurrent  laryngeal  nerve.  Its  upper  border  is  in  relation  with  the 
left  innominate  vein ;  and  from  its  upper  part  are  given  off  the  innominate,  left 
carotid,  and  left  subclavian  arteries.  By  its  lower  border,  with  the  bifurcation  of 
the  pulmonary  artery,  and  the  remains  of  the  ductus  arteriosus,  which  is  connected 
with  the  left  division  of  that  vessel ;  the  left  recurrent  laryngeal  nerve  winds 
round  it  from  before  backwards,  whilst  the  left  bronchus  passes  below  it. 

Plan  of  the  Relations  of  the  Transverse  Part  of  the  Arch. 

Above. 

Left  innominate  vein. 

Arteria  innominata. 

Left  carotid. 

Left  subclavian. 

In  front.  ^ ^  Behind. 

Left  pleura  and  lung.  /  \^  Trachea. 

Left  pneumogastric  nerve-  /     ^rtof     \  Cardiac  plexus. 

Left  phrenic  nerve.  I    Transverse  (Esophagus. 

Cardiac  nerves.  V    Portion.     /  Thoracic  duct. 


Left  recurrent  nerve. 


lii'lnw. 
Bifurcation  of  pulmonary  artery. 
Eemains  of  ductus  arteriosus. 
Left  recurrent  nerve. 
Left  bronchus. 


364  ARTERIES. 

Descending  Part  of  the  Arch. 

The  descending  portion  of  the  arch,  has  a  straight  direction,  inclining  downwards 
on  the  left  side  of  the  body  of  the  third  dorsal  vertebra,  at  the  lower  border  of 
which  it  becomes  the  thoracic  aorta. 

Relations.  Its  anterior  surface  is  covered  by  the  pleura  and  root  of  the  left 
lung ;  behind,  it  lies  on  the  left  side  of  the  body  of  the  third  dorsal  vertebra.  On 
its  right  side  lie  the  oesophagus  and  thoracic  duct ;  on  its  left  side  it  is  covered 
by  the  pleura. 

Plan  of  the  Relations  of  the  Descending  Part  of  the  Arch. 

In  front. 
Pleura. 
Hoot  of  left  lung. 

Right  side.  /r  X  £e/if  s^e- 

(Esophagus.  /     AAr«rhtiiof      \  Pleura. 

Thoracic  duct. 


Behind. 
Left  side  of  body  of  third  dorsal  vertebra. 

The  ascending,  transverse,  and  descending  portions  of  the  arch  vary  in  position 
according  to  the  movements  of  respiration,  being  lowered,  together  with  the 
trachea,  bronchi,  and  pulmonary  vessels,  during  inspiration  by  the  descent  of  the 
Diaphragm,  and  elevated  during  expiration,  when  the  Diaphragm  ascends.  These 
movements  are  greater  in  the  ascending  than  the  transverse,  and  in  the  latter 
than  the  descending  part. 

Peculiarities.  The  height  to  which  the  aorta  rises  in  the  chest  is  usually  about  an  inch  below 
the  upper  border  of  the  sternum ;  but  it  may  ascend  nearly  to  the  top  of  that  bone.  Occasionally 
it  is  found  an  inch  and  a  half,  more  rarely  three  inches,  below  this  point. 

Direction.  Sometimes  the  aorta  arches  over  the  root  of  the  right  instead  of  the  left  lung,  as 
in  birds,  and  passes  down  on  the  right  side  of  the  spine.  In  such  cases,  all  the  viscera  of  the 
thoracic  and  abdominal  cavities  are  transposed.  Less  frequently,  the  aorta,  after  arching  over 
the  root  of  the  right  lung,  is  directed  to  its  usual  position  on  the  left  side  of  the  spine,  this  pecu- 
liarity not  being  accompanied  by  any  transposition  of  the  viscera. 

Conformation.  The  aorta  occasionally  divides  into  an  ascending  and  a  descending  trunk,  as 
in  some  quadrupeds,  the  former,  directed  vertically  upwards,  subdividing  into  three  branches, 
to  supply  the  head  and  upper  extremities.  Sometimes  the  aorta  subdivides  soon  after  its  origin 
into  two  branches,  which  soon  reunite.  In  one  of  these  cases,  the  oesophagus  and  trachea  were 
found  to  pass  through  the  interval  left  by  their  division ;  this  is  the  normal  condition  of  the  vessel 
in  the  reptilia. 

Surgical  Anatomy.  Of  all  the  vessels  of  the  arterial  system,  the  aorta,  and  more  especially 
its  arch,  is  most  frequently  the  seat  of  disease ;  hence  it  is  important  to  consider  some  of  the 
consequences  that  may  ensue  from  aneurism  of  this  part. 

It  will  be  remembered  that  the  ascending  part  of  the  arch  is  contained  in  the  pericardium,  just 
behind  the  sternum,  its  commencement  being  crossed  by  the  pulmonary  artery  and  right  auricular 
appendage,  having  the  root  of  the  right  lung  behind,  the  vena  cava  on  the  right  side,  and  the 
pulmonary  artery  and  left  auricle  on  the  left  side. 

Aneurism  of  the  ascending  aorta,  in  the  situation  of  the  aortic  sinuses,  in  the  great  majority 
of  cases  affects  the  right  coronary  sinus  :  this  is  mainly  owing  to  the  regurgitation  of  blood  upon 
the  sinuses,  taking  place  chiefly  on  the  right  anterior  aspect  of  the  vessel.  As  the  aneurismal 
sac  enlarges,  it  may  compress  any  or  all  of  the  structures  in  immediate  proximity  with  it,  but 
chiefly  projects  towards  the  right  anterior  side ;  and,  consequently,  interferes  mainly  with  those 
structures  that  have  a  corresponding  relation  with  the  vessel.  In  the  majority  of  cases,  it  bursts 
in  the  cavity  of  the  pericardium,  the  patient  suddenly  drops  down  dead,  and,  upon  a  post-mortem 
examination,  the  pericardial  hag  is  found  full  of  blood ;  or  it  may  compress  the  right  auricle,  or 
the  pulmonary  artery,  and  adjoining  part  of  the  right  ventricle,  and  open  into  one  or  the  other 
of  these  parts,  or  it  may  compress  the  superior  cava. 

Aneurism  of  the  ascending  aorta,  originating  above  the  sinuses,  most  frermently  implicates 
the  right  anterior  wall  of  the  vessel ;  this  is  probably  mainly  owing  to  the  blood  being  impelled 


ARCH   OF   AORTA.  365 

against  this  part.  The  direction  of  the  aneurism  is  also  chiefly  towards  the  right  of  the  median 
line.  If  it  attains  a  large  size  and  projects  forwards,  it  may  absorb  the  sternum  and  the  carti- 
lages of  the  ribs,  usually  on  the  right  side,  and  appear  as  a  pulsating  tumor  on  the  front  of  the 
chest,  just  below  the  manubrium  ;  or  it  may  burst  into  the  pericardium,  or  may  compress  or  even 
open  into  the  right  lung,  the  trachea,  bronchi,  or  oesophagus. 

Regarding  the  transverse  part  of  the  arch,  the  student  is  reminded  that  the  vessel  lies  on  the 
trachea,  the  oesophagus,  and  thoracic  duct ;  that  the  recurrent  laryngeal  nerve  winds  around  it ; 
and  that  from  its  upper  part  are  given  off  three  large  trunks,  which  supply  the  head,  neck,  and 
upper  extremities.  Now  an  aneurismal  tumor  taking  origin  from  the  posterior  part  or  right 
aspect  of  the  vessel,  its  most  usual  site,  may  press  upon  the  trachea,  impede  the  breathing,  or 
produce  cough,  haemoptysis,  or  stridulous  breathing,  or  it  may  ultimately  burst  into  that  tube, 
producing  fatal  hemorrhage.  Again,  its  pressure  on  the  laryngeal  nerves  may  give  rise  to  symp- 
toms which  so  accurately  resemble  those  of  laryngitis,  that  the  operation  of  tracheotomy  has  in 
some  cases  been  resorted  to  from  the  supposition  that  disease  existed  in  the  larynx  ;  or  it  may 
press  upon  the  thoracic  duct,  and  destroy  life  by  inanition ;  or  it  may  involve  the  oesophagus, 
producing  dysphagia;  or  may  burst  into  this  tube,  when  fatal  hemorrhage  will  occur.  Again,  the 
innominate  artery,  or  the  left  carotid,  or  subclavian,  may  be  so  obstructed  by  clots,  as  to  produce 
a  weakness,  or  even  a  disappearance,  of  the  pulse  in  one  or  the  other  wrist ;  or  the  tumor  may 
present  itself  at  or  above  the  manubrium,  generally  either  in  the  median  line,  or  to  the  right  of 
the  sternum. 

Aneurism  affecting  the  descending  part  of  the  arch  is  usually  directed  backwards  and  to  the 
left  side,  causing  absorption  of  the  vertebras  and  corresponding  ribs ;  or  it  may  press  upon  the 
trachea,  left  bronchus,  oesophagus,  and  the  right  and  left  lungs,  generally  the  latter.  When  rup- 
ture of  the  sac  occurs,  this  usually  takes  place  into  the  left  pleural  cavity ;  less  frequently  into 
the  left  bronchus,  the  right  pleura,  or  into  the  substance  of  the  lungs  or  trachea.  In  this  form 
of  aneurism,  pain  is  almost  a  constant  and  characteristic  symptom,  existing  either  in  the  back  or 
chest,  and  usually  radiating  from  the  spine  around  the  left  side.  This  symptom  depends  upon 
the  aneurismal  sac  compressing  the  intercostal  nerves  against  the  bone. 

Branches  of  the  Arch  of  the  Aorta  (figs.  205  and  206). 

The  branches  given  off  from  the  arch  of  the  aorta  are  five  in  number.  Two 
of  small  size  from  the  ascending  portion,  the  right  and  left  coronary ;  and  three  of 
large  size  from  the  transverse  portion,  the  innominate  artery,  the  left  carotid,  and 
the  left  subclavian. 

Peculiarities.  Position  of  the  Branches.  The  branches,  instead  of  arising  from  the  highest 
part  of  the  arch  (their  usual  position),  may  be  moved  more  to  the  right,  arising  from  the  com- 
mencement of  the  transverse  or  upper  part  of  the  ascending  portion ;  or  the  distance  from  one 
another  at  their  origin  may  be  increased  or  diminished,  the  most  frequent  change  in  this  respect 
being  the  approximation  of  the  left  carotid  towards  the  innominate  artery. 

The  Number  of  the  primary  branches  may  be  reduced  to  two  :  the  left  carotid  arising  from  the 
innominate  artery,  or  (more  rarely)  the  carotid  and  subclavian  arteries  of  the  left  side  arising 
from  a  left  innominate  artery.  But  the  number  may  be  increased  to  four,  from  the  right  carotid 
and  subclavian  arteries  arising  directly  from  the  aorta,  the  innominate  being  absent.  In  most 
of  these  latter  cases,  the  right  subclavian  arose  from  the  left  end  of  the  arch ;  in  other  cases,  it 
was  the  second  or  third  branch  given  off  instead  of  the  first.  Lastly,  the  number  of  trunks 
from  the  arch  may  be  increased  to  five  or  six  ;  in  these  instances,  the  external  and  internal  caro- 
tids arose  separately  from  the  arch,  the  common  carotid  being  absent  on  one  or  both  sides. 

Usual  Number,  but  Arrangement  different.  When  the  aorta  arches  over  to  the  right  side,  the 
three  branches  have  an  arrangement  the  reverse  of  what  is  usual,  the  innominate  supplying  the 
left  side ;  and  the  carotid  and  subclavian  (which  arise  separately)  the  right  side.  In  other  cases, 
where  the  aorta  takes  its  usual  course,  the  two  carotids  may  be  joined  in  a  common  trunk,  and 
the  subclavians  arise  separately  from  the  arch,  the  right  subclavian  generally  arising  from  the  left 
end  of  the  arch. 

Secondary  Branches  sometimes  arise  from  the  arch ;  most  commonly  it  is  the  left  vertebral, 
which  usually  takes  origin  between  the  left  carotid  and  left  subclavian,  or  beyond  them.  Some- 
times a  thyroid  branch  is  derived  from  the  arch,  or  the  right  internal  mammary,  or  left  vertebral, 
or,  more  rarely,  both  vertebrals. 

The  Coronary  Arteries. 

The  coronary  arteries  supply  the  heart ;  they  are  two  in  number,  right  and  left, 
arising  near  the  commencement  of  the  aorta  immediately  above  the  free  margin 
of  the  semilunar  valves. 

The  Bight  Coronary  Artery,  about  the  size  of  a  crow's  quill,  arises  from  the 
aorta  immediately  above  the  free  margin  of  the  right  semilunar  valve,,  between 


366  ARTERIES. 

the  pulmonary  artery  and  the  appendix  of  the  right  auricle.  It  passes  forwards 
to  the  right  side  in  the  groove  between  the  right  auricle  and  ventricle,  and,  curving 
around  the  right  border  of  the  heart,  runs  along  its  posterior  surface  as  far  as  the 
posterior  interventricular  groove,  where  it  divides  into  two  branches,  one  of  which 
continues  onward  in  the  groove  between  the  left  auricle  and  ventricle,  and  anas- 
tomoses with  the  left  coronary;  the  other  descends  along  the  posterior  inter- 
ventricular furrow,  supplying  branches  to  both  ventricles,  and  to  the  septum, 
anastomosing  at  the  apex  of  the  heart  with  the  descending  branch  of  the  left 
coronary. 

This  vessel  sends  a  large  branch  along  the  thin  margin  of  the  right  ventricle  to 
the  apex,  and  numerous  small  branches  to  the  right  auricle  and  ventricle,  and 
commencement  of  the  pulmonary  artery. 

The  Left  Coronary,  smaller  than  the  former,  arises  immediately  above  the  free 
edge  of  the  left  semilunar  valve,  a  little  higher  than  the  right ;  it  passes  forwards 
between  the  pulmonary  artery  and  the  left  appendix  auriculas,  and  descends 
obliquely  towards  the  anterior  interventricular  groove,  where  it  divides  into  two 
branches.  Of  these,  one  passes  transversely  outwards  in  the  left  auriculo-ventri- 
cular  groove,  and  winds  around  the  left  border  of  the  heart  to  its  posterior  surface, 
where  it  anastomoses  with  the  superior  branch  of  the  right  coronary ;  the  other 
descends  along  the  anterior  interventricular  groove  to  the  apex  of  the  heart, 
where  it  anastomoses  with  the  descending  branch  of  the  right  coronary.  The  left 
coronary  supplies  the  left  auricle  and  its  appendix,  both  ventricles,  and  numerous 
small  branches  to  the  pulmonary  artery,  and  commencement  of  the  aorta. 

Peculiarities.  These  vessels  occasionally  arise  by  a  common  trunk,  or  their  number  may  be 
increased  to  three  ;  the  additional  branch  being  of  small  size.  More  rarely,  there  are  two  addi- 
tional branches. 

Aeteeia  Innominata. 

The  innominate  artery  is  the  largest  branch  given  off  from  the  arch  of  the  aorta. 
It  arises  from  the  commencement  of  the  transverse  portion  in  front  of  the  left 
carotid,  and,  ascending  obliquely  to  the  upper  border  of  the  right  sterno-clavicular 
articulation,  divides  into  the  right  carotid  and  subclavian  arteries.  This  vessel 
varies  from  an  inch  and  a  half  to  two  inches  in  length. 

Relations.  In  front,  it  is  separated  from  the  first  bone  of  the  sternum  by  the 
Sterno-hyoid  and  Sterno-thyroid  muscles,  the  remains  of  the  thymus  gland,  and 
by  the  left  innominate  and  right  inferior  thyroid  veins  which  cross  its  root.  Behind, 
it  lies  upon  the  trachea  which  it  crosses  obliquely.  On  the  right  side  are  the  right 
vena  innominata,  right  pneumogastric  nerve,  and  the  pleura ;  and  on  the  left  side, 
the  remains  of  the  thymus  gland,  and  origin  of  the  left  carotid  artery. 

Plan  of  the  Relations  of  the  Innominate  Aeteey. 

In  front. 
Sternum. 

Sterno-hyoid  and  Sterno-thyroid  muscles. 
Remains  of  thymus  gland. 
Left  innominate  and  right  inferior  thyroid  veins. 

Right  side.  Left  side. 

Right  vena  innominata.  /           ^\                        Remains  of  thymus. 

Right  pneumogastric  nerve.  f                 \                    Left  carotid. 
Pleura. 


Behind. 
Trachea. 


Pecidiarities  in  point  of  division.    "When  the  bifurcation  of  the  innominate  artery  varies 
from  the  point  above  mentioned,  it  sometimes  ascends  a  considerable  distance  above  the  sternal 


INNOMINATE;    COMMON   CAROTID.  367 

end  of  the  clavicle;  less  frequently  it  divides  below  it.  In  the  former  class  of  cases,  its  length 
may  exceed  two  inches;  and,  in  the  latter,  be  reduced  to  an  inch  or  less.  These  are  points  of 
considerable  interest  for  the  surgeon  to  remember  in  connection  with  the  operation  of  including 
this  vessel  in  a  ligature. 

Branches.  The  arteria  innominata  occasionally  supplies  a  thyroid  branch,  the  middle  thyroid 
artery,  which  ascends  along  the  front  of  the  trachea  to  the  thyroid  gland ;  and  sometimes,  a 
thymic  or  bronchial  branch.  The  left  carotid  is  frequently  joined  with  the  innominate  artery  at 
its  origin.  Sometimes,  there  is  no  innominate  artery,  the  right  subclavian  arising  directly  from 
the  arch  of  the  aorta. 

Position.  When  the  aorta  arches  over  to  the  right  side,  the  innominate  is  directed  to  the  left 
side  of  the  neck,  instead  of  the  right. 

Surgical  Anatomy.  Although  the  operation  of  tying  the  innominate  artery  has  been  per- 
formed by  several  surgeons,  for  aneurism  of  the  right  subclavian  extending  inwards  as  far  as  the 
Scalenus,  in  no  instance  has  it  been  attended  with  success.  An  important  fact  has,  however, 
been  established,  viz.,  that  the  circulation  in  the  parts  supplied  by  the  artery  can  be  supported 
after  the  operation  ;  a  fact  which  cannot  but  encourage  surgeons  to  have  recourse  to  it  whenever 
the  urgency  of  the  case  may  require  it,  notwithstanding  that  it  must  be  regarded  as  peculiarly 
hazardous. 

The  failure  of  the  operation  in  those  cases  where  it  has  been  performed  has  depended  on  sub- 
sequent repeated  secondary  hemorrhage,  or  on  inflammation  of  the  adjoining  pleural  sac  and 
lung.  The  main  obstacles  to  its  performance  are,^is  the  student  will  perceive  from  his  dissection 
of  this  vessel,  its  deep  situation  behind  and  beneath  the  sternum,  and  the  number  of  important 
structures  which  surround  it  in  every  part. 

In  order  to  apply  a  ligature  to  this  vessel,  the  patient  is  placed  upon  his  back,  with  the 
shoulders  raised,  and  the  head  bent  a  little  backwards,  so  as  to  draw  out  the  artery  from  behind 
the  sternum  into  the  neck.  An  incision  two  inches  long  is  then  made  along  the  anterior  border 
of  the  Sterno-mastoid  muscle,  terminating  at  the  sternal  end  of  the  clavicle.  From  this  point,  a 
second  incision  is  to  be  carried  about  the  same  length  along  the  upper  border  of  the  clavicle. 
The  skin  is  to  be  dissected  back,  and  the  Platysma  being  exposed  must  be  divided  on  a  director: 
the  sternal  end  of  the  Sterno-mastoid  is  now  brought  into  view,  and  a  director  being  passed 
beneath  it,  and  close  to  its  under  surface,  so  as  to  avoid  any  small  vessels,  it  must  be  divided 
transversely  throughout  the  greater  part  of  its  attachment.  Pressing  aside  any  loose  cellular 
tissue  or  vessels  that  may  now  appear,  the  Sterno-hyoid  and  Sterno-thyroid  muscles  will  be 
exposed,  and  must  be  divided,  a  director  being  previously  passed  beneath  them.  The  inferior 
thyroid  veins  now  come  into  view,  and  must  be  carefully  drawn  either  upwards  or  downwards,  by 
means  of  a  blunt  hook.  On  no  account  should  these  vessels  be  divided,  as  it  would  add  much  to 
the  difficulty  of  the  operation,  and  endanger  its  ultimate  success.  After  tearing  through  a  strong 
fibro-cellular  lamina,  the  right  carotid  is  brought  into  view,  and  being  traced  downwards,  the 
arteria  innominata  is  arrived  at.  The  left  vena  innominata  should  now  be  depressed,  the  right 
vena  innominata,  the  internal  jugular  vein,  and  pneumogastric  nerve  drawn  to  the  right  side,  and 
a  curved  aneurism  needle  may  then  be  passed  around  the  vessel,  close  to  its  surface,  and  in  a 
direction  from  below  upwards  and  inwards ;  care  being  taken  to  avoid  the  right  pleural  sac,  the 
trachea,  and  cardiac  nerves.  The  ligature  should  be  applied  to  the  artery  as  high  as  possible, 
in  order  to  allow  room  between  it  and  the  aorta  for  the  formation  of  a  coagulum. 

It  has  been  seen  that  the  failure  of  this  operation  depends  either  upon  repeated  secondary 
hemorrhage,  or  inflammation  of  the  pleural  sac  and  lung.  The  importance  of  avoiding  the 
thyroid  plexus  of  veins  during  the  primary  steps  of  the  operation,  and  the  pleural  sac  whilst 
including  the  vessel  in  the  ligature,  should  be  most  carefully  attended  to. 


Common  Carotid  Arteries. 

The  common  carotid  arteries,  although  occupying  a  nearly  similar  position  in 
the  neck,  differ  in  position,  and,  consequently,  in  their  relations  at  their  origin. 
The  right  carotid  arises  from  the  arteria  innominata,  behind  the  right  sterno- 
clavicular articulation ;  the  left  from  the  highest  part  of  the  arch  of  the  aorta. 
The  left  carotid  is,  consequently,  longer  and  placed  more  deeply  in  the  thorax.  It 
will,  therefore,  be  more  convenient  to  describe  first  the  course  and  relations  of 
that  portion  of  the  left  carotid  which  intervenes  between  the  arch  of  the  aorta  and 
the  left  sterno-clavicular  articulation  (see  fig.  205). 

The  left  carotid  within  the  thorax  passes  obliquely  outwards  from  the  arch  of 
the  aorta  to  the  root  of  the  neck.  In  front,  it  is  separated  from  the  first  piece  of 
the  sternum  by  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  left  innominate 
vein,  and  the  remains  of  the  thymus  gland ;  behind,  it  lies  on  the  trachea,  ceso- 


368  ARTERIES. 


phagus,  and  thoracic  duct.     Internally,  it  is  in  relation  with  the  arteria  innominata ; 
externally,  with  the  left  pneumogastric  nerve,  and  left  subclavian  artery. 


Plan  of  the  Relations  of  the  Left  Common  Carotid  ; 
Thoracic  Portion. 

In  front. 
Sternum. 

Sternohyoid  and  Sternothyroid  muscles. 
Left  innominate  vein. 
Remains  of  thymus  gland. 

Internally.  .. .  Externally. 

Arteria  innominata.  f     f  M      \^  Left  pneumogastric  nerve. 

Left  subclavian  artery. 


Behind. 
Trachea. 
(Esophagus. 
Thoracic  duct. 

In  the  neck,  the  two  common  carotids  resemble  each  other  so  closely,  that  one 
description  will  apply  to  both.  Starting  from  each  side  of  the  neck,  each  vessel 
passes  obliquely  upwards,  from  behind  the  sterno-clavicular  articulation,  to  a  level 
with  the  upper  border  of  the  thyroid  cartilage,  where  it  divides  into  the  external 
and  internal  carotid ;  these  names  being  derived,  the  former  from  its  distribution 
to  the  external  parts  of  the  head  and  face,  the  latter  from  its  distribution  to  the 
internal  parts  of  the  cranium.  The  course  of  the  vessel  is  indicated  by  a  line 
drawn  from  the  sternal  end  of  the  clavicle  below,  to  a  point  midway  between  the 
angle  of  the  jaw  and  the  mastoid  process  above. 

At  the  lower  part  of  the  neck  the  two  common  carotid  arteries  are  separated 
from  each  other  by  a  very  small  interval,  which  corresponds  to  the  trachea ;  but 
at  the  upper  part,  the  thyroid  body,  the  larynx  and  pharynx  project  forwards 
between  these  vessels,  and  give  the  appearance  of  their  being  placed  further  back 
in  this  situation.  The  common  carotid  artery  is  contained  in  a  sheath,  derived 
from  the  deep  cervical  fascia,  which  also  incloses  the  internal  jugular  vein  and 
pneumogastric  nerve,  the  vein  lying  on  the  outer  side  of  the  artery,  and  the  nerve 
between  the  artery  and  vein,  on  a  plane  posterior  to  both.  On  opening  the 
sheath,  these  three  structures  are  seen  to  be  separated  from  one  another,  each 
being  inclosed  in  a  separate  fibrous  investment. 

Relations.  At  the  lower  part  of  the  neck  the  common  carotid  artery  is  very 
deeply  seated,  being  covered  by  the  superficial  fascia,  Platysma,  and  deep  fascia,  the 
Sterno-mastoid,  Sterno-hyoid,  and  Sterno-thyroid  muscles,  and  by  the  Omo-hyoid 
opposite  the  cricoid  cartilage ;  but  in  the  upper  part  of  its  course,  near  its  ter- 
mination, it  is  more  superficial,  being  covered  merely  by  the  integument,  the 
superficial  fascia,  Platysma,  and  deep  fascia,  and  inner  margin  of  the  Sterno- 
mastoid,  and  is  contained  in  a  triangular  space,  bounded  behind  by  the  Sterno- 
mastoid,  above  by  the  posterior  belly  of  the  Digastric,  and  below  by  the  anterior 
belly  of  the  Omo-hyoid.  This  part  of  the  artery  is  crossed  obliquely  from  within 
outwards  by  the  sterno-mastoid  artery ;  it  is  also  crossed  by  the  facial,  lingual, 
and  superior  thyroid  veins,  which  terminate  in  the  internal  jugular,  and,  descending 
on  its  sheath  in  front,  is  seen  the  descendens  noni  nerve,  this  filament  being  joined 
with  branches  from  the  cervical  nerves,  which  cross  the  vessel  from  without 
inwards.  Sometimes  the  descendens  noni  is  contained  within  the  sheath.  The 
middle  thyroid  vein  crosses  it  about  its  centre,  and  the  anterior  jugular  vein  below. 
Behind,  the  artery  lies  in  front  of  the  cervical  portion  of  the  spine,  resting  first 


COMMON   CAROTID. 


369 


on  the  Longus  colli  muscle,  then  on  the  Rectus  anticus  major,  from  which  it  is 
separated  by  the  sympathetic  nerve.  The  recurrent  laryngeal  nerve  and  inferior 
thyroid  artery  cross  behind  the  vessel  at  its  lower  part.  Internally,  it  is  in 
relation  with  the  trachea  and  thyroid  gland,  the  inferior  thyroid  artery  and 
recurrent  laryngeal  nerve  being  interposed;   higher  up,  with   the   larynx  and 


Fig.  207. — Surgical  Anatomy  of  the  Arteries  of  the  Neck.     Right  Side. 


Fie.  208. 
Pin  n   of  tit 
JZrunclu*  ~.^ 

cfllx  \ 

JXTfRNAL  CAROTID 


pharynx.     On  its  otiter  side  are  placed  the  internal  jugular  vein  and  pneumogas- 
trie  nerve. 

At  the  lower  part  of  the  neck,  the  internal  jugular  vein  on  the  right  side 
recedes  from  the  artery,  but  on  the  left  side  it  approaches  it,  and  often  crosses  its 
lower  part.     This  is  an  important  fact  to  bear  in  mind  during  the  performance  of 
any  operation  on  the  lower  part  of  the  left  common  carotid  artery. 
24 


370  ARTERIES. 


Plan  of  the  Relations  of  the  Common  Carotid  Artery. 

In  front. 
Integument  and  fascia.  Omo-hyoid. 

Platysma.  Descendens  noni  nerve. 

Sterno-mastoid.  Sterno-mastoid  artery. 

Sterno-hyoid.  Thyroid,  lingual,  and  facial  veins. 

Sterno-thyroid.  Anterior  jugular  vein. 

Externally.  ^ — -^  Internally. 

Internal  jugular  vein.  /  \  Trachea. 

Pneumogastric  nerve.  (     Common     \  Thyroid  gland. 

Recurrent  laryngeal  nerve. 

Inferior  thyroid  artery. 

Larynx. 

Pharynx. 

Behind. 
Longus  colli.  Sympathetic  nerve. 

Rectus  anticus  major.  Inferior  thyroid  artery. 

Recurrent  laryngeal  nerve. 

Peculiarities  as  to  Origin.  The  right  common  carotid  may  arise  above  or  below  its  usual 
point  (the  upper  border  of  the  sterno-clavicular  articulation).  This  variation  occurs  in  one  out 
of  about  eight  cases  and  a  half,  and  is  more  frequently  above  than  below  the  point  stated ;  or  its 
origin  may  be  transferred  to  the  arch  of  the  aorta,  or  it  may  arise  in  conjunction  with  the  left 
carotid.  The  left  common  carotid  varies  more  frequently  in  its  origin  than  the  right.  In  the 
majority  of  cases  it  arises  with  the  innominate  artery,  or,  where  the  innominate  artery  was  ab- 
sent, the  two  carotids  arose  usually  by  a  eingle  trunk.  This  vessel  has  a  tendency  towards  the 
right  side  of  the  arch,  occasionally  being  the  first  branch  given  off  from  the  transverse  portion. 
It  rarely  joins  with  the  left  subclavian,  except  in  cases  of  transposition  of  the  arch. 

Point  of  Division.  The  most  important  peculiarities  of  this  vessel,  in  a  surgical  point  of 
view,  relate  to  its  place  of  division  in  the  neck.  In  the  majority  of  cases,  this  occurs  higher  than 
usual,  the  artery  dividing  into  two  branches  opposite  the  hyoidbone,  or  even  higher ;  more  rarely, 
it  occurs  below  its  usual  place,  opposite  the  middle  of  the  larynx,  or  the  lower  border  of  the  cri- 
coid cartilage ;  and  one  case  is  related  by  Morgagni,  where  this  vessel,  only  an  inch  and  a  half 
in  length,  divided  at  the  root  of  the  neck.  Very  rarely,  the  common  carotid  ascends  in  the  neck 
without  any  subdivision,  the  internal  carotid  being  wanting ;  and  in  two  cases  the  common 
carotid  has  been  found  to  be  absent,  the  external  and  internal  carotids  arising  directly  from  the 
arch  of  the  aorta.     This  peculiarity  existed  on  both  sides  in  one  subject,  on  one  side  in  another. 

Occasional  Branches.  The  common  carotid  usually  gives  off  no  branches,  but  it  occasionally 
gives  origin  to  the  superior  thyroid,  or  a  laryngeal  branch,  the  inferior  thyroid,  or,  more  rarely, 
the  vertebral  artery. 

Surgical  Anatomy.  The  operation  of  tying  the  common  carotid  artery  may  be  necessary  in 
a  wound  of  that  vessel  or  its  branches,  in  an  aneurism,  or  in  a  case  of  pulsating  tumor  of  the  orbit 
or  skull.  If  the  wound  involves  the  trunk  of  the  common  carotid,  it  will  be  necessary  to  tie  the 
artery  above  and  below  the  wounded  part.  If.  however,  one  of  the  branches  of  that  vessel  is 
wounded,  or  has  an  aneurismal  tumor  connected  with  it,  a  ligature  maybe  applied  to  any  part  of 
it,  excepting  its  origin  and  termination.  When  the  case  is  such  as  to  allow  of  a  choice  being 
made,  the  lower  part  of  the  carotid  should  never  be  selected  as  the  spot  upon  which  a  ligature 
should  be  placed,  for  not  only  is  the  artery  in  this  situation  placed  very  deeply  in  the  neck,  but 
it  is  covered  by  three  layers  of  muscles,  and  on  the  left  side  of  the  jugular  vein,  in  the  great  ma- 
jority of  cases,  passes  obliquely  in  front  of  it.  Neither  should  the  upper  end  be  selected,  for  here 
the  superior  thyroid,  lingual,  and  facial  veins  would  give  rise  to  very  considerable  difficulty  in  the 
application  of  a  ligature.  The  point  most  favorable  for  the  operation  is  opposite  the  lower  part 
of  the  larynx,  and  here  a  ligature  may  be  applied  on  the  vessel,  either  above  or  below  the  point 
where  it  is  crossed  by  the  Omo-hyoid  muscle.  In  the  former  situation  the  artery  is  most  acces- 
sible, and  it  may  be  tied  there  in  cases  of  wounds,  or  aneurism  of  any  of  the  large  branches  of  the 
carotid;  whilst  in  cases  of  aneurism  of  the  upper  part  of  the  carotid,  that  part  of  the  vessel  may 
be  selected  which  is  below  the  Omo-hyoid.  It  occasionally  happens  that  the  carotid  artery  bifur- 
cates below  its  usual  position  :  if  the  artery  be  exposed  at  its  point  of  bifurcation,  both  divisions 
of  the  vessel  should  be  tied  near  their  origin,  in  preference  to  tying  the  trunk  of  the  artery  near 
its  termination;  and  if,  in  consequence  of  the  entire  absence  of  the  common  carotid,  or  from  its 
early  division,  two  arteries,  the  external  and  internal  carotids,  are  met  with,  the  ligature  should 
be  placed  on  that  vessel  which  is  found  on  compression  to  be  connected  with  the  disease. 


EXTERNAL   CAROTID  371 

In  this  operation,  the  direction  of  the  vessel  and  the  inner  margin  of  the  Sterno-mastoid  are  the 
chief  guides  to  its  performance. 

To  tie  the  Common  Carotid,  above  the  Omo-hyoid.  The  patient  should  be  placed  on  his  back 
with  the  head  thrown  back ;  an  incision  is  to  be  made,  three  inches  long,  in  the  direction  of  the 
anterior  border  of  the  Sterno-mastoid,  from  a  little  below  the  angle  of  the  jaw  to  a  level  with 
the  cricoid  cartilage :  after  dividing  the  integument,  superficial  fascia,  and  Platysma,  the  deep 
fascia  must  be  cut  through  on  a  director,  so  as  to  avoid  wounding  numerous  small  veins  that  are 
usually  found  beneath.  The  head  may  now  be  brought  forwards  so  as  to  relax  the  parts  some- 
what, and  the  margins  of  the  wound  must  be  held  asunder  by  copper  spatulae.  The  descendens 
noni  nerve  is  now  exposed,  and  must  be  avoided,  and  the  sheath  of  the  vessel  having  been  raised 
by  forceps  is  to  be  opened  over  the  artery  to  a  small  extent.  The  internal  jugular  vein  will  now 
present  itself  alternately  distended  and  relaxed;  this  should  be  compressed  both  above  and  below, 
and  drawn  outwards,  in  order  to  facilitate  the  operation.  The  aneurism  needle  is  now  passed 
from  the  outside,  care  being  taken  to  keep  the  needle  in  those  contact  with  tile  artery,  and  thus 
avoid  the  risk  of  injuring  the  jugular  vein,  or  including  the  vagus  nerve.  Be/ore  the  ligature  is 
secured,  it  should  be  ascertained  that  nothing  but  the  artery  is  included  in  it. 

To  tie  the  Common  Carotid,  below  the  Omo-hyoid.  The  patient  should  be  placed  in  the  same 
situation  as  above  mentioned.  An  incision  about  three  inches  in  length  is  to  be  made,  parallel 
with  the  inner  edge  of  the  Sterno-mastoid,  commencing  on  a  level  with  the  cricoid  cartilage. 
The  inner  border  of  the  Sterno-mastoid  having  been  exposed,  the  sterno-mastoid  artery  and  a 
large  vein,  the  middle  thyroid,  will  be  seen,  and  must  be  carefully  avoided ;  the  Sterno-mastoid  is 
to  be  drawn  outwards,  and  the  Sterno-hyoid  and  Sterno-thyroid  muscles  inwards.  The  deep  fascia 
must  now  be  divided  below  the  Omo-hyoid  muscle,  and  the  sheath,  having  been  exposed,  must  be 
opened,  care  being  taken  to  avoid  the  descendens  noni,  which  here  runs  on  the  inner  or  tracheal 
side.  The  jugular  vein  and  vagus  nerve  being  then  pressed  to  the  outer  side,  the  needle  must 
be  passed  round  the  artery  from  without  inwards,  great  care  being  taken  to  avoid  the  inferior 
thyroid  artery,  and  the  recurrent  laryngeal  and  sympathetic  nerves  which  lie  behind  it. 

Collateral  Circulation.  After  ligation  of  the  common  carotid,  the  collateral  circulation  can 
be  perfectly  established,  by  the  free  communication  which  exists  between  the  carotid  arteries  of 
opposite  sides  both  without  and  within  the  cranium,  and  by  enlargement  of  the  branches  of  the 
subclavian  artery  on  the  side  corresponding  to  that  on  which  the  vessel  has  been  tied,  the  chief 
communication  outside  the  skull  taking  place  between  the  superior  and  inferior  thyroid  arteries, 
and  the  profunda  cervicis,  and  arteria  princeps  cervicis  of  the  occipital ;  the  vertebral  taking  the 
place  of  the  internal  carotid  within  the  cranium. 

External  Carotid  Artery. 

The  external  carotid  artery  (fig.  207)  arises  opposite  the  upper  border  of  the 
thyroid  cartilage,  and,  taking  a  slightly  curved  course,  ascends  upwards  and  for- 
wards, and  then  inclines  backwards,  to  the  space  between  the  neck  of  the  condyle 
of  the  lower  jaw  and  the  external  meatus,  where  it  divides  into  the  temporal 
and  internal  maxillary  arteries.  It  rapidly  diminishes  in  size  as  it  ascends  the 
neck,  owing  to  the  number  and  large  size  of  the  branches  given  off  from  it.  In 
the  child,  it  is  somewhat  smaller  than  the  internal  carotid ;  but  in  the  adult,  the 
two  vessels  are  of  nearly  equal  size.  At  its  commencement,  this  artery  is  more 
superficial,  and  placed  nearer  the  middle  line  than  the  internal  carotid,  and  is  con- 
tained in  the  triangular  space  bounded  by  the  Sterno-mastoid  behind,  the  Omo- 
hyoid below,  and  the  posterior  belly  of  the  Digastric  and  Stylo-hyoid  above ;  it 
is  covered  by  the  skin,  Platysma,  deep  fascia,  and  anterior  margin  of  the  Sterno- 
mastoid,  crossed  by  the  hypoglossal  nerve,  and  by  the  lingual  and  facial  veins ; 
it  is  afterwards  crossed  by  the  Digastric  and  Stylo-hyoid  muscles,  and  higher 
up  passes  deeply  into  the  substance  of  the  parotid  gland,  where  it  lies  be- 
neath the  facial  nerve,  and  the  junction  of  the  temporal  and  internal  maxillary 
veins. 

Internally  are  the  hyoid  bone,  the  wall  of  the  pharynx,  and  the  ramus  of  the 
jaw,  from  which  it  is  separated  by  a  portion  of  the  parotid  gland. 

Behind  it,  near  its  origin,  is  the  superior  laryngeal  nerve ;  and,  higher  up,  it  is 
separated  from  the  internal  carotid  by  the  Stylo-glossus  and  Stylo-pharyngeus 
muscles,  the  glosso-pharyngeal  nerve,  and  part  of  the  parotid  gland. 


372  ARTERIES. 


Plan  of  the  Relations  of  the  External  Carotid. 

Infront.  Behind. 

Integument,  superficial  fascia.  ^—~ ^                       Superior  laryngeal  nerve. 

Platysma  and  deep  fascia.  f          ^\                      Stylo-glossus. 

Hypoglossal  nerve.  /                  \                    Stylo-pharyngeus. 

Lingual  and  facial  veins.  I     camid!      I                   Glosso-pharyngeal  nerve. 

Digastric  and  Stylo-hyoid  muscles.  V                    J                    Parotid  gland. 

Facial  nerve  and  parotid  gland.  V                / 

Temporal  and  maxillary  veins.  ^- ^ 

Internally. 
Hyoid  bone. 
Pharynx. 
Parotid  gland. 
Eamus  of  jaw. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  external  carotid  may  be  required  in 
cases  of  wounds  of  this  vessel,  or  of  its  branches  when  these  cannot  be  tied ;  this,  however,  is 
an  operation  very  rarely  performed,  ligation  of  the  common  carotid  being  preferable,  on  account 
of  the  number  of  branches  given  off  from  the  external.  To  tie  this  vessel  near  its  origin,  below 
the  point  where  it  is  crossed  by  the  Digastric,  an  incision  about  three  inches  in  length  should  be 
made  along  the  margin  of  the  Sterno-mastoid,  from  the  angle  of  the  jaw  to  the  cricoid  cartilage, 
as  in  the  operation  for  tying  the  common  carotid.  To  tie  the  vessel  above  the  Digastric,  be- 
tween it  and  the  parotid  gland,  an  incision  should  be  made  from  the  lobe  of  the  ear  to  the  great 
cornu  of  the  os  hyoides,  dividing  successively  the  skin,  Platysma.  and  fascia.  By  separating 
the  posterior  belly  of  the  Digastric  and  Stylo-hyoid  muscles,  which  are  seen  at  the  lower  part 
of  the  wound,  from  the  parotid  gland,  the  vessel  will  be  exposed,  and  a  ligature  may  be  applied 
to  it. 

Branches.  The  external  carotid  artery  gives  off  eight  branches,  which,  for 
convenience  of  description,  may  be  divided  into  four  sets.  (See  Plan  of  the 
Branches,  fig.  208.) 

Anterior.  Posterior.  Ascending.      .  Terminal. 

Superior  thyroid.  Occipital.  Ascending  pha-  Temporal. 

Lingual.  Posterior  auricular.       ryngeal.  Internal  maxillary. 
Facial. 

The  student  is  here  reminded  that  many  variations  are  met  with  in  the  number, 
origin,  and  course  of  these  branches  in  different  subjects ;  but  the  above  arrange- 
ment is  that  which  is  found  in  the  great  majority  of  cases. 

The  Superior  Thyroid  Artery  (figs.  207  and  212)  is  the  first  branch  given 
off  from  the  external  carotid,  being  derived  from  that  vessel  just  below  the  greater 
cornu  of  the  hyoid  bone.  At  its  commencement,  it  is  quite  superficial,  being 
covered  by  the  integument,  fascia,  and  Platysma,  and  is  contained  in  the  trian- 
gular space  bounded  by  the  Sterno-mastoid,  Digastric,  and  Omo-hyoid  muscles. 
After  ascending  upwards  and  inwards  for  a  short  distance,  it  curves  downwards 
and  forwards  in  an  arched  and  tortuous  manner  to  the  upper  part  of  the  thyroid 
gland,  passing  beneath  the  Omo-hyoid,  Sterno-hyoid,  and  Sterno-thyroid  muscles ; 
and  distributes  numerous  branches  to  its  anterior  surface,  anastomosing  with  its 
fellow  of  the  opposite  side,  and  with  the  inferior  thyroid  arteries.  Besides  the 
arteries  distributed  to  the  muscles  and  substance  of  the  gland,  its  branches  are 
the  following : — 

Hyoid.  Superior  laryngeal. 

Superficial  descending  branch.  Crico-thyroid. 

The  hyoid  is  a  small  branch  which  runs  along  the  lower  border  of  the  os 
hyoides,  beneath  the  Thyro-hyoid  muscle ;  after  supplying  the  muscles  connected 
to  that  bone,  it  forms  an  arch,  by  anastomosing  with  the  vessels  of  the  opposite 
side. 

The  superficial  descending  branch  runs  downwards  and  outwards  across  the 
sheath  of  the  common  carotid  artery,  and  supplies  the  Sterno-mastoid  and  neigh- 
boring muscles  and  integument.  It  is  of  importance  that  the  situation  of  this 
vessel  be  remembered,  in  the  operation  for  tying  the  common  carotid  artery. 


SUPERIOR   THYROID;   LINGUAL.  373 

The  superior  laryngeal,  larger  than  either  of  the  preceding,  accompanies  the 
superior  laryngeal  nerve,  beneath  the  Thyro-hyoid  muscle ;  it  pierces  the  thyro- 
hyoid membrane,  and  supplies  the  muscles,  mucous  membrane,  and  glands  of  the 
larynx  and  epiglottis,  anastomosing  with  the  branch  from  the  opposite  side. 

The  crico-thyroid  (inferior  laryngeal)  is  a  small  branch  which  runs  transversely 
across  the  crico-thyroid  membrane,  communicating  with  the  artery  of  the  oppo- 
site side.  The  position  of  this  vessel  should  be  remembered,  as  it  may  prove  the 
source  of  troublesome  hemorrhage  during  the  operation  of  laryngotomy. 

Surgical  Anatomy.  The  superior  thyroid,  or  some  of  its  branches,  is  occasionally  divided 
in  cases  of  cut-throat,  giving  rise  to  considerable  hemorrhage.  In  such  cases,  the  artery  should 
be  secured,  the  wound  being  enlarged  for  that  purpose,  if  necessary.  The  operation  may  be 
easily  performed,  the  position  of  the  artery  being  very  superficial,  and  the  only  structures  of 
importance  covering  it  being  a  few  small  veins.  The  operation  of  tying  the  superior  thyroid 
artery,  in  bronchocele,  has  been  performed  in  numerous  instances  with  partial  or  temporary  suc- 
cess. When,  however,  the  collateral  circulation  between  this  vessel  and  the  artery  of  the  oppo- 
site side,  and  the  inferior  thyroid,  is  completely  re-established,  the  tumor  usually  regains  its 
former  size. 

The  Lingual  Artery  (fig.  212)  arises  from  the  external  carotid  between  the 
superior  thyroid  and  facial ;  it  runs  obliquely  upwards  and  inwards  to  the  great 
cornu  of  the  hyoid  bone,  then  passes  horizontally  forwards  parallel  with  the  great 
cornu,  and,  ascending  perpendicularly  to  the  under  surface  of  the  tongue,  turns 
forwards  on  its  under  surface  as  far  as  the  tip  of  that  organ,  under  the  name  of 
the  ranine  artery. 

Relations.  Its  first,  or  oblique  portion,  is  superficial,  being  contained  in  the 
triangular  intermuscular  space  already  described,  resting  upon  the  Middle  con- 
strictor of  the  pharynx,  and  covered  by  the  Platysma  and  fascia  of  the  neck.  Its 
second  or  horizontal  portion  also  lies  upon  the  Middle  constrictor,  being  covered 
at  first  by  the  tendon  of  the  Digastric,  and  the  Stylo-hyoid  muscle,  and  afterwards 
by  the  Hyo-glossus,  the  latter  muscle  separating  it  from  the  hypoglossal  nerve. 
Its  third  or  ascending  portion  lies  between  the  Hyo-glossus  and  Genio-hyo-glossus 
muscles.  The  fourth  or  terminal  part,  under  the  name  of  the  ranine,  runs  along 
the  under  surface  of  the  tongue  to  its  tip ;  it  is  very  superficial,  being  covered 
only  by  the  mucous  membrane,  and  rests  on  the  Lingualis  on  the  outer  side  of 
the  Genio-hyo-glossus.  The  hypoglossal  nerve  lies  nearly  parallel  with  the  lingual 
artery,  separated  from  it,  in  the  second  part  of  its  course,  by  the  Hyo-glossus 
muscle. 

The  branches  of  the  lingual  artery  are  the 

Hyoid.  Sublingual. 

Dorsalis  linguae.  Ranine. 

The  hyoid  branch  runs  along  the  upper  border  of  the  hyoid  bone,  supplying 
the  muscles  attached  to  it,  and  anastomosing  with  its  fellow  of  the  opposite 
side. 

The  dorsalis  linguse  (fig.  212)  arises  from  the  lingual  artery  beneath  the  Hyo- 
glossus  muscle ;  ascending  to  the  dorsum  of  the  tongue,  it  supplies  its  mucous 
membrane,  the  tonsil,  soft  palate,  and  epiglottis,  and  anastomoses  with  its  fellow 
from  the  opposite  side. 

The  sublingual,  a  branch  of  bifurcation  of  the  lingual  artery,  arises  at  the  ante- 
rior margin  of  the  Hyo-glossus  muscle,  and,  running  forwards  and  outwards 
beneath  the  Mylo-hyoid  to  the  sublingual  gland,  supplies  its  substance,  giving 
branches  to  the  Mylo-hyoid  and  neighboring  muscles,  the  mucous  membrane  of 
the  mouth  and  gums. 

The  ranine  may  be  regarded  as  the  continuation  of  the  lingual  artery ;  it  runs 
along  the  under  surface  of  the  tongue,  resting  on  the  Lingualis,  and  covered  by 
the  mucous  membrane  of  the  mouth ;  it  lies  on  the  outer  side  of  the  Genio-hyo- 
glossus,  and  is  covered  by  the  Hyo-glossus  and  Stylo-glossus,  accompanied  by 
the  gustatory  nerve.     On  arriving  at  the  tip  of  the  tongue,  it  anastomoses  with 


374 

the  artery  of  the  opposite  side, 
each  side  of  the  fraenum. 


ARTERIES. 


These  vessels  in  the  mouth  are  placed  one  on 


Surgical  Anatomy.  The  Lingual  artery  may  be  divided  near  its  origin  in  cases  of  cut-throat, 
a  complication  that  not  unfrequently  happens  in  this  class  of  wounds,  or  severe  hemorrhage, 
which  cannot  be  restrained  by  ordinary  means,  may  ensue  from  a  wound,  or  deep  ulcer  of  the 
tongue.  In  the  former  case,  the  primary  wound  may  be  enlarged,  if  necessary,  and  the  bleeding 
vessel  at  once  secured.  In  the  latter  case,  it  has  been  suggested  that  the  lingual  artery  should 
be  tied  near  its  origin.  If  the  student,  however,  will  observe  the  depth  at  which  this  vessel  is 
placed  from  the  surface,  the  number  of  important  parts  which  surround  it  on  every  side,  and 
its  occasional  irregularity  of  origin,  the  great  difficulty  of  such  an  operation  will  be  apparent; 
under  such  circumstances,  it  is  more  advisable  that  the  external  or  common  carotid  should  be 
tied. 

Troublesome  hemorrhage  may  occur  in  the  division  of  the  fraenum  in  children,  if  the  ranine 
artery,  which  lies  on  each  side  of  it,  is  cut  through.  The'  student  should  remember  that  the 
operation  is  always  to  be  performed  with  a  pair  of  blunt-pointed  scissors,  which  should  be  so 
'held  as  to  divide  the  part  in  the  direction  downwards  and  backwards ;  the  ranine  artery  and 
veins  are  then  avoided. 


Fig.  209. — The  Arteries  of  the  Face  and  Scalp. 


•The  Facial  Artery  (fig.  209)  arises  a  little  above  the  lingual,  and  ascends 
obliquely  forwards  and  upwards,  beneath  the  body  of  the  lower  jaw,  to  the  sub- 
maxillary gland,  in  which  it  is  imbedded ;  this  maybe  called  the  cervical  part  of  the 
artery.  It  then  curves  upwards  over  the  body  of  the  jaw  at  the  anterior  inferior 
angle  of  the  Masseter  muscle,  ascends  forwards  and  upwards  across  the  cheek  to 
the  angle  of  the  mouth,  passes  up  along  the  side  of  the  nose,  and  terminates  at 
the  inner  canthus  of  the  eye,  under  the  name  of  the  angular  artery.     This  vessel, 


FACIAL.  375 

both  in  the  neck,  and  on  the  face,  is  remarkably  tortuous ;  in  the  former  situation, 
to  accommodate  itself  to  the  movements  of  the  pharynx  in  deglutition ;  and  in  the 
latter,  to  the  movements  of  the  jaw,  and  the  lips  and  cheeks. 

Relations.  In  the  neck,  its  origin  is  superficial,  being  covered  by  the  integument, 
Platysma,  and  fascia ;  it  then  passes  beneath  the  Digastric  and  Stylo-hyoid  muscles, 
and  the  submaxillary  gland.  On  the  face,  where  it  passes  over  the  body  of  the  lower 
jaw,  it  is  comparatively  superficial,  being  covered  by  the  Platysma.  In  this  situa- 
tion, its  pulsation  may  be  distinctly  felt,  and  compression  of  the  vessel  effectually 
made  against  the  bone.  In  its  course  over  the  face,  it  is  covered  by  the  integu- 
ment, the  fat  of  the  cheek,  and,  near  the  angle  of  the  mouth,  by  the  Platysma  and 
Zygomatic  muscles.  It  rests  on  the  Buccinator,  the  Levator  anguli  oris,  and  the 
Levator  labii  superioris  alceque  nasi.  It  is  accompanied  by  the  facial  vein 
throughout  its  entire  course ;  the  vein  is  not  tortuous  like  the  artery,  and,  on  the 
face,  is  separated  from  that  vessel  by  a  considerable  interval.  The  branches  of 
the  facial  nerve  cross  this  vessel,  and  the  infra-orbital  nerve  lies  beneath  it. 

The  branches  of  this  vessel  may  be  divided  into  two  sets,  the  cervical,  those 
given  off'  below  the  jaw ;  and  the  facial  those  on  the  face. 

Cervical  Branches.  Facial  Branches. 

Inferior  or  Ascending  Palatine.  Muscular. 

Tonsillar.  Inferior  Labial. 

Submaxillary.  Inferior  Coronary. 

Submental.  Superior  Coronary. 

Lateralis  Nasi. 

Angular. 

The  inferior  or  ascending  palatine  (fig.  212)  passes  up  between  the  Stylo-glossus 
and  Stylo-pharyngeus  to  the  outer  side  of  the  pharynx.  After  supplying  these 
muscles,  the  tonsil,  and  Eustachian  tube,  it  divides,  near  the  Levator  palati,  into 
two  branches ;  one  follows  the  course  of  the  Tensor  palati,  supplies  the  soft  palate 
and  the  palatine  glands ;  the  other  passes  to  the  tonsil,  which  it  supplies,  anasto- 
mosing with  the  tonsillar  artery.  These  vessels  inosculate  with  the  posterior 
palatine  branch  of  the  internal  maxillary  artery. 

The  tonsillar  branch  (fig.  212)  passes  up  along  the  side  of  the  pharynx,  and, 
perforating  the  Superior  constrictor,  ramifies  in  the  substance  of  the  tonsil  and 
root  of  the  tongue. 

The  submaxillary  consist  of  three  or  four  large  branches,  which  supply  the 
submaxillary  gland,  some  being  prolonged  to  the  neighboring  muscles,  lymphatic 
glands,  and  integument. 

The  submental,  the  largest  of  the  cervical  branches,  is  given  off  from  the  facial 
artery,  just  as  that  vessel  quits  the  submaxillary  gland ;  it  runs  forwards  upon  the 
M}do-hyoid  muscle,  just  below  the  body  of  the  jaw,  and  beneath  the  Digastric, 
and,  after  supplying  the  muscles  attached  to  the  jaw,  and  anastomosing  with  the 
sublingual  artery,  arrives  at  the  symphysis  of  the  chin,  where  it  divides  into  a 
superficial  and  a  deep  branch ;  the  former  turns  round  the  chin,  and,  passing 
between  the  integument  and  Depressor  labii  inferioris,  supplies  both,  and  anasto- 
moses with  the  inferior  labial.  The  deep  branch  passes  between  the  latter 
muscle  and  the  bone,  supplies  the  lip,  and  anastomoses  with  the  inferior  labial  and 
mental  arteries. 

The  muscular  branches  are  distributed  to  the  internal  Pterygoid,  Masseter,  and 
Buccinator. 

The  inferior  labial  passes  beneath  the  Depressor  anguli  oris,  to  supply  the 
muscles  and  integument  of  the  lower  lip,  anastomosing  with  the  inferior  coronary 
and  submental  branches  of  the  facial,  and  with  the  mental  branch  of  the  inferior 
dental  artery. 

The  inferior  coronary  is  derived  from  the  facial  artery  near  the  angle  of  the 


376  ARTERIES. 

mouth ;  it  passes  upwards  and  inwards  beneath  the  Depressor  anguli  oris,  and, 
penetrating  the  Orbicularis  muscle,  runs  in  a  tortuous  course  along  the  edge  of 
the  lower  lip  between  this  muscle  and  the  mucous  membrane,  inosculating  with 
the  artery  of  the  opposite  side.  This  artery  supplies  the  labial  glands>  the  mucous 
membrane,  and  muscles  of  the  lower  lip ;  and  anastomoses  with  the  inferior  labial, 
and  mental  branch  of  the  inferior  dental  artery. 

The  superior  coronary  is  larger,  and  more  tortuous  in  its  course  than  the  pre- 
ceding. It  follows  the  same  course  along  the  edge  of  the  upper  lip,  lying  between 
the  mucous  membrane  and  the  Orbicularis,  and  anastomoses  with  the  artery  of 
the  opposite  side.  It  supplies  the  textures  of  the  upper  lip,  and  gives  off  in  its 
course  two  or  three  vessels  which  ascend  to  the  nose.  One,  named  the  artery  of 
the  septum,  ramifies  on  the  septum  of  the  nares  as  far  as  the  point  of  the  nose ; 
another  supplies  the  ala  of  the  nose. 

The  lateralis  nasi  is  derived  from  the  facial,  as  that  vessel  is  ascending  along 
the  side  of  the  nose ;  it  supplies  the  ala  and  dorsum  of  the  nose,  anastomosing 
with  its  fellow,  the  nasal  branch  of  the  ophthalmic,  the  artery  of  the  septum,  and 
the  infra-orbital. 

The  angular  artery  is  the  termination  of  the  trunk  of  the  facial ;  it  ascends  to 
the  inner  angle  of  the  orbit,  accompanied  by  a  large  vein,  the  angular ;  it  dis- 
tributes some  branches  on  the  cheek  which  anastomose  with  the  infra-orbital,  and, 
after  supplying  the  lachrymal  sac,  and  Orbicularis  muscle,  terminates  by  anas- 
tomosing with  the  nasal  branch  of  the  ophthalmic  artery. 

The  anastomoses  of  the  facial  artery  are  very  numerous,  not  only  with  the 
vessel  of  the  opposite  side,  but  with  other  vessels  from  different  sources ;  viz.,  with 
the  sublingual  branch  of  the  lingual,  with  the  mental  branch  of  the  inferior  dental 
as  it  emerges  from  the  dental  foramen,  with  the  ascending  pharyngeal  and  pos- 
terior palatine,  and  with  the  ophthalmic,  a  branch  of  the  internal  carotid ;  it  also 
inosculates  with  the  transverse  facial,  and  with  the  infra-orbital. 

Peculiarities.  The  facial  artery  not  unfrequently  arises  by  a  common  trunk  with  the  lingual. 
This  vessel  also  is  subject  to  some  variations  in  its  size,  and  in  the  extent  to  which  it  supplies 
the  face.  It  occasionally  terminates  as  the  submental,  and  not  unfrequently  supplies  the  face 
only  as  high  as  the  angle  of  the  mouth  or  nose.  The  deficiency  is  then  supplied  by  enlargement 
of  one  of  the  neighboring  arteries. 

Surgical  Anatomy.  The  passage  of  the  facial  artery  over  the  body  of  the  jaw  would  appear  to 
afford  a  favorable  position  for  the  application  of  pressure  in  cases  of  hemorrhage  from  the  lips, 
the  result  either  of  an  accidental  wound,  or  from  an  operation;  but  its  application  is  useless,  on 
account  of  the  free  communication  of  this  vessel  with  its  fellow,  and  with  numerous  branches 
from  different  sources.  In  a  wound  involving  the  lip,  it  is  better  to  seize  the  part  between  the 
fingers,  and  evert  it,  when  the  bleeding  vessel  may  be  at  once  secured  with  a  tenaculum.  In 
order  to  prevent  hemorrhage  in  cases  of  excision,  or  in  the  removal  of  diseased  growths  from  the 
part,  the  lip  should  be  compressed  on  each  side  between  the  finger  and  thumb,  whilst  the  surgeon 
excises  the  diseased  part.  In  order  to  stop  hemorrhage  where  the  lip  has  been  divided  in  an 
operation,  it  is  necessary,  in  uniting  the  edges  of  the  wound,  to  pass  the  sutures  through  the  cut 
edges,  almost  as  deep  as  its  mucous  surface;  by  these  means,  not  only  are  the  cut  surfaces  more 
neatly  adapted  to  each  other,  but  the  possibility  of  hemorrhage  is  prevented  by  including  in  the 
suture  the  divided  artery.  If  the  suture  is.  on  the  contrary,  passed  through  merely  the  cutane- 
ous portion  of  the  wound,  hemorrhage  occurs  into  the  cavity  of  the  mouth.  The  student  should, 
lastly,  observe  the  relation  of  the  angular  artery  to  the  lachrymal  sac,  and  it  will  be  seen  that,  aa 
the  vessel  passes  up  along  the  inner  margin  of  the  orbit,  it  ascends  on  its  nasal  side.  In  operat- 
ing for  fistula  lacrymalis,  the  sac  should  always  be  opened  on  its  outer  side,  in  order  that  this 
vessel  may  be  avoided. 

The  Occipital  Artery  arises  from  the  posterior  part  of  the  external  carotid, 
opposite  the  facial,  near  the  lower  margin  of  the  Digastric  muscle.  At  its  origin, 
it  is  covered  by  the  posterior  belly  of  the  Digastric  and  Stylo-hyoid  muscles,  and 
part  of  the  parotid  gland,  the  hypoglossal  nerve  winding  around  it  from  behind 
forwards ;  higher  up,  it  passes  across  the  internal  carotid  artery,  the  internal  jugular 
vein,  and  the  pneumogastric  and  spinal  accessory  nerves;  it  then  ascends  to  the 
interval  between  the  transverse  process  of  the  atlas  and  the  mastoid  process  of  the 
temporal  bone,  passes  horizontally  backwards,  grooving  the  surface  of  the  latter  bone, 


OCCIPITAL— POSTERIOR   AURICULAR— PHARYNGEAL.     377 

being  covered  by  the  Sternomastoid,  Splenius,  Digastric,  and  Trackelo-mastoid 
muscles,  resting  upon  the  Complexus,  Superior  oblique,  and  Rectus  posticus  major 
muscles ;  it  then  ascends  vertically  upwards,  piercing  the  cranial  attachment  of  the 
Trapezius,  and  passes  in  a  tortuous  course  over  the  occiput,  as  high  as  the  vertex, 
where  it  divides  into  numerous  branches. 

The  branches  given  off  from  this  vessel  are  the 

Muscular.  Inferior  meningeal. 

Auricular.  Arteria  princeps  cervicis. 

The  muscular  branches  supply  the  Digastric,  Stylo-hyoid,  Sterno-mastoid, 
Splenius,  and  Trachelo-mastoid  muscles.  The  branch  distributed  to  the  Sterno- 
mastoid is  of  large  size. 

The  auricular  branch  supplies  the  back  part  of  the  concha. 

The  meningeal  branch  ascends  with  the  internal  jugular  vein,  and  enters  the 
skull  through  the  foramen  lacerum  posterius,  to  supply  the  dura  mater  in  the 
posterior  fossa. 

The  arteria  princeps  cervicis  (fig.  212)  is  a  large  branch  which  descends  along 
the  back  part  of  the  neck,  and  divides  into  a  superficial  and  deep  branch.  The 
former  runs  beneath  the  Splenius,  giving  off  branches  which  perforate  that  muscle 
to  supply  the  Trapezius,  anastomosing  with  the  superficial  cervical  artery ;  the 
latter  passes  beneath  the  Complexus,  between  it  and  the  Semi-spinalis  colli,  and 
anastomoses  with  the  vertebral,  and  deep  cervical  branch  of  the  superior  intercostal. 
The  anastomosis  between  these  vessels  serves  mainly  to  establish  the  collateral 
circulation  after  ligature  of  the  carotid  or  subclavian  artery. 

The  cranial  branches  of  the  occipital  artery  are  distributed  upon  the  occiput; 
they  are  very  tortuous,  and  lie  between  the  integument  and  Occipito-frontalis, 
anastomosing  with  the  artery  of  the  opposite  side,  the  posterior  auricular,  and 
temporal  arteries.  They  supply  the  back  part  of  the  Occipito-frontalis  muscle,  the 
integument,  pericranium,  and  one  or  two  branches  occasionally  pass  through  the 
parietal  or  mastoid  foramina,  to  supply  the  dura  mater. 

The  Posterior  Auricular  Artery  (fig.  209)  is  a  small  vessel,  which  arises 
from  the  external  carotid,  above  the  Digastric  and  Stylo-hyoid  muscles,  opposite 
the  apex  of  the  styloid  process.  It  ascends,  under  cover  of  the  parotid  gland,  to 
the  groove  between  the  cartilage  of  the  ear  and  the  mastoid  process,  immediately 
above  which  it  divides  into  two  branches,  an  anterior,  which  passes  forwards  to 
anastomose  with  the  posterior  division  of  the  temporal ;  and  a  posterior,  which 
communicates  with  the  occipital.  Just  before  arriving  at  the  mastoid  process, 
this  artery  is  crossed  by  the  portio  dura,  and  has  beneath  it  the  spinal  accessory 
nerve. 

Besides  several  small  branches  to  the  Digastric,  Stylo-hyoid,  and  Sterno-mas- 
toid muscles,  and  to  the  parotid  gland,  this  vessel  gives  off  two  branches,  the 

Stylo-mastoid.  Auricular. 

The  stylo-mastoid  branch  enters  the  stylo-mastoid  foramen,  and  supplies  the 
tympanum,  mastoid  cells,  and  semicircular  canals.  In  the  young  subject,  a 
branch  from  this  vessel  forms,  with  the  tympanic  branch  from  the  internal  maxil- 
lary, a  vascular  circle,  which  surrounds  the  auditory  meatus,  and  from  which 
delicate  vessels  ramify  on  the  membrana  tympani. 

The  auricular  branch  is  distributed  to  the  back  part  of  the  cartilage  of  the  ear, 
upon  which  it  minutely  ramifies,  some  branches  curving  round  its  margin,  others 
perforating  the  fibro-cartilage,  to  supply  its  anterior  surface. 

The  Ascending-  Pharyngeal  Artery  (fig.  212),  the  smallest  branch  of  the 
external  carotid,  is  a  long  slender  vessel,  deeply  seated  in  the  neck,  beneath  the 
other  branches  of  the  external  carotid  and  Stylo-pharyngeus  muscle.  It  arises 
from  the  back  part  of  the  external  carotid,  near  the  commencement  of  that  vessel, 
and  passes  up  to  the  under  surface  of  the  base  of  the  skull,  ascending  the  neck 
between  the  internal  carotid  and  the  side  of  the  pharynx,  and  lying  on  the 


378  ARTERIES. 

Rectus  capitis  an  ticus  major.  Its  branches  maybe  subdivided  into  three  sets: 
1.  Those  directed  outwards  to  supply  muscles  and  nerves.  2.  Those  directed 
inwards  to  the  pharynx.     3.  Meningeal  branches. 

The  external  branches  are  numerous  small  vessels,  which  supply  the  Recti  antici 
muscles,  the  sympathetic,  hypoglossal  and  pneumogastric  nerves,  and  the  lymphatic 
glands  of  the  neck,  anastomosing  with  the  ascending  cervical  artery. 

The  pharyngeal  branches  are  three  or  four  in  number.  Two  of  these  descend 
to  supply  the  middle  and  inferior  Constrictors  and  the  Stylo-pharyngeus,  ramifying 
in  their  substance  and  in  the  mucous  membrane  lining  them.  The  largest  of  the 
pharyngeal  branches  passes  inwards,  running  upon  the  Superior  constrictor,  and 
sends  ramifications  to  the  soft  palate,  Eustachian  tube,  and  tonsil,  which  take  the 
place  of  the  ascending  palatine  branch  of  the  facial  artery,  when  that  vessel  is  of 
small  size. 

The  meningeal  branches  consist  of  several  small  vessels,  which  pass  through 
foramina  in  the  base  of  the  skull,  to  supply  the  dura  mater.  One,  the  posterior 
meningeal,  enters  the  cranium  through  the  foramen  lacerum  posterius  with  the 
internal  jugular  vein.  A  second  passes  through  the  foramen  lacerum  basis  cranii ; 
and  occasionally  a  third  through  the  anterior  condyloid  foramen.  They  are  all 
distributed  to  the  dura  mater. 

The  Temporal  Artery  (fig.  209),  the  smaller  of  the  two  terminal  branches 
of  the  external  carotid,  appears,  from  its  direction,  to  be  the  continuation  of  that 
vessel.  It  commences  in  the  substance  of  the  parotid  gland,  in  the  interspace 
between  the  neck  of  the  condyle  of  the  lower  jaw  and  the  external  meatus ;  cross- 
ing over  the  root  of  the  zygoma,  immediately  beneath  the  integument,  it  divides 
about  two  inches  above  the  zygomatic  arch  into  two  branches,  an  anterior  and  a 
posterior. 

The  anterior  temporal  inclines  forwards  over  the  forehead,  supplying  the 
muscles,  integument,  and  pericranium  in  this  region,  and  anastomoses  with  the 
supra-orbital  and  frontal  arteries,  its  branches  being  directed  from  before  back- 
wards. 

The  posterior  temporal,  larger  than  the  anterior,  curves  upwards  and  back- 
wards along  the  side  of  the  head,  lying  above  the  temporal  fascia,  and  inosculates 
with  its  fellow  of  the  opposite  side,  and  with  the  posterior  auricular  and  occipital 
arteries. 

The  temporal  artery,  as  it  crosses  the  zygoma,  is  covered  by  the  Attrahens 
aurem  muscle,  and  by  a  dense  fascia  given  off  from  the  parotid  gland ;  it  is  also 
usually  crossed  by  one  or  two  veins,  and  accompanied  by  branches  of  the  facial 
and  temporo-auricular  nerves.  Besides  some  twigs  to  the  parotid  gland,  the 
articulation  of  the  jaw,  and  the  Masseter  muscle,  its  branches  are  the 

Transverse  facial.  Middle  temporal. 

Anterior  auricular. 

The  transverse  facial  is  given  off  from  the  temporal  before  that  vessel  quits  the 
parotid  gland ;  running  forwards  through  its  substance,  it  passes  transversely 
across  the  face,  between  Stenon's  duct  and  the  lower  border  of  the  zygoma,  and 
divides  on  the  side  of  the  face  into  numerous  branches,  which  supply  the  parotid 
gland,  the  Masseter  muscle,  and  the  integument,  anastomosing  with  the  facial 
and  infra-orbital  arteries.  This  vessel  rests  on  the  Masseter,  and  is  accompanied 
by  one  or  two  branches  of  the  facial  nerve. 

The  middle  tempioral  artery  arises  immediately  above  the  zygomatic  arch,  and, 
perforating  the  temporal  fascia,  supplies  the  Temporal  muscle,  anastomosing  with 
the  deep  temporal  branches  of  the  internal  maxillary.  It  occasionally  gives  off 
an  orbital  branch,  which  runs  along  the  upper  border  of  the  zygoma,  between  the 
two  layers  of  the  temporal  fascia,  to  the  outer  angle  of  the  orbit ;  it  supplies  the 
Orbicularis,  and  anastomoses  with  the  lachrymal  and  palpebral  branches  of  the 
ophthalmic  artery. 


INTERNAL   MAXILLARY.  379 

The  anterior  auricular  branches  are  distributed  to  the  anterior  portion  of  the 
pinna,  the  lobule,  and  part  of  the  external  meatus,  anastomosing  with  branches 
of  the  posterior  auricular. 

Surgical  Anatomy.  It  occasionally  happens  that  the  surgeon  is  called  upon  to  perform  the 
operation  of  arteriotomy  upon  this  vessel  in  cases  of  inflammation  of  the  eye  or  brain.  Under 
these  circumstances,  the  anterior  branch  is  the  one  usually  selected.  If  the  student  will  con- 
sider the  relations  of  the  trunk  of  this  vessel  as  it  crosses  the  zygomatic  arch,  with  the  surround- 
ing structures,  he  will  observe  that  it  is  covered  by  a  thick  and  dense  fascia,  crossed  by  one  or 
'  two  veins,  and  accompanied  by  branches  of  the  facial  and  temporo-auricular  nerves.  Bleeding 
should  not  be  performed  in  this  situation,  as  much  difficulty  may  arise  from  the  dense  fascia 
covering  this  vessel  preventing  a  free  flow  of  blood,  and  considerable  pressure  is  requisite  after- 
wards to  repress  it.  Again,  a  varicose  aneurism  may  be  formed  by  the  accidental  opening  of  one 
of  the  veins  covering  it;  or  severe  neuralgic  pain  may  arise  from  the  operation  implicating  one  of 
the  nervous  filaments  which  accompany  the  artery. 

The  anterior  branch  is,  on  the  contrary,  subcutaneous,  is  a  large  vessel,  and  as  readily  com- 
pressed as  any  other  portion  of  the  artery ;  it  should  consequently  always  be  selected  for  the 
operation. 

The  Internal  Maxillary,  the  larger  of  the  two  terminal  branches  of  the 
external  carotid,  passes  inwards,  at  right  angles  from  that  vessel,  to  the  inner  side 
of  the  neck  of  the  condyle  of  the  lower  jaw,  to  supply  the  deep  structures  of  the 
face.  At  its  origin,  it  is  imbedded  in  the  substance  of  the  parotid  gland,  being 
on  a  level  with  the  lower  extremity  of  the  lobe  of  the  ear. 

In  the  first  part  of  its  course  (maxillary  portion),  the  artery  passes  horizon- 
tally forwards  and  inwards,  between  the  ramus  of  the  jaw  and  the  internal  late- 
ral ligament.  The  artery  here  lies  parallel  with  the  auriculo-temporal  nerve ;  it 
crosses  the  inferior  dental  nerve,  and  lies  beneath  the  narrow  portion  of  the  Ex- 
ternal pterygoid  muscle. 

In  the  second  part  of  its  course  (pterygoid  portion),  it  ascends  obliquely  for- 
wards and  upwards  upon  the  outer  surface  of  the  External  pterygoid  muscle, 
being  covered  by  the  ramus  of  the  lower  jaw,  and  lower  part  of  the  Temporal 
muscle. 

In  the  third  part  of  its  course  (spheno-maxillary  portion),  it  approaches  the 
superior  maxillary  bone,  and  enters  the  spheno-maxillary  fossa,  in  the  interval 
between  the  processes  of  origin  of  the  External  pterygoid,  where  it  lies  in  rela- 
tion with  Meckel's  ganglion,  and  gives  off  its  terminal  branches. 

Peculiarities.  Occasionally,  this  artery  passes  between  the  two  Pterygoid  muscles.  The  ves- 
sel in  this  case  passes  forwards  to  the  interval  between  the  processes  of  origin  of  the  External 
pterygoid,  in  order  to  reach  the  maxillary  bone.  Sometimes  the  vessel  escapes  from  beneath  the 
External  pterygoid  by  perforating  the  middle  of  this  muscle. 

The  branches  of  this  vessel  may  be  divided  into  three  groups,  corresponding 
with  its  three  divisions. 

1.  Branches  from  the  Maxillary  Portion. 

Tympanic.  Small  meningeal. 

Middle  meningeal.  Inferior  dental. 

The  tympanic  branch  passes  upwards  behind  the  articulation  of  the  lower  jmv, 
enters  the  tympanum  through  the  fissura  Glaseri,  supplies  the  Laxator  tympani, 
and  ramifies  upon  the  membrana  tympani,  anastomosing  with  the  stylo-mastoid 
and  Vidian  arteries. 

The  middle  meningeal  is  the  largest  of  the  branches  which  supply  the  dura 
mater.  It  arises  from,  the  internal  maxillary  between  the  internal  lateral  ligament 
and  the  neck  of  the  jaw,  and  ascends  vertically  upwards  to  the  foramen  spinosum 
in  the  spinous  process  of  the  sphenoid  bone.  On  entering  the  cranium,  it  divides 
into  two  branches,  an  anterior  and  a  posterior.  The  anterior  branch,  the  larger, 
crosses  the  great  ala  of  the  sphenoid,  and  reaches  the  groove,  or  canal,  in  the 
anterior  inferior  angle  of  the  parietal  bone ;  it  then  divides  into  branches  which 


380 


ARTERIES. 


spread  out  between  the  dura  mater  and  internal  surface  of  the  cranium,  some 
passing  upwards  over  the  parietal  bone  as  far  as  the  vertex,  and  others  backwards 
to  the  occipital  bone.  The  posterior  branch  crosses  the  squamous  portion  of  the 
temporal,  and  on  the  inner  surface  of  the  parietal  bone  divides  into  branches  which 
supply  the  posterior  part  of  the  dura  mater  and  cranium.  The  branches  of  this 
vessel  are  distributed  to  the  dura  mater,  but  chiefly  to  the  bones;  they  anastomose 


Fig.  210. — The  Internal  Maxillary  Artery,  and  its  Branches. 


tPttryqe  'Palatini 

f  I  &  .  211.   Elan  cf  the  franc  hes  [^tZ^naFaMin. 

\SplunPalat\itt 


with  the  arteries  of  the  opposite  side,  and  with  the  anterior  and  posterior  menin- 
geal. 

The  middle  meningeal,  on  entering  the  cranium,  gives  off  the  following  colla- 
teral branches:  1.  Numerous  small  vessels  to  the  ganglion  of  the  fifth  nerve, 
and  to  the  dura  mater  in  this  situation.  2.  A  branch  to  the  facial  nerve,  which 
enters  the  hiatus  Fallopii,  supplies  the  facial  nerve,  and  anastomoses  with  the  stylo- 
mastoid branch  of  the  posterior  auricular  artery.  3.  Orbital  branches,  which 
pass  through  the  sphenoidal  fissure,  or  through  separate  canals  in  the  great  wing 
of  the  sphenoid,  to  anastomose  with  the  lachrymal  or  other  branches  of  the  oph- 
thalmic artery.  4.  Temporal  branches,  which  pass  through  foramina  in  the  great 
wing  of  the  sphenoid,  and  anastomose  in  the  temporal  fossa  with  the  deep  temporal 
arteries. 

The  small  meningeal  is  sometimes  derived  from  the  preceding.  It  enters  the 
skull  through  the  foramen  ovale,  and  supplies  the  Casserian  ganglion  and  dura 


INTERNAL   MAXILLARY.  381 

mater.     Before  entering  the  cranium,  it  gives  off  a  branch  to  the  nasal  fossa  and 
soft  palate. 

The  inferior  dental  descends  with  the  dental  nerve,  to  the  foramen  on  the  inner 
side  of  the  ramus  of  the  jaw.  It  runs  along  the  dental  canal  in  the  substance  of 
the  bone,  accompanied  by  the  nerve,  and  opposite  the  bicuspid  tooth  divides  into 
two  branches,  incisor  and  mental ;  the  former  is  continued  forwards  beneath  the 
incisor  teeth  as  far  as  the  symphysis,  where  it  anastomoses  with  the  artery  of  the 
opposite  side ;  the  mental  branch  escapes  with  the  nerve  at  the  mental  foramen, 
supplies  the  structures  composing  the  chin,  and  anastomoses  with  the  submental, 
inferior  labial,  and  inferior  coronary  arteries.  As  the  dental  artery  enters  the 
foramen,  it  gives  off  a  mylo-hyoid  branch,  which  runs  in  the  mylo-hyoid  groove, 
and  ramifies  on  the  under  surface  of  the  Mylo-hyoid  muscle.  The  dental  and 
incisor  arteries,  during  their  course  through  the  substance  of  the  bone,  give  off 
a  few  twigs  which  are  lost  in  the  diploe,  and  a  series  of  branches  which  corre- 
spond in  number  to  the  roots  of  the  teeth ;  these  enter  the  minute  apertures  at 
the  extremities  of  the  fangs,  and  ascend  to  supply  the  pulp  of  the  teeth. 

2.  Branches  of  the  Second  or  Pterygoid  Portion. 

Deep  temporal.  Masseteric. 

Pterygoid.  Buccal. 

These  branches  are  distributed,  as  their  names  imply,  to  the  muscles  in  the 
maxillary  region. 

The  deep  temporal  branches,  two  in  number,  anterior  and  posterior,  each  occupy 
that  part  of  the  temporal  fossa  indicated  by  its  name.  Ascending  between  the 
Temporal  muscle  and  pericranium,  they  supply  that  muscle,  and  anastomose  with 
the  other  temporal  arteries ;  the  anterior  branch  communicating  with  the  lach- 
rymal through  small  branches  which  perforate  the  malar  bone. 

The  pterygoid  branches,  irregular  in  their  number  and  origin,  supply  the  Ptery- 
goid muscles. 

The  masseteric  is  a  small  branch  which  passes  outwards  above  the  sigmoid 
notch  of  the  lower  jaw,  to  the  deep  surface  of  the  Masseter.  It  supplies  that 
muscle,  and  anastomoses  with  the  masseteric  branches  of  the  facial  and  transverse 
facial  arteries. 

The  buccal  is  a  small  branch  which  runs  obliquely  forwards  between  the  Internal 
pterygoid  and  the  ramus  of  the  jaw,  to  the  outer  surface  of  the  Buccinator,  to 
which  it  is  distributed,  anastomosing  with  branches  of  the  facial  artery. 

3.  Branches  of  the  Third  or  Spheno-maxillary  Portion. 

Alveolar.  Vidian. 

Infra-orbital.  Ptery  go-palatine. 

Posterior  or  Descending  palatine.  Nasal  or  Spheno-palatine. 

The  alveolar  is  given  off  from  the  internal  maxillary  by  a  common  branch  with 
the  infra-orbital,  and  just  as  the  trunk  of  the  vessel  is  passing  into  the  spheno- 
maxillary fossa.  Descending  upon  the  tuberosity  of  the  superior  maxillary  bone, 
it  divides  into  numerous  branches ;  one,  the  superior  dental,  larger  than  the  rest, 
supplies  the  molar  and  biscuspid  teeth,  its  branches  entering  the  foramina  in 
the  alveolar  process ;  some  branches  pierce  the  bone  to  supply  the  lining  of  the 
antrum,  and  others  are  continued  forwards  on  the  alveolar  process  to  supply  the 
gums. 

The  infra-orbital  appears,  from  its  direction,  to  be  the  continuation  of  the  trunk 
of  the  internal  maxillary.  It  arises  from  that  vessel  by  a  common  trunk  with 
the  preceding  branch,  and  runs  along  the  infra-orbital  canal  with  the  superior 
maxillary  nerve,  emerging  upon  the  face  at  the  infra-orbital  foramen,  beneath  the 
Levator  labii  superioris.  Whilst  contained  in  the  canal,  it  gives  off'  branches 
which  ascend  into  the  orbit,  and  supply  the  Inferior  rectus,  and  Inferior  oblique 


382  SURGICAL   ANATOMY. 

muscles,  and  the  lachrymal  gland.  Other  branches  descend  through  canals  hi  tha 
bone,  to  supply  the  mucous  membrane  of  the  antrum,  and  the  front  teeth  of  the 
upper  jaw.  On  the  face,  it  supplies  the  lachrymal  sac,  and  inner  angle  of  the 
orbit,  anastomosing  with  the  facial  artery  and  nasal  branch  of  the  ophthalmic; 
and  other  branches  descend  beneath  the  elevator  of  the  upper  lip,  and  anastomose 
with  the  transverse  facial  and  buccal  branches. 

The  four  remaining  branches  arise  from  that  portion  of  the  internal  maxillary 
which  is  contained  in  the  spheno-maxillary  fossa. 

The  descending  palatine  passes  down  along  the  posterior  palatine  canal  with  the 
posterior  palatine  branches  of  Meckel's  ganglion,  and,  emerging  from  the  posterior 
palatine  foramen,  runs  forwards  in  a  groove  on  the  inner  side  of  the  alveolar 
border  of  the  hard  palate,  to  be  distributed  to  the  gums,  the  mucous  membrane 
of  the  hard  palate,  and  palatine  glands.  Whilst  it  is  contained  in  the  palatine 
canal,  it  gives  off  branches,  which  descend  in  the  accessory  palatine  canals  to 
supply  the  soft  palate,  anastomosing  with  the  ascending  palatine  artery ;  and  ante- 
riorly it  terminates  in  a  small  vessel,  which  ascends  in  the  anterior  palatine  canal, 
and  anastomoses  with  the  artery  of  the  septum,  a  branch  of  the  spheno-palatine. 

The  Vidian  branch  passes  backwards  along  the  Vidian  canal  with  the  Vidian 
nerve.  It  is  distributed  to  the  upper  part  of  the  pharynx  and  Eustachian  tube, 
sending  a  small  branch  into  the  tympanum. 

The  pterygopalatine  is  also  a  very  small  branch,  which  passes  backwards 
through  the  pterygopalatine  canal  with  the  pharyngeal  nerve,  and  is  distributed 
to  the  upper  part  of  the  pharynx  and  Eustachian  tube. 

The  nasal  or  spheno-palatine  passes  through  the  spheno-palatine  foramen  into 
the  cavity  of  the  nose,  at  the  back  part  of  the  superior  meatus,  and  divides  into 
two  branches ;  one  internal,  the  artery  of  the  septum,  passes  obliquely  downwards 
and  forwards  along  the  septum  nasi,  supplies  the  mucous  membrane,  and  anasto- 
moses in  front  with  the  ascending  branch  of  the  descending  palatine.  The 
external  branches,  two  or  three  in  number,  supply  the  mucous  membrane  cover- 
ing the  lateral  wall  of  the  nares,  the  antrum,  and  the  ethmoid  and  sphenoid  cells. 

Surgical  Anatomy  of  the  Triangles  of  the  Neck. 

The  student  having  considered  the  relative  anatomy  of  the  large  arteries  of  the 
neck  and  their  branches,  and  the  relations  they  bear  to  the  veins  and  nerves, 
should  now  examine  these  structures  collectively,  as  they  present  themselves  in 
certain  regions  of  the  neck,  in  each  of  which  important  operations  are  being  con- 
stantly performed. 

For  this  purpose,  the  Sterno-mastoid,  or  any  other  muscles  that  have  been 
divided  in  the  dissection  of  these  vessels,  should  be  replaced  in  their  normal  posi- 
tion ;  the  head  should  be  supported  by  placing  a  block  at  the  back  of  the  neck, 
and  the  face  turned  to  the  side  opposite  to  that  which  is  being  examined. 

The  side  of  the  neck  presents  a  somewhat  quadrilateral  outline,  limited,  above 
by  the  lower  border  of  the  body  of  the  jaw,  and  an  imaginary  line  extending 
from  the  angle  of  the  jaw  to  the  mastoid  process;  below,  by  the  prominent  upper 
border  of  the  clavicle ;  in  front,  by  the  median  line  of  the  neck ;  behind,  by  the 
anterior  margin  of  the  Trapezius  muscle.  This  space  is  subdivided  into  two  large 
triangles  by  the  Sterno-mastoid  muscle,  which  passes  obliquely  across  the  neck, 
from  the  sternum  and  clavicle,  below,  to  the  mastoid  process,  above.  The  trian- 
gular space  in  front  of  this  muscle  is  called  the  anterior  triangle;  and  that  behind 
it,  the  posterior  triangle. 

Anterior  Triangular  Space. 

The  anterior  triangle  is  limited,  in  front,  by  a  line  extending  from  the  chin  to 
the  sternum;  behind,  by  the  anterior  margin  of  the  Sterno-mastoid;  its  base, 
directed  upwards,  is  formed  by  the  lower  border  of  the  body  of  the  jaw,  and  a  line 


OF  THE  TRIANGLES  OF  THE  NECK.         383 

extending  from  the  angle  of  the  jaw  to  the  mastoid  process ;  its  apex  is  formed 
below  by  the  sternum.  This  space  is  covered  by  the  integument,  superficial 
fascia,  Platysma,  deep  fascia,  crossed  by  branches  of  the  facial  and  superficial  cer- 
vical nerves,  and  subdivided  into  three  smaller  triangles  by  the  Digastric  muscle, 
above,  and  the  anterior  belly  of  the  Omo-hyoid,  below.  These  are  named,  from 
below  upwards,  the  inferior  carotid  triangle,  the  superior  carotid  triangle,  and  the 
submaxillary  triangle. 

The  Inferior  Carotid  Triangle,  is  limited,  in  front,  by  the  median  line  of  the 
neck ;  behind,  by  the  anterior  margin  of  the  Sterno-mastoid  ;  above,  by  the  anterior 
belly  of  the  Omo-hyoid ;  and  it  is  covered  by  the  integument,  superficial  fascia, 
Platysma,  and  deep  fascia ;  ramifying  between  which  is  seen  the  descending 
branch  of  the  superficial  cervical  nerve.  Beneath  these  superficial  structures  are 
the  Sterno-hyoid  and  Sterno-thyroid  muscles,  which,  together  with  the  anterior 
margin  of  the  Sterno-mastoid,  conceal  the  lower  part  of  the  common  carotid  artery. 
This  vessel  is  inclosed  within  its  sheath,  together  with  the  internal  jugular  vein, 
and  pneumogastric  nerve;  the  vein  lying  on  the  outer  side  of  the  artery  on  the 
right  side  of  the  neck,  but  overlapping  it,  or  passing  directly  across  it  on  the  left 
side ;  the  nerve  lying  between  the  artery  and  vein,  on  a  plane  posterior  to  both. 
In  front  of  the  sheath  are  a  few  filaments  descending  from  the  loop  of  communi- 
cation between  the  descendens  and  communicans  noni ;  behind  the  sheath  are  seen 
the  inferior  thyroid  artery,  the  recurrent  laryngeal  and  sympathetic  nerves ;  and 
on  its  inner  side,  the  trachea,  the  thyroid  gland,  much  more  prominent  in  the 
female  than  in  the  male,  and  the  lower  part  of  the  larynx.  In  the  upper  part  of 
this  space,  the  common  carotid  artery  may  be  tied  below  the  Omo-hyoid  muscle. 

The  Superior  Carotid  Triangle  is  bounded,  behind,  by  the  Sterno-mastoid; 
below,  by  the  anterior  belly  of  the  Omo-hyoid ;  and  above,  by  the  posterior  belly 
of  the  Digastric  muscle.  Its  floor  is  formed  by  parts  of  the  Thyro-hyoid,  Hyo- 
glossus,  and  the  inferior  and  middle  Constrictor  muscles  of  the  pharynx ;  and  it  is 
covered  by  the  integument,  superficial  fascia,  Platysma,  and  deep  fascia;  rami- 
fying between  which  are  branches  of  the  facial  and  superficial  cervical  nerves. 
This  space  contains  the  upper  part  of  the  common  carotid  artery,  which  bifurcates 
opposite  the  upper  border  of  the  thyroid  cartilage  into  the  external  and  internal 
carotid.  These  vessels  are  concealed  from  view  by  the  anterior  margin  of  the 
Sterno-mastoid  muscle,  which  overlaps  them.  The  external  and  internal  carotids 
lie  side  by  side,  the  external  being  the  most  anterior  of  the  two.  The  following 
branches  of  the  external  carotid  are  also  met  with  in  this  space :  the  superior 
thyroid,  which  runs  forwards  and  downwards ;  the  lingual,  which  passes  directly 
forwards ;  the  facial,  forwards  and  upwards ;  the  occipital  is  directed  backwards ; 
and  the  ascending  pharyngeal  runs  directly  upwards  on  the  inner  side  of  the  in- 
ternal carotid.  The  veins  met  with  are: — the  internal  jugular,  which  lies  on  the 
outer  side  of  the  common  and  internal  carotid  vessels ;  and  veins  corresponding  to 
the  above-mentioned  branches  of  the  external  carotid,  viz.,  the  superior  thyroid, 
the  lingual,  facial,  ascending  pharyngeal,  and  sometimes  the  occipital;  all  of  which 
accompany  their  corresponding  arteries,  and  terminate  in  the  internal  jugular. 
In  front  of  the  sheath  of  the  common  carotid  is  the  descendens  noni,  the  hypo- 
glossal, from  which  it  is  derived,  crossing  both  carotids  above,  curving  round  the 
occipital  artery  at  its  origin.  Within  the  sheath,  between  the  artery  and  vein, 
and  behind  both,  is  the  pneumogastric  nerve ;  behind  the  sheath,  the  sympathetic. 
On  the  outer  side  of  the  vessels,  the  spinal  accessory  nerve  runs  for  a  short  distance 
before  it  pierces  the  Sterno-mastoid  muscle ;  and  on  the  inner  side  of  the  internal 
carotid,  just  below  the  hyoid  bone,  may  be  seen  the  superior  laryngeal  nerve ;  and 
still  more  inferiorly,  the  external  laryngeal  nerve.  The  upper  part  of  the  larynx 
and  the  pharynx  are  also  found  in  the  front  part  of  this  space. 

The  Submaxillary  Triangle  corresponds  to  that  part  of  the  neck  immediately 
beneath  the  body  of  the  jaw.  It  is  bounded,  above,  by  the  lower  border  of  the 
body  of  the  jaw,  the  parotid  gland,  and  mastoid  process ;  behind  by  the  posterior 
belly  of  the  Digastric  and  Stylo-hyoid  muscles :  in  front,  by  the  middle  line  of 


384  SURGICAL   ANATOMY. 

the  neck.  The  floor  of  this  space  is  formed  by  the  anterior  belly  of  the  Digastric, 
the  Mylo-hyoid,  and  Hyo-glossus  muscles,  and  it  is  covered  by  the  integument, 
superficial  fascia,  Platysma,  and  deep  fascia ;  ramifying  between  which  are  branches 
of  the  facial  and. ascending  filaments  of  the  superficial  cervical  nerve.  This  space 
contains,  in  front,  the  submaxillary  gland,  imbedded  in  the  surface  of  which  is  the 
facial  artery  and  vein,  and  its  glandular  branches ;  beneath  this  gland,  on  the  sur- 
face of  the  Mylo-hyoid  muscle,  are  the  submental  artery,  and  the  mylo-hyoid  artery 
and  nerve.  The  back  part  of  this  space  is  separated  from  the  front  part  by  the 
stylo-maxillary  ligament ;  it  contains  the  external  carotid  artery,  ascending  deeply 
in  the  substance  of  the  parotid  gland;  this  vessel  here  lies  in  front  of,  and  super- 
ficial to,  the  internal  carotid,  being  crossed  by  the  facial  nerve,  and  gives  off  in 
its  course  the  posterior  auricular,  temporal,  and  internal  maxillary  branches ;  more 
deeply  are  the  internal  carotid,  the  internal  jugular  vein,  and  the  pneumogastric 
nerve,  separated  from  the  external  carotid  by  the  Stylo-glossus  and  Stylo-pharyn- 
geus  muscles,  and  the  glosso-pharyngeal  nerve. 

Posteeior  Triangular  Space. 

The  posterior  triangular  space  is  bounded,  in  front,  by  the  Sterno-mastoid 
muscle ;  behind,  by  the  anterior  margin  of  the  Trapezius ;  its  base  corresponds  to 
the  upper  border  of  the  clavicle,  its  apex  to  the  occiput.  This  space  is  crossed, 
about  an  inch  above  the  clavicle,  by  the  posterior  belly  of  the  Omo-hyoid,  which 
divides  it  unequally  into  two  triangles,  an  upper  or  occipital,  and  a  lower  or 
subclavian. 

The  Occipital,  the  larger  of  the  two  posterior  triangles,  is  bounded,  in  front, 
by  the  Sterno-mastoid ;  behind,  by  the  Trapezius ;  below,  by  the  Omo-hyoid.  Its 
floor  is  formed  from  above  downwards  by  the  Splenius,  Levator  anguli  scapulas,  and 
the  middle  and  posterior  Scaleni  muscles.  It  is  covered  by  the  integument, 
the  Platysma  below,  the  superficial  and  deep  fasciae,  and  crossed,  above,  by  the 
ascending  branches  of  the  cervical  plexus :  the  spinal  accessory  nerve  is  directed 
obliquely  across  the  space  from  the  Sterno-mastoid,  which  it  pierces,  to  the  under 
surface  of  the  Trapezius;  below,  it  is  crossed  by  the  descending  branches  of  the 
same  plexus,  and  the  transversalis  colli  artery  and  vein.  A  chain  of  lymphatic 
glands  is  also  found  running  along  the  posterior  border  of  the  Sterno-mastoid, 
from  the  mastoid  process  to  the  root  of  the  neck. 

The  Subclavian,  the  smaller  of  the  two  posterior  triangles,  is  bounded,  above, 
by  the  posterior  belly  of  the  Omo-hyoid ;  below,  by  the  clavicle ;  its  base,  directed 
forwards,  being  formed  by  the  Sterno-mastoid.  The  size  of  this  space  varies 
according  to  the  extent  of  attachment  of  the  clavicular  portion  of  the  Sterno- 
mastoid  and  Trapezius  muscles,  and  also  according  to  the  height  at  which  the 
Omo-hyoid  crosses  the  neck  above  the  clavicle.  The  height  also  of  this  space  varies 
much,  according  to  the  position  of  the  arm,  being  much  diminished  on  raising  the 
limb,  on  account  of  the  ascent  of  the  clavicle,  and  increased  on  drawing  the  arm 
downwards,  when  this  bone  is  consequently  depressed.  This  space  is  covered 
by  the  integument,  superficial  and  deep  fascioa ;  and  crossed  by  the  descending 
branches  of  the  cervical  plexus.  Just  above  the  level  of  the  clavicle,  the  third 
portion  of  the  subclavian  artery  curves  outwards  and  downwards  from  the  outer 
margin  of  the  Scalenus  anticus,  across  the  first  rib,  to  the  axilla.  Sometimes, 
this  vessel  rises  as  high  as  an  inch  and  a-half  above  the  clavicle,  or  to  any  point 
intermediate  between  this  and  its  usual  level.  Occasionally,  it  passes  in  front  of 
the  Scalenus  anticus,  or  pierces  the  fibres  of  this  muscle.  The  subclavian  vein 
lies  beneath  the  clavicle,  and  is  usually  not  seen  in  this  space ;  but  it  occasionally 
rises  as  high  up  as  the  artery,  and  has  even  been  seen  to  pass  with  that  vessel 
behind  the  Scalenus  anticus.  The  brachial  plexus  of  nerves  lies  above  the  artery, 
and  in  close  -contact  with  it.  Passing  transversely  across  the  clavicular  margin 
of  the  space,  are  the  suprascapular  vessels ;  and  traversing  its  upper  angle  in  the 
same  direction,  the  transverse  cervical  vessels.    The  external  jugular  vein  descends 


INTERNAL   CAROTID. 


385 


vertically  downwards  behind  the  posterior  border  of  the  Sterno-mastoid,  to  terminate 
in  the  Subclavian;  it  receives  the  transverse  cervical  and  suprascapular  veins, 
which  occasionally  form  a  plexus  in  front  of  the  artery,  and  a  small  vein  which 
crosses  the  clavicle  from  the  cephalic.  The  small  nerve  to  the  Subclavius  also 
crosses  this  space  about  its  centre. 


Internal  Carotid  Artery. 

The  Internal  Carotid  Artery  commences  at  the  bifurcation  of  the  common 
carotid,  opposite  the  upper  border  of  the  thyroid  cartilage,  and  ascends  perpen- 
dicularly upwards,  in  front  of  the  transverse  processes  of  the  three  upper  cervical 
vertebrae,  to  the  carotid  foramen  in  the  petrous  portion  of  the  temporal  bone. 

Fig.  212. — The  Internal  Carotid  and  Vertebral  Arteries.     Right  Side. 


386  ARTERIES. 

After  ascending  in  it  for  a  short  distance,  it  passes  forwards  and  inwards  through 
the  carotid  canal,  and,  ascending  a  little  by  the  side  of  the  sella  Turcica,  curves 
upwards  by  the  anterior  clinoid  process,  where  it  pierces  the  dura  mater,  and 
divides  into  its  terminal  branches. 

This  vessel  supplies  the  anterior  part  of  the  brain,  the  eye,  and  its  appendages. 
Its  size,  in  the  adult,  is  equal  to  that  of  the  external  carotid.  In  the  child,  it  is 
larger  than  that  vessel.  It  is  remarkable  for  the  number  of  curvatures  that  it 
presents  in  different  parts  of  its  course.  In  its  cervical  portion  it  occasionally  pre- 
sents one  or  two  flexures  near  the  base  of  the  skull,  whilst  through  the  rest  of  its 
extent  it  describes  a  double  curvature,  which  resembles  the  italic  letter  /  placed 
horizontally  S>.  These  curvatures  most  probably  diminish  the  velocity  of  the 
current  of  blood,  by  increasing  the  extent  of  surface  over  which  it  moves,  and 
adding  to  the  amount  of  impediment  produced  from  friction.  In  considering  the 
course  and  relations  of  this  vessel,  it  may  be  conveniently  divided  into  four  por- 
tions, a  cervical,  petrous,  cavernous,  and  cerebral. 

Cervical  Portion.  This  portion  of  the  internal  carotid  at  its  commencement  is 
very  superficial,  being  contained  in  the  superior  carotid  triangle,  on  the  same  level 
as,  but  behind,  the  external  carotid,  overlapped  by  the  Sterno-mastoid,  and  covered 
by  the  Platysma,  deep  fascia,  and  integument ;  it  then  passes  beneath  the  parotid 
gland,  being  crossed  by  the  hypoglossal  nerve,  the  Digastric  and  Stylo-hyoid 
muscles,  and  the  external  carotid  and  occipital  arteries.  Higher  up,  it  is  separated 
from  the  external  carotid  by  the  Stylo-glossus  and  Stylo-pharyngeus  muscles,  the 
glossopharyngeal  nerve,  and  pharyngeal  branch  of  the  vagus.  It  is  in  relation, 
behind,  with  the  Rectus  anticus  major,  the  superior  cervical  ganglion  of  the 
sympathetic,  and  superior  laryngeal  nerve ;  externally,  with  the  internal  jugular 
vein,  and  pneumogastric  nerve ;  internally,  with  the  pharynx,  tonsil,  and  ascend- 
ing pharyngeal  artery. 

Petrous  Portion.  When  the  internal  carotid  artery  enters  the  canal  in  the 
petrous  portion  of  the  temporal  bone,  it  first  ascends  a  short  distance,  then  curves 
forwards  and  inwards,  and  again  ascends  as  it  leaves  the  canal  to  enter  the  cavity 
of  the  skull.  In  this  canal,  the  artery  lies  at  first  anterior  to  the  tympanum, 
from  which  it  is  separated  by  a  thin  bony  lamella,  which  is  cribriform  in  the 
young  subject,  and  often  absorbed  in  old  age.  It  is  separated  from  the  bony  wall 
of  the  carotid  canal  by  a  prolongation  of  dura  mater,  and  is  surrounded  by  fila- 
ments of  the  carotid  plexus. 

Cavernous  Portion.  The  internal  carotid  artery,  in  this  part  of  its  course,  at  first 
ascends  to  the  posterior  clinoid  process,  then  passes  forwards  by  the  side  of  the 
body  of  the  sphenoid  bone,  being  situated  on  the  inner  wall  of  the  cavernous 
sinus,  in  relation,  externally,  with  the  sixth  nerve,  and  covered  by  the  lining 
membrane  of  the  sinus.  The  third,  fourth,  and  ophthalmic  nerves  are  placed  on 
the  outer  wall  of  the  sinus,  being  separated  from  its  cavity  by  the  lining  membrane. 

Cerebral  Portion.  On  the  inner  side  of  the  anterior  clinoid  process  the  internal 
carotid  curves  upwards,  perforates  the  dura  mater  bounding  the  sinus,  and  is 
received  into  a  sheath  of  the  arachnoid.  This  portion  of  the  artery  is  on  the 
outer  side  of  the  optic  nerve ;  it  lies  at  the  inner  extremity  of  the  fissure  of 
Sylvius,  having  the  third  nerve  externally. 

Peculiarities.  The  length  of  the  internal  carotid  varies  according  to  the  length  of  the  neck, 
and  also  according  to  the  point  of  bifurcation  of  the  common  carotid.  Its  origin  sometimes 
takes  place  from  the  arch  of  the  aorta;  in  such  rare  instances,  this  vessel  was  placed  nearer  the 
middle  line  of  the  neck  than  the  external  carotid,  as  far  upwards  as  the  larynx,  when  the  latter 
vessel  crossed  the  internal  carotid.  The  course  of  the  vessel,  instead  of  being  straight,  may  be 
very  tortuous.  A  few  instances  are  recorded  in  which  this  vessel  was  altogether  absent :  in  one 
of  these  the  common  carotid  ascended  the  neck,  and  gave  off  the  usual  branches  of  the  external 
carotid,  the  craninl  portion  of  the  vessel  being  replaced  by  two  branches  of  the  internal  maxil- 
lary, which  entered  the  skull  through  the  foramen  rotundum  and  foramen  ovale,  and  joined  to  form 
a  single  vessel. 

Surgical  Anatomy.  The  cervical  part  of  the  internal  carotid  is  sometimes  wounded  by  a  stab 
or  gunshot  wound  in  the  neck,  or  even  occasionally  by  a  stab  from  within  the  mouth,  as  when 


OPHTHALMIC. 


387 


a  person  receives  a  thrust  from  the  end  of  a  parasol,  or  falls  down  with  a  tobacco-pipe  in  his 
mouth.  In  such  cases  a  ligature  should  be  applied  to  the  common  carotid.  Its  relation  with 
the  tonsil  should  be  especially  remembered,  as  instances  have  occurred  in  which  the  artery  has 
been  wounded,  during  the  operation  of  scarifying  the  tonsil,  and  fatal  hemorrhage  has  super- 
vened. 

The  branches  given  off  from  the  internal  carotid  are : — 

From  the  Petrous  Portion 


From  the  Cavernous  Portion 


From  the  Cerebral  Portion 


Tympanic. 
(  Arteria  receptaculi. 
<  Anterior  meningeal. 
(  Ophthalmic, 
f  Anterior  cerebral. 
J  Middle  cerebral. 
I  Posterior  communicating. 
(_  Anterior  choroid. 


The  cervical  portion  of  the  internal  carotid  gives  off  no  branches. 

The  tympanic  is  a  small  branch  which  enters  the  cavity  of  the  tympanum, 
through  a  minute  foramen  in  the  carotid  canal,  and  anastomoses  with  the  tympanic 
branch  of  the  internal  maxillary,  and  stylo-mastoid  arteries. 

The  arterise  receptaculi  are  numerous  small  vessels,  derived  from  the  internal 
carotid  in  the  cavernous  sinus ;  they  supply  the  pituitary  body,  the  Casserian  gan- 
glion, and  the  walls  of  the  cavernous  and  inferior  petrosal  sinuses.  One  of  these 
branches,  distributed  to  the  dura  mater,  is  called  the  anterior  meningeal;  it  anas- 
tomoses with  the  middle  meningeal. 

The  Ophthalmic  Artery  arises  from  the  internal  carotid,  just  as  that  vessel 
is  emerging  from  the  cavernous  sinus,  on  the  inner  side  of  the  anterior  clinoid 

Fig.  213. — The  Ophthalmic  Artery  and  its  Brandies,  the  Roof  of  the  Orbit  having  been 

removed. 

Katal  PaJfthral 

Itvntal 


AnUrior  X3i<™>Xo.1- 


Ftuttritr  JSSibo. 


Oplukalmio 


Tntemat    Carotid 


process,  and  enters  the  orbit  through  the  optic  foramen,  below,  and  on  the  outer 
side  of,  the  optic  nerve.  It  then  crosses  above,  and  to  the  inner  side  of,  this 
nerve,  to  the  inner  wall  of  the  orbit,  and  passing  horizontally  forwards,  beneath 


388  ARTERIES. 

the  lower  border  of  the  Superior  oblique  muscle,  passes  to  the  inner  angle  of  the 
eye,  where  it  divides  into  two  terminal  branches,  the  frontal  and  nasal. 

Branches.  The  branches  of  this  vessel  may  be  divided  into  an  orbital  group, 
which  are  distributed  to  the  orbit  and  surrounding  parts ;  and  an  ocular  group, 
which  supply  the  muscles  and  globe  of  the  eye. 

Orbital  Group.  Ocular  Group. 

Lachrymal.  .  Muscular. 

Supra-orbital.  Anterior  ciliary. 

Posterior  ethmoidal.  Short  ciliary. 

Anterior  ethmoidal.  Long  ciliary. 

Palpebral.  Arteria  centralis  retinae. 
Frontal. 
Nasal. 

The  lachrymal  is  the  first,  and  one  of  the  largest  branches,  derived  from  the 
ophthalmic,  arising  close  to  the  optic  foramen,  and  not  unfr^quently  from  that 
vessel  before  entering  the  orbit.  It  accompanies  the  lachrymal  nerve  along  the 
upper  border  of  the  External  rectus  muscle,  and  is  distributed  to  the  lachrymal 
gland.  Its  terminal  branches,  escaping  from  the  gland,  are  distributed  to  the 
upper  eyelid  and  conjunctiva,  anastomosing  with  the  palpebral  arteries.  The 
lachrymal  artery  gives  off  one  or  two  malar  branches,  one  of  which  passes 
through  a  foramen  in  the  malar  bone  to  reach  the  temporal  fossa,  and  anastomoses 
with  the  deep  temporal  arteries;  the  other  appears  on  the  cheek,  and  anasto- 
moses with  the  transverse  facial.  A  branch  is  also  sent  backwards,  through  the 
sphenoidal  fissure,  to  the  dura  mater,  which  anastomoses  with  a  branch  of  the 
middle  meningeal  artery. 

Peculiarities.  The  lachrymal  artery  is  sometimes  derived  from  one  of  the  anterior  branches 
of  the  middle  meningeal  artery. 

The  supra-orbital  artery,  the  largest  branch  of  the  ophthalmic,  arises  from  that 
vessel  above  the  optic  nerve.  Ascending  so  as  to  rise  above  all  the  muscles  of 
the  orbit,  it  passes  forwards,  with  the  frontal  nerve,  between  the  periosteum  and 
Levator  palpebrae ;  and,  passing  through  the  supra-orbital  foramen,  divides  into  a 
superficial  and  deep  branch,  which  supply  the  muscles  and  integument  of  the 
forehead  and  pericranium,  anastomosing  with  the  temporal,  angular  branch  of  the 
facial,  and  the  artery  of  the  opposite  side.  This  artery  in  the  orbit  supplies  the 
Superior  rectus  and  the  Levator  palpebral  sends  a  branch  inwards,  across  the 
pulley  of  the  Superior  oblique  muscle,  to  supply  the  parts  at  the  inner  canthus, 
and  at  the  supra-orbital  foramen  frequently  transmits  a  branch  to  the  diploe. 

The  ethmoidal  branches  are  two  in  number,  posterior  and  anterior.  The 
former,  which  is  the  smaller,  passes  through  the  posterior  ethmoidal  foramen, 
supplies  the  posterior  ethmoidal  cells,  and,  entering  the  cranium,  gives  off  a 
meningeal  branch,  which  supplies  the  adjacent  dura  mater,  and  nasal  branches, 
which  descend  into  the  nose  through  apertures  in  the  cribriform  plate,  anasto- 
mosing with  branches  of  the  spheno-palatine.  The  anterior  ethmoidal  artery 
accompanies  the  nasal  nerve  through  the  anterior  ethmoidal  foramen,  supplies  the 
anterior  ethmoidal  cells,  and  frontal  sinuses,  and,  entering  the  cranium,  divides 
into  a  meningeal  branch,  which  supplies  the  adjacent  dura  mater,  and  a  nasal 
branch  which  descends  into  the  nose,  through  an  aperture  in  the  cribriform 
plate. 

The  palpebral  arteries,  two  in  number,  superior  and  inferior,  arise  from  the 
ophthalmic,  opposite  the  pulley  of  the  Superior  oblique  muscle ;  they  encircle  the 
eyelids  near  their  free  margin,  forming  a  superior  and  an  inferior  arch,  which  lie 
between  the  Orbicularis  muscle  and  tarsal  cartilages;  the  superior  palpebral 
inosculating  at  the  outer  angle  of  the  orbit  with  the  orbital  branch  of  the 
temporal  artery;  the  inferior  palpebral  anastomosing  with  the  orbital  branch  of  the 
infra-orbital  artery,  at  the  inner  side  of  the  lid.     From  this  anastomosis,  a  branch 


OPIITHALMIC. 


389 


passes  to  the  nasal  duet,  ramifying,  in  its  mucous  membrane,  as  far  as  the  inferior 
meatus. 

Fig.  214.— The  Arteries  of  the  Base  of  the  Brain.     The  Right  Half  of  the  Cerebellum  and 

Pons  have  been  removed. 


The  fron tal  artery,  one  of  the  terminal  branches  of  the  ophthalmic,  passes  from 
the  orbit  at  its  inner  angle,  and,  ascending  on  the  forehead,  supplies  the  muscles, 
integument,  and  pericranium,  anastomosing  with  the  supra-orbital  artery. 

The  nasal  artery,  the  other  terminal  branch  of  the  ophthalmic,  emerges  from 
the  orbit  above  the  tendo  oculi,  and,  after  giving  a  branch  to  the  lachrymal  sac, 


390  ARTERIES. 

divides  into  two,  one  of  which  anastomoses  with  the  angular  artery ;  the  other 
branch,  the  dorsalis  nasi,  runs  along  the  dorsum  of  the  nose,  supplies  its  entire 
surface,  and  anastomoses  with  the  artery  of  the  opposite  side. 

The  ciliary  arteries  are  divisible  into  three  groups,  the  short,  long,  and 
anterior. 

The  short  ciliary .  arteries,  from  twelve  to  fifteen  in  number,  arise  from  the 
ophthalmic,  or  some  of  its  branches ;  they  surround  the  optic  nerve  as  they  pass 
forwards  to  the  posterior  part  of  the  eyeball,  pierce  the  sclerotic  coat  around  the 
entrance  of  this  nerve,  and  supply  the  choroid  coat  and  ciliary  processes. 

The  long  ciliary  arteries,  two  in  number,  also  pierce  the  posterior  part  of  the 
sclerotic,  and  run  forwards,  along  each  side  of  the  eyeball,  between  the  sclerotic 
and  choroid,  to  the  ciliary  ligament,  where  they  divide  into  two  branches ;  these 
form  an  arterial  circle  around  the  circumference  of  the  iris,  from  which  numerous 
radiating  branches  pass  forwards,  in  its  substance,  to  its  free  margin,  where  they 
form  a  second  arterial  circle  around  its  pupillary  margin. 

The  anterior  ciliary  arteries  are  derived  from  the  muscular  branches;  they 
pierce  the  sclerotic  a  short  distance  from  the  cornea,  and  terminate  in  the  great 
arterial  circle  of  the  iris. 

The  arteria  centralis  retinse  is  one  of  the  smallest  branches  of  the  ophthalmic 
artery.  It  arises  near  the  optic  foramen,  pierces  the  optic  nerve  obliquely,  and 
runs  forwards,  in  the  centre  of  its  substance,  to  the  retina,  in  which  its  branches 
are  distributed  as  far  forwards  as  the  ciliary  processes.  In  the  human  foetus,  a 
small  vessel  passes  forwards,  through  the  vitreous  humor,  to  the  posterior  surface 
of  the  capsule  of  the  lens. 

The  muscular  branches,  two  in  number,  superior  and  inferior,  supply  the 
muscles  of  the  eyeball.  The  superior,  the  smaller,  often  wanting,  supplies  the 
Levator  palpebrse,  Superior  rectus,  and  Superior  oblique.  The  inferior,  more 
constant  in  its  existence,  passes  forwards,  between  the  optic  nerve  and  Inferior 
rectus,  and  is  distributed  to  the  External  and  Inferior  recti,  and  Inferior  oblique. 
This  vessel  gives  off  most  of  the  anterior  ciliary  arteries. 

The  Cerebral  Branches  of  the  internal  carotid  are,  the  anterior  cerebral,  the 
middle  cerebral,  the  posterior  communicating,  and  the  anterior  choroid. 

The  anterior  cerebral  arises  from  the  internal  carotid,  at  the  inner  extremity  of 
the  fissure  of  Sylvius.  It  passes  forwards  in  the  great  longitudinal  fissure  between 
the  two  anterior  lobes  of  the  brain,  being  connected,  soon  after  its  origin,  with  the 
vessel  of  the  opposite  side  by  a  short  anastomosing  trunk,  about  two  lines  in  length, 
the  anterior  communicating.  The  two  anterior  cerebral  arteries,  lying  side  by  side, 
curve  round  the  anterior  border  of  the  corpus  callosum,  and  run  along  its  upper 
surface  to  its  posterior  part,  where  they  terminate  by  anastomosing  with  the 
posterior  cerebral  arteries.  They  supply  the  olfactory  and  optic  nerves,  the  under 
surface  of  the  anterior  lobes,  the  third  ventricle,  the  anterior  perforated  space, 
the  corpus  callosum,  and  the  inner  surface  of  the  hemispheres. 

The  anterior  communicating  artery  is  a  short  branch,  about  two  lines  in  length, 
but  of  moderate  size,  connecting  together  the  two  anterior  cerebral  arteries  across 
the  longitudinal  fissure.  Sometimes  this  vessel  is  wanting,  the  two  arteries  joining 
together  to  form  a  single  trunk,  which  afterwards  subdivides ;  or  the'  vessel  may 
be  wholly  or  partially  subdivided  into  two ;  frequently,  it  is  longer  and  smaller 
than  usual. 

The  middle  cerebral  artery,  the  largest  branch  of  the  internal  carotid,  passes 
obliquely  outwards  along  the  fissure  of  Sylvius,  within  which  it  divides  into  three 
branches :  an  anterior,  which  supplies  the  pia  mater,  investing  the  surface  of  the 
anterior  lobe ;  a  posterior,  which  supplies  the  middle  lobe ;  and  a  median  branch, 
which  supplies  the  small  lobe  at  the  outer  extremity  of  the  Sylvian  fissure.  Near 
its  origin,  this  vessel  gives  off  numerous  small  branches,  which  enter  the  substantia 
perforata,  to  be  distributed  to  the  corpus  striatum. 

The  2losier"l'or  communicating  artery  arises  from  the  back  part  of  the  internal 
carotid,  runs  directly  backwards,  and  anastomoses  with  the  posterior  cerebral,  a 


SUBCLAVIAN.  391 

branch  of  the  basilar.  This  artery  varies  considerably  in  size,  being  sometimes 
small,  and  occasionally  so  large  that  the  posterior  cerebral  may  be  considered  as 
arising  from  the  internal  carotid  rather  than  from  the  basilar.  It  is  frequently 
larger  on  one  side  than  on  the  other. 

The  anterior  choroid  is  a  small  but  constant  branch  which  arises  from  the  back 
part  of  the  internal  carotid,  near  the  posterior  communicating  artery.  Passing 
backwards  and  outwards,  it  enters  the  descending  horn  of  the  lateral  ventricle, 
beneath  the  edge  of  the  middle  lobe  of  the  brain.  It  is  distributed  to  the  hippo- 
campus major,  corpus  flmbriatum,  and  choroid  plexus. 

ARTERIES  OF  THE  UPPER  EXTREMITY. 

The  artery  which  supplies  the  upper  extremity,  continues  as  a  single  trunk  from 
its  commencement,  as  far  as  the  elbow ;  but  different  portions  of  it  have  received 
different  names,  according  to  the  region  through  which  it  passes.  Thus,  that 
part  of  the  vessel  which  extends  from  its  origin,  as  far  as  the  outer  border  of 
the  first  rib,  ds  termed  the  subclavian ;  beyond  this  point  to  the  lower  border  of 
the  axilla,  it  is  termed  the  axillary ;  and  from  the  lower  margin  of  the  axillary 
space  to  the  bend  of  the  elbow,  it  is  termed  the  brachial ;  here,  the  single  trunk 
terminates  by  dividing  into  two  branches,  the  radial  and  ulnar,  an  arrangement 
precisely  similar  to  what  occurs  in  the  lower  limb. 

Subclavian  Aeteries. 

The  Subclavian  Artery  on  the  right  side  arises  from  the  arteria  innominata, 
opposite  the  right  sterno-clavicular  articulation ;  on  the  left  side,  it  arises  from  the 
arch  of  the  aorta.  It  follows,  therefore,  that  these  two  vessels  must,  in  the  first 
part  of  their  course,  differ  in  their  length,  their  direction,  and  in  their  relation 
with  neighboring  parts. 

In  order  to  facilitate  the  description  of  these  vessels,  more  especially  in  a  sur- 
gical point  of  view,  each  subclavian  artery  has  been  divided  into  three  parts. 
The  first  portion,  on  the  right  side,  ascends  obliquely  outwards,  from  the  origin  of 
the  vessel  to  the  inner  border  of  the  Scalenus  anticus.  On  the  left  side,  it  ascends 
perpendicularly  to  the  inner  border  of  that  muscle.  The  second  part  passes  out- 
wards, behind  the  Scalenus  anticus;  and  the  third  part  passes  from  the  outer 
margin  of  that  muscle,  beneath  the  clavicle,  to  the  lower  border  of  the  first  rib, 
where  it  becomes  the  axillary  artery.  The  first  portions  of  these  two  vessels  differ 
so  much  in  their  course,  and  in  their  relation  with  neighboring  parts,  that  they 
will  be  described  separately.  The  second  and  third  parts  are  precisely  alike  on 
both  sides. 

First  Part  of  the  Right  Subclavian  Artery  (figs.  205  and  207). 

It  arises  from  the  arteria  innominata,  opposite  the  right  sterno-clavicular  arti- 
culation, passes  upwards  and  outwards  across  the  root  of  the  neck,  and  terminates 
at  the  inner  margin  of  the  Scalenus  anticus  muscle.  In  this  part  of  its  course,  it 
ascends  a  little  above  the  clavicle,  the  extent  to  which  it  does  so  varying  in  different 
cases.  It  is  covered,  in  front,  by  the  integument,  •  superficial  fascia,  Platysma,  deep 
fascia,  the  clavicular  origin  of  the  Sterno-mastoid,  the  Sterno-hyoid  and  Sterno- 
thyroid muscles,  and  another  layer  of  the  deep  fascia.  It  is  crossed  by  the 
internal  jugular  and  vertebral' veins,  and  by  the  pneumogastric,  the  cardiac 
branches  of  the  sympathetic,  and  phrenic  nerves.  Beneath,  the  artery  is  invested 
by  the  pleura,  and  behind,  it  is  separated  by  a  cellular  interval  from  the  Longus 
colli,  the  transverse  process  of  the  seventh  cervical  vertebra,  and  the  sympathetic; 
the  recurrent  laryngeal  nerve  winding  around  the  lower  and  back  part  of  this 
vessel.  The  subclavian  vein  lies  below  the  subclavian  artery,  immediately  behind 
the  clavicle. 


392  ARTERIES. 


Plan  of  Relations  of  First  Portion  of  Right  Subclavian  Artery. 

In  front. 
Integument  and  superficial  fascia. 
Platysma  and  deep  fascia. 
Clavicular  origin  of  Sterno-mastoid. 
Sterno-hyoid  and  Sterno-thyroid. 
Internal  jugular  and  vertebral  veins. 
Pneumogastric,  cardiac,  and  phrenic  nerves. 


Beneath. 
Pleura. 


Behind. 
Recurrent  laryngeal  nerve. 
Sympathetic. 

Longus  colli.  , 

Transverse  process  of  seventh  cervical  vertebra. 

First  Part  of  the  Left  Subclavian  Artery  (fig.  205). 

It  arises  from  the  end  of  the  transverse  portion  of  the  arch  of  the  aorta,  oppo- 
site the  second  dorsal  vertebra,  and  ascends  to  the  inner  margin  of  the  first  rib, 
behind  the  insertion  of  the  Scalenus  anticus  muscle.  This  vessel  is,  therefore, 
longer  than  the  right,  situated  more  deeply  in  the  cavity  of  the  chest,  and 
directed  almost  vertically  upwards,  instead  of  arching  outwards  like  the  vessel  of 
the  opposite  side. 

It  is  in  relation,  in  front,  with  the  pleura,  the  left  lung,  the  pneumogastric, 
phrenic,  and  cardiac  nerves,  which  lie  parallel  with  it,  the  left  carotid  artery,  left 
internal  jugular  and  innominate  veins,  and  is  covered  by  the  Sterno-thyroid, 
Sterno-hyoid,  and  Sterno-mastoid  muscles ;  behind,  with  the  oesophagus,  thoracic 
duct,  inferior  cervical  ganglion  of  the  sympathetic,  Longus  colli,  and  vertebral 
column.  To  its  inner  side,  are  the  oesophagus,  trachea,  and  thoracic  duct ;  to  its 
outer  side,  the  pleura. 

Plan  of  Relations  of  First  Portion  of  Left  Subclavian  Artery. 

In  front. 
Pleura  and  left  lung. 

Pneumogastric,  cardiac,  and  phrenic  nerves. 
Left  carotid  artery. 

Left  internal  jugular  and  innominate  veins. 
Sterno-thyroid,  Sterno-hyoid,  and  Sterno-mastoid  muscles. 

Inner  side.  /  \  Outer  side. 

(Esophagus.  /  _  tL,eft.       \  Pleura. 

I rachea. 
Thoracic  duct. 

Behind. 
(Esophagus  and  thoracic  duct. 
Inferior  cervical  ganglion  of  sympathetic. 
Longus  colli  and  vertebral  column. 

The  relations  of  the  second  and  third  portions  of  the  subclavian  arteries  are 
precisely  similar  on  both  sides. 

The  Second  Portion  of  the  Subclavian  Artery  lies  between  the  two  Scaleni 
muscles ;  it  is  very  short,  and  forms  the  highest  part  of  the  arch  described  by  that 
vessel. 


SUBCLAVIAN. 


393 


Relations.  It  is  covered,  in  front,  by  the  integument,  Platysma,  Sterno-  mastoid, 
cervical  fascia,  and  by  the  phrenic  nerve,  which  is  separated  from  the  artery  by 
the  Scalenus  anticus  muscle.  Behind,  it  is  in  relation  with  the  Middle  scalenus. 
Above,  with  the  brachial  plexus  of  nerves.  Below,  with  the  pleura.  The  sub- 
clavian vein  lies  below  and  in  front  of  the  artery,  separated  from  it  by  the  Scalenus 
anticus.    „ 

Plan  of  Eelations  of  Second  Portion  of  Subclavian  Artery. 

In  front. 


Platysma. 
Stern  o-mastoid. 
Cervical  fascia. 


Scalenus  anticus. 
Phrenic  nerve. 

Subclavian  Vein. 


Above. 
Brachial  plexus. 


Beloio. 
Pleura. 


Behind. 
Middle  scalenus. 

The  Third  Portion  of  the  Subclavian  Artery  passes  downwards  and  outwards 
from  the  outer  margin  of  the  Scalenus  anticus  to  the  lower  border  of  the  first 
rib,  where  it  becomes  the  axillary  artery.  This  portion  of  the  vessel  is  the  most 
superficial,  and  is  contained  in  a  triangular  space,  the  base  of  which  is  formed  in 
front  by  the  Anterior  scalenus,  and  the  two  sides  by  the  Omo-hyoid  above  and 
the  clavicle  below. 

Relations.  It  is  covered,  in  front,  by  the  integument,  the  superficial  fascia,  the 
Platysma,  deep  fascia ;  and  by  the  clavicle,  the  Subclavius  muscle,  and  the  supra- 
scapular artery  and  vein;  the  clavicular  descending  branches  of  the  cervical 
plexus  and  the  nerve  to  the  Subclavius  pass  vertically  downwards  in  front  of  the 
artery.  The  external  jugular  vein  crosses  it  at  its  inner  side,  and  receives  the 
suprascapular  and  transverse  cervical  veins,  which  occasionally  form  a  plexus  in 
front  of  it.  The  subclavian  vein  is  below  the  artery,  lying  close  behind  the 
clavicle.  Behind,  it  lies  on  the  Middle  scalenus  muscle.  Above  it,  and  to  its 
outer  side,  are  the  brachial  plexus  and  Omo-hyoid  muscle.  Below,  it  rests  on  the 
outer  surface  of  the  first  rib. 


Plan  of  Eelations  of  Third  Portion  of  Subclavian  Artery. 

In  front. 

Integument,  fasciae,  and  Platysma. 

The  external  jugular,  suprascapular,  and  transverse  cervical  veins. 

Descending  branches  of  cervical  plexus. 

Subclavius  muscle,  suprascapular  artery,  and  clavicle. 


Above. 
Brachial  plexus. 
Omo-hyoid. 


Below. 
First  rib. 


Behind. 
Scalenus  medius. 

Peculiarities.  The  subclavian  arteries  vary  in  their  origin,  their  course,  and  in  the  height  to 
which  they  rise  in  the  neck. 

The  origin  of  the  right  subclavian  from  the  innominate  takes  place,  in  some  cases,  above  the 
sterno-clavicular  articulation;  more  frequently  in  the  cavity  of  the  thorax,  below  that  joint.     Or 


394  ARTERIES. 

the  artery  may  arise  as  a  separate  trunk  from  the  arch  of  the  aorta ;  in  such  cases  it  may  be 
either  the  first,  second,  third,  or  even  the  last  branch  derived  from  that  vessel:  in  the  majority 
of  cases,  it  is  the  first  or  last,  rarely  the  second  or  third. 

When  it  is  the  first  branch,  it  occupies  the  ordinary  position  of  the  innominate  artery;  when 
the  second  or  third,  it  gains  its  usual  position  by  passing  behind  the  right  carotid ;  and  when  the 
last  branch,  it  arises  from  the  left  extremity  of  the  arch,  at  its  upper  or  back  part,  and  passes 
obliquely  towards  the  right  side,  behind  the  oesophagus  and  right  carotid,  sometimes  between  the 
oesophagus  and  trachea,  to  the  upper  border  of  the  first  rib,  where  it  follows  its  ordinary  course. 
In  very  rare  instances,  this  vessel  arises  from  the  thoracic  aorta,  as  low  down  as  the  fourth  dorsal 
vertebra.  Occasionally  it  perforates  the  Anterior  scalenus  ;  more  rarely  it  passes  in  front  of  this 
muscle :  sometimes  the  subclavian  vein  passes  with  the  artery  behind  the  Scalenus.  The  artery 
sometimes  ascends  as  high  as  an  inch  and  a  half  above  the  clavicle,  or  to  any  intermediate  point 
between  this  and  the  upper  border  of  this  bone,  the  right  subclavian  usually  ascending  higher 
than  the  left. 

The  left  subclavian  is  occasionally  joined  at  its  origin  with  the  left  carotid. 

Surgical  Anatomy.  The  relations  of  the  subclavian  arteries  of  the  two  sides  having  been 
examined,  the  student  should  direct  his  attention  to  consider  the  best  position  in  which  compres- 
sion of  the  vessel  may  be  effected,  or  in  what  situation  a  ligature  may  be  best  applied  in  cases  of 
aneurism  or  wounds. 

Compression  of  the  subclavian  artery  is  required  in  cases  of  operations  about  the  shoulder,  in 
the  axilla,  or  at  the  upper  part  of  the  arm  ;  and  the  student  will  observe  that  there  is  only  one 
situation  in  which  it  can  be  effectually  applied,  viz.,  where  the  artery  passes  across  the  outer 
surface  of  the  first  rib.  In  order  to  compress  the  vessel  in  this  situation,  the  shoulder  should  be 
depressed,  and  the  surgeon,  grasping  the  side  of  the  neck,  may  press  with  his  thumb  in  the  hollow 
behind  the  clavicle  downwards  against  the  rib  ;  if  from  any  cause  the  shoulder  cannot  be  suffi- 
ciently depressed,  pressure  may  be  made  from  before  backwards,  so  as  to  compress  the  artery 
against  the  Middle  scalenus  and  transverse  process  of  the  seventh  cervical  vertebra. 

Ligature  of  the  subclavian  artery  may  be  required  in  cases  of  wounds  of  the  axillary  artery,  or 
in  aneurism  of  that  vessel ;  and  the  third  part  of  the  artery  is  consequently  that  which  is  most 
favorable  for  such  an  operation,  on  account  of  its  being  comparatively  superficial,  and  most  re- 
mote from  the  origin  of  the  large  branches.  In  those  cases  where  the  clavicle  is  not  displaced, 
this  operation  may  be  performed  with  comparative  facility ;  but  where  the  clavicle  is  elevated 
from  the  presence  of  a  large  aneurismal  tumor  in  the  axilla,  the  artery  is  placed  at  a  great  depth 
from  the  surface,  which  materially  increases  the  difficulty  of  the  operation.  Under  these  circum- 
stances, it  becomes  a  matter  of  importance  to  consider  the  height  to  which  this  vessel  reaches 
above  the  bone.  In  ordinary  cases,  its  arch  is  about  half  an  inch  above  the  clavicle,  occasionally 
as  high  as  an  inch  and  a  half,  and  sometimes  so  low  as  to  be  on  a  level  with  its  upper  border. 
If  displacement  of  the  clavicle  occurs,  these  variations  will  necessarily  make  the  operation  more 
or  less  difficult,  according  as  the  vessel  is  more  or  less  accessible. 

The  chief  points  in  the  operation  of  tying  the  third  portion  of  the  subclavian  artery  are  as  fol- 
lows :  The  patient  being  placed  on  a  table  in  the  horizontal  position,  and  the  shoulder  depressed 
as  much  as  possible,  the  integument  should  be  drawn  downwards  upon  the  clavicle  and  an  inci- 
sion made  through  it  upon  that  bone  from  the  anterior  border  of  the  Trapezius  to  the  posterior 
border  of  the  Sterno-mastoid,  to  which  may  be  added  a  short  vertical  incision  meeting  the  centre 
of  the  preceding;  the  Platysma  and  cervical  fascia  should  be  divided  upon  a  director,  and  if  the 
interval  between  the  Trapezius  and  Sterno-mastoid  muscles  be  insufficient  for  the  performance 
of  the  operation,  a  portion  of  one  or  both  -may  be  divided.  The  external  jugular  vein  will  now  be 
seen  towards  the  inner  side  of  the  wound ;  this  and  the  suprascapular  and  transverse  cervical  veins 
which  terminate  in  it  should  be  held  aside,  and  if  divided  both  ends  should  be  included  in  a  ligature  : 
the  suprascapular  artery  should  be  avoided,  and  the  Omo-hyoid  muscle  must  now  be  looked  for, 
and  held  aside  if  necessary.  In  the  space  beneath  this  muscle,  careful  search  must  be  made  for 
the  vessel ;  the  deep  fascia  having  been  divided  with  the  finger-nail  or  silver  scalpel,  the  outer 
margin  of  the  Scalenus  muscle  must  be  felt  for,  and  the  finger  being  guided  by  it  to  the  first  rib, 
the  pulsation  of  the  subclavian  artery  will  be  felt  as  it  passes  over  its  surface.  The  aneurism 
needle  may  then  be  passed  around  the  vessel  from  before  backwards,  by  which  means  the  vein 
will  be  avoided,  care  being  taken  not  to  include  a  branch  of  the  brachial  plexus  instead  of  the 
artery  in  the  ligature.  If  the  clavicle  is  so  raised  by  the  tumor  that  the  application  of  the  liga- 
ture cannot  be  effected  in  this  situation,  the  artery  may  be  tied  above  the  first  rib,  or  even  behind 
the  Scalenus  muscle :  the  difficulties  of  the  operation  in  such  a  case  will  be  materially  increased, 
on  account  of  the  greater  depth  of  the  artery,  and  alteration  of  the  surrounding  parts. 

The  second  division  of  the  subclavian  artery,  from  being  that  portion  which  rises  highest 
in  the  neck,  has  been  considered  favorable  for  the  application  of  the  ligature,  where  it  is  diffi- 
cult to  apply  it  in  the  third  part  of  its  course.  There  are,  however,  many  objections  to  the 
operation  in  this  situation.  It  is  necessary  to  divide  the  Scalenus  anticus  muscle,  upon  which 
lies  the  phrenic  nerve,  and  at  the  inner  side  of  which  is  situated  the  internal  jugular  vein;  a 
wound  of  either  of  these  structures  might  lead  to  the  most  dangerous  consequences.  Again,  the 
artery  is  in  contact,  below,  with  the  pleura,  which  must  also  be  avoided ;  and,  lastly,  the  prox- 
imity of  so  many  of  its  larger  branches  arising  internal  to  this  point,  must  be  a  still  further 


SUBCLAVIAN. 


395 


objection  to  the  operation.  If,  however,  it  has  been  determined  upon  to  perform  the  operation 
in  this  situation,  it  should  be  remembered  that  it  occasionally  happens,  that  the  artery  passes  in 
front  of  the  Scalenus  anticus,  or  through  the  fibres  of  that  muscle ;  or  that  the  vein  sometimes 
passes  with  the  artery  behind  the  Scalenus  anticus. 

In  those  cases  of  aneurism  of  the  axillary  or  subclavian  artery  which  encroach  upon  the  outer 
portion  of  the  Scalenus  muscle  to  such  an  extent  that  a  ligature  cannot  be  applied  in  that  situa- 
tion, it  may  be  deemed  advisable,  as  a  last  resource,  to  tie  the  first  portion  of  the  subclavian 
artery.  On  the  left  side,  this  operation  is  quite  impracticable ;  the  great  depth  of  the  artery 
from  the  surface,  its  intimate  relation  with  the  pleura,  and  its  close  proximity  with  so  many  im- 
portant veins  and  nerves,  present  a  series  of  difficulties  which  it  is  impossible  to  overcome.  On 
the  right  side,  the  operation  is  practicable,  and  has  been  performed,  though  not  with  success. 
The  main  objection  to  the  operation  in  this  situation  is  the  smallness  of  the  interval  which  usu- 
ally exists  between  the  commencement  of  the  vessel,  and  the  origin  of  the  nearest  branch. 
This  operation  may  be  performed  in  the  following  manner.  The  patient  being  placed  on  a 
table  in  the  horizontal  position,  with  the  neck  extended,  an  incision  should  be  made  parallel  with 
the  inner  part  of  the  clavicle,  and  a  second  along  the  inner  border  of  the  Sterno-mastoid.  meet- 
ing it  at  right  angles.  The  sternal  attachment  of  the  Sterno-mastoid  may  now  be  divided  on  a 
director,  and  turned  outwards ;  a  few  small  arteries  and  veins,  and  occasionally  the  anterior 
jugular,  must  be  avoided,  and  the  Sterno-hyoid  and  Sterno-thyroid  muscles  divided  in  the  same 
manner  as  the  preceding  muscle.  After  tearing  through  the  deep  fascia  with  the  finger-nail,  the 
internal  jugular  vein  will  be  seen  crossing  the  artery  ;  this  should  be  pressed  aside,  and  the  artery 
secured  by  passing  the  needle  from  below  upwards,  by  which  the  pleura  is  more  effectually  avoided. 
The  exact  position  of  the  vagus  nerve,  the  recurrent  laryngeal,  the  phrenic  and  sympathetic 
nerves,  should  be  remembered,  and  the  ligature  should  be  applied  near  the  origin  of  the  vertebral, 
in  order  to  afford  as  much  room  as  possible  for  the  formation  of  a  coagulum  between  the  ligature 
and  the  origin  of  the  vessel.  It  should  be  remembered,  that  the  right  subclavian  artery  is  occa- 
sionally deeply  placed  in  the  first  part  of  its  course,  when  it  arises  from  the  left  side  of  the  aortic 
arch,  and  passes  in  such  cases  behind  the  oesophagus,  or  between  it  and  the  trachea. 

Collateral  Circulation.  After  ligation  of  the  third  part  of  the  subclavian  artery,  the  collate- 
ral circulation  is  mainly  established  by  three  sets  of  vessels,  as  was  described  in  a  case  of  axillary 
aneurism,  in  which  Mr,  Aston  Key  had  tied  the  subclavian  artery  on  the  outer  edge  of  the 
Scalenus  muscle,  twelve  years  previously.1 

"  1.  A  posterior  set,  consisting  of  the  suprascapular  and  posterior  scapular  branches  of  the 
subclavian,  which  anastomosed  with  the  infrascapular  from  the  axillary. 

"  2.  An  internal  set,  produced  by  the  connection  of  the  internal  mammary  on  the  one  hand, 
with  the  short  and  long  thoracic  arteries,  and  the  infrascapular,  on  the  other. 

"3.  A  middle  or  axillary  set,  which  consisted  of  a  number  of  small  vessels  derived  from 
branches  of  the  subclavian,  above ;  and  passing  through  the  axilla,  to  terminate  either  in  the 
main  trunk,  or  some  of  the  branches  of  the  axillary,  below.  This  last  set  presented  most  con- 
spicuously the  peculiar  character  of  newly-formed,  or,  rather,  dilated  arteries,"  being  excessively 
tortuous,  and  forming  a  complete  plexus. 

"The  chief  agent  in  the  restoration  of  the  axillary  artery  below  the  tumor,  was  the  infra- 
scapular artery,  which  communicated  most  freely  with  the  internal  mammary,  suprascapular,  and 
posterior  scapular  branches  of  the  subclavian,  from  all  of  which  it  received  so  great  an  influx 
of  blood  as  to  dilate  it  to  three  times  its  natural  size." 


Branches  of  the  Subclavian  Artery. 


These  are  four  in  number.  Three 
arising  from  the  first  portion  of  the  vessel, 
the  vertebra],  the  internal  mammary,  and 
the  thyroid  axis ;  and  one  from  the  second 
portion,  the  superior  intercostal.  The 
vertebral  arises  from  the  upper  and  back 
part  of  the  first  portion  of  the  arterj^ ;  the 
thyroid  axis  from  the  front,  and  the  in- 
ternal mammary  from  the  under  part  of 
this  vessel.  The  superior  intercostal  is 
given  off  from  the  upper  and  back  part 
of  the  second  portion  of  the  artery.  On 
the  left  side,  the  second  portion  usually 
gives  off  no  branch,  the  superior  inter- 


Fig.  215. — Plan  of  the  Branches  of  the 
Subclavian  Artery. 


Right 


1  Guy's  Hospital  Reports,  vol.  i.  1836. 


396  'ARTERIES. 

costal  arising  at  the  inner  side  of  the  Scalenus  anticus.  On  both  sides  of  the  body, 
the  first  three  branches  arise  close  together  at  the  inner  margin  of  the  Scalenus 
anticus ;  in  the  majority  of  cases,  a  free  interval  of  half  an  inch  to  an  inch  exist- 
ing between  the  commencement  of  the  artery  and  the  origin  of  the  nearest  branch  ; 
in  a  smaller  number  of  cases,  an  interval  of  more  than  an  inch  existed,  never 
exceeding  an  inch  and  three-quarters.  In  a  very  few  instances,  the  interval  was 
less  than  half  an  inch. 

The  Vertebral  Artery  (fig.  212)  is  generally  the  first  and  largest  branch  of 
the  subclavian ;  it  arises  from  the  upper  and  back  part  of  the  first  portion  of  the 
vessel,  and,  passing  upwards,  enters  the  foramen  in  the  transverse  process  of  the 
sixth  cervical  vertebra,  and  ascends  through  the  foramina  in  the  transverse  processes 
of  all  the  vertebra?  above  this.  Above  the  upper  border  of  the  axis,  it  inclines  out- 
wards and  upwards  to  the  foramen  in  the  transverse  process  of  the  atlas,  through 
which  it  passes ;  it  then  winds  backwards  behind  its  articular  process,  runs  in  a 
deep  groove  on  the  surface  of  the  posterior  arch  of  this  bone,  and,  piercing  the 
posterior  occipito-atloid  ligament  and  dura  mater,  enters  the  skull  through  the 
foramen  magnum.  It  then  passes  in  front  of  the  medulla  oblongata,  and  unites 
writh  the  vessel  of  the  opposite  side  at  the  lower  border  of  the  pons  Varolii,  to 
form  the  basilar  artery. 

At  its  origin,  it  is  situated  behind  the  internal  jugular  vein,  and  inferior  thyroid 
artery ;  and,  near  the  spine,  lies  between  the  Longus  colli  and  Scalenus  anticus 
muscles,  having  the  thoracic  duct  in  front  of  it  on  the  left  side.  Within  the  foramina 
formed  by  the  transverse  processes  of  the  vertebrae,  it  is  accompanied  by  a  plexus 
of  nerves  from  the  sympathetic,  and  lies  between  the  vertebral  vein,  which  is  in 
front,  and  the  cervical  nerves,  which  issue  from  the  intervertebral  foramina  behind 
it.  Whilst  winding  round  the  articular  process  of  the  atlas,  it  is  contained  in  a 
triangular  space  formed  by  the  Rectus  posticus  minor,  the  Superior  and  Inferior 
oblique  muscles ;  and  it  is  covered  by  the  Rectus  posticus  major  and  Complexus. 
Within  the  skull,  as  it  winds  round  the  medulla  oblongata,  it  is  placed  between 
the  hypoglossal  and  anterior  root  of  the  suboccipital  nerves. 

Branches.  These  may  be  divided  into  two  sets,  those  given  off  in  the  neck,  and 
those  within  the  cranium. 

Cervical  Branches.  Cranial  Branches. 

Lateral  spinal.  Posterior  meningeal. 

Muscular.  Anterior  spinal. 

Posterior  spinal. 

Inferior  cerebellar. 

The  lateral  spinal  branches  enter  the  spinal  canal  through  the  intervertebral 
foramina,  each  dividing  into  two  branches.  Of  these,  one  passes  along  the  roots 
of  the  nerves,  to  supply  the  spinal  cord  and  its  membranes,  anastomosing  with  the 
other  spinal  arteries ;  the  other  is  distributed  to  the  posterior  surface  of  the  bodies 
of  the  vertebrae. 

Musctdar  branches  are  given  off  to  the  deep  muscles  of  the  neck,  where  the 
vertebral  artery  curves  round  the  articular  process  of  the  atlas.  They  anastomose 
with  the  occipital  and  deep  cervical  arteries. 

The  posterior  meningeal  are  one  or  two  small  branches  given  off  from  the  ver- 
tebral opposite  the  foramen  magnum.  They  ramify  between  the  bone  and  dura 
mater  in  the  cerebellar  fossa?,  and  supply  the  falx  cerebelli. 

The  anterior  spinal  is  a  small  branch,  larger  than  the  posterior  spinal,  which 
arises  near  the  termination  of  the  vertebral,  and  unites  with  its  fellow  of  the 
opposite  side  in  front  of  the  medulla  oblongata.  The  single  trunk  thus  formed 
descends  a  short  distance  on  the  front  of  the  spinal  cord,  and  joins  with  a 
succession  of  small  branches  which  enter  the  spinal  canal  through  some  of  the 
intervertebral  foramina ;  these  branches  are  derived  from  the  vertebral  and  ascend- 
ing cervical,  in  the  neck ;  fronTthe  intercostal,  in  the  dorsal  region ;  and  from  the 


VERTEBRAL.  397 

xumbar,  iliolumbar,  and  lateral  sacral  arteries  in  the  lower  part  of  the  spine.  They 
unite,  by  means  of  ascending  and  descending  branches,  to  form  a  single  anterior 
median  artery,  which  extends  as  far  as  the  lower  part  of  the  spinal  cord.  This 
vessel  is  placed  beneath  the  pia  mater  along  the  anterior  median  fissure ;  it  supplies 
that  membrane  and  the  substance  of  the  cord,  and  sends  oft'  branches  at  its  lower 
part,  to  be  distributed  to  the  cauda  equina. 

The  posterior  spinal  arises  from  the  vertebral,  at  the  side  of  the  medulla  ob- 
longata; passing  backwards  to  the  posterior  aspect  of  the  spinal  cord,  it  descends 
on  either  side,  lying  behind  the  posterior  roots  of  the  spinal  nerves ;  and  is  re- 
inforced by  a  succession  of  small  branches,  which  enter  the  spinal  canal  through 
the  intervertebral  foramina,  and  by  which  it  is  continued  to  the  lower  part  of  the 
cord,  and  to  the  cauda  equina.  Branches  from  these  vessels  form  a  free  anastomosis 
round  the  posterior  roots  of  the  spinal  nerves,  and  communicate,  by  means  of  very 
tortuous  transverse  branches,  with  the  vessel  of  the  opposite  side.  At  its  com- 
mencement, it  gives  off  an  ascending  branch,  which  terminates  on  the  side  of  the 
fourth  ventricle. 

The  inferior  cerebellar  artery,  the  largest  branch  of  the  vertebral,  winds  back- 
wards round  the  upper  part  of  the  medulla  oblongata,  passing  between  the  origin 
of  the  spinal  accessory  and  pneumogastric  nerves,  over  the  restiform  body,  to  the 
under  surface  of  the  cerebellum,  where  it  divides  into  two  branches ;  an  internal 
one,  which  is  continued  backwards  to  the  notch  between  the  two  hemispheres  of 
the  cerebellum ;  and  an  external  one,  which  supplies  the  under  surface  of  the 
cerebellum,  as  far  as  its  outer  border,  where  it  anastomoses  with  the  superior 
cerebellar.  Branches  from  this  artery  supply  the  choroid  plexus  of  the  fourth 
ventricle. 

The  Basilar  artery,  so  named  from  its  position  at  the  base  of  the  skull,  is  a 
single  trunk,  formed  by  the  junction  of  the  two  vertebral  arteries ;  it  extends 
from  the  posterior  to  the  anterior  border  of  the  pons  Varolii,  where  it  divides 
into  two  terminal  branches,  the  posterior  cerebral  arteries.  Its  branches  are,  on 
each  side,  the  following: — 

Transverse.  Superior  cerebellar. 

Anterior  cerebellar.  Posterior  cerebral. 

The  transverse  branches  supply  the  pons  Varolii  and  adjacent  parts  of  the 
brain ;  one  accompanies  the  auditory  nerve  into  the  internal  auditory  meatus : 
and  another,  of  larger  size,  passes  along  the  crus  cerebelli,  to  be  distributed  to 
the  anterior  border  of  the  under  surface  of  the  cerebellum.  It  is  called  the 
anterior  (inferior)  cerebellar  artery. 

The  superior  cerebellar  arteries  arise  near  the  termination  of  the  basilar.  They 
wind  round  the  crus  cerebri,  close  to  the  fourth  nerve,  and,  arriving  at  the  upper 
surface  of  the  cerebellum,  divide  into  branches  which  supply  the  pia  mater, 
covering  its  surface,  anastomosing  with  the  inferior  cerebellar.  It  gives  several 
branches  to  the  pineal  gland,  and  also  to  the  velum  interpositum. 

The  posterior  cerebral  arteries,  the  two  terminal  branches  of  the  basilar,  are 
larger  than  the  preceding,  from  which  they  are  separated  near  their  origin  by  the 
third  nerves.  Winding  round  the  crus  cerebri,  they  pass  to  the  under  surface  of 
the  posterior  lobes  of  the  cerebrum,  which  they  supply,  anastomosing  with  the 
anterior  and  middle  cerebral  arteries.  Near  their  origin,  they  give  oft*  numerous 
branches,  which  enter  the  posterior  perforated  spot,  and  receive  the  posterior 
communicating  arteries  from  the  internal  carotid.  They  also  give  off  a  branch, 
the  posterior  choroid,  which  supplies  the  velum  interpositum  and  choroid  plexus, 
entering  the  interior  of  the  brain,  beneath  the  posterior  border  of  the  corpus 
callosum. 

Circle  of  Willis.  The  remarkable  anastomosis  which  exists  between  the  branches 
of  the  internal  carotid  and  vertebral  arteries  at  the  base  of  the  brain,  constitutes 
the  circle  of  "Willis.  It  is  formed,  in  front,  by  the  anterior  cerebral  and  anterior 
communicating  arteries ;  on  each  side,  by  the  trunk  of  the  internal  carotid,  and  the 


398  ARTERIES. 

posterior  communicating ;  behind,  by  the  posterior  cerebral,  and  point  of  the  basilar 
It  is  by  this  anastomosis  that  the  cerebral  circulation  is  equalized,  and  provision 
made  for  effectually  carrying  it  on  if  one  or  more  of  the  branches  are  obliterated. 
The  parts  of  the  brain  included  within  this  arterial  circle  are,  the  lamina  cinerea, 
the  commissure  of  the  optic  nerves,  the  infundibulum,  the  tuber  cinereum,  the 
corpora  albicantia,  and  the  pars  perforata  postica. 

The  Thyroid  Axis  is  a  short,  thick  trunk,  which  arises  from  the  fore  part  of 
the  first  portion  of  the  subclavian  artery,  close  to  the  inner  side  of  the  Scalenus 
anticus  muscle,  and  divides,  almost  immediately  after  its  origin,  into  three 
branches,  the  inferior  thyroid,  suprascapular,  and  transversalis  colli. 

The  Inferior  Thyroid  Artery  passes  upwards,  in  a  serpentine  course,  behind 
the  sheath  of  the  common  carotid  vessel  and  sympathetic  nerve  (the  middle 
cervical  ganglion  resting  upon  it),  and  is  distributed  to  the  under  surface  of  the 
thyroid  gland,  anastomosing  with  the  superior  thyroid,  and  with  the  correspond- 
ing artery  of  the  opposite  side.     Its  branches  are  the 

Laryngeal.  (Esophageal. 

Tracheal.  Ascending  cervical. 

The  laryngeal  branch  ascends  upon  the  trachea  to  the  back  part  of  the  larynx, 
and  supplies  the  muscles  and  the  mucous  membrane  of  this  part. 

The  tracheal  branches  are  distributed  upon  the  trachea,  anastomosing  below 
with  the  bronchial  arteries. 

The  esophageal  branches  are  distributed  to  the  oesophagus. 

The  ascending  cervical  is  a  small  branch  which  arises  from  the  inferior  thyroid, 
just  where  that  vessel  is  passing  behind  the  common  carotid  artery,  and  runs  up 
the  neck  in  the  interval  between  the  Scalenus  anticus  and  Rectus  anticus  major. 
It  gives  branches  to  the  muscles  of  the  neck,  which  communicate  with  those  sent 
out  from  the  vertebral,  and  sends  one  or  two  through  the  intervertebral  foramina, 
along  the  cervical  nerves,  to  supply  the  bodies  of  the  vertebrae,  the  spinal  cord, 
and  its  membranes. 

The  Suprascapular  Artery,  smaller  than  the  transversalis  colli,  passes 
obliquely  from  within  outwards,  across  the  root  of  the  neck.  It  at  first  lies  on 
the  lower  part  of  the  Scalenus  anticus,  being  covered  by  the  Sterno-mastoid ;  it 
then  crosses  the  subclavian  artery,  and  runs  outwards  behind  and  parallel  with 
the  clavicle  and  Subclavius  muscle,  and  beneath  the  posterior  belly  of  the  Omo- 
hyoid, to  the  superior  border  of  the  scapula,  where  it  passes  over  the  transverse 
ligament  of  the  scapula  to  the  supra-spinous  fossa.  In  this  situation  it  lies  close 
to  the  bone,  and  ramifies  between  it  and  the  Supra-spinatus  muscle  to  which  it  is, 
mainly  distributed,  giving  off  a  communicating  branch,  which  crosses  the  neck  of 
the  scapula,  to  reach  the  infra-spinous  fossa,  where  it  anastomoses  with  the  dorsal 
branch  of  the  subscapular  artery.  Besides  distributing  branches  to  the  Sterno- 
mastoid,  and  neighboring  muscles,  it  gives  off"  a  supra-acromial  branch,  which, 
piercing  the  Trapezius  muscle,  supplies  the  cutaneous  surface  of  the  acromion, 
anastomosing  with  the  acromial  thoracic  artery.  As  the  artery  passes  across  the 
suprascapular  notch,  a  branch  descends  into  the  subscapular  fossa,  ramifies 
beneath  that  muscle,  and  anastomoses  with  the  posterior  and  subscapular  arteries. 
It  also  supplies  the  shoulder-joint. 

The  Transversalis  Colli  passes  transversely  outwards,  across  the  upper  part  01' 
the  subclavian  triangle,  to  the  anterior  margin  of  the  Trapezius  muscle,  beneath 
which  it  divides  into  two  branches,  the  superficial  cervical,  and  the  posterior 
scapular.  In  its  passage  across  the  neck,  it  crosses  in  front  of  the  Scaleni  muscles 
and  the  brachial  plexus,  between  the  divisions  of  which  it  sometimes  passes, 
and  is  covered  by  the  Platysma,  Sterno-mastoid,  Omo-hyoid,  and  Trapezius 
muscles. 

The  superficial  cervical  ascends  beneath  the  anterior  margin  of  the  Trapezius, 
distributing  branches  to  it,  and  to  the  neighboring  muscles  and  glands  in  the 
neck. 


INTERNAL   MAMMARY. 


399 


The  posterior  scapular,  the  continuation  of  the  transversalis  colli,  passes  beneath 
the  Levator  anguli  scapulas  to  the  superior  angle  of  the  scapula,  and  descends 
along  the  posterior  border  of  that  bone  as  far  as  the  inferior  angle,  where  it  anas- 
tomoses with  the  subscapular  branch  of  the  axillary.     In  its  course  it  is  covered 


Fig.  216. — The  Scapular  and  Circumflex  Arteries. 

Better  it  r  Srafia/ar 


ial  Brarrb 


by  the  Rhomboid  muscles,  supplying  these,  the  Latissimus  dorsi  and  Trapezius, 
and  anastomosing  with  the  suprascapular  and  subscapular  arteries,  and  with  the 
posterior  branches  of  some  of  the  intercostal  arteries. 

Peculiarities.  The  superficial  cervical  frequently  arises  as  a  separate  branch  from  the  thyroid 
axis ;  and  the  posterior  scapular  from  the  third,  more  rarely  from  the  second,  part  of  the  sub- 
clavian. 

The  Internal  Mammary  arises  from  the  under  surface  of  the  first  portion  of 
the  subclavian  artery,  opposite  the  thyroid  axis.  It  descends  behind  the  clavicle, 
to  the  inner  surface  of  the  anterior  wall  of  the  chest,  resting  upon  the  costal 
cartilages,  a  short  distance  from  the  margin  of  the  sternum ;  and,  at  the  interval 
between  the  sixth  and  seventh  cartilages,  divides  into  two  branches,  the  musculo- 
phrenic, and  superior  epigastric. 

At  its  origin,  it  is  covered  by  the  internal  jugular  and  subclavian  veins,  and 
crossed  by  the  phrenic  nerve.  In  the  upper  part  of  the  thorax,  it  lies  upon  the 
costal  cartilages,  and  Internal  intercostal  muscles  in  front,  covered  by  the  pleura 
behind.  At  the  lower  part  of  the  thorax,  the  Triangularis  sterni  separates  this 
vessel  from  the  pleura.  It  is  accompanied  by  two  veins,  which  join  at  the  upper 
part  of  the  thorax  into  a  single  trunk. 

The  branches  of  the  internal  mammary  are  the 


Comes  nervi  phrenici  or  Superior  phrenic. 

Mediastinal. 

Pericardiac. 

Sternal. 


Anterior  intercostal. 
Perforating. 
Musculo-phrenic. 
Superior  epigastric. 


The  comes  nervi  phrenici  or  superior  phrenic  is  a  long  slender  branch,  which 
accompanies  the  phrenic  nerve,  between  the  pleura  and  pericardium,  to  the  Dia- 
phragm, to  which  it  is  distributed ;  anastomosing  with  the  other  phrenic  arteries 
from  the  internal  mammary,  and  abdominal  aorta. 


400  ARTERIES. 

The  mediastinal  branches  are  small  vessels,  which  are  distributed  to  the  areolar 
tissue  in  the  anterior  mediastinum,  and  the  remains  of  the  thymus  gland. 

The  pericardiac  branches  supply  the  upper  part,  of  the  pericardium,  the  lower 
part  receiving  branches  from  the  musculo-phrenic  artery.  Some  sternal  branches 
are  distributed  to  the  Triangularis  sterni,  and  both  surfaces  of  the  sternum. 

The  anterior  intercostal  arteries  supply  the  five  or  six  upper  intercostal  spaces. 
The  branch  corresponding  to  each  space  passes  outwards,  and  soon  divides  into 
two,  which  run  along  the  opposite  borders  of  the  ribs,  and  inosculate  with  the 
intercostal  arteries  from  the  aorta.  They  are  at  first  situated  between  the  pleura 
and  the  Internal  intercostal  muscles,  and  then  between  the  two  layers  of  these 
muscles.  They  supply  the  Intercostal  and  Pectoral  muscles,  and  the  mammary 
gland. 

The  anterior  or  perforating  arteries  correspond  to  the  five  or  six  upper  inter- 
costal spaces.  They  arise  from  the  internal  mammary,  pass  forwards  through  the 
intercostal  spaces,  and,  curving  outwards,  supply  the  Pectoralis  major,  and  the 
integument.  Those  which  correspond  to  the  first  three  spaces  are  distributed  to 
the  mammary  gland.  In  females,  during  lactation,  these  branches  are  of  large 
size. 

The  musculo-phrenic  artery  is  directed  obliquely  downwards  and  outwards,  behind 
the  cartilages  of  the  false  ribs,  perforating  the  Diaphragm  at  the  eighth  or  .ninth 
rib,  and  terminating,  considerably  reduced  in  size,  opposite  the  last  intercostal 
space.  It  gives  off  anterior  intercostal  arteries  to  each  of  the  intercostal  spaces 
across  which  it  passes ;  they  diminish  in  size  as  the  spaces  decrease  in  length,  and 
are  distributed  in  a  manner  precisely  similar  to  the  anterior  intercostals  from  the 
internal  mammary.  It  also  gives  branches  backwards  to  the  Diaphragm,  and 
downwards  to  the  abdominal  muscles. 

The  superior  epigastric  continues  in  the  original  direction  of  the  internal  mam- 
mary, descends  behind  the  Rectus  muscle,  and,  perforating  its  sheath,  divides  into 
branches  which  supply  the  Rectus,  anastomosing  with  the  epigastric  artery  from 
the  external  iliac.  Some  vessels  perforate  the  sheath  of  the  Rectus,  and  supply 
the  muscles  of  the  abdomen  and  the  integument,  and  a  small  branch,  which  passes 
inwards  upon  the  side  of  the  ensiform  appendix,  anastomoses  in  front  of  that 
cartilage  with  the  artery  of  the  opposite  side. 

The  Superior  Intercostal  arises  from  the  upper  and  back  part  of  the  sub- 
clavian artery,  beneath  the  anterior  scalenus  on  the  right  side,  and  to  the  inner  side 
of  the  muscle  on  the  left  side.  Passing  backwards,  it  gives  off  the  deep  cervical 
branch,  and  then  descends  behind  the  pleura  in  front  of  the  necks  of  the  first  two 
ribs,  and  inosculates  with  the  first  aortic  intercostal.  In  the  first  intercostal  space, 
it  gives  off  a  branch  which  is  distributed  in  a  similar  manner  with  the  aortic 
intercostals.  The  branch  for  the  second  intercostal  space  usually  joins  with  one 
from  the  first  aortic  intercostal.  Each  intercostal  gives  off  a  branch  to  the  posterior 
spinal  muscles,  and  a  small  one,  which  passes  through  the  corresponding  inter- 
vertebral foramen  to  the  spinal  cord  and  its  membranes. 

The  deep  cervical  branch  [profunda  cervicis)  arises,  in  most  cases,  from  the  superior 
intercostal,  and  is  analogous  to  the  posterior  branch  of  an  aortic  intercostal  artery. 
Passing  backwards,  between  the  transverse  process  of  the  seventh  cervical  vertebra 
and  the  first  rib,  it  ascends  the  back  part  of  the  neck,  between  the  Complexus 
and  Semi-spinalis  colli  muscles,  as  high  as  the  axis,  supplying  these  and  adjacent 
muscles,  and  anastomosing  with  the  arteria  princeps  cervicis  of  the  occipital,  and 
with  branches  which  pass  outwards  from  the  vertebral. 


OF   THE   AXILLA. 


401 


Surgical  Anatomy  of  the  Axilla. 

The  Axilla  is  a  conical  space,  situated  between  the  upper  and  lateral  parts  of 
the  chest,  and  inner  side  of  the  arm. 

Boundaries.  Its  apex,  which  is  directed  upwards  towards  the  root  of  the  neck, 
corresponds  to  the  interval  between  the  first  rib  internally,  the  superior  border  of 
the  scapula  externally,  and  the  clavicle  and  Subclavius  muscle  in  front.  The  base, 
directed  downwards,  is  formed  by  the  integument,  and  a  thick  layer  of  fascia, 
extending  between  the  lower  border  of  the  Pectoralis  major  in  front,  and  the  lower 
border  of  the  Latissimus  dorsi  behind ;  it  is  broad  internally,  at  the  chest,  but 
narrow  and  pointed  externally,  at  the  arm.  Its  anterior  boundary  is  formed  by 
the  Pectoralis  major  and  Pectoralis  minor  muscles,  the  former  covering  the  whole  of 


Fig.  217. — The  Axillary  Artery  and  its  Branches. 


the  anterior  wall  of  the  axilla,  the  latter  covering  only  its  central  part.  Its  posterior 
boundary,  which  extends  somewhat  lower  than  the  anterior,  is  formed  by  the  Sub- 
scapulars above,  the  Teres  major  and  Latissimus  dorsi  below.  On  the  inner  side 
are  the  first  four  ribs  and  their  corresponding  Intercostal  muscles,  and  part  of  the 
Serratus  magnus.  On  the  outer  side,  where  the  anterior  and  posterior  boundaries 
converge,  the  space  is  narrow,  and  bounded  by  the  humerus,  the  Coraco-brachialis 
and  Biceps  muscles. 

^  Contents.  This  space  contains  the  axillary  vessels,  and  brachial  plexus  of  nerve? 
with  their  branches,  some  branches  of  the  intercostal  nerves,  and  a  large  number  of 
lymphatic  glands ;  all  connected  together  by  a  quantity  of  fat  and  loose  areolar 
tissue. 

26 


402  ARTERIES. 

Tlieir  Position.  The  axillary  artery  and  vein,  with  the  brachial  plexus  of  nerves, 
extend  obliquely  along  the  outer  boundary  of  the  axillary  space,  from  its  apex  to 
its  base,  and  are  placed  much  nearer  the  anterior  than  the  posterior  wall,  the  vein 
lying  to  the  inner  or  thoracic  side  of  the  artery,  and  altogether  concealing  it. 
At  the  fore  part  of  the  axillary  space,  in  contact  with  the  Pectoral  muscles,  are 
the  thoracic  branches  of  the  axillary  artery,  and,  along  the  anterior  margin  of  the 
axilla,  the  long  thoracic  artery  extends  to  the  side  of  the  chest.  At  the  back 
part,  in  contact  with  the  lower  margin  of  the  Subscapularis  muscle,  are  the  sub- 
scapular vessels  and  nerves ;  winding  around  the  lower  border  of  this  muscle,  are 
the  dorsalis  scapulee  artery  and  veins ;  and  towards  the  outer  extremity  of  the 
muscle,  the  posterior  circumflex  vessels  and  nerve  are  seen  curving  backwards  to 
the  shoulder. 

Along  the  inner  or  thoracic  side,  no  vessel  of  any  importance  exists,  its  upper 
part  being  crossed  by  a  few  small  branches  from  the  superior  thoracic  artery. 
There  are  some  important  nerves,  however,  in  this  situation ;  the  posterior  thoracic 
or  external  respiratory  nerve,  descending  on  the  surface  of  the  Serratus  magnus, 
to  which  it  is  distributed ;  and  perforating  the  upper  and  anterior  part  of  this 
wall,  are  the  intercosto-humeral  nerves,  which  pass  across  the  axilla  to  the  inner 
side  of  the  arm. 

The  cavity  of  the  axilla  is  filled  by  a  quantity  of  loose  areolar  tissue,  a  large 
number  of  small  arteries  and  veins,  all  of  which  are,  however,  of  inconsiderable 
size,  and  numerous  lymphatic  glands ;  these  are  from  ten  to  twelve  in  number, 
and  situated  chiefly  on  the  thoracic  side,  and  lower  and  back  part  of  this  space. 

The  student  should  attentively  consider  the  relation  of  the  vessels  and  nerves 
in  the  several  parts  of  the  axilla ;  for  it  not  unfrequently  happens,  that  the  sur- 
geon is  called  upon  to  extirpate  diseased  glands,  or  to  remove  a  tumor  from  this 
situation.  In  performing  such  an  operation,  it  will  be  necessary  to  proceed  with 
much  caution  in  the  direction  of  the  outer  wall  and  apex  of  the  space,  as  here  the 
axillary  vessels  will  be  in  danger  of  being  wounded.  Towards  the  posterior  wall, 
it  will  be  necessary  to  avoid  the  subscapular,  dorsalis  scapulae,  and  posterior 
circumflex  vessels,  and,  along  the  anterior  wall,  the  thoracic  branches.  It  is  only 
along  the  inner  or  thoracic  wall,'  and  in  the  centre  of  the  axillary  cavity,  that 
there  are  no  vessels  of  any  importance;  a  most  fortunate  circumstance,  for  it 
is  in  this  situation  more  especially  that  tumors  requiring  removal  are  most  fre- 
quently situated. 


The  Axillary  Artery. 

The  axillary  artery,  the  continuation  of  the  subclavian,  commences  at  the  lower 
border  of  the  first  rib,  and  terminates  at  the  lower  border  of  the  tendons  of  the 
Latissimus  dorsi  and  Teres  major  muscles,  when  it  becomes  the  brachial.  Its 
direction  varies  with  the  position  of  the  limb ;  when  the  arm  lies  by  the  side  of 
the  chest,  the  vessel  forms  a  gentle  curve,  the  convexity  being  upwards  and  out- 
wards ;  when  it  is  directed  at  right  angles  with  the  trunk,  the  vessel  is  nearly 
straight ;  and  if  elevated  still  higher,  it  describes  a  curve,  the  concavity  of  which 
is  directed  upwards.  At  its  commencement  the  artery  is  very  deeply  situated, 
but  near  its  termination  is  superficial,  being  covered  only  by  the  skin  and  fascia. 
The  description  of  the  relations  of  this  vessel  may  be  facilitated  by  its  division 
into  three  portions ;  the  first  portion  being  that  above  the  Pectoralis  minor,  the 
second  portion  beneath,  and  the  third,  below,  that  muscle. 

The  first  portion  of  the  axillary  artery  is  in  relation,  in  front,  with  the  clavicular 
portion  of  the  Pectoralis  major,  the  costo-coracoid  membrane,  and  the  cephalic 
vein  ;  behind,  with  the  first  intercostal  space,  the  corresponding  Intercostal  muscle, 
the  first  serration  of  the  Serratus  magnus,  and  the  posterior  thoracic  nerve; 
on  its  outer  side  with  the  brachial  plexus,  from  which  it  is  separated  by  a  little 
cellular  interval;  on  its  inner  or  thoracic  side,  with  the  axillary  vein. 


AXILLARY.  403 

Relations  of  First  Portion  of  the  Axillary  Artery. 

In  front. 
Pectoralis  major. 
Costo-coracoid  membrane. 
Cephalic  vein. 


Order  side.  I     Axillary     \  Inner  side. 

Brachial  plexus.  I  HrBtportton.  J  Axillary  vein. 


Behind. 
First  intercostal  space,  and  Intercostal  muscle. 
First  serration  of  Serratus  magnus. 
Posterior  thoracic  nerve. 

The  second  portion  of  the  axillary  artery  lies  beneath  the  Pectoralis  minor.  It 
is  covered,  in  front,  by  the  Pectoralis  major  and  Pectoralis  minor  muscles;  behind^ 
it  is  separated  from  the  Subscapulars  by  a  cellular  interval ;  on  the  inner  side,  it  is 
in  contact  with  the  axillary  vein.  The  brachial  plexus  of  nerves  surrounds  the 
artery,  and  separates  it  from  direct  contact  with  the  vein  and  adjacent  muscles. 

Relations  of  Second  Portion  of  the  Axillary  Artery. 

In  front. 
Pectoralis  major  and  Pectoralis  minor. 


Outer  side.  I     %$£?    \  Inner  side. 

Brachial  plexus.  Isecoiid  portion.)  Axillary  vein. 


Behind. 
Subscapularis. 

The  third  portion  of  the  axillary  artery  lies  below  the  Pectoralis  minor.  It  is 
in  relation,  in  front,  with  the  lower  border  of  the  Pectoralis  major  above,  being 
covered  only  by  the  integument  and  fascia  below ;  behind,  with  the  lower  part  of 
the  Subscapularis,  and  the  tendons  of  the  Latissimus  dorsi  and  Teres  major ;  on 
its  outer  side,  with  the  Coraco-brachialis ;  on  its  inner  or  thoracic  side,  with  the 
axillary  vein.  The  brachial  plexus  of  nerves  bears  the  following  relation  to  the 
artery  in  this  part  of  its  course  ;  on  the  outer  side  are  the  median  nerve,  and  the 
musculo-cutaneous  for  a  short  distance ;  on  the  inner  side,  the  ulnar,  the  internal,  and 
lesser  internal  cutaneous  nerves ;  and  behind,  the  musculo-spiral  and  circumflex, 
the  latter  extending  only  to  the  lower  border  of  the  Subscapularis  muscle. 

Relations  of  Third  Portion  of  the  Axillary  Artery. 

In  front. 
Integument  and  fascia. 
Pectoralis  major. 

Outer  side.  f                 \                          Inner  side. 

Coraco-brachialis.  |      briery7     j  Ulnar  nerve. 

Median  nerve.  \  Third  portion./  Internal  cutaneous  nerr 33. 

Musculo-cutaneous  nerve.  \                 /  Axillary  vein. 

Behind. 
Subscapularis. 

Tendons  of  Latissimus  dorsi  and  Teres  major. 
Musculo-spiral,  and  circumflex  nerves. 


404  ARTERIES. 

Peculiarities.  The  axillary  artery,  in  about  one  case  out  of  every  ten,  gives  off  a  large 
branch,  which  forms  either  one  of  the  arteries  of  the  forearm,  or  a  large  muscular  trunk.  In 
the  first  set  of  cases,  this  artery  is  most  frequently  the  radial  (1  in  33),  sometimes  the  ulnar  (1 
in  72),  and,  very  rarely,  the  interosseous  (1  in  506).  In  the  second  set  of  cases,  the  trunk  gave 
origin  to  the  subscapular,  circumflex,  and  profunda  arteries  of  the  arm.  Sometimes  only 
one  of  the  circumflex,  or  one  of  the  profunda  arteries,  arose  from  the  trunk.  In  these  cases, 
the  brachial  plexus  surrounded  the  trunk  of  the  branches,  and  not  the  main  vessel. 

Surgical  Anatomy.  The  student  having  carefully  examined  the  relations  of  the  axillary 
artery  in  its  various  parts,  should  now  consider  in  what  situation  compression  of  this  vessel 
may  be  most  easily  effected,  and  the  best  position  for  the  application  of  a  ligature  to  it  when 
necessary. 

Compression  of  this  vessel  is  required  in  the  removal  of  tumors,  or  in  amputation  of  the 
upper  part  of  the  arm  ;  and  the  only  situation  in  which  this  can  be  effectually  made,  is  in  the 
lower  part  of  its  course ;  on  compressing  it  in  this  situation  from  within  outwards  upon  the 
humerus,  the  circulation  may  be  effectually  suspended. 

The  application  of  a  ligature  to  the  axillary  artery  may  be  required  in  cases  of  aneurism  of 
the  upper  part  of  the  brachial ;  and  there  are  only  two  situations  in  which  it  may  be  secured, 
viz.,  in  the  upper,  or  in  the  lower  part  of  its  course  ;  for  the  axillary  artery  at  its  central  part  is 
«o  deeply  seated,  and,  at  the  same  time,  so  closely  surrounded  with  large  nervous  trunks,  that  the 
application  of  a  ligature  to  it  in  this  situation  would  be  almost  impracticable. 

In  the  lower  part  of  its  course,  the  operation  is  more  simple,  and  may  be  performed  in  the 
following  manner :  The  patient  being  placed  on  a  bed,  and  the  arm  separated  from  the  side,  with 
the  hand  supinated,  the  head  of  the  humerus  is  felt  for,  and  an  incision  made  through  the  integu- 
ment over  it,  about  two  inches  in  length,  a  little  nearer  to  the  anterior  than  the  posterior  fold  of 
the  axilla.  After  carefully  dissecting  through  the  areolar  tissue  and  fascia,  the  median  nerve 
and  axillary  vein  are  exposed  ;  the  former  having  been  displaced  to  the  outer,  and  the  latter  to 
the  inner  side  of  the  arm,  the  elbow  being  at  the  same  time  bent,  so  as  to  relax  these  structures, 
and  facilitate  their  separation,  the  ligature  may  be  passed  round  the  artery  from  the  ulnar  to  the 
radial  side.  This  portion  of  the  artery  is  occasionally  crossed  by  a  muscular  slip  derived  from 
the  Latissimus  dorsi,  which  may  mislead  the  surgeon  during  an  operation.  It  may  easily  be 
recognized  by  the  transverse  direction  of  its  fibres  (see  p.  272). 

The  upper  portion  of  the  axillary  artery  may  be  tied,  in  cases  of  aneurism  encroaching  so 
far  upwards  that  a  ligature  cannot  be  applied  in  the  lower  part  of  its  course.  Notwithstanding 
that  this  operation  has  been  performed  in  some  few  cases,  and  with  success,  its  performance  is 
attended  with  much  difficulty  and  danger.  The  student  will  remark,  that  in  this  situation  it 
would  be  necessary  to  divide  a  thick  muscle,  and,  after  separating  the  costo-coracoid  mem- 
brane, the  artery  would  be  exposed  at  the  bottom  of  a  more  or  less  deep  space,  with  the  cepha- 
lic and  axillary  veins  in  such  relation  with  it  as  must  render  the  application  of  a  ligature  to 
this  part  of  the  vessel  particularly  hazardous.  Under  such  circumstances,  it  is  an  easier,  and, 
at  the  same  time,  more  advisable  operation,  to  tie  the  subclavian  artery  in  the  third  part  of  its 
course. 

In  a  case  of  wound  of  this  vessel  the  general  practice  of  cutting  down  upon  it,  and  tying  it 
above  and  below  the  wounded  point,  should  be  adopted  in  all  cases. 

The  branches  of1  the  axillary  artery  are 

From  1st  Part.     J  Superior  thoracic. 

(  Acromial  thoracic. 
From  2d  Part.     J  Thoracica  longa. 

(  Thoracica  alaris. 

I  Subscapular. 
From  3d  Part.     <  Anterior  circumflex. 

(  Posterior  circumflex. 

The  superior  thoracic  is  a  small  artery,  which  arises  from  the  axillary,  or  by  a 
common  trunk  with  the  acromial  thoracic.  Running  forwards  and  inwards  along 
the  upper  border  of  the  Pectoralis  minor,  it  passes  between  it  and  the  Pectoralis 
major  to  the  side  of  the  chest.  It  supplies  these  muscles,  and  the  parietes  of  the 
thorax,  anastomosing  with  the  internal  mammary  and  intercostal  arteries. 

The  acromial  thoracic  is  a  short  trunk,  which  arises  from  the  fore  part  of  the 
axillary  artery.  Projecting  forwards  to  the  upper  border  of  the  Pectoralis  minor, 
it  divides  into  three  sets  of  branches,  thoracic,  acromial,  and  descending.  The 
thoracic  branches,  two  or  three  in  number,  are  distributed  to  the  Serratus  magnus 
and  Pectoral  muscles,  anastomosing  with  the  intercostal  branches  of  the  internal 


AXILLARY— BRACHIAL.  405 

mammary.  The  acromial  branches  are  directed  outwards  towards  the  acromion, 
supplying  the  Deltoid  muscle,  and  anastomosing,  on  the  surface  of  the  acromion, 
with  the  suprascapular  and  posterior  circumflex  arteries.  The  descending  branch 
passes  in  the  interspace  between  the  Pectoralis  major  and  Deltoid,  accompanying 
the  cephalic  vein,  and  supplying  both  muscles. 

The  thoracica  longa  passes  downwards  and  inwards  along  the  lower  border  of 
the  Pectoralis  minor  to  the  side  of  the  chest,  supplying  the  Serratus  magnus,  the 
Pectoral  muscles,  and  mammary  gland,  and  sending  branches  across  the  axilla  to 
the  axillary  glands  and  Subscapularis,  which  anastomose  with  the  internal  mam- 
mary and  intercostal  arteries. 

The  thoracica  alaris  is  a  small  branch,  which  supplies  the  glands  and  areolar 
tissue  of  the  axilla.  Its  place  is  frequently  supplied  by  branches  from  some  of 
the  other  thoracic  arteries. 

The  subscapular,  the  largest  branch  of  the  axillary  artery,  arises  opposite  the 
lower  border  of  the  Subscapularis  muscle,  and  passes  downwards  and  backwards 
along  its  lower  margin  to  the  inferior  angle  of  the  scapula,  where  it  anastomoses 
with  the  posterior  scapular,  a  branch  of  the  subclavian.  It  distributes  branches  to 
the  Subscapularis,  Serratus  magnus,  Teres  major,  and  Latissimus  dorsi  muscles, 
and  gives  off,  about  an  inch  and  a-half  from  its  origin,  a  large  branch,  the  dorsalis 
scapulae.  This  vessel  curves  round  the  inferior  border  of  the  scapula,  leaving  the 
axilla  in  the  interspace  between  the  Teres  minor  above,  the  Teres  major  below, 
and  the  long  head  of  the  Triceps  in  front ;  and  divides  into  three  branches,  a  sub- 
scapular, which  enters  the  subscapular  fossa  beneath  the  Subscapularis  which  it 
supplies,  anastomosing  with  the  subscapular  and  suprascapular  arteries ;  an  infra- 
spinous  branch  (dorsalis  scapulas),  which  turns  round  the  axillary  border  of  the 
scapula,  between  the  Teres  minor  and  the  bone,  enters  the  infra-spinous  fossa, 
supplies  the  Infra-spinatus  muscle,  and  anastomoses  with  the  suprascapular  and 
posterior  scapular  arteries ;  and  a  median  branch,  which  is  continued  along  the 
axillary  border  of  the  scapula,  between  the  Teres  major  and  minor,  and,  at  the 
dorsal  surface  of  the  inferior  angle  of  the  bone,  anastomoses  with  the  supra- 
scapular. 

The  circumflex  arteries  wind  round  the  neck  of  the  humerus. 

The  posterior  circumflex,  the  larger  of  the  two,  arises  from  the  back  part  of 
the  axillary,  opposite  the  lower  border  of  the  Subscapularis  muscle,  and,  passing 
backwards  with  the  circumflex  veins  and  nerve,  through  the  quadrangular  space 
bounded  by  the  Teres  major  and  Teres  minor,  the  scapular  head  of  the  Triceps  and 
the  humerus,  winds  round  the  neck  of  that  bone,  is  distributed  to  the  Deltoid  muscle 
and  shoulder-joint,  anastomosing  with  the  anterior  circumflex,  suprascapular,  and 
acromial  thoracic  arteries. 

The  anterior  circumflex,  considerably  smaller  than  the  preceding,  arises  just 
below  that  vessel,  from  the  outer  side  of  the  axillary  artery.  It  passes  horizontally 
outwards,  beneath  the  Coraco-brachialis  and  short  head  of  the  Biceps,  lying  upon 
the  fore  part  of  the  neck  of  the  humerus,  and,  on  reaching  the  bicipital  groove, 
gives  off  an  ascending  branch,  which  passes  upwards  along  it,  to  supply  the  head 
of  the  bone  and  the  shoulder-joint.  The  trunk  of  the  vessel  is  then  continued 
•outwards  beneath  the  Deltoid  which  it  supplies,  and  anastomoses  with  the  posterior 
circumflex  and  acromial  thoracic  arteries. 


Brachial  Artery  (fig.  218). 

The  brachial  artery  commences  at  the  lower  margin  of  the  tendon  of  the  Teres 
major,  and,  passing  down  the  inner  and  anterior  aspect  of  the  arm,  terminates 
about  half  an  inch  below  the  bend  of  the  elbow,  where  it  divides  into  the  radial 
and  ulnar  arteries. 

The  direction  of  this  vessel  is  marked  by  a  line  drawn  from  the  outer  side  of 
the  axillary  space  between  the  folds  of  the  axilla,  to  a  point  midway  between  the 


406 


ARTERIES. 


Fig.  218.— The  Surgical 


Jtirrv* 


Anatomy  of  the  Brachial  Artery,  condyles    of    the     humerus,     which 

corresponds  to  the  depression  along 
the  inner  border  of  the  Coraco- 
brachial! s  and  Biceps  muscles.  In 
the  upper  part  of  its  course,  this 
vessel  lies  internal  to  the  humerus ; 
but  below,  it  is  in  front  of  that 
bone. 

Relations.  This  artery  is  super- 
ficial throughout  its  entire  extent, 
being  covered,  in  front,  by  the  in- 
tegument, the  superficial  and  deep 
fasciae ;  the  bicipital  fascia  separates 
it  opposite  the  elbow  from  the  me- 
dian basilic  vein ;  the  median  nerve 
crosses  it  at  its  centre ;  and  the  basilic 
vein  lies  in  the  line  of  the  artery, 
but  separated  from  it  by  the  fascia, 
in  the  lower  half  of  its  course. 
Behind,  it  is  separated  from  the 
inner  side  of  the  humerus  above, 
by  the  long  and  inner  heads  of  the 
Triceps,  the  musculo- spiral  nerve 
and  superior  profunda  artery  inter- 
vening ;  and  from  the  front  of  the 
bone  below,  by  the  insertion  of  the 
Coraco-brachialis  and  the  Brachialis 
anticus  muscles.  By  its  outer  side, 
it  is  in  relation  with  the  commence- 
ment of  the  median  nerve,  and 
the  Coraco-brachialis  and  Biceps 
muscles,  which  slightly  overlap  the 
artery.  By  its  inner  side,  with  the 
internal  cutaneous  and  ulnar  nerves, 
its  upper  half;  the  median  nerve, 
its  lower  half.  It  is  accompanied 
by  two  veins,  the  venae  comites; 
they  lie  in  close  contact  with  the 
artery,  being  connected  together 
at  intervals  by  short  transverse 
communicating  branches. 


Aniaatomo  ticct 


Plan  of  the  Kelations  of  the  Brachial  Artery. 

In  front. 
Integument  and  fascia?. 
Bicipital  fascia,  median  basilic  vein. 
Median  nerve. 


Outer  side. 
Median  nerve. 
Coraco-brachialis. 
Biceps. 


Inner  side. 
Internal  cutaneous. 
Ulnar  and  median  nervea. 


Behind. 
Triceps. 

Musculo-spiral  nerve. 
Superior  profunda  artery. 
Coraco-brachialis. 
Brachialis  anticus. 


BRACHIAL.  407 


Bexd  of  the  Elbow. 

At  the  bend  of  the  elbow,  the  brachial  artery  sinks  deeply  into  a  triangular 
interval,  the  base  of  which  is  directed  upwards  towards  the  humerus,  and  the  sides 
of  which  are  bounded,  externally,  by  the  Supinator  longus ;  internally,  by  the 
Pronator  radii  teres ;  its  floor  is  formed  by  the  Brachialis  anticus  and  Supinator 
brevis.  This  space  contains  the  brachial  artery,  with  its  accompanying  veins ;  the 
radial  and  ulnar  arteries;  the  median  and  musculo-spiral  nerves;  and  the  tendon 
of  the  Biceps.  The  brachial  artery  occupies  the  middle  line  of  this  space,  and 
divides  opposite  the  coronoid  process  of  the  ulna  into  the  radial  and  ulnar  arteries ; 
it  is  covered,  in  front,  by  the  integument,  the  superficial  fascia,  and  the  median 
basilic  vein,  the  vein  being  separated  from  direct  contact  with  the  artery  by  the 
bicipital  fascia.  Behind,  it  lies  on  the  Brachialis  anticus,  which  separates  it  from 
the  elbow-joint.  The  median  nerve  lies  on  the  inner  side  of  the  artery,  but  is 
separated  from  it  below  by  an  interval  of  half  an  inch.  The  tendon  of  the  Biceps 
lies  to  the  outer  side  of  the  space,  and  the  musculo-spiral  nerve  still  more 
externally,  lying  upon  the  Supinator  brevis,  and  partly  concealed  by  the  Supinator 
longus. 

Peculiarities  of  the  Artery  as  regards  its  Course.  The  brachial  artery,  accompanied  by  the 
median  nerve,  may  leave  the  inner  border  of  the  Biceps,  and  descend  towards  the  inner  condyle 
of  the  humerus,  where  it  usually  curves  round  a  prominence  of  bone,  to  which  it  is  connected  by 
a  fibrous  band ;  it  then  inclines  outwards,  beneath  or  through  the  substance  of  the  Pronator  teres 
muscle,  to  the  bend  of  the  elbow.  This  variation  bears  considerable  analogy  with  the  normal 
condition  of  the  artery  in  some  of  the  carnivora  (see  p.  131). 

Peculiarities  as  regards  its  Division.  Occasionally,  the  artery  is  divided  for  a  short  distance 
at  its  upper  part  into  two  trunks,  which  are  united  above  and  below.  A  similar  peculiarity  occurs 
in  the  main  vessel  of  the  lower  limb. 

The  point  of  bifurcation  may  be  above  or  below  th»  usual  point,  the  former  condition  being 
by  far  the  most  frequent.  Out  of  481  examinations  recorded  by  Mr.  Quain,  some  made  on  the 
right,  and  some  on  the  left  side  of  the  body,  in  386  the  artery  bifurcated  in  its  normal  position. 
In  one  case  only  was  the  place  of  division  lower  than  usual,  being  two  or  three  inches  below  the 
elbow-joint.  In  90  cases  out  of  481,  or  about  1  in  5£,  there  were  two  arteries  instead  of  one  in 
some  part,  or  in  the  whole  of  the  arm. 

There  appears,  however,  to  be  no  correspondence  between  the  arteries  of  the  two  arms,  with 
respect  to  their  irregular  division;  for  in  61  bodies  it  occurred  on  one  side  only  in  43 ;  on 
both  sides,  in  different  positions,  in  13 ;  on  both  sides,  in  the  same  position,  in  5. 

The  point  of  bifurcation  takes  place  at  different  parts  of  the  arm,  being  most  frequent  in  the 
upper  part,  less  so  in  the  lower  part,  and  least  so  in  the  middle,  the  most  usual  point  for  the 
application  of  a  ligature  ;  under  any  of  these  circumstances,  two  large  arteries  would  be  found 
in  the  arm  instead  of  one.  The  most  frequent  (in  three  out  of  four)  of  these  peculiarities  is  the 
high  division  of  the  radial.  It  often  arises  from  the  inner  side  of  the  brachial,  and  runs  parallel 
with  the  main  trunk  to  the  elbow,  where  it  crosses  it,  lying  beneath  the  fascia ;  or  it  may  perfo- 
rate the  fascia,  and  pass  over  the  artery,  immediately  beneath  the  integument. 

The  ulnar  sometimes  arises  from  the  brachial  high  up,  and  then  occasionally  leaves  that  vessel 
at  the  lower  part  of  the  arm,  and  descends  towards  the  inner  condyle.  In  the  forearm,  it  gene- 
rally lies  beneath  the  deep  fascia,  superficial  to  the  Flexor  muscles ;  occasionally  between  the 
integument  and  deep  fascia,  and  very  rarely  beneath  the  Flexor  muscles. 

The  interosseous  artery  sometimes  arises  from  the  upper  part  of  the  brachial  or  axillary :  as 
it  descends  the  arm,  it  lies  behind  the  main  trunk,  and  at  the  bend  of  the  elbow  regains  its  usual 
position. 

In  some  cases  of  high  division  of  the  radial,  the  remaining  trunk  (ulnar  interosseous)  occasion- 
ally passes,  together  with  the  median  nerve,  along  the  inner  margin  of  the  arm  to  the  inner  con- 
dyle, and  then  passing  from  within  outwards,  beneath  or  through  the  Pronator  teres,  regains  its 
usual  position  at  the  end  of  the  elbow. 

Occasionally,  the  two  arteries  representing  the  brachial  are  connected  at  the  bend  of  the  elbow 
by  a  short  transverse  branch,  and  are  even  sometimes  reunited. 

Sometimes,  long  slender  vessels,  vasa  aberrantia,  connect  the  brachial  or  axillary  arteries 
with  one  of  the  arteries  of  the  forearm,  or  a  branch  from  them.  These  vessels  usually  join  the 
radial. 


408  ARTERIES. 

Varieties  in  3Iuscular  Relations}  The  brachial  artery  is  occasionally  concealed,  in  some  part 
of  its  course,  by  muscular  or  tendinous  slips  derived  from  various  sources.  In  the  upper  third 
of  the  arm,  the  brachial  vessels  and  median  nerve  have  been  seen  concealed  to  the  extent  of 
three  inches  by  a  muscular  layer  of  considerable  thickness,  derived  from  the  Coraco-brachialis, 
which  passed  round  to  the  inner  side  of  the  vessel,  and  joined  the  internal  head  of  the  Triceps. 
In  the  lower  half  of  the  arm  it  is  occasionally  concealed  by  a  broad  thin  head  to  the  Biceps 
muscle  (see  p.  303).  A  narrow  fleshy  slip  from  the  Biceps  has  been  seen  to  cross  the  artery, 
concealing  it  for  an  inch  and  a  half,  its  tendon  ending  in  the  aponeurosis  covering  the  Pronator 
teres.  A  muscular  and  tendinous  slip  has  been  seen  to  arise  from  the  external  bicipital  ridge 
by  a  long  tendon,  cross  obliquely  behind  the  long  tendon  of  the  Biceps,  end  in  a  fleshy  belly, 
which  appears  on  the  inner  side  of  the  arm  between  the  Biceps  and  Coraco-brachialis.  passes 
down  along  the  inner  edge  of  the  former,  and  crosses  the  artery  very  obliquely,  so  as  to  lie  in 
front  of  it  for  three  inches,  and,  finally,  end  in  a  narrow  flattened  tendon,  which  is  inserted  into 
the  aponeurosis  over  the  Pronator  teres.  A  tendinous  slip,  arising  from  the  deep  part  of  the 
tendon  of  the  Pectoralis  major,  has  been  seen  to  cross  the  artery  obliquely  at  or  below  the 
Coraco-brachialis,  and  join  the  intermuscular  septum  above  the  inner  condyle.  The  Brachialis 
anticus  not  unfrequently  projects  at  the  outer  side  of  the  artery,  occasionally  overlaps  it,  sending 
inwards,  across  the  artery,  an  aponeurosis  which  binds  the  vessel  down  upon  the  Brachialis 
anticus.  Sometimes  a  fleshy  slip  from  the  muscle  covers  the  vessel,  in  one  case,  to  the  extent 
of  three  inches.  In  some  cases  of  high  origin  of  the  Pronator  radii  teres,  an  aponeurosis  extends 
from  it  to  join  the  Brachialis  anticus  external  to  the  artery;  a  kind  of  arch  being  thus  formed, 
under  which  the  principal  artery  and  median  nerve  pass,  so  as  to  be  concealed  for  half  an  inch 
above  the  transverse  level  of  the  condyle. 

Surgical  Anatomy.  Compression  of  the  brachial  artery  is  required  in  cases  of  amputation  of 
the  arm  or  forearm,  in  resection  of  the  elbow-joint,  and  the  removal  of  tumors ;  and  it  will  be 
observed,  that  it  may  be  effected  in  almost  any  part  of  its  course  ;  if  pressure  is  made  in  the  upper 
part  of  the  limb  it  should  be  directed  from  within  outwards,  and  if  in  the  lower  part  from  before 
backwards,  as  the  artery  lies  on  the  inner  side  of  the  humerus  above,  and  in  front  of  it  below. 
The  most  favorable  situation  is  either  above  or  below  the  insertion  of  the  Coraco-brachialis. 

The  application  of  a  ligature  to  the  brachial  artery  may  be  required  in  cases  of  wounds  of  the 
vessel,  or  in  wounds  of  the  palmar  arch,  where  compression  of  the  radial  and  ulnar  arteries  fails  to 
arrest  the  hemorrhage.  It  is  also  necessary  in  cases  of  aneurism  of  the  brachial,  the  radial,  ulnar, 
or  interosseous  arteries;  and  it  may  be  secured  in  any  part  of  its  course.  The  chief  guides  in 
determining  its  position  are  the  surface-markings  produced  by  the  inner  margin  of  the  Coraco- 
brachialis  and  Biceps,  the  known  course  of  the  vessel,  and  its  pulsation,  which  should  be  care- 
fully felt  for  before  any  operation  is  performed,  as  the  vessel  occasionally  deviates  from  its  usual 
position  in  the  arm.  In  whatever  situation  the  operation  is  performed,  great  care  is  necessary 
on  account  of  the  extreme  thinness  of  the  parts  covering  the  artery,  and  the  intimate  connection 
which  the  vessel  has  throughout  its  whole  course  with  important  nerves  and  veins.  Sometimes 
a  thin  layer  of  muscular  fibre  is  met  with  concealing  the  artery;  if  such  is  the  case,  it  must  be 
divided  across,  in  order  to  expose  the  vessel. 

In  the  upper  third  <f  the  arm  the  artery  maybe  exposed  in  the  following  manner: — The  patient 
being  placed  horizontally  upon  a  table,  the  affected  limb  should  be  raised  from  the  side,  and  the 
hand  supinated.  An  incision  about  two  inches  in  length  should  be  made  on  the  ulnar  side  of  the 
Coraco-brachialis  muscle,  and  the  subjacent  fascia  cautiously  divided  so  as  to  avoid  wounding  the 
internal  cutaneous  nerve  or  basilic  vein,  which  sometimes  run  on  the  surface  of  the  artery  as  high 
as  the  axilla.  The  fascia  having  been  divided,  it  should  be  remembered,  that  the  ulnar  and  internal 
cutaneous  nerves  lie  on  the  inner  side  of  the  artery,  the  median  on  the  outer  side,  the  latter  nerve 
being  occasionally  superficial  to  the  artery  in  this  situation,  and  that  the  vena?  comites  are  also 
in  relation  with  the  vessel,  one  on  either  side.  These  being  carefully  separated,  the  aneurism 
needle  should  be  passed  round  the  artery  from  the  ulnar  to  the  radial  side. 

If  two  arteries  are  present  in  the  arm  in  consequence  of  a  high  division,  they  are  usually  placed 
side  by  side ;  and  if  they  are  exposed  in  an  operation,  the  surgeon  should  endeavor  to  ascertain, 
by  alternately  pressing  on  one  or  the  other  vessel,  which  of  the  two  communicates  with  the  wound 
or  aneurism,  when  a  ligature  may  be  applied  accordingly;  or  if  pulsation  or  hemorrhage  ceases 
only  when  both  vessels  are  compressed,  both  vessels  may  be  tied,  as  it  may  be  concluded  that 
the  two  communicate  above  the  seat  of  disease  or  are  reunited. 

It  should  also  be  remembered,  that  two  arteries  may  be  present  in  the  arm  in  a  case  of  high 
division,  and  that  one  of  these  may  be  found  along  the  inner  intermuscular  septum,  in  a  line 
towards  the  inner  condyle  of  the  humerus,  or  in  its  usual  position,  but  deeply  placed  beneath  the 
common  trunk:  a  knowledge  of  these  facts  will  at  once  suggest  the  precautions  necessary  in 
every  case,  and  indicate  the  necessary  measures  to  be  adopted  when  met  with. 

In  the  middle  of  the  arm  the  brachial  artery  may  be  exposed  by  making  an  incision  along  the 
inner  margin  of  the  Biceps  muscle.  The  forearm  being  bent  so  as  to  relax  the  muscle,  it  should 
be  drawn  slightly  aside,  and  the  fascia  being  carefully  divided,  the  median  nerve  will  be  exposed 
tying  upon  the  artery,  sometimes  beneath ;  this  being  drawn  inwards  and  the  muscle  outwards, 

1  Stbuther's  Anatomical  and  Physiological  Observations. 


SURGICAL   ANATOMY   OF   BRACHIAL   ARTERY.        409 

the  artery  should  be  separated  from  its  accompanying  veins  and  secured.  In  this  situation  the 
inferior  profunda  may  be  mistaken  for  the  main  trunk,  especially  if  enlarged,  from  the  collateral 
circulation  having  become  established  ;  this  may  be  avoided  by  directing  the  incision  externally 
towards  the  Biceps  rather  than  inwards  or  backwards  towards  the  Triceps. 

The  lower  part  of  the  brachial  artery  is  of  extreme  interest  in  a  surgical  point  of  view,  on  ac- 
count of  the  relation  which  it  bears  to  those  veins  most  commonly  opened  in  venesection.  Of 
these  vessels,  the  median  basilic  is  the  largest  and  most  prominent,  and,  consequently,  the  one 
usually  selected  for  the  operation.  It  should  be  remembered,  that  this  vein  runs  parallel  with 
the  brachial  artery,  from  which  it  is  separated  by  the  bicipital  fascia,  and  that  in  no  case  should 
this  vessel  be  selected  for  venesection,  except  in  a  part  which  is  not  in  contact  with  the  artery. 

Collateral  Circulation.  After  the  application  of  a  ligature  to  the  brachial  artery  in  the  upper 
third  of  the  arm,  the  circulation  is  carried  on  by  branches  from  the  circumflex  and  subscapular 
arteries,  anastomosing  with  ascending  branches  from  the  superior  profunda.  If  the  brachial  is 
tied  below  the  origin  of  the  profunda  arteries,  the  circulation  is  maintained  by  the  branches  of  the 
profundae,  anastomosing  with  the  recurrent  radial,  ulnar,  and  interosseous  arteries.  In  two  cases 
described  by  Mr.  South,1  in  which  the  brachial  artery  had  been  tied  some  time  previously,  in  one 
"a  long  portion  of  the  artery  had  been  obliterated,  and  sets  of  vessels  are  descending  on  either 
side  from  above  the  obliteration,  to  be  received  into  others  which  ascend  in  a  similar  manner 
from  below  it.  In  the  other,  the  obliteration  is  less  extensive,  and  a  single  curved  artery  about 
as  big  as  a  crow-quill  passes  from  the  upper  to  the  lower  open  part  of  the  artery." 

The  branches  of  the  brachial  artery  are  the 

Superior  profunda.  Inferior  profunda. 

Nutrient  artery.  Anastomotica  magna. 

Muscular. 

The  superior  profunda  arises  from  the  inner  and  back  part  of  the  brachial, 
opposite  the  lower  border  of  the  Teres  major,  and  passes  backwards  to  the 
interval  between  the  outer  and  inner  heads  of  the  Triceps  muscle,  accompanied 
by  the  musculo-spiral  nerve ;  it  winds  round  the  back  part  of  the  shaft  of  the 
humerus  in  the  spiral  groove,  between  the  Triceps  and  the  bone,  and  descends  on 
the  outer  side  of  the  arm  to  the  space  between  the  Brachialis  anticus  and 
Supinator  longus,  as  far  as  the  elbow,  where  it  anastomoses  with  the  recurrent 
branch  of  the  radial  artery.  It  supplies  the  Deltoid,  Coraco-brachialis,  and 
Triceps  muscles,  and  whilst  in  the  groove,  between  the  Triceps  and  the  bone,  it 
gives  off  the  posterior  articular  artery,  which  descends  perpendicularly  between 
the  Triceps  and  the  bone,  to  the  back  part  of  the  elbow-joint,  where  it  anastomo- 
ses with  the  interosseous  recurrent  branch,  and,  on  the  inner  side  of  the  arm, 
with  the  posterior  ulnar  recurrent,  and  with  the  anastomotica  magna  or  inferior 
profunda  (fig.  221). 

The  nutrient  artery  of  the  shaft  of  the  humerus  arises  from  the  brachial,  about 
the  middle  of  the  arm.  Passing  downwards,  it  enters  the  nutritious  canal  of  that 
bone,  near  the  insertion  of  the  Coraco-brachialis  muscle. 

The  inferior  profunda,  of  small  size,  arises  from  the  brachial,  a  little  below  the 
middle  of  the  arm ;  piercing  the  internal  intermuscular  septum,  it  descends  on  the 
surface  of  the  inner  head  of  the  Triceps  muscle,  to  the  space  between  the  inner 
condyle  and  olecranon,  accompanied  by  the  ulnar  nerve,  and  terminates  by  anas- 
tomosing with  the  posterior  ulnar  recurrent,  and  anastomotica  magna. 

The  anastomotica  magna  arises  from  the  brachial,  about  two  inches  above  the 
elbow-joint.  It  passes  transversely  inwards  upon  the  Brachialis  anticus,  and, 
piercing  the  internal  intermuscular  septum,  winds  round  the  back  part  of  the 
humerus,  between  the  Triceps  and  the  bone,  forming  an  arch  above  the  olecranon 
fossa,  by  its  junction  with  the  posterior  articular  branch  of  the  superior  profunda. 
As  this  vessel  lies  on  the  Brachialis  anticus,  an  offset  passes  between  the  internal 
condyle  and  olecranon,  which  anastomoses  with  the  inferior  profunda  and  pos- 
terior ulnar  recurrent  arteries.  Other  branches  ascend  to  join  the  inferior  pro- 
funda ;  and  some  descend  in  front  of  the  inner  condyle,  to  anastomose  with  the 
anterior  ulnar  recurrent. 

The  muscular  are  three  or  four  large  branches,  which  are  distributed  to  the 

1  Chelins's  Surgery,  p.  254. 


410 


ARTERIES. 


muscles  in  the  course  of  the  artery.     They  supply  the  Coraco-brachialis,  Biceps, 
and  Brachialis  anticus  muscles. 


Fig.  219. — The  Surgical  Anatomy  of  the  Radial  and  Ulnar 
Arteries. 


J!jrli<il  Seoarrr-nt. 


JDmOP  k-rancA  if  Ulnar 


Superficial)*  Vila 


Radial  Artery. 

The  Radial  artery  appears, 
from  its  direction,  to  be  the 
continuation  of  the  brachial, 
but,  in  size,  it  is  smaller  than 
the  ulnar.     It  commences  at 
the  bifurcation  of  the  brachial, 
just   below  the   bend  of   the 
elbow,  and  passes  along  the 
radial  side  of  the  forearm  to 
the  wrist ;  it  then  winds  back- 
wards, round  the   outer  side 
of   the    carpus,    beneath    the 
Extensor      tendons     of     the 
thumb,  and,  running  forwards, 
passes  between  the  two  heads 
of   the   first    Dorsal    interos- 
seous muscle,  into   the  palm 
of  the  hand.     It  then  crosses 
the  metacarpal  bones   to  the 
ulnar    border    of    the    hand, 
forming  the  deep  palmar  arch, 
and,  at  its  termination,  inos- 
culates with  the  deep  branch 
of   the    ulnar    artery.      The 
relations  of  this  vessel  may 
thus  be  conveniently  divided 
into  three  parts,  viz.,  in  front 
of  the  forearm,  at  the  back 
of  the  wrist,  and  in  the  hand. 
Relations.     In   the  forearm, 
this  vessel  extends  from  op- 
posite the  neck  of  the  radius, 
to  the  fore  part  of  the  styloid 
process,  being    placed  to  the 
inner  side  of  the  shaft  of  that 
bone  above,  and  in  front  of  it 
below.        It      is      superficial 
throughout  its   entire  extent, 
being  covered  by  the  integu- 
ment,    the     superficial     and 
deep     fasciae,     and     slightly 
overlapped     above      by    the 
Supinator     longus.       In     its 
course     downwards     it     lies 
upon  the  tendon   of  the  Bi- 
ceps,   the    Supinator    brevis, 
the  Pronator  radii  teres,  radial 
origin  of  the  Flexor  sublimis 
digitorum,  the  Flexor  longus 
pollicis,   Pronator   quadratus, 
and  the  lower    extremity  of 
the    radius.       In    the    upper 


RADIAL.  411 

third  of  its  course,  it  lies  between  the  Supinator  longus  and  the  Pronator  radii 
teres ;  in  its  lower  two-thirds,  between  the  tendons  of  the  Supinator  longus  and 
the  Flexor  carpi  radialis.  The  radial  nerve  lies  along  the  outer  side  of  the  artery, 
in  the  middle  third  of  its  course ;  and  some  filaments  of  the  musculocutaneous 
nerve,  after  piercing  the  deep  fascia,  run  along  the  lower  part  of  the  artery  as  it 
winds  round  the  wrist.  The  vessel  is  accompanied  by  vense  comites  throughout 
its  whole  course. 


Plan  of  the  Relations  of  the  Radial  Artery  in  the  Forearm. 

In  front. 

Integument,  superficial  and  deep  fasciae. 

Supinator  longus. 

Inner  side.  /^       ~\  Outer  side. 

Pronator  radii  teres.  f  \  Supinator  longus. 

Flexor  carpi  radialis.  /     Arteryin      \  Badial  nerve  (middle 

third). 


Behind. 

Tendon  of  Biceps. 
Supinator  brevis. 
Pronator  radii  teres. 
Flexor  sublimis  digitorum. 
Flexor  longus  pollicis. 
Pronator  quadratus. 
Badius. 

At  the  wrist,  as  it  winds  round  the  outer  side  of  the  carpus,  from  the  styloid 
process  to  the  first  interosseous  space,  it  lies  upon  the  external  lateral  ligament, 
being  covered  by  the  Extensor  tendons  of  the  thumb,  subcutaneous  veins,  some 
filaments  of  the  radial  nerve,  and  the  integument.  It  is  accompanied  by  two 
veins,  and  a  filament  of  the  musculo-cutaneous  nerve. 

In  the  hand,  it  passes  from  the  upper  end  of  the  first  interosseous  space,  between 
the  heads  of  the  Abductor  indicis,  transversely  across  the  palm,  to  the  base  of 
the  metacarpal  bone  of  the  little  finger,  where  it  inosculates  with  the  communi- 
cating branch  from  the  ulnar  artery,  forming  the  deep  palmar  arch.  It  lies  upon 
the  carpal  extremities  of  the  metacarpal  bones  and  the  Interossei  muscles,  being 
covered  by  the  Flexor  tendons  of  the  fingers,  the  Lumbricales,  the  muscles  of  the 
little  finger,  and  the  Flexor  brevis  pollicis,  and  is  accompanied  by  the  deep  branch 
of  the  ulnar  nerve. 

Peculiarities.  The  origin  of  the  radial  artery  varies  nearly  in  the  proportion  of  one  case  in 
eight.  In  one  case  the  origin  was  lower  than  usual;  in  the  others,  the  upper  part  of  the 
brachial  was  a  more  frequent  source  of  origin  than  the  axillary.  The  variations  in  the 
position  of  this  vessel  in  the  arm,  and  at  the  bend  of  the  elbow,  have  been  already  mentioned. 
In  the  forearm  it  deviates  less  frequently  from  its  position  than  the  ulnar.  It  has  been  found 
lying  over  the  fascia,  instead  of  beneath  it.  It  has  also  been  observed  on  the  surface  of  the 
Supinator  longus,  instead  of  along  its  inner  border ;  and  in  turning  round  the  wrist,  it  has  been 
seen  lying  over,  instead  of  beneath,  the  Extensor  tendons. 

Surgical  Anatomy.  The  operation  of  tying  the  radial  artery  is  required  in  cases  of  wounds 
either  of  its  trunk,  or  of  some  of  its  branches,  or  for  aneurism ;  and  it  will  be  observed,  that  the 
vessel  may  be  easily  exposed  in  any  part  of  its  course  through  the  forearm.  The  operation  in 
the  middle  or  inferior  third  of  this  region  is  easily  performed  ;  but  in  the  upper  third,  near  the 
elbow,  the  operation  is  attended  with  some  difficulty,  from  the  greater  depth  of  the  vessel,  and 
from  its  being  overlapped  by  the  Supinator  longus  and  Pronator  radii  teres  muscles. 

To  tie  the  artery  in  this  situation,  an  incision  three  inches  in  length  should  be  made  through 
the  integument,  from  the  bend  of  the  elbow  obliquely  downwards  and  outwards,  on  the  radial 
side  of  the  forearm,  avoiding  the  branches  of  the  median  vein;  the  fascia  of  the  arm  being 


412 


ARTERIES. 


divided,  and  the  Supinator  longus  drawn  a  little  outwards,  the  artery  will  be  exposed.  The 
vena;  comites  should  be  carefully  separated  from  the  vessel,  and  the  ligature  passed  from  the 
radial  to  the  ulnar  side. 

In  the  middle  third  of  the  forearm  the  artery  may  be  exposed  by  making  an  incision  of  similar 
length  on  the  inner  margin  of  the  Supinator  longus.  In  this  situation  the  radial  nerve  lies 
in  close  relation  with  the  outer  side  of  the  artery,  and  should,  as  well  as  the  veins,  be  carefully 
avoided. 

In  the  lower  third,  the  artery  is  easily  secured  by  dividing  the  integument  and  fasciae  in  the 
interval  between  the  tendons  of  the  Supinator  Longus  and  Flexor  carpi  radialis  muscles. 

The  branches  of  the  radial  artery  may  be  divided  into  three  groups,  correspond- 
ing with  the  three  regions  in  which  this  vessel  is  situated. 


In  the 
Forearm. 


Radial  recurrent. 
Muscular. 
Superficialis  volse. 
Anterior  carpal. 

Hand. 


Wrist. 


Princeps  pollicis. 
Radialis  indicis. 
Perforantes. 
Interossese. 


I  Dorsales  pollicis. 
[_  Dorsalis  indicis. 


Posterior  carpal. 
j   Metacarpal. 


The  radial  recurrent  is  given  off'  immediately  below  the  elbow.  It  ascends 
between  the  branches  of  the  musculo-spiral  nerve,  lying  on  the  Supinator  brevis, 
and  then  between  the  Supinator  longus  and  Brachialis  anticus,  supplying  these 
muscles,  the  elbow-joint,  and  anastomosing  with  the  terminal  branches  of  the 
superior  profunda. 

The  muscular  branches  are  distributed  to  the  muscles  on  the  radial  side  of  the 
forearm. 

The  superficialis  volse  arises  from  the  radial  artery,  just  where  this  vessel  is 
about  to  wind  round  the  wrist.  Running  forwards,  it  passes  between  the  muscles 
of  the  thumb,  which  it  supplies,  and  anastomoses  with  the  termination  of  the  ulnar 
artery,  completing  the  superficial  palmar  arch.  This  vessel  varies  considerably 
in  size,  usually  being  very  small,  and  terminating  in  the  muscles  of  the  thumb ; 
sometimes  it  is  as  large  as  the  continuation  of  the  radial. 

The  carpal  branches  supply  the  joints  of  the  wrist.  The  anterior  carpal  is  a 
small  vessel  which  arises  from  the  radial  artery  near  the  lower  border  of  the  Pro- 
nator quadratus,  and,  running  inwards  in  front  of  the  radius,  anastomoses  with  the 
anterior  carpal  branch  of  the  ulnar  artery.  From  the  arch  thus  formed,  branches 
descend  to  supply  the  articulations  of  the  wrist. 

The  posterior  carpal  is  a  small  vessel  which  arises  from  the  radial  artery  beneath 
the  Extensor  tendons  of  the  thumb ;  crossing  the  carpus  transversely  to  the  inner 
border  of  the  hand,  it  anastomoses  with  the  posterior  carpal  branch  of  the  ulnar. 
It  sends  branches  upwards,  which  anastomose  with  the  termination  of  the  ante- 
rior interosseous  artery  ;  other  branches  descend  to  the  metacarpal  spaces ;  they 
are  the  dorsal  interosseous  arteries  for  the  third  and  fourth  interosseous  spaces, 
and  anastomose  with  the  posterior  perforating  branches  from  the  deep  palmar 
arch. 

The  metacarpal  {first  dorsal  interosseous  brayich)  arises  beneath  the  Extensor 
tendons  of  the  thumb,  sometimes  with  the  posterior  carpal  artery,  running  for- 
wards on  the  second  Dorsal  interosseous  muscle ;  communicating,  behind,  with 
the  corresponding  perforating  branch % of  the  deep  palmar  arch;  and,  in  front, 
inosculating  with  the  digital  branch  of  the  superficial  palmar  arch,  and  supplying 
the  adjoining  sides  of  the  index  and  middle  fingers. 

The  dorsales  pollicis  are  two  small  vessels  which  run  along  the  sides  of  the 
dorsal  aspect  of  the  thumb.  They  sometimes  arise  separately,  or  occasionally  by 
a  common  trunk,  near  the  base  of  the  first  metacarpal  bone. 

The  dorsalis  indicis,  also  a  small  branch,  runs  along  the  radial  side  of  the  back 
of  the  index  finger,  sending  a  few  branches  to  the  Abductor  indicis. 


BRANCHES   OP   THE   RADIAL. 


413 


The  princeps  pollicis  arises  from  the  radial  just  as  it  turns  inwards  to  the  deep 
part  of  jthe  hand ;  it  descends  between  the  Abductor  indicis  and  Adductor  pollicis, 
along  the  ulnar  side  of  the  meta- 


Fig.  220. — Ulnar  and  Radial  Arteries. 
Deep  View. 


Axbiior  Ylnar 

Recurrent 


Fosftricr  Vlnar 
llerurrtiit 


carpal  bone  of  the  thumb,  to  the 
base  of  the  first  phalanx,  where  it 
divides  into  two  branches,  which 
run  along  the  sides  of  the  palmar 
aspect  of  the  thumb,  and  form  an 
arch  on  the  under  surface  of  the 
last  phalanx,  from  which  branches 
are  distributed  to  the  integument 
and  cellular  membrane  of  the  thumb. 

The  radialis  indicis  arises  close 
to  the  preceding,  descends  between 
the  Abductor  indicis  and  Adductor 
pollicis,  and  runs  along  the  radial 
side  of  the  index-finger  to  its  ex- 
tremity, where  it  anastomoses  with 
the  collateral  digital  artery  from  the 
superficial  palmar  arch.  At  the 
lower  border  of  the  Adductor 
pollicis  this  vessel  anastomoses  with 
the  princeps  pollicis,  and  gives  a 
communicating  branch  to  the  super- 
ficial palmar  arch. 

The  perforantes,  three  in  number, 
pass  backwards  between  the  heads 
of  the  last  three  Dorsal  interossei 
muscles,  to  inosculate  with  the  dor- 
sal interosseous  arteries. 

The  palmar  inter  ossese,  three  or 
four  in  number,  are  branches  of  the 
deep  palmar  arch ;  they  run  for- 
wards upon  the  Interossei  muscles, 
and  anastomose  at  the  clefts  of  the 
fingers  with  the  digital  branches  of 
the  superficial  arch. 

Ulnar  Artery. 


The  Ulnar  Artery,  the  larger  of 
the  two  subdivisions  of  the  bra- 
chial, commences  a  little  below  the 
bend  of  the  elbow,  and  crosses  the 
inner  side  of  the  forearm  obliquely 
to  the  commencement  of  its  lower 
half;  it  then  runs  along  its  ulnar 
border  to  the  wrist,  crosses  the  annu- 
lar ligament  on  the  radial  side  of  the 

pisiform  bone  and  passes  across  the  palm  of  the  hand,  forming  the  superficial 
palmar  arch,  which  terminates  by  inosculating  with  the  superficialis  voice. 

Relations  in  the  Forearm.  In  its  upper  half,  it  is  deeply  seated,  being  covered 
by  all  the  superficial  Flexor  muscles,  excepting  the  Flexor  carpi  ulnaris ;  crossed 
by  the  median  nerve,  which,  for  about  an  inch  lies  to  its  inner  side ;  and  it  lies 
upon  the  Brachialis  anticus  and  Flexor  profundus  digitorum  muscles.  In  the 
lower  half  of  the  forearm,  it  lies  upon  the  Flexor  profundus,  being  covered  by  the 
integument,  and  the  superficial  and  deep  fasciae,  and  is  placed  between  the  Flexor 


414 


ARTERIES. 


carpi  ulnaris  and  Flexor  sublimis  digitorum  muscles.  It  is  accompanied  by  two 
veins,  which  lie  one  on  each  side  of  the  vessel ;  the  ulnar  nerve  lies  on  its  inner 
side  for  the  lower  two-thirds  of  its  extent,  and  a  small  branch  from  it  descends  on 
the  lower  part  of  the  vessel  to  the  palm  of  the  hand. 

Plan  of  Relations  of  the  Ulnar  Artery  in  the  .Forearm. 

In  front. 

MeT™.eMr  m°SClCS'  }  UPPer  Wf  .r  the  arte^. 
Superficial  and  deep  fasciee.      Lower  half  of  the  artery. 


Inner  side. 
Flexor  carpi  ulnaris. 
Ulnar  nerve  (lower  two-thirds  of 
the  artery.) 


Outer  side. 
Flexor  sublimis  digitorum. 


Behind. 
Brachialis  anticus. 
Flexor  profundus  digitorum. 

At  the  wrist,  the  ulnar  artery  is  covered  by  the  integument  and  fascia,  and  lies 
upon  the  anterior  annular  ligament.  On  its  inner  side  is  the  pisiform  bone.  The 
ulnar  nerve  lies  at  the  inner  side,  and  somewhat  behind  the  artery. 

In  the  palm  of  the  hand,  the  continuation  of  the  ulnar  artery  is  called  the  super- 
ficial palmar  arch ;  it  passes  obliquely  outwards  to  the  interspace  between  the 
ball  of  the  thumb  and  the  index-finger,  where  it  anastomoses  with  the  superficialis 
volae,  and  a  branch  from  the  radialis  indicis,  thus  completing  the  superficial  pal- 
mar arch.  The  convexity  of  this  arch  is  directed  towards  the  fingers,  its  concav- 
ity towards  the  muscles  of  the  thumb. 

The  superficial  palmar  arch  is  covered  by  the  Palmaris  brevis,  the  palmar  fascia, 
and  integument ;  and  lies  upon  the  annular  ligament,  the  muscles  of  the  little  finger, 
the  tendons  of  the  superficial  Flexor,  and  the  divisions  of  the  median  and  ulnar 
nerves,  the  latter  accompanying  the  artery  a  short  part  of  its  course. 


Relations  of  the  Superficial  Palmar  Arch. 


In  front. 
Integument. 
Palmaris  brevis. 
Palmar  fascia. 


Behind. 
Annular  ligament. 
Origin  of  muscles  of  little  finger. 
Superficial  Flexor  tendons. 
Divisions  of  median  and  ulnar  nerves. 


Peculiarities.  The  ulnar  artery  was  found  to  vary  in  its  origin  nearly  in  the  proportion  of 
one  in  thirteen  cases,  in  one  case  arising  lower  than  usual,  about  two  or  three  inches  below  the 
elbow,  and  in  all  the  other  cases  much  higher,  the  brachial  being  a  more  frequent  source  of  origin 
than  the  axillary. 

Variations  in  the  position  of  this  vessel  are  more  frequent  than  in  the  radial.  When  its  ori- 
gin is  normal,  the  course  of  the  vessel  is  rarely  changed.  When  it  arises  high  up,  its  position 
id  the  forearm  is  almost  invariably  superficial  to  the  Flexor  muscles,  lying  commonly  beneath  the 
fascia,  more  rarely  between  the  fascia  and  integument.  In  a  few  cases,  its  position  was  subcu- 
taneous in  the  upper  part  of  the  forearm,  sub-aponeurotic  in  the  lower  part. 

Surgical  Anatomy.  The  application  of  a  ligature  to  this  vessel  is  required  in  cases  of  wound 
of  the  artery,  or  of  "its  branches,  or  in  consequence  of  aneurism.  In  the  upper  half  of  the  fore- 
arm, the  artery  is  deeply  seated  beneath  the  superficial  Flexor  muscles,  and  their  division  would 
be  requisite  in  a  case  of  recent  wound  of  the  artery  in  this  situation,  in  order  to  secure  it,  but 
under  no  other  circumstances.  In  the  middle  and  lower  third  of  the  forearm,  this  vessel  may  be 
easily  secured  by  making  an  incision  on  the  radial  side  of  the  tendon  of  the  Flexor  carpi  ulnaris  ; 
the  deep  fascia  being  divided,  and  the  Flexor  carpi  ulnaris  and  its  companion  muscle,  the  Flexor 
sublimis,  being  separated  from  each  other,  the  vessel  will  be  exposed,  accompanied  by  its  venae 
comites,  the  ulnar  nerve  lying  on  its  inner  side.  The  veins  being  separated  from  the  artery,  the 
ligature  should  be  passed  from  the  ulnar  to  the  radial  side,  taking  care  to  avoid  the  ulnar  nerve. 


BRANCHES   OF   THE   ULNAR. 


415 


The  branches  of  the  ulnar  artery  may  be  arranged  into  the  following  groups : — 
(  Anterior  ulnar  recurrent. 
Posterior  ulnar  recurrent. 
Forearm.  \   T  '.  \   Anterior  interosseous. 

I   Interosseous  j   Posterior  interosSeous. 

1   Muscular. 


-prr  .  ,   j    Anterior  carpal. 


Sand. 


\ 


The  anterior  ulnar  re- 
current arises  immediately 
below  the  elbow-joint,  passes 
upwards  and  inwards  be- 
tween the  Brachialis  anticus 
and  Pronator  radii  teres, 
supplies  these  muscles,  and, 
in  front  of  the  inner  con- 
dyle, anastomoses  with  the 
anastomotica  magna  and  in- 
ferior profunda. 

The  posterior  ulnar  re- 
current is  much  larger,  and 
arises  somewhat  lower  than 
the  preceding.  It  passes 
backwards  and  inwards,  be- 
neath the  Flexor  sublimis, 
and  ascends  behind  the  inner 
condyle  of  the  humerus.  In 
the  interval  between  this 
eminence  and  the  olecranon, 
it  lies  beneath  the  Flexor 
carpi  ulnaris,  ascending  be- 
tween the  heads  of  that 
muscle,  beneath  the  ulnar 
nerve ;  it  supplies  the  neigh- 
boring muscles  and  joint, 
and  anastomoses  with  the 
inferior  profunda,  anasto- 
motica magna,  and  inter- 
osseous recurrent  arteries. 

The  interosseous  artery  is 
a  short  trunk,  about  an 
inch  in  length,  and  of  con- 
siderable size,  which  arises 
immediately  below  the  tu- 
berosity of  the  radius,  and, 
passing  backwards  to  the 
upper  border  of  the  inter- 
osseous membrane,  divides 
into  two  branches,  the  an- 
terior and  posterior  inter- 
osseous. 

The  anterior  interosseous 
passes  down  the  forearm 
on  the  anterior  surface  of 
the   interosseous   membrane, 


Posterior  carpal. 

Deep  or  communicating  branch. 

Digital. 

Fig.  221. — Arteries  of  the  Back  of  the  Forearm  and  Hand. 


rerrndintj  Branrfl  frvtm 

Sup  t  rio  rProfu  n  da, 


Anasrta  mot  tea 

Magna 


Tturtrrici- 

Viiiarlitcui- 


Posterior  Interoeseoit* 


Poxtrrfor  Carpal 
(  Ulnar) 


Termination     rf 
ieriorlnterotvr  out 


Posterior  Carpal 
(Radial ) 


Dortalix  fo/f/eU 
Dorsalt 't  Indiclt 


416  ARTERIES. 

to  which,  it  is  connected  by  a  thin  aponeurotic  arch.  It  is  accompanied  by  the 
interosseous  branch  of  the  median  nerve,  and  overlapped  by  the  contiguous 
margins  of  the  Flexor  profundus  digitorum  and  Flexor  longus  pollicis  muscles, 
giving  off  in  this  situation  muscular  branches,  and  the  nutrient  arteries  of  the 
radius  and  ulna.  At  the  upper  border  of  the  Pronator  quadratus,  a  branch 
descends  in  front  of  that  muscle,  to  anastomose  in  front  of  the  carpus  with 
branches  from  the  anterior  carpal  and  deep  palmar  arch.  The  continuation  of 
the  artery  passes  behind  the  Pronator  quadratus,  and,  piercing  the  interosseous 
membrane,  descends  to  the  back  of  the  wrist,  where  it  anastomoses  with  the 
posterior  carpal  branches  a?  the  radial  and  ulnar  arteries.  The  anterior  inter- 
osseous gives  off  a  long,  slender  branch,  which  accompanies  the  median  nerve, 
and  gives  offsets  to  its  substance.  This,  the  median  artery,  is  sometimes  much 
enlarged. 

The  posterior  interosseous  artery  passes  backwards  through  the  interval  be- 
tween the  oblique  ligament  and  the  upper  border  of  the  interosseous  membrane, 
and  down  the  back  part  of  the  forearm,  between  the  superficial  and  deep 
layers  of  muscles,  to  both  of  which  it  distributes  branches.  Descending  to  the 
back  of  the  wrist,  it  anastomoses  with  the  termination  of  the  anterior  inter- 
osseous, and  with  the  posterior  carpal  branches  of  the  radial  and  ulnar  arteries. 
This  artery  gives  off,  near  its  origin,  the  posterior  interosseous  recurrent  branch, 
a  large  vessel,  which  ascends  to  the  interval  between  the  external  condyle  and 
olecranon,  beneath  the  Anconeus  and  Supinator  brevis,  anastomosing  with  a 
branch  from  the  superior  profunda,  and  with  the  posterior  ulnar  recurrent 
artery. 

The  muscular  branches  are  distributed  to  the  muscles  along  the  ulnar  side  of 
the  forearm. 

The  carpal  branches  are  intended  for  the  supply  of  the  wrist-joint. 

The  anterior  carpal  is  a  small  vessel,  which  crosses  the  front  of  the  carpus 
beneath  the  tendons  of  the  Flexor  profundus,  and  inosculates  with  a  corresponding 
branch  of  the  radial  artery. 

The  posterior  carpal  arises  immediately  above  the  pisiform  bone,  winding 
backwards  beneath  the  tendon  of  the  Flexor  carpi  ulnaris ;  it  gives  off  a  branch 
which  passes  across  the  dorsal  surface  of  the  carpus  beneath  the  Extensor  tendons, 
anastomosing  with  a  corresponding  branch  of  the  radial  artery,  and  forming  the 
posterior  carpal  arch ;  it  is  then  continued  along  the  metacarpal  bone  of  the  little 
finger,  forming  its  dorsal  branch. 

The  deep  or  communicating  branch  arises  at  the  commencement  of  the  palmar 
arch,  passing  deeply  inwards  between  the  Abductor  minimi  digiti  and  Flexor 
brevis  minimi  digiti,  near  their  origins ;  it  anastomoses  with  the  termination  of 
the  radial  artery,  completing  the  deep  palmar  arch. 

The  digital  branches,  four  in  number,  are  given  off  from  the  convexity  of  the 
superficial  palmar  arch.  They  supply  the  ulnar  side  of  the  little  finger,  and  the 
adjoining  sides  of  the  ring,  middle.,  and  index-fingers;  the  radial  side  of  the  index- 
finger  and  thumb  being  supplied  from  the  radial  artery.  The  digital  arteries  at 
first  lie  superficial  to  the  Flexor  tendons,  but  as  they  pass  forwards  with  the  digital 
nerves  to  the  clefts  between  the  ringers,  they  lie  between  them,  and  are  there  joined 
by  the  interosseous  branches  from  the  deep  palmar  arch.  The  digital  arteries  on 
the  sides  of  the  fingers  lie  beneath  the  digital  nerves;  and,  about  the  middle  of  the 
last  plialanx,  the  two  branches  for  each  finger  form  an  arch,  from  the  convexity 
of  which  branches  pass  to  supply  the  matrix  of  the  nail. 


The  Descending  Aoeta. 

The  Descending  Aorta  is  divided  into  two  portions,  thet  horacic  and  abdominal, 
in  correspondence  with  the  two  great  cavities  of  the  trunk  in  which  it  is 
situated. 


THORACIC   AORTA.  41T 


The  Thoracic  Aorta. 


The  Thoracic  Aorta  commences  at  the  lower  border  of  the  third  dorsal 
vertebra,  on  the  left  side,  and  terminates  at  the  aortic  opening  in  the  Diaphragm, 
in  front  of  the  last  dorsal  vertebra.  At  its  commencement,  it  is  situated  on  the 
left  side  of  the  spine ;  it  approaches  the  median  line  as  it  descends ;  and,  at  its 
termination,  lies  directly  in  front  of  the  column.  The  direction  of  this  vessel 
beino-  influenced  by  the  spine,  upon  which  it  rests,  it  is  concave  forwards  in  the 
dorsal  region,  and,  as  the  branches  given  off'  from  it  are  small,  the  diminution  in 
the  size  of  the  vessel  is  inconsiderable.  It  is  contained  in  the  back  part  of  the 
posterior  mediastinum,  being  in  relation,  in  front,  from  above  downwards,  with  the 
left  pulmonary  artery,  the  left  bronchus,  the  pericardium,  and  the  oesophagus ; 
behind,  with  the  vertebral  column,  and  the  vena  azygos  minor ;  on  the  right  side, 
with  the  vena  azygos  major,  and  thoracic  duct ;  on  the  left  side,  with  the  left 
pleura,  and  lung.  The  oesophagus,  with  its  accompanying  nerves,  lies  on  the  right 
side  of  the  aorta  above  ;  in  front  of  this  vessel,  in  the  middle  of  its  course ;  whilst, 
at  its  lower  part,  it  is  on  the  left  side,  on  a  plane  anterior  to  it. 

Plan  of  the  Relations  of  the  Thoracic  Aorta. 

In  front. 
Left  pulmonary  artery. 
Left  bronchus. 
Pericardium. 
(Esophagus. 

Right  side.  /  \  haft  side. 

(Esophagus  (above).  /    Thoracic     \  Pleura. 

Vena  azygos  major.  1       Aorta.        I  Left  lung. 

Thoracic  duct.  \  J  (Esophagus  (below). 

Behind. 
Vertebral  column. 
Vena  azygos  minor. 

Surgical  Anatomy.  The  student  should  now  consider  the  effects  likely  to  be  produced  by 
aneurism  of  the  thoracic  aorta,  a  disease  of  common  occurrence.  "When  we  consider  the  great 
depth  of  the  vessel  from  the  surface,  and  the  number  of  important  structures  which  surround  it 
on  every  side,  it  may  be  easily  conceived  what  a  variety  of  obscure  symptoms  may  arise  from  dis- 
ease of  this  part  of  the  arterial  system,  and  how  they  may  be  liable  to  be  mistaken  for  those  of 
other  affections.  Aneurism  of  the  thoracic  aorta  most  usually  extends  backwards,  along  the  left 
side  of  the  spine,  producing  absorption  of  the  bodies  of  the  vertebrae,  causing  extensive  curva- 
ture of  the  spine ;  whilst  the  irritation  or  pressure  on  the  cord  will  give  rise  to  pain,  either  in 
the  chest,  back,  or  loins,  with  radiating  pain  in  the  left  upper  intercostal  spaces,  from  pressure 
on  the  intercostal  nerves;  at  the  same  time,  the  tumor  may  project  back  on  each  side  of  the 
spine,  beneath  the  integument,  as  a  pulsating  swelling,  simulating  abscess  connected  with  dis- 
eased bone  ;  or  it  may  displace  the  oesophagus,  and  compress  the  lung  on  one  or  the  other  side. 
If  the  tumor  extend  forward,  it  may  press  upon  and  displace  the  heart,  giving  rise  to  palpitation, 
and  other  symptoms  of  disease  of  that  organ ;  or  it  may  displace,  or  even  compress,  the  oeso- 
phagus, causing  pain  and  difficulty  of  swallowing,  as  in  stricture  of  that  tube,  and  ultimately  even 
open  into  it  by  ulceration,  producing  fatal  hemorrhage.  If  the  disease  make  its  way  to  either  side, 
it  may  press  upon  the  thoracic  duct;  or  it  may  burst  into  the  pleural  cavity,  or  into  the  trachea 
or  lung ;  and  lastly,  it  may  open  into  the  posterior  mediastinum. 

Branches  of  the  Thoracic  Aorta. 

Pericardiac.  (Esophageal. 

Bronchial.  Posterior  mediastinal. 

Intercostal. 

The  pericardiac  are  a  few  small  vessels,  irregular  in  their  origin,  distributed  to 
the  pericardium. 
27 


413  ARTERIES. 

The  bronchial  arteries  are  the  nutrient  vessels  of  the  lungs,  and  vary  in  number, 
size,  and  origin.  That  of  the  right  side  arises  from  the  first  aortic  intercostal,  or, 
by  a  common  trunk  with  the  left  bronchial,  from  the  front  of  the  thoracic  aorta. 
Those  of  the  left  side,  usually  two  in  number,  arise  from  the  thoracic  aorta,  one 
a  little  lower  than  the  other.  Each  vessel  is  directed  to  the  back  part  of  the 
corresponding  bronchus,  along  which  they  run,  dividing  and  subdividing,  upon 
the  bronchial  tubes,  supplying  them,  the  cellular  tissue  of  the  lungs,  the  bronchial 
glands,  and  the  oesophagus. 

The  oesophageal  arteries,  usually  four  or  five  in  number,  arise  from  the  front  of 
the  aorta,  and  pass  obliquely  downwards  to  the  oesophagus,  forming  a  chain  of 
anastomoses  along  that  tube,  with  the  oesophageal  branches  of  the  inferior  thyroid 
arteries  above,  and  with  ascending  branches  from  the  phrenic  and  gastric  arteries 
below. 

The  posterior  mediastinal  arteries  are  numerous  small  vessels  which  supply  the 
glands  and  loose  areolar  tissue  in  the  mediastinum. 

The  Intercostal  arteries  arise  from  the  back  part  of  the  aorta.  They  are  usually 
ten  in  number  on  each  side,  the  superior  intercostal  space  (and  occasionally  the 
second  one)  being  supplied  by  the  superior  intercostal,  a  branch  of  the  subclavian. 
The  right  intercostals  are  longer  than  the  left,  on  account  of  the  position  of  the 
aorta  to  the  left  side  of  the  spine ;  they  pass  outwards,  across  the  bodies  of  the 
vertebrae,  to  the  intercostal  spaces,  being  covered  by  the  pleura,  the  oesophagus, 
thoracic  duct,  sympathetic  nerve,  and  the  vena  azygos  major;  the  left  passing 
beneath  the  superior  intercostal  vein,  the  vena  azygos  minor,  and  sympathetic. 
In  the  intercostal  spaces,  each  artery  divides  into  two  branches,  an  anterior  or 
proper  intercostal  branch ;  and  a  posterior  or  dorsal  branch. 

The  anterior  branch  passes  outwards,  at  first  lying  upon  the  External  inter- 
costal muscle,  covered  in  front  by  the  pleura,  and  a  thin  fascia.  It  then  passes 
between  the  two  layers  of  Intercostal  muscles,  and,  having  ascended  obliquely 
to  the  lower  border  of  the  rib  above,  divides,  near  the  angle  of  that  bone,  into 
two  branches ;  of  these,  the  larger  runs  in  the  groove,  on  the  lower  border  of 
the  rib  above;  the  smaller  branch  along  the  upper  border  of  the  rib  below ;  passing 
forward,  they  supply  the  Intercostal  muscles,  and  anastomose  with  the  anterior 
intercostal  branches  of  the  internal  mammary,  and  with  the  thoracic  branches  of 
the  axillary  artery.  The  first  aortic  intercostal  anastomoses  with  the  superior 
intercostal,  and  the  last  three  pass  between  the  abdominal  muscles,  inosculating 
with  the  epigastric  in  front,  and  with  the  phrenic  and  lumbar  arteries.  Each 
intercostal  artery  is  accompanied  by  a  vein  and  nerve,  the  former  being  above, 
and  the  latter  below,  except  in  the  upper  intercostal  spaces,  where  the  nerve  is  at 
first  above  the  artery.  The  arteries  are  protected  from  pressure  during  the  action 
of  the  Intercostal  muscles,  by  fibrous  arches  thrown  across,  and  attached  by  each 
extremity  to  the  bone. 

The  posterior  or  dorsal  branch  of  each  intercostal  artery  passes  backwards 
to  the  inner  side  of  the  anterior  costo-transverse  ligament,  and  divides  into  a 
spinal  branch,  which  supplies  the  vertebrae,  and  the  spinal  cord  and  its  membranes, 
and  a  muscular  branch,  which  is  distributed  to  the  muscles  and  integument  of  the 
back. 


The  Abdominal  Aoeta  (fig.  222). 

The  Abdominal  Aorta  commences  at  the  aortic  opening  of  the  Diaphragm,  in 
front  of  the  body  of  the  last  dorsal  vertebra,  and,  descending  a  little  to  the  left 
side  of  the  vertebral  column,  terminates  on  the  left  side  of  the  body  of  the  fourth 
lumbar  vertebra,  where  it  divides  into  the  two  common  iliac  arteries.  As  it  lies 
upon  the  bodies  of  the  vertebrae,  it  is  convex  forwards,  the  greatest  convexity 
corresponding  to  the  third  lumbar  vertebra,  which  is  a  little  above  and  to  the  left 
side  of  the  umbilicus. 


ABDOMINAL   AORTA. 


419 


Relations.  It  is  covered,  in  front,  by  the  lesser  omentum  and  stomach,  behind 
which  are  the  branches  of  the  coeliac  axis  and  the  solar  plexus ;  below  these,  by 
the  splenic  vein,  the  pancreas,  the  left  renal  vein,  the  transverse  portion  of  the 
duodenum,  the  mesentery,  and  aortic  plexus.  Behind,  it  is  separated  from  the 
lumbar  vertebrae  by  the  left  lumbar  veins,  the  receptaculum  chyli,  and  thoracic 


Fig.  222. — The  Abdominal  Aorta  and  its  Branches. 


duct.  On  the  right  side,  with  the  inferior  vena  cava  (the  right  crus  of  the 
Diaphragm  being  interposed  above),  the  vena  azygos,  thoracic  duct,  and  right 
semilunar  ganglion.  On  the  left  side,  with  the  sympathetic  nerve,  and  left  semi- 
lunar ganglion. 


420 


ARTERIES. 


Plan  of  the  Eelations  of  the  Abdominal  Aorta. 

In  front. 

Lesser  omentum  and  stomach. 

Branches  of  cceliac  axis  and  solar  plexus. 

Splenic  vein. 

Pancreas. 

Left  renal  vein. 

Transverse  duodenum. 

Mesentery. 

Aortic  plexus. 

Right  side.  Left  side. 

Right  crus  of  Diaphragm.  f         >.  Sympathetic  nerve. 

Inferior  vena  cava.  /  \  Left  semilunar  ganglion. 

Vena  azygos.      r 

Thoracic  duct. 

Right  semilunar  ganglion. 

Behind. 
Left  lumbar  veins. 
Receptaculum  chyli. 
Thoracic  duct. 
Vertebral  column. 

Surgical  Anatomy.  Aneurisms  of  the  abdominal  aorta  near  the  cceliac  axis  communicate  in 
nearly  equal  proportion  with  the  anterior  and  posterior  parts  of  this  vessel. 

"When  an  aneurismal  sac  is  connected  with  the  back  part  of  the  abdominal  aorta,  it  usually 
produces  absorption  of  the  bodies  of  the  vertebra;,  and  forms  a  pulsating  tumor,  that  presents 
itself  in  the  left  hypochondriac  or  epigastric  regions,  accompanied  by  symptoms  of  disturbance 
of  the  alimentary  canal.  Pain  is  invariably  present,  and  is  usually  of  two  kinds,  a  fixed  and 
constant  pain  in  the  back,  caused  by  the  tumor  pressing  on  or  displacing  the  branches  of  the 
solar  plexus  and  splanchnic  nerves,  and  a  sharp  lancinating  pain,  radiating  along  those  branches 
of  the  lumbar  nerves  pressed  on  by  the  tumor;  hence  the  pain  in  the  loins,  the  testes,  the  hypo- 
gastrium,  and  in  the  lower  lfmb.  usually  of  the  left  side.  This  form  of  aneurism  usually  bursts 
into  the  peritoneal  cavity,  or  behind  the  peritoneum,  in  the  left  hypochondriac  region ;  or  it  may 
form  a  large  aneurismal  sac,  extending  down  as  low  as  Poupart's  ligament ;  hemorrhage  in  these 
cases  being  generally  very  extensive,  but  slowly  produced,  and  never  rapidly  fatal. 

When  aij  aneurismal  sac  is  connected  with  the  front  of  the  aorta,  near  the  cceliac  axis,  it  forms 
a  pulsating  tumor  in  the  left  hypochondriac  or  epigastric  regions,  usually  attended  with  symptoms 
of  disturbance  of  the  alimentary  canal,  as  sickness,  dyspepsia,  or  constipation,  and  accompanied- 
by  pain,  which  is  constant  but  nearly  always  fixed  in  the  loins,  epigastrium,  or  some  part  of  the 
abdomen ;  the  radiating  pain  being  rare,  as  the  lumbar  nerves  are  seldom  implicated.  This  form 
of  aneurism  may  Lyurst  into  the  peritoneal  cavity,  or  behind  the  peritoneum,  between  the  layers 
of  the  mesentery,  or,  more  rarely,  into  the  duodenum ;  it  rarely  extends  backwards  so  as  to  affect 
the  spine. 

Branches  of  the  Abdominal  Aorta. 


Phrenic. 

I  Gastric. 
Cceliac  axis.     I  Hepatic. 

(  Splenic. 
Superior  mesenteric. 
Supra-renal. 


Renal. 
Spermatic. 
Inferior  mesenteric. 
Lumbar. 
Sacra  media. 


The  branches  of  the  abdominal  aorta  may  be  divided  into  two  sets :  1.  Those 
supplying  the  viscera.     2.  Those  distributed  to  the  walls  of  the  abdomen. 


Visceral  Branches. 

[  Gastric. 
Cceliac  axis.     -!  Hepatic. 

(  Splenic. 
Superior  mesenteric. 
Inferior  mesenteric. 
Supra-renal. 
Renal. 
Spermatic. 


Parietal  Branches. 
Phrenic. 
Lumbar. 
Sacra  media. 


CCELIAC   AXIS. 


421 


Qeliac  Axis  * 

To  expose  this  artery,  raise  the  liver,  draw  down  the  stomach,  and  then  tear  through  the  layers 
of  the  lesser  omentum. 

The  Coeliac  Axis  is  a  short  thick  trunk,  about  half  an  inch  in  length,  arising 
from  the  aorta,  opposite  the  margin  of  the  Diaphragm,  and,  passing  nearly  hori- 
zontally forwards  (in  the  erect  posture),  divides  into  three  large  branches,  the 
gastric,  hepatic,  and  splenic,  occasionally  giving  off  one  of  the  phrenic  arteries. 

Relations.  It  is  covered  by  the  lesser  omentum.  On  the  right  side,  it  is  in 
relation  with  the  right  semilunar  ganglion,  and  the  lobus  Spigelii.  On  the  left 
side,  with  the  right  semilunar  ganglion  and  cardiac  end  of  the  stomach.  Below, 
it  rests  upon  the  upper  border  of  the  pancreas. 


Fig.  223.- 


-The  Coeliac  Axis  and  its  Branches,  the  Liver  having  been  raised,  and 
the  Lesser  Omentum  removed. 


The  5a.stric  Artery  (Coronaria  ventriculi),  the  smallest  of  the  three  brandies 
of  the  coeliac  axis,  passes  upwards  and  to  the  left  side,  to  the  cardiac  orifice  of 
the  stomach,  distributing  branches  to  the  oesophagus,  which  anastomose  with  the 
aortic  oesophageal  arteries ;  others  supply  the  cardiac  end  of  the  stomach,  inoscu- 
lating with  branches  of  the  splenic  artery ;  it  then  passes  from  left  to  right,  along 
the  lesser  curvature  of  the  stomach  to  the  pylorus,  lying  in  its  course  between 
the  layers  of  the  lesser  omentum,  and  giving  branches  to  both  surfaces  of  the 
organ ;  at  its  termination  it  anastomoses  with  the  pyloric  branch  of  the  hepatic. 

The  Hepatic  Artery  in  the  adult  is  intermediate  in  size  between  the  gastric 
and  splenic ;  in  the  foetus,  it  is  the  largest  of  the  three  branches  of  the  coeliac 


422 


ARTERIES. 


axis. 


It  passes  upwards  to  the  right  side,  between  the  layers  of  the  lesser 
omentum,  and  in  front  of  the  foramen  of  Winslow,  to  the  transverse  fissure  of  the 
liver,  where  it  divides  into  two  branches  (right  and  left),  which  supply  the  cor- 
responding lobes  of  that  organ,  accompanying  the  ramifications  of  the  vena  portse 
and  hepatic  duct.  The  hepatic  artery,  in  its  course  along  the  right  border  of  the 
lesser  omentum,  is  in  relation  with  the  ductus  communis  choledochus  and  portal 
vein,  the  former  lying  to  the  right  of  the  artery,  and  the  vena  portae  behind. 
Its  branches  are  the 


Pyloric. 

Gastro-d  uodenalis 
Cystic. 


Qastro-epiploica  dextra. 
Pancreatico-duodenalis. 


Fip 


224. — The  Cceliac  Axis  and  its  Blanches,  the  Stomach  having  been  raised,  and 
the  Transverse  Meso-colon  removed. 


Grtnt 


K 


The  "pyloric  branch  arises  from  the  hepatic,  above  the  pylorus,  descends  to  the 
pyloric  end  of  the  stomach,  and  passes  from  right  to  left  along  its  lesser  curvature, 
supplying  it  with  branches,  and  inosculating  with  the  gastric  artery. 

The  gastro-duodenalis  is  a  short  but  large  branch,  which  descends  behind 
the  duodenum,  near  the  pylorus,  and  divides  at  the  lower  border  of  the  stomach 
into  two  branches,  the  gastro-epiploica  dextra  and  the  pancreatico-duodenalis. 
Previous  to  its  division,  it  gives  off  two  or  three  small  inferior  pyloric  branches 
to  the  pyloric  end  of  the  stomach  and  pancreas. 

The  gastro-ejriploica  dextra  runs  from  right  to  left  along  the  greater  curvature 


SUPERIOR   MESENTERIC-  423 

of  the  stomach,  between  the  layers  of  the  great  omentum,  anastomosing  about  the 
middle  of  the  lower  border  of  this  organ  with  the  gastro-epiploica  sinistra  from 
the  splenic  artery.  This  vessel  gives  off  numerous  branches,  some  of  which 
ascend  to  supply  both  surfaces  of  the  stomach,  whilst  others  descend  to  supply 
the  great  omentum. 

The  pancreatico-duodenalis  descends  along  the  contiguous  margins  of  the  duode- 
num and  pancreas.  It  supplies  both  these  organs,  and  anastomoses  with  the 
inferior  pancreatico-duodenal  branch  of  the  superior  mesenteric  artery. 

In  ulceration  of  the  duodenum,  which  frequently  occurs  in  connection  with 
severe  burns,  this  artery  is  often  involved,  and  death  may  occur  from  hemorrhage 
into  the  intestinal  canal. 

The  cystic  artery,  usually  a  branch  of  the  right  hepatic,  passes  upwards  and 
forwards  along  the  neck  of  the  gall-bladder,  and  divides  into  two  branches,  one 
of  which  ramifies  on  its  free  surface,  the  other  between  it  and  the  substance  of 
the  liver. 

The  Splenic  Artery,  in  the  adult,  is  the  largest  of  the  three  branches  of  the 
cceliac  axis,  and  is  remarkable  for  the  extreme  tortuosity  of  its  course.  It  passes 
horizontally  to  the  left  side  behind  the  upper  border  of  the  pancreas,  accompanied 
by  the  splenic  vein,  which  lies  below  it ;  and,  on  arriving  near  the  spleen,  divides 
into  branches,  some  of  which  enter  the  hilus  of  that  organ  to  be  distributed  to 
its  structure,  whilst  others  are  distributed  to  the  great  end  of  the  stomach. 

The  branches  of  this  vessel  are  the 

Pancreaticae  parvae.  Gastric  (Yasa  brevia). 

Pancreatica  magna.  Gastro-epiploica  sinistra. 

The  pancreaticse  are  numerous  small  branches  derived  from  the  splenic  as  it  runs 
behind  the  upper  border  of  the  pancreas,  supplying  its  middle  and  left  parts. 
One  of  these,  larger  than  the  rest,  is  given  off  from  the  splenic  near  the  left 
extremity  of  the  pancreas ;  it  runs  from  left  to  right  near  the  posterior  surface  of 
the  gland,  following  the  course  of  the  pancreatic  duct,  and  is  called  the  pancreatica 
magna.  These  vessels  anastomose  with  the  pancreatic  branches  of  the  pancreatico- 
duodenal arteries. 

The  gastric  (vasa  brevia)  consist  of  from  five  to  seven  small  branches,  which 
arise  either  from  the  termination  of  the  splenic  artery,  or  from  its  terminal 
branches ;  and  passing  from  left  to  right,  between  the  layers  of  the  gastro-splenic 
omentum,  are  distributed  to  the  great  curvature  of  the  stomach ;  anastomosing 
with  branches  of  the  gastric  and  gastro-epiploica  sinistra  arteries. 

The  gastro-epiploica  sinistra,  the  largest  branch  of  the  splenic,  runs  from  left 
to  right  along  the  great  curvature  of  the  stomach,  between  the  layers  of  the  great 
omentum,  and  anastomoses  with  the  gastro-epiploica  dextra.  In  its  course,  it 
distributes  several  branches  to  the  stomach,  which  ascend  upon  both  surfaces; 
others  descend  to  supply  the  omentum. 

Superior  Mesenteric  Artery. 

In  order  to  expose  this  vessel,  raise  the  great  omentum  and  transverse  colon,  draw  down  the 
small  intestines,  and,  if  the  peritoneum  is  divided  where  the  transverse  meso-colon  and  mesentery 
join,  this  artery  will  be  exposed  just  as  it  issues  beneath  the  lower  border  of  the  pancreas. 

The  Superior  Mesenteric  Artery  (fig.  225)  supplies  the  whole  length  of  the 
small  intestine,  except  the  first  part  of  the  duodenum  ;  it  also  supplies  the  caecum, 
ascending  and  transverse  colon.  It  is  a  vessel  of  large  size,  arising  from  the  fore 
part  of  the  aorta,  about  a  quarter  of  an  inch  below  the  cceliac  axis ;  being  covered, 
at  its  origin,  by  the  splenic  vein  and  pancreas.  It  passes  forwards,  between  the 
pancreas  and  transverse  portion  of  the  duodenum,  crosses  in  front  of  this  portion 
of  the  intestine,  and  descends  between  the  layers  of  the  mesentery  to  the  right 
iliac  fossa,  where  it  terminates  considerably  diminished  in  size.  In  its  course  it 
forms  an  arch,  the  convexity  being  directed  forwards  and  downwards  to  the  left 
side,  the  concavity  backwards  and  upwards  to  the  right.     It  is  accompanied  by 


424 


ARTERIES. 


the  superior  mesenteric  vein,  and  is  surrounded  by  the  superior  mesenteric  plexus 
of  nerves.     Its  branches  are  the 

Inferior  pancreatico-duodenal.  Ileo-colic. 

Vasa  intestini  tenuis.       .  Colica  dextra. 

Colica  media. 
The  inferior  pancreatico-duodenal  is  given  off  from  the  superior   mesenteric 
below  the  pancreas,  and  is  distributed  to  the  head  of  the  pancreas,  and  the  trans- 
verse and  descending  portions  of  the  duodenum ;  anastomosing  with  the  pancrea- 
tico-duodenal artery. 


Fig.  225.— The  Superior  Mesenteric  Artery  and  its  Branches. 


The  vasa  intestini  tenuis  arise  from  the  convex  side  of  the  superior  mesenteric 
artery.  They  are  usually  from  twelve  to  fifteen  in  number,  and  are  distributed  to 
the  jejunum  and  ileum.  They  run  parallel  with  one  another  between  the  layers  of 
the  mesentery ;  each  vessel  dividing  into  two  branches,  which  unite  with  a  similar 
branch  on  each  side,  forming  a  series  of  arches,  the  convexities  of  which  are 
directed  towards  the  intestine.  From  this  first  set  of  arches  branches  arise,  which 
again  unite  with  similar  branches  from  either  side,  and  thus  a  second  series  of 
arches  is  formed;  and  from -these  latter,  a  third,  and  even  a  fourth  or  fifth  series 
of  arches  is  constituted,  diminishing  in  size  the  nearer  they  approach  the  intes- 
tine. From  the  terminal  arches  numerous  small  straight  vessels  arise  which 
encircle  the  intestine,  upon  which  they  are  minutely  distributed,  ramifying  between 
its  coats. 


INFERIOR   MESENTERIC.  425 

The  ileo-colic  artery  is  the  lowest  branch  given  off  from  the  concavity  of  the 
superior  mesenteric  artery.  It  descends  between  the  layers  of  the  mesentery  to 
the  right  iliac  fossa,  where  it  divides  into  two  branches.  Of  these  the  inferior 
one  inosculates  with  the  lowest  branches  of  the  vasa  intestini  tenuis,  from  the 
convexity  of  which  branches  proceed  to  supply  the  termination  of  the  ileum,  the 
ccecum  and  appendix  cceci,  and  the  ileo-ccecal  and  ileo-colic  valves.  The  superior 
division  inosculates  with  the  colica  dextra,  and  supplies  the  commencement  of 
the  colon. 

The  colica  dextra  arises  from  about  the  middle  of  the  concavity  of  the  superior 
mesenteric  artery,  and,  passing  beneath  the  peritoneum  to  the  middle  of  the  ascend- 
ing colon,  divides  into  two  branches ;  a  descending  branch,  which  inosculates  with 
the  ileo-colic,  and  an  ascending  branch  which  anastomoses  with  the  colica  media. 
These  branches  form  arches,  from  the  convexity  of  which  vessels  are  distributed 
to  the  ascending  colon.  The  branches  of  this  vessel  are  covered  with  peritoneum 
only  on  their  anterior  aspect. 

The  colica  media  arises  from  the  upper  part  of  the  concavity  of  the  superior 
mesenteric,  and,  passing  forwards  between  the  layers  of  the  transverse  mesocolon, 
divides  into  two  branches ;  the  one  on  the  right  side  inosculating  with  the  colica 
dextra,  that  on  the  left  side  with  the  colica  sinistra,  a  branch  of  the  inferior 
mesenteric.  From  the  arches  formed  by  their  inosculation,  branches  are  dis- 
tributed to  the  transverse  colon.  The  branches  of  this  vessel  lie  between  two 
layers  of  peritoneum. 

Inferior  Mesenteric  Artery. 

In  order  to  expose  this  vessel,  draw  the  small  intestines  and  mesentery  over  to  the  right  side 
of  the  abdomen,  raise  the  transverse  colon  towards  the  thorax,  and  divide  the  peritoneum  cover- 
ing the  left  side  of  the  aorta. 

The  Inferior  Mesenteric  Artery  (fig.  226)  supplies  the  descending  and  sig- 
moid flexure  of  the  colon,  and  greater  part  of  the  rectum.  It  is  smaller  than  the 
superior  mesenteric,  and  arises  from  the  left  side  of  the  aorta,  between  one  and 
two  inches  above  its  division  into  the  common  iliacs.  It  passes  downwards  to  the 
left  iliac  fossa,  and  then  descends,  between  the  layers  of  the  mesorectum,  into  the 
pelvis,  under  the  name  of  the  superior  hemorrhoidal  artery.  It  lies  at  first  in  close 
relation  with  the  left  side  of  the  aorta,  and  then  passes  in  front  of  the  left  common 
iliac  artery.     Its  branches  are  the 

Colica  sinistra.  Sigmoid. 

Superior  hemorrhoidal. 

The  colica  sinistra  passes  behind  the  peritoneum,  in  front  of  the  left  kidney, 
to  reach  the  descending  colon,  and  divides  into  two  branches ;  an  ascending  branch, 
which  inosculates  with  the  colica  media,  and  a  descending  branch,  which  anasto- 
moses with  the  sigmoid  artery.  From  the  arches  formed  by  these  inosculations, 
branches  are  distributed  to  the  descending  colon. 

The  sigmoid  artery  runs  obliquely  downwards  across  the  Psoas  muscle  to  the 
sigmoid  flexure  of  the  colon,  and  divides  into  branches  which  supply  that  part  of 
the  intestine ;  anastomosing  above,  with  the  colica  sinistra,  and,  below,  with  the 
superior  hemorrhoidal  artery.  This  vessel  is  sometimes  replaced  by  three  or  four 
small  branches. 

The  superior  hemorrhoidal  artery,  the  continuation  of  the  inferior  mesen- 
teric, descends  into  the  pelvis  between  the  layers  of  the  mesorectum,  crossing,  in 
its  course,  the  ureter,  and  left  common  iliac  vessels.  Opposite  the  middle 
of  the  sacrum  it  divides  into  two  branches,  which  descend  one  on  each  side  of  the 
rectum,  where  they  divide  into  several  small  branches,  which  are  distributed 
between  the  mucous  and  muscular  coats  of  that  tube,  to  near  its  lower  end ;  anas- 
tomosing with  each  other,  with  the  middle  hemorrhoidal  arteries,  branches  of  the 
internal  iliac,  and  with  the  inferior  hemorrhoidal,  branches  of  the  internal  pudic. 

The  student  should  especially  remark,  that  the  trunk  of  the  vessel  descends 


426 


ARTERIES. 


along  the  hack  part  of  the  rectum  as  far  as  the  middle  of  the  sacrum  before  it 
divides ;  this  is  about  a  finger's  length  or  four  inches  from  the  anus.     In  disease 

Fig.  226. — The  Inferior  Mesenteric  Artery  and  its  Branches. 


Midd.lt    Jluviarrko. 
Inferior  KsmorrhoiJul 


of  this  tube,  the  rectum  should  never  be  divided  beyond  this  point  in  that  direc- 
tion, for  fear  of  involving  the  artery. 

SUPRA-RENAL   ARTERIES. 

The  Supra-renal  Arteries  are  two  small  vessels  which  arise,  one  on  each  side 
of  the  aorta,  opposite  the  superior  mesenteric  artery.  They  pass  obliquely 
upwards  and  outwards,  to  the  under  surface  of  the  supra-renal  capsules,  to  which 
they  are  distributed,  anastomosing  with  capsular  branches  from  the  phrenic  and 
renal  arteries.  In  the  adult  these  arteries  are  of  small  size ;  in  the  foetus  they  are 
as  large  as  the  renal  arteries. 

Renal  Arteries. 

The  Renal  Arteries  are  two  large  trunks,  which  arise  from  the  sides  of  the 
aorta,  immediately  below  the  superior  mesenteric  artery.  Each  is  directed  out- 
wards, so  as  to  form  nearly  a  right  angle  with  the  aorta.  The  right  one  longer 
than  the  left,  on  account  of  the  position  of  the  aorta,  passes  behind  the  inferior 
vena  cava.  The  left  is  somewhat  higher  than  the  right.  Previously  to  entering 
the  kidney,  each  artery  divides  into  four  or  five  branches,  which  are  distributed 
to  its  substance.     At  the  hilum,  these  branches  lie  between  the  renal  vein  and 


PHRENIC   AND    LUMBAR.  427 

ureter,  the  vein  being  usually  in  front,  the  ureter  behind.  Each  vessel  gives  off 
some  small  branches  to  the  supra-renal  capsules,  the  ureter,  and  to  the  surround- 
ing cellular  membrane  and  muscles. 

Spermatic  Arteries. 

The  Spermatic  Arteries  are  distributed  to  the  testes  in  the  male,  and  to  the 
ovaria  in  the  female.  They  are  two  slender  vessels,  of  considerable  length, 
which  arise  from  the  front  of  the  aorta,  a  little  below  the  renal  arteries.  Each 
artery  passes  obliquely  outwards  and  downwards,  behind  the  peritoneum,  cross- 
ing the  ureter,  and  resting  on  the  Psoas  muscle,  the  right  spermatic  lying  in 
front  of  the  inferior  vena  cava,  the  left  behind  the  sigmoid  flexure  of  the  colon. 
On  reaching  the  margin  of  the  pelvis,  each  vessel  passes  in  front  of  the 
corresponding  external  iliac  artery,  and  takes  a  different  course  in  the  two  sexes. 

In  the  male,  it  is  directed  outwards,  to  the  internal  abdominal  ring,  and 
accompanies  the  other  constituents  of  the  spermatic  cord  along  the  spermatic 
canal  to  the  testis,  where  it  becomes  tortuous,  and  divides  into  several  branches, 
two  or  three  of  which  accompany  the  vas  deferens,  and  supply  the  epididymis, 
anastomosing  with  the  artery  of  the  vas  deferens ;  others  pierce  the  back  part  of 
the  tunica  albuginea,  and  supply  the  substance  of  the  testis. 

At  an  early  period  of  foetal  life,  when  the  testes  lie  by  the  side  of  the  spine, 
below  the  kidneys,  the  spermatic  arteries  are  short ;  but  as  these  organs  descend 
from  the  abdomen  into  the  scrotum,  they  become  gradually  lengthened. 

In  the  female,  the  spermatic  arteries  (ovarian)  are  shorter  than  in  the  male, 
and  do  not  pass  out  of  the  abdominal  cavity.  On  arriving  at  the  margins  of  the 
pelvis,  each  artery  passes  inwards,  between  the  two  laminae  of  the  broad  ligament 
of  the  uterus,  to  be  distributed  to  the  ovary.  One  or  two  small  branches  supply 
the  Fallopian  tube ;  another  passes  on  to  the  side  of  the  uterus,  and  anastomoses 
with  the  uterine  arteries.  Other  offsets  are  continued  along  the  round  ligament, 
through  the  inguinal  canal,  to  the  integument  of  the  labium  and  groin. 

Phrenic  Arteries. 

The  Phrenic  Arteries  are  two  small  vessels,  which  present  much  variety  in  their 
origin.  They  may  arise  separately  from  the  front  of  the  aorta,  immediately  below 
the  coeliac  axis,  or  by  a  common  trunk,  which  may  spring  either  from  the  aorta,  or 
from  the  coeliac  axis.  Sometimes  one  is  derived  from  the  aorta,  and  the  other  from 
one  of  the  renal  arteries.  In  only  one  out  of  thirty -six  cases,  did  these  arteries 
arise  as  two  separate  vessels  from  the  aorta.  They  diverge  from  one  another 
across  the  crura  of  the  Diaphragm,  and  then  pass  obliquely  upwards  and  outwards 
upon  its  under  surface.  The  left  phrenic  passes  behind  the  oesophagus,  and  runs 
forwards  on  the  left  side  of  the  oesophageal  opening.  The  right  phrenic  passes 
behind  the  liver  and  inferior  vena  cava,  and  ascends  along  the  right  side  of  the 
aperture  for  transmitting  that  vein.  Near  the  back  part  of  the  central  tendon, 
each  vessel  divides  into  two  branches.  The  internal  branch  runs  forwards  to  the 
front  of  the  thorax,  supplying  the  Diaphragm,  and  anastomosing  with  its  fellow 
of  the  opposite  side,  and  with  the  musculo-phrenic,  a  branch  of  the  internal 
mammary.  The  external  branch  passes  towards  the  side  of  the  thorax,  and  in- 
osculates with  the  intercostal  arteries.  The  internal  branch  of  the  right  phrenic 
gives  off  a  few  vessels  to  the  inferior  vena  cava;  and  the  left  one  some  branches 
to  the  oesophagus.  Each  vessel  also  sends  capsular  branches  to  the  supra-renal 
capsule  of  its  own  side.  The  spleen  on  the  left  side,  and  the  liver  on  the  right, 
also  receive  a  few  branches  from  these  vessels. 

Lumbar  Arteries. 

The  Lumbar  Arteries  are  analogous  to  the  intercostal.  They  are  usually  four 
in  number  on  each  side,  and  arise  from  the  back  part  of  the  aorta,  nearly  at  right 
angles  with  that  vessel.     They  pass  outwards  and  backwards,  around  the  sides  of 


428  ARTERIES. 

the  body  of  the  corresponding  lumbar  vertebra,  behind  the  sympathetic  nerve 
and  the  Psoas  muscle ;  those  on  the  right  side  being  covered  by  the  inferior  vena 
cava,  and  the  two  upper  ones  on  each  side  by  the  crura  of  the  Diaphragm.  In  the 
interval  between  the  transverse  processes  of  the  vertebrae,  each  artery  divides 
into  a  dorsal  and  an  abdominal  branch. 

The  dorsal  branch  gives  off)  immediately  after  its  origin,  a  spinal  branch, 
which  enters  the  spinal  canal;  it  then  continues  its  course  backwards,  between 
the  transverse  processes,  and  is  distributed  to  the  muscles  and  integument  of  the 
back,  anastomosing  with  its  fellow,  and  with  the  posterior  branches  of  the  inter- 
costal arteries. 

The  spinal  branch,  besides  supplying  offsets  which  run  along  the  nerves  to  the 
dura  mater  and  cauda  equina,  anastomosing  with  the  other  spinal  arteries,  divides 
into  two  branches,  one  of  which  ascends  on  the  posterior  surface  of  the  body  of 
the  vertebra  above,  and  the  other  descends  on  the  posterior  surface  of  the  body  of 
the  vertebra  below,  both  vessels  anastomosing  with  similar  branches  from  neigh- 
boring spinal  arteries.  The  inosculations  of  these  vessels  on  each  side,  throughout 
the  whole  length  of  the  spine,  form  a  series  of  arterial  arches  behind  the  bodies 
of  the  vertebras,  which  are  connected  with  each  other,  and  with  a  median  longi- 
tudinal vessel,  extending  along  the  middle  of  the  posterior  surface  of  the  bodies 
of  the  vertebrae,  by  transverse  branches.  From  these  vessels  offsets  are  distributed 
to  the  periosteum  and  bones. 

The  abdominal  branches  pass  outwards,  behind  the  Quadratus  lumborum,  the 
lowest  branch  occasionally  in  front  of  that  muscle,  and,  being  continued  between 
the  abdominal  muscles,  anastomose  with  branches  of  the  epigastric  and  internal 
mammary  in  front,  the  intercostals  above,  and  those  of  the  ilio-lumbar  and  circum- 
flex iliac,  below. 

Middle  Saceal  Arteey. 

The  Middle  Sacral  Artery  is  a  small  vessel,  about  the  size  of  a  crow-quill, 
which  arises  from  the  back  part  of  the  aorta,  just  at  its  bifurcation.  It  descends 
upon  the  last  lumbar  vertebra,  and  along  the  middle  line  of  the  front  of  the 
sacrum,  to  the  upper  part  of  the  coccyx,  where  it  terminates  by  anastomosing 
with  the  lateral  sacral  arteries.  From  it,  branches  arise  which  run  through  the 
mesorectum,  to  supply  the  posterior  surface  of  the  rectum.  Other  branches  are 
given  off  on  each  side,  which  anastomose  with  the  lateral  sacral  arteries,  and  send 
off  small  offsets  which  enter  the  anterior  sacral  foramina. 

Common  Iliac  Arteeies. 

The  abdominal  aorta  divides  into  the  two  common  iliac  arteries.  The  bifurcation 
usually  takes  place  on  the  left  side  of  the  body  of  the  fourth  lumbar  vertebra. 
This  point  corresponds  to  the  left  side  of  the  umbilicus,  and  is  on  a  level  with  a 
line  drawn  from  the  highest  point  of  one  iliac  crest  to  the  other.  The  common 
iliac  arteries  are  about  two  inches  in  length;  diverging  from  the  termination  of  the 
aorta,  they  pass  downwards  and  outwards  to  the  margin  of  the  pelvis,  and  divide 
opposite  the  intervertebral  substance,  between  the  last  lumbar  vertebra  and  the 
sacrum,  into  two  branches,  the  external  and  internal  iliac  arteries;  the  former 
supplying  the  lower  extremity ;  the  latter,  the  viscera  and  parietes  of  the  pelvis. 

The  right  common  iliac  is  somewhat  larger  than  the  left,  and  passes  more  ob- 
liquely across  the  body  of  the  last  lumbar  vertebra.  It  is  covered  by  the  peri- 
toneum, the  ileum,  the  branches  of  the  sympathetic  nerve ;  and  crossed,  at  its 
point  of  division,  by  the  ureter.  Behind,  it  is  separated  from  the  last  lumbar 
vertebra,  by  the  two  common  iliac  veins.  On  its  outer  side,  it  is  in  relation  with 
the  inferior  vena  cava,  and  right  common  iliac  vein,  above ;  and  the  Psoas  magnus 
muscle,  below. 

The  left  common  iliac  is  in  relation,  in  front,  with  the  peritoneum,  branches  of 
the  sympathetic  nerve,  the  rectum  and  superior  hemorrhoidal  artery ;  and  crossed, 
::t  its  point  of  bifurcation,  by  the  ureter.     The  left  common  iliac  vein  lies  partly 


COMMON   ILIAC. 


429 


on  the  inner  side,  and  partly  beneath  the  artery;  on  its  outer  side,  it  is  in  relation 
with  the  Psoas  magnus. 

Branches.  The  common  iliac  arteries  give  off  small  branches  to  the  peritoneum, 
Psoae  muscles,  ureters,  and  to  the  surrounding  cellular  membrane,  and  occasionally 
give  origin  to  the  ilio-lumbar,  or  renal  arteries. 

Peculiarities.  Its  point  of  origin  varies  according  to  the  bifurcation  of  the  aorta.  In  three- 
fourths  of  a  large  number  of  cases,  the  aorta  bifurcated  either  upon  the  fourth  lumbar  vertebra, 
or  upon  the  intervertebral  disk  between  it  and  the  fifth ;  one  case  in  nine  being  below,  and  one  in 
eleven  above  this  point.  In  ten  out  of  every  thirteen  cases,  the  vessel  bifurcated  within  half  an 
inch  above  or  below  the  level  of  the  crest  of  the  ilium ;  more  frequently  below  than  above. 

The  point  of  division  is  subject  to  great  variety.  In  two-thirds  of  a  large  number  of  cases,  it 
was  between  the  last  lumbar  vertebra  and  the  upper  border  of  the  sacrum  ;  in  one  case  in  eight 
being  above,  and  in  one  in  six  below  that  point.  The  left  common  iliac  artery  divides  lower 
down  more  frequently  than  the  right. 

The  relative  length,  also,  of  the  two  common  iliac  arteries  varies.  The  right  common  iliac 
was  longest  in  sixty-three  cases ;  the  left,  in  fifty-two ;  whilst  they  were  both  equal  in  fifty-three. 
The  length  of  the  arteries  varied  in  five-sevenths  of  the  cases  examined,  from  an  inch  and  a  half 
to  three  inches ;  in  about  half  of  the  remaining  cases,  the  artery  was  longer ;  and  in  the  other 
half,  shorter ;  the  minimum  length  being  less  than  half  an  inch,  the  maximum  four  and  a  half 
inches.  In  one  instance,  the  right  common  iliac  was  found  wanting,  the  external  and  internal 
iliacs  arising  directly  from  the  aorta. 

Fig.  227. — Arteries  of  the  Felvis. 


Surgical  Anatomy.    The  application  of  a  ligature  to  the  common  iliac  artery  may  be  required 
on  account  of  aneurism  or  hemorrhage,  implicating  the  external  or  internal  iliacs,  or  on  account 


430  ARTERIES. 

of  secondary  hemorrhage  after  amputation  of  the  thigh  high  up.  It  has  been  seen,  that  the 
origin  of  this  vessel  corresponds  to  the  left  side  of  the  umbilicus  on  a  level  with  a  line  drawn 
from  the  highest  point  of  one  iliac  crest  to  the  opposite  one,  and  its  course  to  a  line  extending 
from  the  left  side  of  the  umbilicus  downwards  towards  the  middle  of  Poupart's  ligament  The 
line  of  incision  required  in  the  first  steps  of  an  operation  for  securing  this  vessel,  would  materially 
depend  upon  the  nature  of  the  disease.  If  the  surgeon  select  the  iliac  region,  a  curved  incision, 
about  five  inches  in  length,  may  be  made,  commencing  on  the  left  side  of  the  umbilicus,  carried 
outwards  towards  the  anterior  superior  iliac  spine,  and  then  along  the  upper  border  of  Poupart's 
ligament,  as  far  as  its  middle.  But  if  the  aneurismal  tumor  should  extend  high  up  in  the  abdo- 
men, along  the  external  iliac,  it  is  better  to  select  the  side  of  the  abdomen,  approaching  the  artery 
from  above,  by  making  an  incision  from  four  to  five  inches  in  length,  from  about  two  inches  above 
and  to  the  left  of  the  umbilicus,  carried  outwards  in  a  curved  direction  towards  the  lumbar  region, 
and  terminating  a  little  below  the  anterior  superior  iliac  spine.  The  abdominal  muscles  (in  either 
case)  having  been  cautiously  divided  in  succession,  the  transversalis  fascia  must  be  carefully  cut 
through,  and  the  peritoneum,  together  with  the  ureter,  separated  from  the  artery,  and  pushed 
aside :  the  sacro-iliac  articulation  must  then  be  felt  for,  and  upon  it  the  vessel  will  be  felt  pulsat- 
ing, and  may  be  fully  exposed  in  close  connection  with  its  accompanying  vein.  On  the  right 
side,  both  common  iliac  veins,  as  well  as  the  inferior  vena  cava,  are  in  close  connection  with  the 
artery,  and  must  be  carefully  avoided.  On  the  left  side,  the  vein  usually  lies  on  the  inner  side, 
and  behind  the  artery  ;  but  it  occasionally  happens,  that  the  two  common  iliac  veins  are  joined 
on  the  left  instead  of  the  right  side,  which  would  add  much  to  the  difficulty  of  an  operation  in 
such  a  case.  If  the  common  iliac  artery  is  so  short  that  danger  is  to  be  apprehended  from 
secondary  hemorrhage  if  a  ligature  is  applied  to  it,  it  would  be  preferable,  in  such  a  case,  to  tie 
both  the  external  and  internal  iliacs  near  their  origin.  This  operation  has  been  performed  in  17 
cases,  9  of  which  were  cured,  and  8  died. 

Collateral  Circulation.  The  principal  agents  in  carrying  on  the  collateral  circulation  after 
the  application  of  a  ligature  to  the  common  iliac,  are,  the  anastomoses  of  the  hemorrhoidal 
branches  of  the  internal  iliac  with  the  superior  hemorrhoidal  from  the  inferior  mesenteric  ;  and 
by  the  anastomoses  of  the  uterine  and  ovarian  arteries,  and  of  the  vesical  arteries  of  opposite 
sides;  of  the  lateral  sacral  with  the  middle  sacral  artery;  of  the  epigastric  with  the  internal 
mammary,  inferior  intercostal  and  lumbar  arteries  ;  of  the  ilio-lumbar  with  the  last  lumbar  artery  ; 
of  the  obturator  artery,  by  means  of  its  pubic  branch,  with  the  vessel  of  the  opposite  side,  and 
with  the  internal  epigastric  ;  and  of  the  gluteal  with  the  posterior  branches  of  the  sacral  arteries. 

Internal  Iliac  Artery. 

The  Internal  Iliac  Artery  supplies  the  walls  and  viscera  of  the  pelvis,  the  gene- 
rative organs,  and  inner  side  of  the  thigh.  It  is  a  short,  thick  vessel,  smaller  than 
the  external  iliac,  and  about  an  inch  and  a-half  in  length,  which  arises  at  the  point 
of  bifurcation  of  the  common  iliac ;  and,  passing  downwards  to  the  upper  margin 
of  the  great  sacro-sciatic  foramen,  divides  into  two  large  trunks,  an  anterior  and 
posterior ;  a  partially  obliterated  cord,  the  hypogastric  artery,  extending  from  the 
extremity  of  the  vessel  forwards  to  the  bladder. 

Relations.  In  front,  with  the  ureter,  which  separates  it  from  the  peritoneum. 
Behind,  with  the  internal  iliac  vein,  the  lumbo-sacral  nerve,  and  Pyriformis 
muscle.     By  its  outer  side,  near  its  origin,  with  the  Psoas  magnus  muscle. 

Plan  of  the  Relations  of  the  Internal  Iliac  Artery. 

In  front. 
Peritoneum, 
Ureter. 


Outer  side. 
Psoas  magnus. 


Behind. 
Internal  iliac  vein. 
Lumbo-sacral  nerve. 
Pyriformis  muscle. 


In  the  foetus,  the  internal  iliac  artery  (hypogastric)  is  twice  as  large  as  the 
external  iliac,  and  appears  the  continuation  of  the  common  iliac.     Passing  forwards 


INTERNAL   ILIAC.  431 

to  the  bladder,  it  ascends  along  the  side  of  that  viscus  to  its  summit,  to  which 
it  gives  branches ;  it  then  passes  upwards  along  the  back  part  of  the  anterior  wall 
of  the  abdomen  to  the  umbilicus,  converging  towards  its  fellow  of  the  opposite 
side.  Having  passed  through  the  umbilical  opening,  the  two  arteries  twine  round 
the  umbilical  vein,  forming  with  it  the  umbilical  cord ;  and,  ultimately,  ramify  in 
the  placenta.  That  portion  of  the  vessel  placed  within  the  abdomen  is  called  the 
hypogastric  artery ;  and  that  external  to  that  cavity,  the  umbilical  artery. 

At  birth,  when  the  placental  circulation  ceases,  that  portion  of  the  hypogastric 
artery  which  extends  from  the  umbilicus  to  the  summit  of  the  bladder,  contracts, 
and  ultimately  dwindles  to  a  solid  fibrous  cord;  the  portion  of  the  same  vessel 
extending  from  the  summit  of  the  bladder  to  within  an  inch  and  a  half  of  its  origin, 
is  not  totally  impervious,  though  it  becomes  considerably  reduced  in  size,  and 
serves  to  convey  blood  to  the  bladder,  under  the  name  of  the  superior  vesical 
artery. 

Peculiarities,  as  regards  its  length.  In  two-thirds  of  a  large  number  of  cases,  the  length  of 
the  internal  iliac  varied  between  an  inch  and  an  inch  and  a  half;  in  the  remaining  third,  it  was 
more  frequently  longer  than  shorter,  the  maximum  length  being  three  inches,  the  minimum  half 
an  inch. 

The  lengths  of  the  common  and  internal  iliac  arteries  bear  an  inverse  proportion  to  each  other, 
the  internal  iliac  artery  being  long  when  the  common  iliac  is  short,  and  vice  versa. 

As  regards  its  place  of  division.  The  place  of  division  of  the  internal  iliac  va/ies  between 
the  upper  margin  of  the  sacrum,  and  the  upper  border  of  the  sacro-sciatic  foramen. 

The  arteries  of  the  two  sides  in  a  series  of  cases  often  differed  in  length,  but  neither  seemed 
constantly  to  exceed  the  other. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  internal  iliac  artery  may  be  required 
in  cases  of  aneurism  or  hemorrhage  affecting  one  of  its  branches.  This  vessel  may  be  secured 
by  making  an  incision  through  the  abdominal  parietes  in  the  iliac  region,  in  a  direction  and  to  an 
extent  similar  to  that  for  securing  the  common  iliac ;  the  transversalis  fascia  having  been  cau- 
tiously divided,  and  the  peritoneum  pushed  inwards  from  the  iliac  fossa  towards  the  pelvis,  the 
finger  may  feel  the  pulsation  of  the  external  iliac  at  the  bottom  of  the  wound ;  and,  by  tracing 
this  vessel  upwards,  the  internal  iliac  is  arrived  at,  opposite  the  sacro-iliac  articulation.  It  should 
be  remembered  that  the  vein  lies  behind,  and  on  the  right  side,  a  little  external  to  the  artery,  and 
in  close  contact  with  it ;  the  ureter  and  peritoneum,  which  lie  in  front,  must  also  be  avoided. 
The  degree  of  facility  in  applying  a  ligature  to  this  vessel  will  mainly  depend  upon  its  length. 
It  has  been  seen  that,  in  the  great  majority  of.  the  cases  examined,  the  artery  was  short,  varying 
from  an  inch  to  an  inch  and  a  half;  in  these  cases,  the  artery  is  deeply  seated  in  the  pelvis;  when, 
on  the  contrary,  the  vessel  is  longer,  it  is  found  partly  above  that  cavity.  If  the  artery  is  very 
short,  which  occasionally  happens,  it  would  be  preferable  to  apply  a  ligature  to  the  common  iliac, 
or  upon  the  external  and  internal  iliacs  at  their  origin.  This  operation  has  been  performed  in 
seven  cases,  four  of  which  recovered,  and  three  died. 

Collateral  Circulation.  In  Mr.  Owen's  dissection  of  a  case  in  which  the  internal  iliac  artery 
hid  been  tied  by  Stevens  ten  years  before  death,  for  aneurism  of  the  sciatic  artery,  the  internal 
iliac  was  found  impervious  for  about  an  inch  above  the  point  where  the  ligature  had  been  applied; 
but  the  obliteration  did  not  extend  to  the  origin  of  the  external  iliac,  as  the  ilio-lumbar  artery 
arose  just  above  this  point.  Below  the  point  of  obliteration,  the  artery  resumed  its  natural 
diameter,  and  continued  so  for  half  an  inch ;  the  obturator,  lateral  sacral,  and  gluteal,  arising  in 
succession  from  the  latter  portion.  The  obturator  artery  was  entirely  obliterated.  The  lateral 
sacral  artery  was  as  large  as  a  crow's  quill,  and  had  a  very  free  anastomosis  with  the  artery  of 
the  opposite  side,  and  with  the  middle  sacral  artery.  The  sciatic  artery  was  entirely  obliterated 
as  far  as  its  point  of  connection  with  the  aneurismal  tumor ;  but,  on  the  distal  side  of  the  sac,  it 
was  continued  down  along  the  back  of  the  thigh  nearly  as  large  in  size  as  the  femoral,  being 
pervious  about  an  inch  below  the  sac  by  receiving  an  anastomosing  vessel  from  the  superior 
profunda.1  In  addition  to  the  above,  the  circulation  in  the  parts  supplied  by  the  internal  iliac 
would  be  carried  on  by  the  anastomoses  of  the  uterine  and  ovarian  arteries ;  of  the  opposite 
vesical  arteries  ;  of  the  hemorrhoidal  branches  of  the  internal  iliac  with  those  from  the  inferior 
mesenteric ;  of  the  obturator  artery,  by  means  of  its  pubic  branch,  with  the  vessel  of  the  opposite 
side,  and  with  the  epigastric  and  internal  circumflex ;  by  the  anastomoses  of  the  circumflex,  and 
perforating  branches  of  the  femoral,  with  the  sciatic  ;  of  the  gluteal  with  the  posterior  branches 
of  the  sacral  arteries ;  of  the  ilio-lumbar  with  the  last  lumbar ;  of  the  lateral  sacral  with  the 
middle  sacral ;  and  by  the  anastomoses  of  the  circumflex  iliac  with  the  ilio-lumbar  and  gluteal. 

1  Medico-Chirurgical  Transactions,  vol.  xvi. 


432  ARTERIES. 

Branches  of  the  Internal  Iliac. 

From  the  Anterior  Trunk.  From  the  Posterior  Trunk. 

Superior  vesical.  Gluteal. 

Middle  vesical.  Ilio-lumbar. 

Inferior  vesical.  Lateral  sacral. 

Middle  hemorrhoidal. 

T    r       7    (  Uterine. 

In  female.  {  T7-     •     1 

J  [  Vaginal. 

Obturator. 

Internal  pudic. 

Sciatic. 

The  superior  vesical  is  that  part  of  the  foetal  hypogastric  artery,  which  remains 
pervious  after  birth.  It  extends  to  the  side  of  the  bladder,  distributing  numerous 
branches  to  the  body  and  fundus  of  this  organ.  From  one  of  these,  a  slender  vessel 
is  derived,  which  accompanies  the  vas  deferens  in  its  course  to  the  testis,  where  it 
anastomoses  with  the  spermatic  artery.  This  is  the  artery  of  the  vas  deferens. 
Other  branches  supply  the  ureter. 

The  middle  vesical,  usually  a  branch  of  the  superior,  is  distributed  to  the  base 
of  the  bladder,  and  under  surface  of  the  vesiculoe  seminales. 

The  inferior  vesical  arises  from  the  anterior  division  of  the  internal  iliac,  in 
common  with  the  middle  hemorrhoidal,  and  is  distributed  to  the  base  of  the  bladder, 
the  prostate  gland,  and  vesiculae  seminales.  Those  branches  distributed  to  the 
prostate  communicate  with  the  corresponding  vessel  of  the  opposite  side. 

The  middle  hemorrhoidal  artery  usually  arises  together  with  the  preceding 
vessel.  It  supplies  the  rectum,  anastomosing  with  the  other  hemorrhoidal 
arteries. 

The  uterine  artery  passes  downwards  from  the  anterior  trunk  of  the  internal 
iliac  to  the  neck  of  the  uterus.  Ascending,  in  a  tortuous  course,  on  the  side  of 
this  viscus,  between  the  laj^ers  of  the  broad  ligament,  it  distributes  branches  to  its 
substance,  anastomosing,  near  its  termination,  with  a  branch  from  the  ovarian 
artery.     Branches  from  this  vessel  are  also  distributed  to  the  bladder  and  ureter. 

The  vaginal  artery  is  analogous  to  the  inferior  vesical  in  the  male ;  it  descends 
upon  the  vagina,  supplying  its  mucous  membrane,  and  sending  branches  to  the 
neck  of  the  bladder,  and  contiguous  part  of  the  rectum. 

The  Obturator  Artery  usually  arises  from  the  anterior  trunk  of  the  internal 
iliac,  frequently  from  the  posterior.  It  passes  forwards  below  the  brim  of  the 
pelvis,  to  the  canal  in  the  upper  border  of  the  obturator  foramen,  and,  escaping 
from  the  pelvic  cavity  through  this  aperture,  divides  into  an  internal  and  an 
external  branch.  In  the  pelvic  cavity,  this  vessel  lies  upon  the  pelvic  fascia, 
beneath  the  peritoneum,  and  a  little  below  the  obturator  nerve;  and,  whilst 
passing  through  the  obturator  foramen,  is  contained  in  an  oblique  canal,  formed 
by  the  horizontal  branch  of  the  pubes,  above;  and  the  arched  border  of  the 
obturator  membrane,  below. 

Branches.  Within  the  pelvis,  the  obturator  artery  gives  off  an  iliac  branch  to 
the  iliac  fossa,  which  supplies  the  bone  and  the  Iliacus  muscle,  and  anastomoses 
with  the  ilio-lumbar  artery ;  a  vesical  branch,  which  runs  backwards  to  supply 
the  bladder;  and  &  pubic  branch,  which  is  given  off  from  the  vessel  just  before  it 
leaves  the  pelvic  cavity.  This  branch  ascends  upon  the  back  of  the  pubes,  com- 
municating with  offsets  from  the  epigastric  artery,  and  with  the  corresponding 
vessel  of  the  opposite  side.  This  branch  is  placed  on  the  inner  side  of  the  femoral 
ring.  External  to  the  pelvis,  the  obturator  artery  divides  into  an  external  and 
an  internal  branch,  which  are  deeply  situated  beneath  the  Obturator  externus 
muscle ;  skirting  the  circumference  of  the  obturator  foramen,  they  anastomose  at 
the  lower  part  of  this  aperture  with  each  other,  and  with  branches  of  the  internal 
circumflex  artery. 


OBTURATOR— INTERNAL   PUDIC.  433 

The  internal  branch  curves  inwards  along  the  inner  margin  of  the  obturator 
foramen,  distributing  branches  to  the  Obturator  muscles,  Pectineus,  Adductors, 
and  Gracilis,  and  anastomoses  with  the  external  branch,  and  with  the  internal 
circumflex  artery. 

The  external  branch  curves  round  the  outer  margin  of  the  foramen,  to  the  space 
between  the  Gemellus  inferior  and  Quadratus  femoris,  where  it  anastomoses  with 
the  sciatic  artery.  It  supplies  the  Obturator  muscles,  anastomoses,  as  it  passes 
backwards,  with  the  internal  circumflex,  and  sends  a  branch  to  the  hip-joint 
through  the  cotyloid  notch,  which  ramifies  on  the  round  ligament  as  far  as  the 
head  of  the  femur. 

Peculiarities.  In  two  out  of  every  three  cases  the  obturator  arises  from  the  internal  iliae.  In 
one  case  in  three  and  a  half  cases,  from  the  epigastric ;  and  in  about  one  in  seventy-two  cases  by 
two  roots  from  both  vessels.  It  arises  in  about  the  same  proportion  from  the  external  iliac 
artery.  The  origin  of  the  obturator  from  the  epigastric  is  not  commonly  found  on  both  sides  of 
the  same  body.  ,     .     , 

When  the  obturator  artery  arises  at  the  front  of  the  pelvis  from  the  epigastric,  it  descends 
almost  vertically  downwards  to  the  upper  part  of  the  obturator  foramen.  The  artery  in  this 
course  usually  descends  in  contact  with  the  external  iliac  vein,  and  lies  on  the  outer  side  of  the 
femoral  ring  (fig.  228) ;  in  such  cases  it  would  not  be  endangered  in  the  operation  for  femoral 
hernia.  Occasionally,  however,  it  curves  inwards  along  the  free  margin  of  Gimbernat's  ligament 
(fig.  229),  and  under  such  circumstances  would  almost  completely  encircle  the  neck  of  a  hernial 
sac' (supposing  a  hernia  to  exist  in  such  a  case),  and  would  be  in  great  danger  of  being  wounded 
if  an  operation  was  performed. 

Variations  in  Origin  and  Course  of  Obturator  Artery. 
Fig.  228.  Fig.  229. 


The  Internal  Pudic  is  the  smaller  of  the  two  terminal  branches  of  the  anterior 
trunk  of  the  internal  iliac,  and  supplies  the  external  organs  of  generation.  It  passes 
downwards  and  outwards  to  the  lower  border  of  the  great  sacro-sciatic  foramen, 
and  emerges  from  the  pelvis  between  the  Pyriformis  and  Coccygeus  muscles ;  it 
then  crosses  the  spine  of  the  ischium,  and  re-enters  the  pelvis  through  the  lesser 
sacro-sciatic  foramen.  The  artery  now  crosses  the  Obturator  internus  muscle,  to 
the  ramus  of  the  ischium,  being  covered  by  the  obturator  fascia,  and  situated 
about  an  inch  and  a  half  from  the  margin  of  the  tuberosity ;  it  then  ascends  for- 
wards and  upwards  along  the  ramus  of  the  ischium,  pierces  the  posterior  layer  of 
the  deep  perineal  fascia,  and  runs  forwards  along  the  inner  margin  of  the  ramus 
of  the  pubes ;  finally,  it  perforates  the  anterior  layer  of  the  deep  perineal  fascia, 
and  divides  into  its  two  terminal  branches,  the  dorsal  artery  of  the  penis  and  the 
artery  of  the  corpus  cavernosum. 

Relations.  In  the  first  part  of  its  course,  within  the  pelvis,  it  lies  in  front  of  the 
Pyriformis  muscle  and  sacral  plexus  of  nerves,  and  on  the  outer  side  of  the  rectum 
(on  the  left  side).  As  it  crosses  the  spine  of  the  ischium,  it  is  covered  by  the 
Gluteus  maximus,  and  great  sacro-sciatic  ligament ;  and  when  it  enters  the  pelvis, 
it  lies  on  the  outer  side  of  the  ischio-rectal  fossa,  upon  the  surface  of  the  Obtura- 
tor internus  muscle,  contained  in  a  fibrous  canal  formed  by  the  obturator  fascia 
and  the  falciform  process  of  the  great  sacro-sciatic  ligament.  It  is  accompanied 
by  the  pudic  veins,  and  the  internal  pudic  nerve. 

Peculiarities.  The  internal  pudic  is  sometimes  smaller  than  usual,  or  fails  to  give  off  one  oi 
two  of  its  usual  branches;  in  such  cases,  the  deficiency  is  supplied  by  branches  derived  from  an 
additional  vessel,  the  accessory  pudic,  which  generally  arises  from  the  pudic  artery  before  its  exit 

28 


434  ARTERIES. 

from  the  great  sacro-sciatic  foramen,  and  passes  forwards  near  the  base  of  the  bladder,  on  the 
upper  part  of  the  prostate  gland,  to  the  perineum,  where  it  gives  off  those  branches  usually 
derived  from  the  pudic  artery.  The  deficiency  most  frequently  met  with,  is  that  in  which  the 
internal  pudic  ends  as  the  artery  of  the  bulb ;  the  artery  of  the  corpus  cavernosum  and  arteria 
dorsalis  penis  being  derived  from  the  accessory  pudic.  Or  the  pudic  may  terminate  as  the  super- 
ficial  perineal,  the  artery  of  the  bulb  being  derived,  with  the  other  two  branches,  from  the  acces- 
sory vessel. 

The  relation  of  the  accessory  pudic  to  the  prostate  gland  and  urethra,  is  of  the  greatest  interest 
in  a  surgical  point  of  view,  as  this  vessel  is  in  danger  of  being  wounded  in  the  lateral  operation 
of  lithotomy. 

Branches.  Within  the  pelvis,  the  internal  pudic  gives  off  several  small  branches, 
which  supply  the  muscles,  sacral  nerves,  and  viscera  in  this  cavity.  In  the  peri- 
neum the  following  branches  are  given  off. 

Inferior  or  external  hemorrhoidal.  Artery  of  the  bulb. 

Superficial  perineal.  Artery  of  the  corpus  cavernosum. 

Transverse  perineal.  Dorsal  artery  of  the  penis. 

The  external  hemorrhoidal  are  two  or  three  small  arteries,  which  arise  from 
the  internal  pudic  as  it  passes  above  the  tuberosity  of  the  ischium.  Crossing  the 
ischio-rectal  fossa,  they  are  distributed  to  the  muscles  and  integument  of  the  anal 
region. 

The  superficial  perineal  artery  supplies  the  scrotum,  and  muscles  and  integu- 
ment of  the  perineum.  It  arises  from  the  internal  pudic,  in  front  of  the  preceding 
branches,  and  piercing  the  lower  border  of  the  deep  perineal  fascia,  runs  across 
the  Transversus  perinei,  and  through  the  triangular  space  between  the  Accelerator 
urinas  and  Erector  penis,  both  of  which  it  supplies,  and  is  finally  distributed  to 
the  skin  of  the  scrotum  and  dartos.  In  its  passage  through  the  perineum  it  lies 
beneath  the  superficial  perineal  fascia. 

The  transverse  perineal  is  a  small  branch  which  arises  either  from  the  internal 
pudic,  or  from  the  superficial  perineal  artery  as  it  crosses  the  Transversus  perinei 
muscle.  Piercing  the  lower  border  of  the  deep  perineal  fascia,  it  runs  trans- 
versely inwards  along  the  cutaneous  surface  of  the  Transversus  perinei  muscle, 
which  it  supplies,  as  well  as  the  structures  between  the  anus  and  bulb  of  the 
urethra. 

The  artery  of  the  bulb  is  a  large  but  very  short  vessel,  arising  from  the  internal 
pudic  between  the  two  layers  of  the  deep  perineal  fascia,  and  passing  nearly 
transversely  inwards,  pierces  the  bulb  of  the  urethra,  in  which  it  ramifies.  It 
gives  off  a  small  branch  which*  descends  to  supply  Cowper's  gland.  This  artery 
is  of  considerable  importance  in  a  surgical  point  of  view,  as  it  is  in  danger  of 
being  wounded  in  the  lateral  operation  of  lithotomy,  an  accident  usually  attended 
with  severe  and  alarming  hemorrhage.  This  vessel  is  sometimes  very  small, 
occasionally  wanting,  or  even  double.  It  sometimes  arises  from  the  internal  pudic 
earlier  than  usual,  and  crosses  the  perineum  to  reach  the  back  part  of  the  bulb. 
In  such  a  case  the  vessel  could  hardly  fail  to  be  wounded  in  the  performance  of 
the  lateral  operation  for  lithotomy.  If,  on  the  contrary,  it  should  arise  from  an 
accessory  pudic,  it  lies  more  forward  than  usual,  and  is  out  of  daDger  in  the 
operation. 

The  artery  of  the  corpus  cavernosum,  one  of  the  terminal  branches  of  the  inter- 
nal pudic,  arises  from  that  vessel  while  it  is  situated  between  the  crus  penis  and 
the  ramus  of  the  pubes ;  piercing  the  crus  penis  obliquely,  it  runs  forwards  in  the 
corpus  cavernosum  by  the  side  of  the  septum  pectiniforme,  to  which  its  branches 
are  distributed. 

The  dorsal  artery  of  the  penis  ascends  between  the  crus  and  pubic  symphysis, 
and,  piercing  the  suspensory  ligament,  runs  forward  on  the  dorsum  of  the  penis  to 
the  glans,  where  it  divides  into  two  branches,  which  supply  the  glans  and  prepuce. 
On  the  dorsum  of  the  penis,  it  lies  immediately  beneath  the  integument,  parallel 
with  the  dorsal  vein  and  corresponding  artery  of  the  opposite  side.  It  supplies 
the  integument  and  fibrous  sheath  of  the  corpus  cavernosum. 


SCIATIC. 


435 


Iuttrnai  CircumjiMC 


The  internal  pudic  artery  in  the  female  is  smaller  than  in  the  male.  Its  origin 
and  course  are  similar,  and  there  is  considerable  analogy  in  the  distribution  of  its 
branches.  The  superficial  artery  supplies  the  labia  pudendi ;  the  artery  of  the 
bulb  supplies  the  erectile  tissue  of  the  bulb  of  the  vagina,  whilst  the  two  terminal 
branches  supply  the  clitoris ;  the  artery  of  the  corpus  cavernosum,  the  cavernous 
body  of  the  clitoris;  and 

the  arteria  dorsalis  clitori-  FiS-  230.-The  Arteries  of  the  Gluteal  and  Posterior  Femoral 

dis,   the   dorsum   of  that 

organ. 

The  Sciatic  Artery 
(fig.  230),  the  larger  of  the 
two  terminal  branches  of 
the  anterior  trunk  of  the 
internal  iliac,  is  distributed 
to  the  muscles  on  the  back 
of  the  pelvis.  It  passes 
down  to  the  lower  part  of 
the  great  sacro-sciatic  fora- 
men, behind  the  internal 
pudic,  resting  on  the  sacral 
plexus  of  nerves  and  Pyri- 
formis muscle,  and  escapes 
from  the  pelvis  between 
the  Pyriformis  and  Coccy- 
geus.  It  then  descends  in 
the  interval  between  the 
trochanter  major  and  tu- 
berosity of  the  ischium, 
accompanied  by  the  sciatic 
nerves,  and  covered  by  the 
Gluteus  maximus,  and  di- 
vides into  branches,  which 
supply  the  deep  muscles  at 
the  back  of  the  hip. 

Within  the  pelvis,  it  dis- 
tributes branches  to  the 
Pyriformis,  Coccygeus,  and 
Levator  ani  muscles ;  some 
hemorrhoidal  branches, 
which  supply  the  rectum, 
and  occasionally  take  the 
place  of  the  middle  hemor- 
rhoidal artery;  and  vesical 
branches  to  the  base  and 
neck  of  the  bladder,  vesi- 
culae  seminales,  and  pros- 
tate gland.  External  to  the 
pelvis,  it  gives  off  the  coccy- 
geal, inferior  gluteal,  comes 
nervi  ischiadici,  muscular, 
and  articular  branches. 

The  coccygeal  branch  runs  inwards,  pierces  the  great  sacro-sciatic  ligament, 
and  supplies  the  Gluteus  maximus,  the  integument,  and  other  structures  on  the 
back  of  the  coccyx. 

The  inferior  gluteal  branches,  three  or  four  in  number,  supply  the  Gluteus 
maximus  muscle. 

The  comes  nervi  ischiadici  is  a  long  slender  vessel,  which  accompanies  the  great 


Super Untcrnal  Art^ula 


Terferntiny 


Inferior  Titrating 


moruiia* 


JJusruIam 


External Jlrtlcular 


436  ARTERIES. 

sciatic  nerve  for  a  short  distance ;  it  then  penetrates  it,  and  runs  in  its  substance 
to  the  lower  part  of  the  thigh. 

The  muscular  branches  supply  the  muscles  on  the  back  part  of  the  hip,  anas- 
tomosing with  the  gluteal,  internal  and  external  circumflex,  and  superior  per- 
forating arteries. 

Some  articular  branches  are  distributed  to  the  capsule  of  the  hip-joint. 

The  Gluteal  Artery  is  the  largest  branch  of  the  internal  iliac,  and  appears  to 
he  the  continuation  of  the  posterior  division  of  that  vessel.  It  is  a  short  thick 
trunk,  which  passes  out  of  the  pelvis  above  the  upper  border  of  the  Pyriformis 
muscle,  and  immediately  divides  into  a  superficial  and  deep  branch.  Within  the 
pelvis,  it  gives  off  a  few  muscular  branches  to  the  Iliacus,  Pyriformis,  and  Obtu- 
rator internus,  and  just  previous  to  quitting  that  cavity  a  nutritious  artery,  which 
enters  the  ilium. 

The  superficial  branch  passes  beneath  the  Gluteus  maximus,  and  divides  into 
numerous  branches,  some  of  which  supply  this  muscle,  whilst  others  perforate  its 
tendinous  origin,  and  supply  the  integument  covering  the  posterior  surface  of  the 
sacrum,  anastomosing  with  the  posterior  branches  of  the  sacral  arteries. 

_  The  deep  branch  runs  between  the  Gluteus  medius  and  Gluteus  minimus,  and  sub- 
divides into  two.  Of  these,  the  superior  division,  continuing  the  original  course  of 
the  vessel,  passes  along  the  upper  border  of  the  Gluteus  minimus  to  the  anterior 
superior  spine  of  the  ilium,  anastomosing  with  the  circumflex  iliac  and  ascending 
branches  of  the  external  circumflex  artery.  The  inferior  division  crosses  the 
Gluteus  minimus  obliquely  to  the  trochanter  major,  distributing  branches  to  the 
Glutei  muscles,  and  inosculates  with  the  external  circumflex  artery.  Some 
branches  pierce  the  Gluteus  minimus  to  supply  the  hip-joint. 

The  llio-lumbar  Artery  ascends  beneath  the  Psoas  muscle  and  external  iliac 
vessels,  to  the  upper  part  of  the  iliac  fossa,  where  it  divides  into  a  lumbar  and  an 
iliac  branch. 

The  lumbar  branch  supplies  the  Psoas  and  Quadratus  lumborum  muscles,  anas- 
tomosing with  the  last  lumbar  artery,  and  sends  a  small  spinal  branch  through 
the  intervertebral  foramen,  between  the  last  lumbar  vertebra  and  the  sacrum,  into 
the  spinal  canal,  to  supply  the  spinal  cord  and  its  membranes. 

The  iliac  branch  descends  to  supply  the  Iliacus  internus,  some  offsets  running 
between  the  muscle  and  the  bone,  one  of  which  enters  an  oblique  canal  to  supply 
the  diploe,  whilst  others  run  along  the  crest  of  the  ilium,  distributing  branches  to 
the  Gluteal  and  abdominal  muscles,  and  anastomosing  in  their  course  with  the 
gluteal,  circumflex  iliac,  external  circumflex,  and  epigastric  arteries. 

The  Lateral  Sacral  Arteries  are  usually  two  in  number  on  each  side,  superior 
and  inferior. 

The  superior,  which  is  of  large  size,  passes  inwards,  and,  after  anastomosing  with 
branches  from  the  middle  sacral,  enters  the  first  or  second  sacral  foramen,  is  dis- 
tributed to  the  contents  of  the  sacral  canal,  and,  escaping  by  the  corresponding 
posterior  sacral  foramen,  supplies  the  skin  and  muscles  on  the  dorsum  of  the  sacrum. 

The  inferior  branch  passes  obliquely  across  the  front  of  the  Pyriformis  muscle 
and  sacral  nerves  to  the  inner  side  of  the  anterior  sacral  foramina,  descends  on 
the  front  of  the  sacrum,  and  anastomoses  over  the  coccyx  with  the  sacra  media 
and  opposite  lateral  sacral  arteries.  In  its  course,  it  gives  off  branches,  which 
enter  the  anterior  sacral  foramina ;  these,  after  supplying  the  bones  and  membranes 
of  the  interior  of  the  spinal  canal,  escape  by  the  posterior  sacral  foramina,  and  are 
distributed  to  the  muscles  and  skin  on  the  dorsal  surface  of  the  sacrum. 

External  Iliac  Artery. 

The  External  Iliac  Artery  is  the  chief  vessel  which  supplies  the  lower  limb.  It 
is  larger  in  the  adult  than  the  internal  iliac,  and  passes  obliquely  downwards  and 
outwards  along  the  inner  border  of  the  Psoas  muscle,  from  the  bifurcation  of  the 
common  iliac  to  the  femoral  arch,  where  it  enters  the  thigh,  and  becomes  the 


EXTERNAL   ILIAC.  43t 

femoral  artery.  The  course  of  this  vessel  would  be  indicated  by  a  line  drawn 
from  the  left  side  of  the  umbilicus  to  a  point  midway  between  the  anterior  supe- 
rior spinous  process  of  the  ilium  and  the  symphysis  pubis. 

Relations.  In  front,  with  the  peritoneum,  sub-peritoneal  areolar  tissue,  the 
intestines,  and  a  thin  layer  of  fascia,  derived  from  the  iliac  fascia,  which  surrounds 
the  artery  and  vein.  At  its  origin  it  is  occasionally  crossed  by  the  ureter.  The 
spermatic  vessels  descend  for  some  distance  upon  it  near  its  termination,  and  it  is 
crossed  in  this  situation  by  a  branch  of  the  genito-crural  nerve  and  the  circumflex 
iliac  vein ;  the  vas  deferens  curves  down  along  its  inner  side.  Behind,  it  is  in  rela- 
tion with  the  external  iliac  vein,  which,  at  the  femoral  arch,  lies  at  its  inner  side ; 
on  the  left  side  the  vein  is  altogether  internal  to  the  artery.  Externally,  it  rests 
against  the  Psoas  muscle,  from  which  it  is  separated  by  the  iliac  fascia.  The 
artery  rests  upon  this  muscle  near  Poupart's  ligament.  Numerous  lymphatic 
vessels  and  glands  are  found  lying  on  the  front  and  inner  side  of  the  vessel. 

Plan  of  the  Eelations  of  the  External  Artery. 

In  front. 
Peritoneum,  intestines,  and  iliac  fascia. 
Near         f  Spermatic  vessels. 
Poupart's     j    Genito-crural  nerve. 
Ligament,    "j   Circumflex  iliac  vein. 

I  Lymphatic  vessels  and  glands. 

Outer  side.  /  \  Inner  side. 

Psoas  magnus.  (      External      j  External  iliac  vein  and  vas  deferens 

Iliac  fascia.  I        Ihac-        /  at  femoral  arch. 


Behind. 
External  iliac  vein. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  external  iliac  maybe  required  in 
cases  of  aneurism  of  the  femoral  artery,  or  in  cases  of  secondary  hemorrhage,  after  the  latter 
vessel  has  been  tied  for  popliteal  aneurism.  This  vessel  may  be  secured  in  any  part  of  its  course, 
excepting  near  its  upper  end,  on  account  of  the  circulation  through  the  internal  iliac,  and  near 
its  lower  end,  on  account  of  the  origin  of  the  epigastric  and  circumflex  iliac  vessels.  One  of 
the  chief  points  in  the  performance  of  the  operation  is  to  secure  the  vessel  without  injury  to  the 
peritoneum.  The  patient  having  been  placed  in  the  recumbent  position,  an  incision  should  be 
made,  commencing  about  an  inch  above  and  to  the  inner  side  of  the  anterior  superior  spinous 
process  of  the  ilium,  and  running  downwards  and  outwards  to  the  outer  end  of  Poupart's  liga- 
ment, and  parallel  with  its  outer  half,  to  a  little  above  its  middle.  The  abdominal  muscles  and 
transversalis  fascia  having  been  cautiously  divided,  the  peritoneum  should  be  separated  from  the 
iliac  fossa  and  pushed  towards  the  pelvis ;  and  on  introducing  the  finger  to  the  bottom  of  the 
wound  the  artery  may  be  felt  pulsating  along  the  inner  border  of  the  Psoas  muscle.  The  external 
iliac  vein  is  situated  along  the  inner  side  of  the  artery,  and  must  be  cautiously  separated  from  it 
by  the  finger-nail,  or  handle  of  the  knife,  and  the  aneurism  needle  should  be  introduced  on  the 
inner  side,  between  the  artery  and  vein. 

Collateral  Circulation.  The  principal  anastomoses  in  carrying  on  the  collateral  circulation, 
after  the  application  of  a  ligature  to  the  external  iliac,  are,  the  ilio-lumbar  with  the  circumflex 
iliac  ;  the  gluteal  with  the  external  circumflex  ;  the  obturator  with  the  internal  circumflex  ;  the 
sciatic  with  the  profunda  artery;  the  internal  pudic  with  the  external  pudic,  and  with  the  internal 
circumflex.  When  the  obturator  arises  from  the  epigastric,  it  is  supplied  with  blood  by  branches, 
either  from  the  internal  iliac,  the  lateral  sacral,  or  from  the  internal  pudic.  The  epigastric 
receives  its  supply  from  the  internal  mammary  and  inferior  intercostal  arteries,  and  from  the 
internal  iliac,  hy  the  anastomoses  of  its  branches  with  the  obturator. 

Branches.  Besides  several  small  branches  to  the  Psoas  muscle  and  the  neigh- 
boring lymphatic  glands,  the  external  iliac  gives  off  two  branches  of  considerable 
size : — 

Epigastric.  Circumflex  iliac. 

The  epigastric  artery  arises  from  the  external  iliac,  a  few  lines  above  Poupart's 
ligament.  It  at  first  descends  to  reach  this  ligament,  and  then  ascends  obliquely 
upwards  and  inwards  between  the  peritoneum  and  transversalis  fascia,  to  the 


438  ARTERIES. 

margin  of  the  sheath  of  the  Rectus  muscle.  Having  perforated  the  sheath  near 
its  lower  third,  it  ascends  vertically  upwards  behind  the  Rectus,  to  which  it  is 
distributed,  dividing  into  numerous  branches,  which  anastomose  above  the  umbi- 
licus with  the  terminal  branches  of  the  internal  mammary  and  inferior  intercostal 
arteries.  It  is  accompanied  by  two  veins,  which  usually  unite  into  a  single  trunk 
before  their  termination  in  the  external  iliac  vein.  As  this  artery  ascends  from 
Poupart's  ligament  to  the  Rectus,  it  lies  behind  the  inguinal  canal,  to  the  inner 
side  of  the  internal  abdominal  ring,  and  immediately  above  the  femoral  ring,  the 
vas  deferens  in  the  male  and  the  round  ligament  in  the  female  crossing  behind 
the  artery  in  descending  into  the  pelvis. 

Branches.  The  branches  of  this  vessel  are  the  cremasteric,  which  accompanies 
the  spermatic  cord,  and  supplies  the  Cremaster  muscle,  anastomosing  with  the 
spermatic  artery ;  a  pubic  branch,  which  runs  across  Poupart's  ligament,  and  then 
descends  behind  the  pubes  to  the  inner  side  of  the  femoral  ring,  and  anastomoses 
•with  offsets  from  the  obturator  artery;  muscular  branches,  some  of  which  are 
distributed  to  the  abdominal  muscles  and  peritoneum,  anastomosing  with  the 
lumbar  and  circumflex  iliac  arteries ;  others  perforate  the  tendon  of  the  External 
oblique  and  supply  the  integument,  anastomosing  with  branches  of  the  external 
epigastric. 

Peculiarities.  The  origin  of  the  epigastric  may  take  place  from  any  part  of  the  external 
iliac  between  Poupart's  ligament  and  two  inches  and  a  half  above  it ;  or  it  may  arise  below  this 
ligament,  from  the  femoral,  or  from  the  deep  femoral. 

Union  with  Branches.  It  frequently  arises  from  the  external  iliac  by  a  common  trunk  with 
the  obturator.  Sometimes  the  epigastric  arises  from  the  obturator,  the  latter  vessel  being  fur- 
nished by  the  internal  iliac,  or  the  epigastric  may  be  formed  of  two  branches,  one  derived  from 
the  external  iliac,  the  other  from  the  internal  iliac. 

The  circumflex  iliac  artery  arises  from  the  outer  side  of  the  external  iliac,  nearly 
opposite  the  epigastric  artery.  It  ascends  obliquely  outwards  behind  Poupart's 
ligament,  and  runs  along  the  inner  surface  of  the  crest  of  the  ilium  to  about  its 
middle,  where  it  pierces  the  Transversalis  and  runs  backwards  between  this 
muscle  and  the  Internal  oblique,  to  anastomose  with  the  ilio-lumbar  and  gluteal 
arteries.  Opposite  the  anterior  superior  spine  of  the  ilium,  it  gives  off  a  large 
branch,  which  ascends  between  the  Internal  oblique  and  Transversalis  muscles, 
supplying  them  and  anastomosing  with  the  lumbar  and  epigastric  arteries.  The 
circumflex  iliac  artery  is  accompanied  by  two  veins,  which,  uniting  into  a  single 
trunk,  cross  the  external  iliac  artery  just  above  Poupart's  ligament,  and  enter 
the  external  iliac  vein. 

Femoral  Artery. 

The  Femoral  Artery  is  the  continuation  of  the  external  iliac.  It  commences 
immediately  beneath  Poupart's  ligament,  midway  between  the  anterior  superior 
spine  of  the  ilium  and  the  symphysis  pubis,  and,  passing  down  the  fore  part  and 
inner  side  of  the  thigh,  terminates  at  the  opening  in  the  Adductor  magnus,  at  the 
junction  of  the  middle  with  the  lower  third  of  the  thigh,  where  it  becomes  the 
popliteal  artery.  A  line  drawn  from  a  point  midway  between  the  anterior  supe- 
rior spine  of  the  ilium  and  the  symphysis  pubis  to  the  inner  side  of  the  inner 
condyle  of  the  femur,  will  be  nearly  parallel  with  the  course  of  the  artery.  This 
vessel,  at  the  upper  part  of  the  thigh,  lies  a  little  internal  to  the  head  of  the 
femur ;  in  the  lower  part  of  its  course,  on  the  inner  side  of  the  shaft  of  this  bone ; 
and  between  these  two  points,  the  vessel  is  separated  from  the  bone  by  a  consi- 
derable interval. 

In  the  upper  third  of  the  thigh  the  femoral  artery  is  very  superficial,  being  covered 
by  the  integument,  inguinal  glands,  and  by  the  superficial  and  deep  fasciae,  and 
is  contained  in  a  triangular  space,  called  "  Scarpa's  triangle." 

Scarpa's  triangle  corresponds  to  the  depression  seen  immediately  below  the  fold 
of  the  groin.  It  is  a  triangular  space,  the  apex  of  which  is  directed  downwards, 
and  the  sides  of  which  are  formed  externally  by  the  Sartorius,  internally  by  the 


FEMORAL. 


439 


Adductor  longus,  and  the  base,  by  Poupart's  ligament.  The  floor  of  this  space 
is  formed  from  without  inwards  by  the  Iliacus,  Psoas,  Pectineus,  Adductor 
longus,  and  a  small  part  of  the  Adductor  brevis  muscles;  and  it  is  divided 
into  two  nearly  equal  parts  by  the  femoral  vessels,  which  extend  from  the  middle 
of  its  base  to  its  apex ;  the 

artery    giving    off    in    this  Fig.  231. — Surgical  Anatomy  of  the  Femoral  Artery, 

situation  its  cutaneous  and 
profunda  branches,  the  vein 
receiving  the  deep  femoral 
and  internal  saphenous 
veins.  In  this  space,  the 
femoral  artery  rests  on  the 
inner  margin  of  the  Psoas 
muscle,  which  separates  it 
from  the  capsular  ligament 
of  the  hip-joint.  The  artery 
in  this  situation  is  crossed 
in  front  by  the  crural 
branch  of  the  genito-crural 
nerve,  and  behind  by  the 
branch  to  the  Pectineus 
from  the  anterior  crural. 
The  femoral  vein  lies  at 
its  inner  side,  between  the 
margins  of  the  Pectineus 
and  Psoas  muscles.  The 
anterior  crural  -  nerve  lies 
about  half  an  inch  to  the 
outer  side  of  the  femoral 
artery,  deeply  imbedded 
between  the  Iliacus  and 
Psoas  muscles;  and  on  the 
Iliacus  muscle,  internal  to 
the  anterior  superior  spi- 
nous process  of  the  ilium, 
is  the  external  cutaneous 
nerve.  The  femoral  artery 
and  vein  are  inclosed  in  a 
strong  fibrous  sheath,  form- 
ed by  fibrous  and  cellular 
tissue,  and  by  a  process  of 
fascia  sent  inwards  from 
the  fascia  lata ;  the  vessels 
are  separated,  however, 
from  one  another  by  thin 
fibrous  partitions. 

In  the  middle  third  of  the 
thigh,  the  femoral  artery  is 
more  deeply  seated,  being 
covered  by  the  integument, 
the  superficial  and  deep 
fascise,  and  the  Sartorius,  and  is  contained  in  an  aponeurotic  canal,  formed  by  a 
dense  fibrous  band,  which  extends  transversely  from  the  Vastus  internus  to  the 
tendons  of  the  Adductor  longus  and  Adductor  magnus  muscles.  In  this  part  of 
its  course  it  lies  in  a  depression,  bounded  externally  by  the  Vastus  internus, 
internally  by  the  Adductor  longus  and  Adductor  magnus.     The  femoral  vein  lies 


Zettg  Saphenous  Kern* 
Ajiaetomcti en  JUJucna 


Super.  External Art-infa 


Jnfir.  Eztrrnal  Arlio 


Anter.  Tibial 


—■AmultomoHrt*-  XVxern 
Sup*'.J*C*r*alArU**lut 


.LUmnuil  Artie  f- 


440  ARTERIES. 

on  the  outer  side  of  the  artery,  in  close  apposition  with  it,  and,  still  more  ex. 
ternally,  is  the  internal  or  long  saphenous  nerve. 

Relations.  From  above  downwards,  the  femoral  artery  rests  upon  the  Psoas 
muscle,  which  separates  it  from  the  margin  of  the  pelvis  and  capsular  ligament 
of  the  hip;  it  is  next  separated  from  the  Pectineus  by  the  profunda  vessels  and 
femoral  vein ;  it  then  lies  upon  the  Adductor  longus ;  and  lastly,  upon  the  tendon 
of  the  Adductor  magnus,  the  femoral  vein  being  interposed.  To  its  inner  side, 
it  is  in  relation,  above,  with  the  femoral  vein,  and,  lower  down,  with  the  Ad- 
ductor longus  and  Sartorius.  To  its  outer  side,  the  Vastus  internus  separates  it 
from  the  femur,  in  the  lower  part  of  its  course. 

The  femoral  vein,  at  Poupart's  ligament,  lies  close  to  the  inner  side  of  the  artery, 
separated  from  it  by  a  thin  fibrous  partition,  but,  as  it  descends,  gets  behind  it, 
and  then  to  its  outer  side. 

The  internal  saphenous  nerve  is  situated  on  the  outer  side  of  the  artery,  in 
the  middle  third  of  the  thigh,  beneath  the  aponeurotic  covering,  but  not  within 
the  sheath  of  the  vessels.  Small  cutaneous  nerves  cross  the  front  of  the 
sheath. 

Peculiarities.  Double  femoral  reunited.  Four  cases  are  at  present  recorded,  in  which  the 
femoral  artery  divided  into  two  trunks  below  the  origin  of  the  profunda,  and  became  reunited 
near  the  opening  in  the  Adductor  magnus,  so  as  to  form  a  single  popliteal  artery.  One  of  them 
occurred  in  a  patient  operated  upon  for  popliteal  aneurism. 

Change  of  Position.  A  similar  number  of  cases  have  been  recorded,  in  which  the  femoral 
artery  was  situated  at  the  back  of  the  thigh,  the  vessel  being  continuous  above  with  the  internal 
iliac,  escaping  from  the  pelvis  through  the  great  sacro-sciatic  foramen,  and  accompanying  the 
great  sciatic  nerve  to  the  popliteal  space,  where  its  division  occurred  in  the  usual  manner. 

Position  of  the  Vein.  The  femoral  vein  is  occasionally  placed  along  the  inner  side  of  the 
artery,  throughout  the  entire  extent  of  Scarpa's  triangle  ;  or  it  may  be  slit,  so  that  a  large  vein 
is  placed  on  each  side  of  the  artery  for  a  greater  or  less  extent. 

Origin  of  the  Profunda.  This  vessel  occasionally  arises  from  the  inner  side,  and  more  rarely, 
from  the  back  of  the  common  trunk ;  but  the  more  important  peculiarity,  in  a  surgical  point  of 
view,  is  that  which  relates  to  the  height  at  which  the  vessel  arises  from  the  femoral.  In  three- 
foui'ths  of  a  large  number  of  cases,  it  arose  between  one  and  two  inches  below  Poupart's  liga- 
ment ;  in  a  few  cases,  the  distance  was  less  than  an  inch  ;  more  rarely,  opposite  the  ligament ; 
and  in  one  case,  above  Poupart's  ligament,  from  the  external  iliac.  Occasionally,  the  distance 
between  the  origin  of  the  vessel  and  Poupart's  ligament  exceeds  two  inches,  and  in  one  case  it 
was  found  to  be  as  much  as  four  inches. 

Surgical  Anatomy.  Compression  of  the  femoral  artery,  which  is  constantly  requisite  in  am- 
putations or  other  operations  on  the  lower  limb,  is  most  effectually  made  immediately  below 
Poupart's  ligament.  In  this  situation,  the  artery  is  very  superficial,  and  is  merely  separated 
from  the  margin  of  the  acetabulum  and  front  of  the  head  of  the  femur,  by  the  Psoas  muscle ;  so 
that  the  surgeon,  by  means  of  his  thumb,  or  any  other  resisting  body  may  effectually  control  the 
circulation  through  it.  This  vessel  may  also  be  compressed  in  the  middle  third  of  the  thigh,  by 
placing  a  compress  over  the  artery,  beneath  the  tourniquet,  and  directing  the  pressure  from 
within  outwards,  so  as  to  compress  the  vessel  on  the  inner  side  of  the  shaft  of  the  femur. 

The  application  of  a  ligature  to  the  femoral  artery  may  be  required  in  cases  of  wound  or 
aneurism  of  the  arteries  of  the  leg,  of  the  popliteal  or  femoral ;  and  the  vessel  may  be  exposed 
and  tied  in  any  part  of  its  course.  The  great  depth  of  this  vessel  in  the  lower  part  of  its  course, 
its  close  connection  with  important  structures,  and  the  density  of  its  sheath,  render  the  operation 
in  this  situation  one  of  much  greater  difficulty  than  the  application  of  a  ligature  at  its  upper 
part,  where  it  is  more  superficial. 

Ligation  of  the  femoral  artery,  within  two  inches  of  its  origin,  is  usually  considered  very  unsafe, 
on  account  of  the  connection  of  large  branches  with  it,  the  epigastric  and  circumflex  iliac  arising 
just  above  its  origin ;  the  profunda,  from  one  to  two  inches  below;  occasionally,  also,  one  of  the 
circumflex  arteries  arises  from  the  vessel  in  the  interspace  between  these.  The  profunda  some- 
times arises  higher  than  the  point  above-mentioned,  and  rarely  between  two  or  three  inches  (in 
one  case  four)  below  Pouparfs  ligament.  It  would  appear,  then,  that  the  most  favorable  situa- 
tion for  the  application  of  a  ligature  to  this  vessel  is  between  four  and  five  inches  from  its  point 
of  origin.  In  order  to  expose  the  artery  in  this  situation,  an  incision,  between  two  and  three 
inches  long,  should  be  made  in  the  course  of  the  vessel,  the  patient  lying  in  the  recumbent  posi- 
tion, with  the  limb  slightly  flexed  and  abducted.  A  large  vein  is  frequently  met  with,  passing 
in  the  course  of  the  artery  to  join  the  saphena ;  this  must  be  avoided,  and  the  fascia  lata  having 


BRANCHES  OF  THE  FEMORAL.  441 

been  cautiously  divided,  and  the  Sartorius  exposed,  this  muscle  must  be  drawn  outwards,  in  order 
to  fully  expose  the  sheath  of  the  vessels.  The  finger  being  introduced  into  the  wound,  and  the 
pulsation  of  the  artery  felt,  the  sheath  should  be  divided  over  it  to  a  sufficient  extent  to  allow  of 
the  introduction  of  the  ligature,  but  no  further;  otherwise  the  nutrition  of  the  coats  of  the  vessel 
may  be  interfered  with,  or  muscular  branches  which  arise  from  the  vessel  at  irregular  intervals 
may  be  divided.  In  this  part  of  the  operation,  a  small  nerve  which  crosses  the  sheath  should 
be  avoided.  The  aneurism  needle  must  be  carefully  introduced  and  kept  close  to  the  artery,  to 
avoid  the  femoral  vein,  which  lies  behind  the  vessel  in  this  part  of  its  course. 

To  expose  the  artery  in  the  middle  of  the  thigh,  an  incision  should  be  made  through  the  integu- 
ment, between  three  and  four  inches  in  length,  over  the  inner  margin  of  the  Sartorius,  taking  care 
to  avoid  the  internal  saphenous  vein,  the  situation  of  which  may  be  previously  known  by  com- 
pressing it  higher  up  in  the  thigh.  The  fascia  lata  having  been  divided,  and  the  Sartorius  muscle 
exposed,  it  should  be  drawn  outwards,  when  the  strong  fascia  which  is  stretched  across  from  the 
Adductors  to  the  Vastus  internus,  will  be  exposed,  and  must  be  freely  divided ;  the  sheath  of  the 
vessels  is  now  seen,  and  must  be  opened,  and  the  artery  secured  by  passing  the  aneurism  needle 
between  the  vein  and  artery,  in  the  direction  from  within  outwards.  The  femoral  vein  in  this 
situation  lies  on  the  outer  side  of  the  artery,  the  long  saphenous  nerve  on  its  anterior  and  outer 
side. 

It  has  been  seen  that  the  femoral  artery  occasionally  divides  into  two  trunks,  below  the  origin 
of  the  profunda.  If,  in  the  operation  for  tying  the  femoral,  two  vessels  are  met  with,  the  surgeon 
should  alternately  compress  each,  in  order  to  ascertain  which  vessel  is  connected  with  the  aneu- 
rismal  tumor,  or  with  the  bleeding  from  the  wound,  and  that  one  only  tied  which  controls  it.  If, 
however,  it  is  necessary  to  compress  both  vessels  before  the  circulation  in  the  tumor  is  controlled, 
both  should  be  tied,  as  it  would  be  probable  that  they  had  become  reunited,  as  is  mentioned  above. 

Collateral  Circulation.  The  principal  agents  in  carrying  on  the  collateral  circulation  after 
ligature  of  the  femoral  artery  are,  according  to  .Sir  A.  Cooper,  as  follows :' — 

"  The  arteria  profunda  formed  the  new  channel  for  the  blood."  "  The  first  artery  sent  off 
passed  down  close  to  the  back  of  the  thigh  bone,  and  entered  the  two  superior  articular  branches 
of  the  popliteal  artery." 

"  The  second  new  large  vessel  arising  from  the  profunda  at  the  same  part  with  the  former, 
passed  down  by  the  inner  side  of  the  Biceps  muscle,  to  an  artery  of  the  popliteal  which  was  dis- 
tributed to  the  Gastrocnemius  muscle;  whilst  a  third  artery  dividing  into  several  branches  passed 
down  with  the  sciatic  nerve  behind  the  knee-joint,  and  some  of  its  branches  united  themselves 
with  the  inferior  articular  arteries  of  the  popliteal,  with  some  recurrent  branches  of  those  arteries, 
with  arteries  passing  to  the  Gastrocnemii,  and,  lastly,  with  the  origin  of  the  anterior  and  posterior 
tibial  arteries." 

"  It  appears  then  that  it  is  those  branches  of  the  profunda  which  accompany  the  sciatic  nerve, 
that  are  the  principal  supporters  of  the  new  circulation." 

Branches.     The  branches  of  the  femoral  artery  are  the 

Superficial  epigastric. 
Superficial  circumflex  iliac. 
Superficial  external  pudic. 
Deep  external  pudic. 

{External  circumflex. 
Internal  circumflex. 
Three  perforating. 
Muscular. 
Anastomotica  magna. 

The  superficial  epigastric  arises  from  the  femoral,  about  half  an  inch  below 
Poupart's  ligament,  and,  passing  through  the  saphenous  opening  in  the  fascia  lata, 
ascends  on  to  the  abdomen,  in  the  superficial  fascia  covering  the  External  oblique 
muscle,  nearly  as  high  as  the  umbilicus.  It  distributes  branches  to  the  inguinal 
glands,  the  superficial  fascia  and  integument,  anastomosing  with  branches  of  the 
deep  epigastric  and  internal  mammary  arteries. 

The  superficial  circumflex  iliac,  the  smallest  of  the  cutaneous  branches,  arises 
close  to  the  preceding,  and,  piercing  the  fascia  lata,  runs  outwards,  parallel  with 
Poupart's  ligament,  as  far  as  the  crest  of  the  ilium,  dividing  into  branches  which 
supply  the  integument  of  the  groin,  the  superficial  fascia,  and  inguinal  glands- 
anastomosing  with  the  circumflex  iliac,  and  with  the  gluteal  and  external  circum 
flex  arteries. 

1  Medico-Chirurgical  Transactions,  vol.  ii.  1811. 


442  ARTERIES. 

The  superficial  external  pudic  (superior)  arises  from  the  inner  side  of  the  femoral 
artery,  close  to  the  preceding  vessels,  and,  after  piercing  the  fascia  lata  at  the 
saphenous  opening,  passes  inwards,  across  the  spermatic  cord,  to  be  distributed  to 
the  integument  on  the  lower  part  of  the  abdomen,  and  of  the  penis  and  scrotum 
in  the  male,  and  to  the  labia  in  the  female,  anastomosing  with  branches  of  the 
internal  pudic. 

The  deep  external  pudic  (inferior),  more  deeply  seated  than  the  preceding,  passes 
inwards  on  the  Pectineus  muscle,  covered  by  the  fascia  lata,  which  it  pierces 
opposite  the  ramus  of  the  pubes,  its  branches  being  distributed,  in  the  male,  to 
the  integument  of  the  scrotum  and  perinaeum,  and  in  the  female  to  the  labium, 
anastomosing  with  branches  of  the  superficial  perineal  artery. 

The  Peofunda  Femoris  or  Deep  Femoral  Artery  nearly  equals  the  size  of  the 
superficial  femoral.  It  arises  from  the  outer  and  back  part  of  the  femoral  artery, 
from  one  to  two  inches  below  Poupart's  ligament.  It  at  first  lies  on  the  outer 
side  of  the  superficial  femoral,  and  then  passes  beneath  it  and  the  femoral  vein  to 
the  inner  side  of  the  femur,  and  terminates  at  the  lower  third  of  the  thigh  in  a 
small  branch,  which  pierces  the  Adductor  magnus,  to  be  distributed  to  the  Flexor 
muscles,  on  the  back  of  the  thigh,  anastomosing  with  branches  of  the  popliteal 
and  inferior  perforating  arteries. 

Relations.  Behind,  it  lies  first  upon  the  Iliacus,  and  then  on  the  Adductor 
brevis  and  Adductor  magnus  muscles.  In  front,  it  is  separated  from  the  femoral 
artery,  above,  by  the  femoral  and  profunda  veins,  and  below  by  the  Adductor 
longus.  On  its  outer  side,  the  insertion  of  the  Yastus  internus  separates  it  from 
the  femur. 

Plan  of  the  Relations  of  the  Profunda  Artery. 

In  front. 
Femoral  and  profunda  veins. 
Adductor  longus. 


Outer  side. 
Vastus  internus. 


Behind. 
Iliacus. 

Adductor  brevis. 
Adductor  magnus. 

The  External  Circumflex  Artery  supplies  the  muscles  on  the  front  of  the  thigh. 
It  arises  from  the  outer  side  of  the  profunda,  passes  horizontally  outwards, 
between  the  divisions  of  the  anterior  crural  nerve,  and  beneath  the  Sartorius  and 
Rectus  muscles,  and  divides  into  three  sets  of  branches,  ascending,  transverse,  and 
descending. 

The  ascending  tranches  pass  upwards,  beneath  the  Tensor  vaginas  femoris 
muscle,  to  the  outer  side  of  the  hip,  anastomosing  with  the  terminal  branches 
of  the  gluteal  and  circumflex  iliac  arteries. 

The  descending  branches,  three  or  four  in  number,  pass  downwards,  beneath 
the  Rectus,  upon  the  Vasti  muscles,  to  which  they  are  distributed,  one  or  two 
passing  beneath  the  Vastus  externus  as  far  as  the  knee,  anastomosing  with  the 
superior  articular  branches  of  the  popliteal  artery. 

The  transverse  branches,  the  smallest  and  least  numerous,  pass  outwards  over 
the  Crureus,  pierce  the  Vastus  externus,  and  wind  round  the  femur  to  its  back 
part,  just  below  the  great  trochanter,  anastomosing  at  the  back  of  the  thigh  with 
the  internal  circumflex,  sciatic,  and  superior  perforating  arteries. 

The  Internal  Circumflex  Artery,  smaller  than  the  external,  arises  from  the  inner 
and  back  part  of  the  profunda,  and  winds  round  the  inner  side  of  the  femur, 


POPLITEAL   SPACE.  443 

between  the  Pectineus  and  Psoas  muscles.  On  reaching  the  tendon  of  the  Obtu- 
rator externus,  it  divides  into  two  branches ;  one,  ascending,  is  distributed  to  the 
Adductor  muscles,  the  Gracilis,  and  Obturator  externus,  anastomosing  with  the 
obturator  artery,  the  other  descending,  which  passes  beneath  the  Adductor  brevis, 
to  supply  it  and  the  great  Adductor ;  the  continuation  of  the  vessel  passing  back- 
wards, between  the  Quadratus  femoris  and  upper  border  of  the  Adductor  magnus, 
anastomosing  with  the  sciatic,  external  circumflex,  and  superior  perforating  arte- 
ries. Opposite  the  hip-joint,  this  branch  gives  off  an  articular  vessel,  which 
enters  the  joint  beneath  the  transverse  ligament ;  and,  after  supplying  the  adipose 
tissue,  passes  along  the  round  ligament  to  the  head  of  the  bone. 

The  Perforating  Arteries  (fig.  230),  usually  three  in  number,  are  so  called  from 
their  perforating  the  tendons  of  the  Adductor  brevis  and  Adductor  magnus  muscles 
to  reach  the  back  of  the  thigh.  The  first  is  given  off  above  the  A  dductor  brevis, 
the  second  in  front  of  that  muscle,  and  the  third  immediately  below  it. 

The  first  or  superior  perforating  artery  passes  backwards  between  the  Pectineus 
and  Adductor  brevis  (sometimes  perforates  the  latter) ;  it  then  pierces  the  Adduc- 
tor magnus  close  to  the  linea  aspera,  and  divides  into  branches  which  supply  both 
Adductors,  the  Biceps,  and  Gluteus  maximus  muscle ;  anastomosing  with  the 
sciatic,  internal  circumflex,  and  middle  perforating  arteries. 

The  second  or  middle  perforating  artery,  larger  than  the  first,  pierces  the  tendons 
of  the  Adductor  brevis  and  Adductor  magnus  muscles,  divides  into  ascending 
and  descending  branches,  which  supply  the  Flexor  muscles  of  the  thigh,  anasto- 
mosing with  the  superior  and  inferior  perforantes.  The  nutrient  artery  of  the 
femur  is  usually  given  off  from  this  branch. 

The  third  or  inferior  perforating  artery  is  given  off  below  the  Adductor  brevis ; 
it  pierces  the  Adductor  magnus,  and  divides  into  branches  which  supply  the  Flexor 
muscles  of  the  thigh,  anastomosing  with  the  perforating  arteries,  above,  and  with 
the  terminal  branches  of  the  profunda,  below. 

Muscular  Branches  are  given  off  from  the  superficial  femoral  throughout  its 
entire  course.  They  vary  from  two  to  seven  in  number,  and  supply  chiefly  the 
Sartorius  and  Vastus  internus. 

The  Anastomotica  Magna  arises  from  the  femoral  artery  just  before  it  passes 
through  the  tendinous  opening  in  the  Adductor  magnus  muscle,  and  divides  into 
a  superficial  and  deep  branch. 

The  superficial  branch  accompanies  the  long  saphenous  nerve,  beneath  the 
Sartorius,  and,  piercing  the  fascia  lata,  is  distributed  to  the  integument. 

The  deep  branch  descends  in  the  substance  of  the  Vastus  internus,  lying  in  front 
of  the  tendon  of  the  Adductor  magnus,  to  the  inner  side  of  the  knee,  where  it 
anastomoses  with  the  superior  internal  articular  artery  and  recurrent  branch  of  the 
anterior  tibial.  A  branch  from  this  vessel  crosses  outwards  above  the  articular 
surface  of  the  femur,  forming  an  anastomotic  arch  with  the  superior  external  arti- 
cular artery,  and  supplies  branches  to  the  knee-joint. 

The  Popliteal  Space. 

Dissection.  A  vertical  incision  about  eight  inches  in  length  should  be  made  along  the  back 
part  of  the  knee-joint,  connected  above  and  below  by  a  transverse  incision  passing  from  the  inner 
to  the  outer  side  of  the  limb.  The  flaps  of  integument  included  between  these  incisions  should 
be  reflected  in  the  direction  shown  in  tig.  189. 

On  removing  the  integument,  the  superficial  fascia  is  exposed,  and  ramifying  in 
it  along  the  middle  line  are  found  some  filaments  of  the  small  sciatic  nerve,  and, 
towards  the  inner  part,  some  offsets  from  the  internal  cutaneous  nerve. 

The  superficial  fascia  having  been  removed,  the  fascia  lata  is  brought  into  view. 
In  this  region  it  is  strong  and  dense,  being  strengthened  by  transverse  fibres,  and 
firmly  attached  to  the  tendons  on  the  inner  and  outer  sides  of  the  space.  It  is 
perforated  below  by  the  external  saphenous  vein.  This  fascia  having  been  reflected 
back  in  the  same  direction  as  the  integument,  the  small  sciatic  nerve  and  external 


444  ARTERIES. 

saphenous  vein  are  seen  immediately  beneath  it,  in  the  middle  line.  If  the  loose 
adipose  tissue  is  now  removed,  the  boundaries  and  contents  of  the  space  may  be 
examined. 

Boundaries.  The  popliteal  space,  or  the  ham,  occupies  the  lower  third  of  the 
thigh  and  the  upper  fifth  of  the  leg ;  extending  from  the  aperture  in  the  Adductor 
magnus  to  the  lower  border  of  the  Popliteus  muscle.  It  is  a  lozenge-shaped 
space,  being  widest  at  the  back  part  of  the  knee-joint,  and  deepest  above  the  arti- 
cular end  of  the  femur.  It  is  bounded,  externally,  above  the  joint,  by  the  Biceps, 
and  below  the  articulation,  by  the  Plantaris  and  external  head  of  the  Gastroc- 
nemius ;  internally,  above  the  joint,  by  the  Semi-membranosus,  Semi-ten- 
dinosus,  Gracilis,  and  Sartorius;  below  the  joint,  by  the  inner  head  of  the 
Gastrocnemius. 

Above,  it  is  limited  by  the  apposition  of  the  inner  and  outer  hamstring  muscles: 
below  by  the  junction  of  the  two  heads  of  the  Gastrocnemius.  The  floor  is 
formed  by  the  lower  part  of  the  posterior  surface  of  the  shaft  of  the  femur,  the 
posterior  ligament  of  the  knee-joint,  the  upper  end  of  the  tibia,  and  the  fascia 
covering  the  Popliteus  muscle,  and  the  space  is  covered  in  by  the  fascia  lata. 

Contents.  It  contains  the  popliteal  vessels  and  their  branches,  together  with  the 
termination  of  the  external  saphenous  vein,  the  internal  and  external  popliteal 
nerves  and  their  branches,  the  small  sciatic  nerve,  the  articular  branch  from  the 
obturator  nerve,  a  few  small  lymphatic  glands,  and  a  considerable  quantity  of 
loose  adipose  tissue. 

Position  of  contained  parts.  The  internal  popliteal  nerve  descends  in  the  middle 
line  of  the  space,  lying  superficial,  and  a  little  external  to  the  vein  and  artery. 
The  external  popliteal  nerve  descends  on  the  outer  side  of  the  space,  lying  close 
to  the  tendon  of  the  Biceps  muscle.  More  deeply  at  the  bottom  of  the  space  are 
the  popliteal  vessels,  the  vein  lying  superficial  and  a  little  external  to  the  artery, 
to  which  it  is  closely  united  by  dense  areolar  tissue ;  sometimes  the  vein  is  placed 
on  the  inner  instead  of  the  outer  side  of  the  artery ;  or  the  vein  may  be  double, 
the  artery  then  lying  between  them,  the  two  veins  being  usually  connected  by  short 
transverse  branches.  More  deeply,  and  close  to  the  surface  of  the  bone,  is  the 
popliteal  artery,  and  passing  off  from  it  at  right  angles  are  its  articular  branches. 
The  articular  branch  from  the  obturator  nerve  descends  upon  the  popliteal  artery 
to  supply  the  knee ;  and  occasionally  there  is  found  deep  in  the  space  an  articular 
filament  from  the  great  sciatic  nerve.  The  popliteal  lymphatic  glands,  four  or 
five  in  number,  are  found  surrounaing  the  artery ;  one  usually  lies  superficial  to 
the  vessel,  another  is  situated  between  it  and  the  bone,  and  the  rest  are  placed  on 
either  side  of  it.  In  health,  these  glands  are  small ;  but  when  enlarged  and  indu- 
rated from  inflammation,  the  pulsation  communicated  to  them  from  the  popliteal 
artery  makes  them  resemble  so  closely  an  aneurismal  tumor,  that  it  requires  a 
very  careful  examination  to  discriminate  between  them. 

Popliteal  Artery. 

The  Popliteal  Artery  commences  at  the  termination  of  the  femoral,  at  the 
opening  in  the  Adductor  magnus,  and,  passing  obliquely  downwards  and  outwards 
behind  the  knee-joint  to  the  lower  border  of  the  Popliteus  muscle,  divides  into 
the  anterior  and  posterior  tibial  arteries.  Through  this  extent  the  artery  lies  in 
the  popliteal  space. 

In  its  course  downwards  from  the  aperture  in  the  Adductor  magnus  to  the  lower 
border  of  the  Popliteus  muscle,  the  Popliteal  artery  (fig.  232)  rests  first  on  the 
inner,  and  then  on  the  posterior  surface  of  the  femur ;  in  the  middle  of  its  course, 
on  the  posterior  ligament  of  the  knee-joint ;  and  below,  on  the  fascia  covering 
the  Popliteus  muscle.  Superficially,  it  is  covered,  above,  by  the  Semi-membra- 
nosus ;  in  the  middle  of  its  course,  by  a  quantity  of  fat,  which  separates  it  from  the 
deep  fascia  and  integument ;  and  below,  it  is  overlapped  by  the  Gastrocnemius, 
Plantaris  and  Soleus  muscles,  the  popliteal  vein,  and  the  internal  popliteal  nerve. 


POPLITEAL.  445 

The  popliteal  vein,,  which  is  intimately  attached  to  the  artery,  lies  superficial  and 
external  to  it,  until  near  its  termination,  when  it  crosses  it  and  lies  to  its  inner 
side.  The  popliteal  nerve  is  still  more  superficial  and  external,  crossing,  however,' 
the  artery  below  the  joint,  and  lying  on  its  inner  side.  Laterally,  it  is  bounded 
by  the  muscles  which  form  the  boundaries  of  the  popliteal  space. 

/'  culiarttiea  in  point  of  division.  Occasionally  the  popliteal  artery  divides  prematurely  into 
its  terminal  branches ;  this  division  occurs  most  frequently  opposite  the  knee-joint. 

Unusual  branches.  This  artery  sometimes  divides  into  the  anterior  tibia2  and  peroneal,  the 
posterior  tibial  being  wanting,  or  very  small.  In  a  single  case,  this  artery  divided  into  three 
branches,  the  anterior  and  posterior  tibial,  and  peroneal. 

Surgical  Anatomy.  Ligation  of  the  popliteal  artery  is  required  in  cases  of  wound  of  that 
vessel,  but  for  aneurism  of  the  posterior  tibial  it  is  preferable  to  tie  the  superficial  femoral.  The 
popliteal  may  be  tied  in  the  upper  or  lower  part  of  its  course ;  but  in  the  middle  of  the  space 
the  operation  is  attended  with  considerable  difficulty,  from  the  great  depth  of  the  artery,  and 
from  the  extreme  degree  of  tension  of  its  lateral  boundaries. 

In  order  to  expose  the  vessel  in  the  upper  part  of  its  course,  the  patient  should  be  placed  in 
the  prone  position,  with  the  limb  extended.  An  incision  about  three  inches  in  length  should  then 
be  made  through  the  integument,  along  the  posterior. margin  of  the  Semi-membranosus,  and,  the 
fascia  lata  having  been  divided,  this  muscle  must  be  drawn  inwards,  when  the  pulsation  of  the 
Vessel  will  be  detected  with  the  finger;  the  nerve  lies  on  the  outer  or  fibular  side  of  the  artery, 
the  vein,  superficial  and  also  to  its  outer  side  ;  having  cautiously  separated  it  from  the  artery, 
the  aneurism  needle  should  be  passed  around  the  latter  vessel  from  without  inwards. 

To  expose  the  vessel  in  the  lower  part  of  its  course,  where  the  artery  lies  between  the  two 
heads  of  the  Gastrocnemius,  the  patient  should  be  placed  in  the  same  position  as  in  the  preceding 
operation.  An  incision  should  then  be  made  through  the  integument  in  the  middle  line,  com- 
mencing opposite  the  bend  of  the  knee-joint,  care  being  taken  to  avoid  the  external  saphenous  vein 
and  nerve.  After  dividing  the  deep  fascia  and  separating  some  dense  cellular  membrane,  the 
artery,  vein,  and  nerve  will  be  exposed,  descending  between  the  two  heads  of  the  Gastrocnemius. 
Some  muscular  branches  of  the  popliteal  should,  if  possible,  be  avoided,  or,  if  divided,  tied  immedi- 
ately. The  leg  being  now  flexed,  in  order  the  more  effectually  to  separate  the  two  heads  of  the 
Gastrocnemius,  the  nerve  should  be  drawn  inwards  and  the  vein  outwards.  &ad  the  aneurism 
needle  passed  between  the  artery  and  vein  from  without  inwards. 

The  branches  of  the  popliteal  artery  are  the 

Muscular  \  T  JP  .      '     0       , 
(  Interior  or  Sural. 

Cutaneous. 

Superior  external  articular. 

Superior  internal  articular. 

Azygos  articular. 

Inferior  external  articular. 

Inferior  internal  articular. 

The  superior  muscular  branches,  two  or  three  in  number,  arise  from  the  upper 
part  of  the  popliteal  artery,  and  are  distributed  to  the  Vastus  externus  and  Flexor 
muscles  of  the  thigh;  anastomosing  with  the  inferior  perforating,  and  terminal 
branches  of  the  profunda. 

The  inferior  muscular  or  sural  are  two  large  branches,  which  are  distributed 
to  the  two  heads  of  the  Gastrocnemius  and  Plantaris  muscles.  They  arise  from 
the  popliteal  artery  opposite  the  knee-joint. 

Cutaneous  branches  descend  on  each  side  and  in  the  middle  of  the  limb,  between 
the  Gastrocnemius  and  integument ;  they  arise  separately  from  the  popliteal 
artery,  or  from  some  of  its  branches,  and  supply  the  integument  of  the  calf. 

The  superior  articular  arteries,  two  in  number,  arise  one  on  either  side  of  the 
popliteal,  and  wind  round  the  femur  immediately  above  its  condyles  to  the  front 
of  the  knee-joint. 

The  internal  branch  passes  beneath  the  tendon  of  the  Adductor  magnus,  and 
divides  into  two,  one  of  which  supplies  the  Vastus  internus,  inosculating  with  the 
aua.stomotica  magna  and  inferior  internal  articular ;  the  other  ramifies  close  to  the 


446 


ARTERIES. 


232.— The  Popliteal,  Posterior  Tibial, 
and  Peroneal  Arteries. 


*'•■ 


surface  of  the  femur,  supplying  it  and  the  knee-joint,  and  anastomosing  with  the 
superior  external  articular  artery. 

The  external  branch  passes  above  the  outer  condyle,  beneath  the  tendon  of  the 

Biceps,  and  divides  into  a  superficial  and 
Fig.  232.— The  Popliteal,  Posterior  Tibial,  deep  branch :  the  superficial  branch  sup- 
plies the  Vastus  externus,  and  anastomoses 
with  the  descending  branch  of  the  exter- 
nal circumflex  artery ;  the  deep  branch 
supplies  the  lower  part  of  the  femur  and 
knee-joint,  and  forms  an  anastomotic  arch 
across  the  bone  with  the  anastomotica 
magna  artery. 

The  azygos  articular  is  a  small  branch, 
arising  from  the  popliteal  artery  opposite 
the  bend  of  the  knee-joint.  It  pierces 
the  posterior  ligament,  and  supplies  the 
ligaments  and  synovial  membrane  in  the 
interior  of  the  articulation. 

The  inferior  articular  arteries,  two  in 
number,  arise  from  the  popliteal,  beneath 
the  Gastrocnemius,  and  wind  round  the 
head  of  the  tibia,  below  the  joint. 

The  internal  one  passes  below  the  inner 
tuberosity,  beneath  the  internal  lateral 
ligament,  at  the  anterior  border  of  which 
it  ascends  to  the  front  and  inner  side  of 
the  joint,  to  supply  the  head  of  the  tibia 
and  the  articulation  of  the  knee. 

The  external  one  passes  outwards  above 
the  head  of  the  fibula,  to  the  front  of  the 
knee-joint,  lying  in  its  course  beneath  the 
outer  head  of  the  Gastrocnemius,  the 
external  lateral  ligament,  and  the  tendon 
of  the  Biceps  muscle,  and  divides  into 
tfM  J^Lhicus  I  branches,   which    anastomose   with    the 

\{:'J  artery  of  the  opposite  side,  the  superior 

articular,  and  the  recurrent  branch  of  the 
anterior  tibial. 


Anterior  Tibial  Arteey. 

The  Anterior  Tibial  Artery  commences 
-Anterior  Peroneal  at  the  bifurcation  of  the  popliteal,  at  the 

lower  border  of  the  Popliteus  muscle, 
passes  forwards  between  the  two  heads 
of  the  Tibialis  posticus,  and  through  the 
aperture  left  between  the  bones  at  the 
upper  part  of  the  interosseous  membrane, 
to  the  deep  part  of  the  front  of  the  leg; 
it  then  descends  on  the  anterior  surface 
of  the  interosseous  ligament,  and  of  the 
tibia,  to  the  front  of  the  ankle-joint,  where 
it  lies  more  superficially,  and  becomes  the 
dorsalis  pedis.  A  line  drawn  from  the 
inner  side  of  the  head  of  the  fibula  to 
midway  between  the  two  malleoli,  will 
be  parallel  with  the  course  of  the  artery. 


ANTERIOR   TIBIAL.  447 

Relations.  In  the  upper  tworthirds  of  its  extent,  it  rests  upon  the  interosseous 
ligament,  to  which  it  is  connected  by  delicate  fibrous  arches  thrown  across  it. 
In  the  lower  third,  upon  the  front  of  the  tibia,  and  the  anterior  ligament  of  the 
ankle-joint.  In  the  upper  third  of  its  course,  it  lies  between  the  Tibialis  anticus 
and  Extensor  longus  digitorum;  in  the  middle  third,  between  the  Tibialis  anticus 
and  Extensor  proprius  pollicis.  In  the  lower  third,  it  is  crossed  by  the  tendon  of 
the  Extensor  proprius  pollicis,  and  lies  between  it  and  the  innermost  tendon  of  the 
Extensor  longus  digitorum.  It  is  covered,  in  the  upper  two-thirds  of  its  course, 
by  the  muscles  which  lie  on  either  side  of  it,  and  by  the  deep  fascia ;  in  the  lower 
third,  by  the  integument,  annular  ligament,  and  fascia. 

The  anterior -tibial  artery  is  accompanied  by  two  veins  (venae  comites),  which 
lie  one  on  either  side  of  the  artery ;  the  anterior  tibial  nerve  lies  at  first  to  its  outer 
side,  and  about  the  middle  of  the  leg  is  placed  superficial  to  it ;  at  the  lower  part 
of  the  artery,  the  nerve  is  on  the  outer  side. 


Plan  of  the  Kelations  of  the  Anterior  Tibial  Artery. 

In  front. 
Integument,  superficial  and  deep  fasciae. 
Tibialis  anticus. 
Extensor  longus  digitorum. 
Extensor  proprius  pollicis. 
Anterior  tibial  nerve. 

Inner  side.  •  f  \  Outer  side. 

Tibialis  anticus.  /  .        \  Anterior  tibial  nerve. 

Extensor  proprius  pollicis.  (      Vibiai°r      )  Extensor  longus  digitorum. 

Extensor  proprius  pollicis. 


Behind. 
Interosseous  membrane. 
Tibia. 
Anterior  ligament  of  ankle-joint. 

Peculiarities  in  Size.  This  vessel  may  be  diminished  in  size,  or  it  may  be  deficient  to  a  greater 
or  less  extent,  or  it  may  be  entirely  wanting,  its  place  being  supplied  by  perforating  branches 
from  the  posterior  tibial,  or  by  the  anterior  division  of  the  peroneal  artery. 

Course.  This  artery  occasionally  deviates  in  its  course  towards  the  fibular  side  of  the  leg, 
regaining  its  usual  position  beneath  the  annular  ligament  at  the  front  of  the  ankle.  In  two 
instances,  this  vessel  has  approached  the  surface  in  the  middle  of  the  leg,  from  this  point  onwards 
being  covered  merely  by  the  integument  and  fascia. 

Surgical  Anatomy.  The  anterior  tibial  artery  may  be  tied  in  the  upper  or  lower  part  of  the 
leg.  In  the  upper  part,  the  operation  is  attended  with  great  difficulty,  on  account  of  the  depth 
of  the  vessel  from  the  surface.  An  incision,  about  four  inches  in  length,  should  be  made  through 
the  integument,  midway  between  the  spine  of  the  tibia  and  the  outer  margin  of  the  fibula,  the 
fascia  and  intermuscular  septum  between  the  Tibialis  anticus  and  Extensor  communis  digitorum 
being  divided  to  the  same  extent.  The  foot  must  be  flexed  to  relax  these  muscles,  which 
must  be  separated  from  each  other  by  the  finger.  The  artery  is  then  exposed,  deeply  seated, 
lying  upon  the  interosseous  membrane,  the  nerve  lying  externally,  and  one  of  the  venae  comites 
on  either  side ;  these  must  be  separated  from  the  artery  before  the  aneurism  needle  is  passed 
round  it.    . 

To  tie  this  vessel  in  the  lower  third  of  the  leg  above  the  ankle-joint,  an  incision  about  three 
inches  in  length  should  be  made  through  the  integument  between  the  tendons  of  the  Tibialis 
anticus  and  Extensor  proprius  pollicis  muscles,  the  deep  fascia  being  divided  to  the  same  extent; 
the  tendon  on  either  side  should  be  held  aside,  when  the  vessel  will  be  seen  lying  upon  the  tibia, 
with  the  nerve  superficial  to  it,  and  one  of  the  venae  comites  on  either  side. 

In  order  to  secure  this  vessel  over  the  instep,  an  incision  should  be  made  on  the  fibular  side 
of  the  tendon  of  the  Extensor  proprius  pollicis,  between  it  and  the  innermost  tendon  of  the  long 
Extensor ;  the  deep  fascia  having  been  divided,  the  artery  will  be  exposed,  the  nerve  lying  either 
superficial  to  it,  or  to  its  outer  side. 


448* 


ARTERIES. 


The  branches  of  the  anterior  tibial 


Fit 


233. — Snrgical  Anatomy  of  the  Anterior 
Tibial  and  Dorsalis  Pedis  Arteries. 


CnurauicaZl 


xrtery  are  the 

Recurrent  tibial. 
Muscular. 
Internal  malleolar. 
External  malleolar. 
The  recurrent  branch  arises  from  the 
anterior  tibial,  as  soon  as  that  vessel  has 
passed  through  the  interosseous  space ;  it 
ascends  in  the  Tibialis   anticus  muscle, 
and  ramifies  on  the  front  and  sides  of  the 
knee-joint,  anastomosing  with  the  articular 
branches  of  the  popliteal. 

The  'muscular  branches  are  numerous ; 
they  are  distributed  to  the  muscles  which 
lie  on  either  side  of  the  vessel,  some 
piercing  the  deep  fascia  to  supply  the 
integument,  others  passing  through  the 
interosseous  membrane,  and  anastomosing 
with  branches  of  the  posterior  tibial  and 
peroneal  arteries. 

The  malleolar  arteries  supply  the  ankle- 
joint. 

The  internal  arises  about  two  inches 
above  the  articulation,  passes  beneath  the 
tendon  of  the  Tibialis  anticus  to  the  inner 
ankle,  upon  which  it  ramifies,  anastomos- 
ing with  branches  of  the  posterior  tibial 
and  internal  plantar  arteries. 

The  external  passes  beneath  the  ten- 
dons of  the  Extensor  longus  digitorum 
and  Extensor  proprius  pollicis,  and  sup- 
plies the  outer  ankle,  anastomosing  with 
the  anterior  peroneal  artery,  and  with 
ascending  branches  from  the  tarsea  branch 
of  the  dorsalis  pedis. 

Doesalis  Pedis  Artery. 

The  Dorsalis  Pedis,  the  continuation  of 
the  anterior  tibial,  passes  forwards  from 
the  bend  of  the  ankle  along  the  tibial  side 
of  the  foot  to  the  back  part  of  the  first 
interosseous  space,  where  it  divides  into 
two  branches,  the  dorsalis  hallucis  and 
communicating. 

Relations.  This  vessel,  in  its  course  for- 
wards, rests  upon  the  astragalus,  scaphoid, 
and  internal  cuneiform  bones,  and  the 
ligaments  connecting  them,  being  covered 
by  the  integument  and  fascia,  and  crossed 
near  its  termination  by  the  innermost 
tendon  of  the  Extensor  brevis  digitorum. 
On  its  tibial  side  is  the  tendon  of  the 
Extensor  proprius  pollicis ;  on  its  fibular 
side,  the  innermost  tendon  of  the  Extensor 
longus  digitorum.  It  is  accompanied  by 
two  veins,  and  by  the  anterior  tibial  nerve, 
which  lies  on  its  outer  side. 


DORSALIS   PEDIS.  449 

Plan  of  the  Kelations  of  the  Dorsalis  Pedis  Artery. 

In  front. 
Integument  and  fascia. 
Innermost  tendon  of  Extensor  brevis  digitorum. 

Tibial  side.  /  \  Fibular  side. 

Extensor  proprius  pollicis.  (     1klLIMa31a     \  Extensor  longus  digitorum 

Anterior  tibial  nerve. 


Behind. 
Astragalus. 
Scaphoid. 
Internal  cuneiform. 
Their  ligaments. 

Peculiarities  in  Size.  The  dorsal  artery  of  the  foot  may  be  larger  than  usual,  to  compensate 
for  a  deficient  plantar  artery;  or  it  may  be  deficient  in  its  terminal  branches  to  the  toes,  which 
are  then  derived  from  the  internal  plantar ;  or  its  place  may  be  supplied  altogether  by  a  large 
anterior  peroneal  artery. 

Position.  This  artery  frequently  curves  outwards,  lying  external  to  the  line  between  the 
middle  of  the  ankle  and  the  back  part  of  the  first  interosseous  space. 

Surgical  Anatomy.  This  artery  may  be  tied,  by  making  an  incision  through  the  integument, 
between  two  and  three  inches  in  length,  on  the  fibular  side  of  the  tendon  of  the  Extensor  pro- 
prius pollicis,  in  the  interval  between  it  and  the  inner  border  of  the  short  Extensor  muscle.  The 
incision  should  not  extend  further  forwards  than  the  back  part  of  the  first  interosseous  space,  as 
the  artery  divides  in  this  situation.  The  deep  fascia  being  divided  to  the  same  extent,  the  artery 
will  be  exposed,  the  nerve  lying  upon  its  outer  side. 

Branches.     The  branches  of  the  dorsalis  pedis  are  the 

Tarsea.  .    Interossese. 

Metatarsea.  Dorsalis  hallucis. 

Communicating. 

The  tarsea  artery  arises  from  the  dorsalis  pedis,  as  that  vessel  crosses  the  sca- 
phoid bone ;  it  passes  in  an  arched  direction  outwards,  lying  upon  the  tarsal  bones, 
and  covered  by  the  Extensor  brevis  digitorum ;  it  supplies  that  muscle  and  the 
articulations  of  the  tarsus,  and  anastomoses  with  branches  from  the  metatarsea, 
external  malleolar,  peroneal,  and  external  plantar  arteries. 

The  metatarsea  arises  a  little  anterior  to  the  preceding ;  it  passes  outwards  to 
the  outer  part  of  the  foot,  over  the  bases  of  the  metatarsal  bones,  beneath  the 
tendons  of  the  short  Extensor,  its  direction  being  influenced  by  its  point  of 
origin ;  and  it  anastomoses  with  the  tarsea  and  external  plantar  arteries.  This 
vessel  gives  off  three  branches,  the  interossese,  which  pass  forwards  upon  the 
three  outer  Dorsal  interossei  muscles,  and,  in  the  clefts  between  the  toes,  divide 
into  two  dorsal  collateral  branches  for  the  adjoining  toes.  At  the  back  part  of 
each  interosseous  space  these  vessels  receive  the  posterior  perforating  branches 
from  the  plantar  arch ;  and  at  the  fore  part  of  each  interosseous  space,  they  are 
joined  by  the  anterior  perforating  branches  from  the  digital  arteries.  The  outer- 
most interosseous  artery  gives  off  a  branch  which  supplies  the  outer  side  of  the 
little  toe. 

The  dorsalis  halhicis  runs  forwards  along  the  outer  border  of  the  first  meta- 
tarsal bone,  and,  at  the  cleft  between  the  first  and  second  toes,  divides  into  two 
branches,  one  of  which  passes  inwards,  beneath  the  tendon  of  the  Flexor  longus 
pollicis,  and  is  distributed  to  the  inner  border  of  the  great  toe ;  the  other  branch 
bifurcating  to  supply  the  adjoining  sides  of  the  great  and  second  toes. 

The  communicating  artery  dips  down  into  the  sole  of  the  foot,  between  the  two 
heads  of  the  first  Dorsal  interosseous  muscle,  and  inosculates  with  the  termination 
29 


450  ARTERIES. 

of  the  external  plantar  artery,  to  complete  the  plantar  arch.  It  here  gives  off 
two  digital  branches ;  one  runs  along  the  inner  side  of  the  great  toe,  on  its  plantar 
surface,  the  other  passes  forwards  along  the  first  metatarsal  space,  and  bifurcates 
for  the  supply  of  the  adjacent  sides  of  the  great  and  second  toes. 

Posterior  Tibial  Artery. 

The  Posterior  Tibial  is  an  artery  of  large  size,  which  extends  obliquely  down- 
wards from  the  lower  border  of  the  Popliteus  muscle,  along  the  tibial  side  of  the 
leg,  to  the  fossa  between  the  inner  ankle  and  the  heel,  where  it  divides  beneath 
the  origin  of  the  Abductor  pollicis,  into  the  internal  and  external  plantar  arteries. 
At  its  origin  it  lies  opposite  the  interval  between  the  tibia  and  fibula;  as  it 
descends,  it  approaches  the  inner  side  of  the  leg,  lying  behind  the  tibia,  and,  in 
the  lower  part  of  its  course,  is  situated  midway  between  the  inner  malleolus  and 
the  tuberosity  of  the  os  calcis. 

Relations.  It  lies  successively  upon  the  Tibialis  posticus,  the  Flexor  longus 
digitorum,  and,  below,  upon  the  tibia  and  back  part  of  the  ankle-joint.  It  is 
covered  by  the  intermuscular  fascia,  which  separates  it  above  from  the  Gastroc- 
nemius and  Soleus  muscles.  In  the  lower  third,  where  it  is  more  superficial,  it  is 
covered  only  by  the  integument  and  fascia,  and  runs  parallel  with  the  inner  border 
of  the  tendo  Achillis.  It  is  accompanied  by  two  veins,  and  by  the  posterior  tibial 
nerve,  which  lies  at  first  to  the  inner  side  of  the  artery,  but  soon  crosses  it,  and  is. 
in  the  greater  part  of  its  course,  on  its  outer  side. 

Plan"  of  the  Relations  of  the  Posterior  Tibial  Artery. 

In  front. 
Tibialis  posticus. 
Flexor  longus  digiterum. 
Tibia. 
Ankle-joint. 

Inner  side.  f  \  Outer  side. 

Posterior  tibial  nerve,  /     Posterior    \  Posterior  tibial  nerve, 

upper  third.  I       Tibial.       I  lower  two-thirds. 


Behind. 
Gastrocnemius. 
Soleus. 
Deep  fascia  and  integument. 

Behind  the  Inner  Ankle,  the  tendons  and  bloodvessels  are  arranged  in  the 
following  order,  from  within  outwards :  First,  the  tendons  of  the  Tibialis  posticus 
and  Flexor  longus  digitorum,  lying  in  the  same  groove,  behind  the  inner  mal- 
leolus, the  former  being  the  most  internal.  External  to  these  is  the  posterior 
tibial  artery,  having  a  vein  on  either  side ;  and,  still  more  externally,  the  posterior 
tibial  nerve.  About  half  an  inch  nearer  the  heel  is  the  tendon  of  the  Flexor 
longus  pollicis. 

Peculiarities  in  Size.  The  posterior  tibial  is  not  unfrequently  smaller  than  usual,  or  absent, 
its  place  being  compensated  for  by  a  large  peroneal  artery,  which  passes  inwards  at  the  lower  end 
of  the  tibia,  and  either  joins  the  small  tibial  artery,  or  continues  alone  to  the  sole  of  the  foot. 

Surgical  Anatomy.  The  application  of  a  ligature  to  the  posterior  tibial  may  be  required  in 
cases  of  wound  of  the  sole  of  the  foot,  attended  with  great  hemorrhage,  when  the  vessel  should 
be  tied  at  the  inner  ankle.  In  cases  of  wound  of  the  posterior  tibial,  it  will  be  necessary  to  enlarge 
the  opening  so  as  to  expose  the  vessel  at  the  wounded  point  (excepting  where  the  vessel  is  injured 
by  a  punctured  wound  from  the  front  of  the  leg).     In  cases  of  aneurism  from  injury  of  the  artery 


PERONEAL.  451 

low  down,  the  vessel  should  be  tied  in  the  middle  of  the  leg.  But  in  aneurism  of  the  posterior 
tibial  high  up,  it  would  be  better  to  tie  the  femoral  artery. 

To  tie  the  posterior  tibial  artery  at  the  ankle,  a  semilunar  incision  should  be  made  through 
the  integument,  about  two  inches  and  a  half  in  length,  midway  between  the  heel  and  inner  ankle, 
but  a  little  nearer  the  latter.  The  subcutaneous  cellular  membrane  having  been  divided,  a  strong 
and  dense  fascia,  the  internal  annular  ligament,  is  exposed.  This  ligament  is  continuous  above 
with  the  deep  fascia  of  the  leg,  covers  the  vessels  and  nerves,  and  is  intimately  adherent  to  the 
sheaths  of  the  tendons.  This  having  been  cautiously  divided  upon  a  director,  the  sheath  of  the 
vessels  is  exposed,  and,  being  opened,  the  artery  is  seen  with  one  of  the  venae  comites  on  each 
side.  The  aneurism  needle  should  be  passed  round  the  vessel  from  the  heel  towards  the  ankle, 
in  order  to  avoid  the  posterior  tibial  nerve,  care  being  at  the  same  time  taken  not  to  include  the 
venae  comites. 

The  vessel  may  also  be  tied  in  the  lower  third  of  the  leg,  by  making  an  incision  about  three 
inches  in  length,  parallel  with  the  inner  margin  of  the  tendo  Achillis.  The  internal  saphenous 
vein  being  carefully  avoided,  the  two  layers  of  fascia  must  be  divided  upon  a  director,  when  the 
artery  is  exposed  along  the  inner  margin  of  the  Flexor  longus  digitorum,  with  one  of  its  venae 
comites  on  either  side,  and  the  nerve  lying  external  to  it. 

To  tie  the  posterior  tibial  in  the  middle  of  the  leg,  is  a  very  difficult  operation,  on  account  of 
the  great  depth  of  the  vessel  from  the  surface,  and  from  its  being  covered  in  by  the  Gastrocne- 
mius a"d  Soleus  muscles.  The  patient  being  placed  in  the  recumbent  position,  the  injured  limb 
should  rest  on  its  outer  side,  the  knee  being  partially  bent,  and  the  foot  extended,  so  as  to  relax 
the  muscles  of  the  calf.  An  incision  about  four  inches  in  length  should  then  be  made  through 
the  integument,  along  the  inner  margin  of  the  tibia;  taking  care  to  avoid  the  internal  saphenous 
vein.  The  deep  fascia  having  been  divided,  the  margin  of  the  Gastrocnemius  is  exposed,  and 
must  be  drawn  aside,  and  the  tibial  attachment  of  the  Soleus  divided,  a  director  being  previously 
passed  beneath  it.  The  artery  may  now  be  felt  pulsating  beneath  the  deep  fascia,  about  an  inch 
from  the  margin  of  the  tibia.  The  fascia  having  been  divided,  and  the  limb  placed  in  such  a 
position  as  to  relax  the  muscles  of  the  calf  as  much  as  possible,  the  veins  should  be  separated 
from  the  artery,  and  the  aneurism  needle  passed  round  the  vessel  from  without  inwards,  so  as  to 
avoid  wounding  the  posterior  tibial  nerve. 

The  branches  of  the  posterior  tibial  artery  are  the 

Peroneal.  Nutritious. 

Muscular.  Communicating. 

Internal  calcanean. 

The  Peroneal  Artery  lies,  deeply  seated,  along  the  back  part  of  the  fibular 
side  of  the  leg.  It  arises  from  the  posterior  tibial,  about  an  inch  below  the  lower 
border  of  the  Popliteus  muscle,  passes  obliquely  outwards  to  the  fibula,  and  then 
descends  along  the  inner  border  of  this  bone  to  the  lower  third  of  the  leg,  where 
it  gives  off  the  anterior  peroneal.  It  then  passes  across  the  articulation,  between 
the  tibia  and  fibula,  to  the  outer  side  of  the  os  calcis,  supplying  the  neighboring 
muscles  and  back  of  the  ankle,  and  anastomosing  with  the  external  malleolar, 
tarsal,  and  external  plantar  arteries. 

Relations.  This  vessel  rests  at  first  upon  the  Tibialis  posticus,  and,  in  the 
greater  part  of  its  course,  in  the  fibres  of  the  Flexor  longus  pollicis,  in  a  groove 
between  the  interosseous  ligament  and  the  bone.  It  is  covered,  in  the  upper  part 
of  its  course,  by  the  Soleus  and  deep  fascia :  below,  by  the  Flexor  longus  pollicis. 

Plan  of  the  Relations  of  the  Peroneal  Artery. 

In  front. 
Tibialis  posticus. 
Flexor  longus  pollicis. 


Outer  side. 
Fibula. 


Behind. 
Soleus. 
Deep  fascia. 
Flexor  longus  pollicis. 


452  ARTERIES. 

Peculiarities  in  Origin.  The  Peroneal  artery  may  arise  three  inches  below  the  Popliteus,  or 
from  the  posterior  tibial  high  up,  or  even  from  the  popliteal. 

Its  Size  is  more  frequently  increased  than  diminished,  either  reinforcing  the  posterior  tibial  by 
its  junction  with  it,  or  by  altogether  taking  the  place  of  the  posterior  tibial,  in  the  lower  part  of 
the  leg  and  foot,  the  latter  vessel  only  existing  as  a  short  muscular  branch.  In  those  rare  cases, 
where  the  peroneal  artery  is  smaller  than  usual,  a  branch  from  the  posterior  tibial  supplies  its 
place,  and  a  branch  from  the  anterior  tibial  compensates  for  the  diminished  anterior  peroneal 
artery.     In  one  case,  the  peroneal  artery  has  been  found  entirely  wanting. 

The  anterior  peroneal  is  sometimes  enlarged,  and  takes  the  place  of  the  dorsal  artery  of  the  foot. 

The  peroneal  artery,  in  its  course,  gives  off  branches  to  the  Soleus,  Tibialis 
posticus,  Flexor  longus  pollicis,  and  Peronei  muscles,  and  a  nutrient  branch  to 
the  fibula.  The  anterior  peroneal  pierces  the  interosseous  membrane,  about  two 
inches  above  the  outer  malleolus,  to  reach  the  fore  part  of  the  leg,  and,  passing 
down  beneath  the  Peroneus  tertius  to  the  outer  ankle,  ramifies  on  the  front  and 
outer  side  of  the  tarsus,  anastomosing  with  the  external  malleolar  and  tarsal  arteries. 

The  nutritious  artery  of  the  tibia  arises  from  the  posterior  tibial  near  its  origin, 
and,  after  supplying  a  few  muscular  branches,  enters  the  nutritious  canal  of  that 
bone,  which  it  traverses  obliquely  from  above  downwards.  This  is  the  largest 
nutrient  artery  of  bone  in  the  body. 

The  muscular  branches  are  distributed  to  the  Soleus  and  deep  muscles  along 
the  back  of  the  leg. 

The  communicating  branch  to  the  peroneal  runs  transversely  across  the  back 
of  the  tibia,  about  two  inches  above  its  lower  end,  passing  beneath  the  Flexor 
longus  pollicis. 

The  internal  calcanean  consists  of  several  large  branches,  which  arise  from 
the  posterior  tibial  just  before  its  division ;  they  are  distributed  to  the  fat  and 
integument  behind  the  tendo  Achillis  and  about  the  heel,  and  to  the  muscles  on 
the  inner  side  of  the  sole,  anastomosing  with  the  peroneal  and  internal  malleolar 
arteries. 

Plantae  Aeteeies. 

The  Internal  Plantar  Artery,  much  smaller  than  the  external,  passes  forwards 
along  the  inner  side  of  the  foot.  It  is  at  first  situated  above  the  Abductor  pollicis, 
and  then  between  it  and  the  Flexor  brevis  digitorum,  both  of  which  it  supplies. 
At  the  base  of  the  first  metatarsal  bone,  where  it  has  become  much  diminished  in 
size,  it  passes  along  the  inner  border  of  the  great  toe,  inosculating  with  its  digital 
branches. 

The  External  Plantar  Artery,  much  larger  than  the  internal,  passes  obliquely 
outwards  and  forwards  to  the  base  of  the  fifth  metatarsal  bone.  It  then  turns 
obliquely  inwards  to  the  interval  between  the  bases  of  the  first  and  second  meta- 
tarsal bones,  where  it  inosculates  with  the  communicating  branch  from  the  dorsalis 
pedis  artery,  thus  completing  the  plantar  arch.  As  this  artery  passes  outwards  it 
is  at  first  placed  between  the  os  calcis  and  Abductor  pollicis,  and  then  between 
the  Flexor  brevis  digitorum  and  Flexor  accessorius ;  and  as  it  passes  forwards 
to  the  base  of  the  little  toe,  it  lies  more  superficially  between  the  Flexor  brevis 
digitorum  and  Abductor  minimi  digiti,  covered  by  the  deep  fascia  and  integument. 
The  remaining  portion  of  the  vessel  is  deeply  situated :  it  extends  from  the  base 
of  the  metatarsal  bone  of  the  little  toe  to  the  back  part  of  the  first  interosseous 
space,  and  forms  the  plantar  arch ;  it  is  convex  forwards,  lies  upon  the  Interossei 
muscles,  opposite  the  tarsal  ends  of  the  metatarsal  bones,  and  is  covered  by  the 
Adductor  pollicis,  the  Flexor  tendons  of  the  toes,  and  the  Lumbricales. 

Branches.  The  plantar  arch,  besides  distributing  numerous  branches  to  the 
muscles,  integument,  and  fascia3  in  the  sole,  gives  off  the  following  branches : — 

Posterior  perforating.  Digital — Anterior  perforating. 

The  Posterior  Perforating  are  three  small  branches,  which  ascend  through  the 
back  part  of  the  three  outer  interosseous  spaces,  between  the  heads  of  the  Dorsal 


PLANTAR— PULMONARY. 


453 


interossei  muscles,  and  anastomose  with  the  interosseous  branches  from  the  meta- 
tarsal artery. 

The  Digital  Branches  are  four  in  number,  and  supply  the  three  outer  toes  and 
half  the  second  toe.  The  first  passes  outwards  from  the  outer  side  of  the  plantar  arch, 
and  is  distributed  to  the  outer  side  of  the  little  toe,  passing  in  its  course  beneath 
the  Abductor  and  short  Flexor  muscles.  The  second,  third,  and  fourth  run  for- 
wards along  the  metatarsal  spaces,  and,  on  arriving  at  the  clefts  between  the  toes, 
divide  into  collateral  branches,  which  supply  the  adjacent  sides  of  the  three  outer 
toes  and  the  outer  side  of  the  second.  At  the  bifurcation  of  the  toes,  each  digital 
artery  sends  upwards,  through  the  fore  part  of  the  corresponding  metatarsal  space, 
a  small  branch,  which  inosculates  with  the  interosseous  branches  of  the  metatarsal 
artery.     These  are  the  anterior  perforating  branches. 


Fig.  234.— The  Plantar  Arteries. 
Superficial  View. 


Fig.  235.— The  Plantar  Arteries. 
Deep  View. 


Cemmanicattnj 

Branch      of 
QOASAli*    PUIS 


From  the  arrangement '  already  described  of  the  distribution  of  the  vessels  to 
the  toes,  it  will  be  seen  that  both  sides  of  the  three  outer  toes,  and  the  outer  side 
of  the  second  toe,  are  supplied  by  branches  from  the  plantar  arch ;  both  sides  of  the 
great  toe,  and  the  inner  side  of  the  second,  being  supplied  by  the  dorsal  artery  of 
the  foot. 

Pulmonary  Artery. 

The  Pulmonary  Artery  conveys  the  venous  blood  from  the  right  side  of  the  heart 
to  the  lungs.  It  is  a  short  wide  vessel,  about  two  inches  in  length,  arising  from 
the  left  side  of  the  base  of  the  right  ventricle,  in  front  of  the  ascending  aorta. 
It  ascends  obliquely  upwards,  backwards,  and  to  the  left  side,  as  far  as  the  under 
surface  of  the  arch  of  the  aorta,  where  it  divides  into  two  branches  of  nearly 
equal  size,  the  right  and  left  pulmonary  arteries. 

Relations.  The  greater  part  of  this  vessel  is  contained,  together  with  the 
ascending  part  of  the  arch  of  the  aorta,  in  the  pericardium,  being  inclosed  with  it 
in  a  tube  of  serous  membrane,  continued  upwards  from  the  base  of  the  heart, 


454  ARTERIES. 

and  has  attached  to  it,  above,  the  fibrous  layer  of  this  membrane.  Behind,  it 
rests  at  first  upon  the  ascending  aorta,  and  higher  up  in  front  of  the  left  auricle. 
On  either  side  of  its  origin  are  the  appendix  of  the  corresponding  auricle,  and  a 
coronary  artery ;  and  higher  up  it  passes  to  the  left  side  of  the  ascending  aorta. 
A  little  to  the  left  of  its  point  of  bifurcation,  it  is  connected  to  the  under  surface 
of  the  arch  of  the  aorta  by  a  short  fibrous  cord,  the  remains  of  a  vessel  peculiar 
to  foetal  life,  the  ductus  arteriosus. 

The  right  pulmonary  artery,  longer  and  larger  than  the  left,  runs  horizontally 
outwards,  behind  the  ascending  aorta  and  superior  vena  cava,  to  the  root  of  the 
right  lung,  where  it  divides  into  two  branches,  of  which  the  lower,  the  larger, 
supplies  the  lower  lobe ;  the  upper  giving  a  branch  to  the  middle  lobe. 

The  left  pulmonary  artery,  shorter  and  somewhat  smaller  than  the  right,  passes 
horizontally  in  front  of  the  descending  aorta  and  left  bronchus  to  the  root  of  the 
left  lung,  where  it  divides  into  two  branches  for  the  two  lobes. 


The  author  has  to  acknowledge  valuable  aid  derived  from  the  following  works  :  Harrison's  "  Sur- 
gical Anatomy  of  the  Arteries  of  the  Human  Body,"  Dublin,  1824. — Richard  Quain's  ''Ana- 
tomy of  the  Arteries  of  the  Human  Body,"  London,  1844. — Sibson's  "  Medical  Anatomy,"  and 
the  other  works  on  General  and  Microscopic  Anatomy  before  referred  to. 


Of  the  Veins. 

The  Veins  are  the  vessels  which  serve  to  return  the  blood  from  the  capillaries 
of  the  different  parts  of  the  body  to  the  heart.  They  consist  of  two  distinct  sets 
of  vessels,  the  pulmonary  and  systemic. 

The  Pulmonary  Veins,  unlike  other  vessels  of  this  kind,  contain  arterial  blood, 
which  they  return  from  the  lungs  to  the  left  auricle  of  the  heart. 

The  Systemic  Veins  return  the  venous  blood  from  the  body  generally  to  the 
right  auricle  of  the  heart. 

The  Portal  Vein,  an  appendage  to  the  systemic  venous  system,  is  confined  to  the 
abdominal  cavity,  returning  the  venous  blood  from  the  viscera  of  digestion,  and 
carrying  it  to  the  liver  by  a  single  trunk  of  large  size,  the  vena  portae.  From 
this  organ,  the  same  blood  is  conveyed  to  the  inferior  vena  cava  by  means  of  the 
hepatic  veins. 

The  veins,  like  the  arteries,  are  found  in  nearly  every  tissue  of  the  body ;  they 
commence  by  minute  plexuses,  which  communicate  with  the  capillaries,  the 
branches  from  which,  uniting  together,  constitute  trunks,  which  increase  in  size 
as  they  pass  towards  the  heart,  from  the  termination  of  larger  branches  in  them. 
The  veins  are  larger  and  altogether  more  numerous  than  the  arteries ;  hence,  the 
entire  capacity  of  the  venous  system  is  much  greater  than  the  arterial,  the  pul- 
monary veins  excepted,  which  do  not  exceed  in  capacity  the  pulmonary  arteries. 
From  the  combined  area  of  the  smaller  venous  branches  being  greater  than  the 
main  trunks,  it  results,  that  the  venous  system  represents  a  cone,  the  summit  of 
which  corresponds  to  the  heart ;  its  base,  to  the  circumference  of  the  body.  In 
form,  the  veins  are  not  perfectly  cylindrical,  like  the  arteries,  their  walls  being 
collapsed  when  empty,  and  the  uniformity  of  their  surface  being  interrupted  at 
intervals  by  slight  contractions,  which  indicate  the  existence  of  valves  in  their 
interior.  They  usually  retain,  however,  the  same  calibre  as  long  as  they  receive 
no  neighboring  branches. 

The  veins  communicate  very  freely  with  one  another,  especially  in  certain 
regions  of  the  body ;  and  this  communication  exists  between  the  larger  trunks 
as  well  as  between  the  smaller  branches.  Thus  in  the  cavity  of  the  cranium,  and 
between  the  veins  of  the  neck,  where  obstruction  of  the  cerebral  venous  system 
would  be  attended  with  imminent  danger,  we  find  that  the  sinuses  and  larger 
veins  have  large  and  very  frequent  anastomoses.  The  same  free  communication 
exists  between  the  veins  throughout  the  whole  extent  of  the  spinal  canal,  and 
between  the  veins  composing  the  various  venous  plexuses  in  the  abdomen  and 
pelvis,  as  the  spermatic,  uterine,  vesical,  prostatic,  etc. 

The  veins  are  subdivided  into  three  sets ;  superficial,  deep,  and  sinuses. 

The  Superficial  or  Cutaneous  Veins  are  found  between  the  layers  of  superficial 
fascia,  immediately  beneath  the  integument;  they  return  the  blood  from  these 
structures,  and  communicate  with  the  deep  veins  by  perforating  the  deep 
fascia. 

The  Deep  Vein's  accompany  the  arteries,  and  are  usually  inclosed  in  the  same 
sheath  with  those  vessels.  In  the  smaller  arteries,  as  the  radial,  ulnar,  brachial, 
tibial,  peroneal,  they  exist  generally  in  pairs,  one  lying  on  each  side  of  the  vessel, 
and  are  called  vense  comites.  The  larger  arteries,  as  the  axillary,  subclavian, 
popliteal  and  femoral,  have  usually  only  one  accompanying  vein.  In  certain 
organs  of  the  body,  however,  the  deep  veins  do  not  accompany  the  arteries ;  for 
instance,  the  veins  in  the  skull  and  spinal  canal,  the  hepatic  veins  in  the  liver, 
and  the  larger  veins  returning  blood  from  the  osseous  tissue. 

Sinuses  are  venous  channels,  which,  in  their  structure  and  mode  of  distribution, 
differ  altogether  from  the  veins.  They  exist,  for  example,  in  the  interior  of  the  skull, 
and  are  formed  by  a  subdivision  of  the  layers  of  the  dura  mater ;  their  outer  coat 

455 


456  VEINS. 

consisting  of  fibrous  tissue,  their  inner  of  a  serous  membrane  continuous  with  the 
serous  membrane  of  the  veins. 

Veins  have  thinner  walls  than  the  arteries,  which  is  due  to  the  small  amount 
of  elastic  and  muscular  tissues  which  they  contain.  The  superficial  veins  usually 
have  thicker  coats  than  the  deep  veins,  and  the  veins  of  the  lower  limbs  are 
thicker  than  those  of  the  upper. 

Veins  are  composed  of  three  coats ;  internal,  middle,  and  external. 

The  internal  coat  is  similar  in  structure  to  that  of  the  arteries.  In  the  smallest 
veins,  it  consists  of  epithelium  and  nucleated  connective  tissue,  arranged  so  as  to 
form  an  outer  and  an  inner  layer ;  the  latter,  which  is  the  thinnest,  representing 
the  middle  coat.  As  these  vessels  approach  the  capillaries,  the  epithelium  and 
outer  layer  of  connective  tissue  become  gradually  lost.  On  the  contrary,  in  those 
of  rather  larger  size,  there  is  superadded  a  layer  of  muscular  fibre-cells,  a  circu- 
lar fibrous  coat,  with  areolar  elastic  tissue  beneath  the  epithelium,  and  in  the 
muscular  and  external  coats.  In  medium-sized  veins,  the  internal  coat  consists  of 
epithelium  supported  on  one  or  more  striped  nucleated  lamellae,  external  to  which 
is  a  layer  of  elastic  fibrous  tissue.  In  the  veins  of  the  gravid  uterus,  and  in  the 
long  saphenous  and  popliteal  veins,  muscular  tissue  is  one  of  the  component  parts 
of  the  inner  coat.  In  the  largest  veins,  as  the  inferior  vena  cava,  the  trunks  of 
the  hepatic,  and  in  the  innominate  veins,  the  internal  coat  has  a  structure  similar 
to  that  already  mentioned ;  but  is  somewhat  thicker,  owing  to  the  increase  in  the 
number  of  the  striped  lamellae,  and  the  greater  thickness  of  the  elastic  fibrous  coat. 

The  middle  coat  is  thin,  and  differs  in  structure  from  the  middle  coat  of  arteries 
in  containing  a  smaller  amount  of  elastic  and  muscular  tissues,  and  more  con- 
nective tissue.  In  the  smallest  veins,  as  already  mentioned,  it  consists  merely  of 
a  thin  layer  of  nucleated  connective  tissue,  the  fibres  of  which  run  in  a  longitu- 
dinal direction ;  to  which  is  added,  in  those  of  rather  larger  size,  a  layer  of  mus- 
cular tissue,  the  cells  of  which  are  disposed  transversely.  In  medium-sized  veins, 
such  as  the  cutaneous  and  deep  veins  of  the  limbs,  as  far  as  the  brachial  and  pop- 
liteal, and  the  visceral  veins,  the  middle  coat  is  of  a  reddish-yellow  color,  remark- 
able for  its  great  thickness,  being  more  developed  than  the  same  coat  in  the  large 
veins.  It  consists  of  a  thick  inner  layer  of  connective  tissue  with  elastic  fibres, 
having  intermixed  in  some  veins  a  transverse  layer  of  muscular  fibres ;  and  an 
outer  layer  consisting  of  longitudinal  elastic  lamellae,  varying  from  five  to  ten  in 
number,  alternating  with  layers  of  transverse  muscular  fibres  and  connective 
tissue,  which  resembles  somewhat  in  structure  the  middle  coat  of  large  arteries. 
In  the  large  veins,  as  in  the  commencement  of  the  vena  portas,  in  the  upper  part 
of  the  abdominal  portion  of  the  inferior  vena  cava,  and  in  the  large  hepatic 
trunks  within  the  liver,  the  middle  coat  is  thick,  and  its  structure  similar  to  that 
of  the  middle  coat  in  medium-sized  veins ;  but  its  muscular  tissue  is  scanty,  and 
the  longitudinal  elastic  networks  less  distinctly  lamellated.  The  muscular  tissue 
of  this  coat  is  best  marked  in  the  splenic  and  portal  veins,  it  is  absent  in  certain 
parts  of  the  vena  cava  below  the  liver,  and  wanting  in  the  subclavian  vein  and 
terminal  parts  of  the  two  cavae. 

The  external  coat  is  usually  the  thickest,  increasing  in  thickness  with  the  size 
of  the  vessel ;  it  is  similar  in  structure  to  the  external  coat  of  arteries,  but  its 
chief  peculiarity  is  that  in  some  veins  it  contains  a  longitudinal  network  of  mus- 
cular fibres.  In  the  smallest  veins,  it  consists  of  a  thick  layer  of  nucleated  con- 
nective tissue.  In  medium-sized  veins,  it  is  much  thicker  than  the  middle^  coat, 
and  consists  of  elastic  and  connective  tissues,  the  fibres  of  which  are  longitudinally 
arranged.  In  the  largest  veins,  this  coat  is  from  two  to  five  times  thicker  than 
the  middle  coat,  and  contains  a  large  number  of  longitudinal  muscular  fibres. 
This  is  most  distinct  in  the  hepatic  part  of  the  inferior  vena  cava,  and  at  the 
termination  of  this  vein  in  the  heart ;  in  the  trunks  of  the  hepatic  veins ;  in  all 
the  large  trunks  of  the  vena  portae ;  in  the  splenic,  superior  mesenteric,  external 
iliac,  renal,  and  azygos  veins.  Where  the  middle  coat  is  absent,  this_  muscular 
layer  extends  as  far  as  the  inner  coat.     In  the  renal  and  portal  veins,  it  extends 


GENERAL   ANATOMY.  457 

through  the  whole  thickness  of  the  outer  coat ;  but  in  the  other  veins  mentioned, 
a  layer  of  connective  and  elastic  tissues  is  found  external  to  the  muscular  fibres. 
All  the  large  veins  which  open  into  the  heart  are  covered  for  a  short  distance  by 
a  layer  of  muscular  tissue  continued  on  to  them  from  the  heart. 

Muscular  tissue  is  wanting  in  the  veins :  1.  Of  the  maternal  part  of  the  placenta. 
2.  In  most  of  the  cerebral  veins  and  sinuses  of  the  dura  mater.  3.  In  the  veins 
of  the  retina.  4.  In  the  veins  of  the  cancellous  tissue  of  bones.  5.  In  the  venous 
spaces  of  the  corpora  cavernosa.  The  veins  of  the  above-mentioned  parts  have 
an  internal  epithelial  lining,  supported  on  one  or<more  layers  of  areolar  tissue. 

Most  veins  are  provided  with  valves,  which  serve  to  prevent  the  reflux  of  the 
blood.  They  are  formed  by  a  reduplication  of  the  middle  and  inner  coats,  and 
consist  of  connective  tissue  and  elastic  fibres,  covered  on  both  surfaces  by  epithe- 
lium ;  their  form  is  semilunar.  They  are  attached,  by  their  convex  edge,  to  the 
wall  of  the  vein ;  the  concave  margin  is  free,  directed  in  the  course  of  the  venous 
current,  and  lies  in  close  apposition  with  the  wall  of  the  vein,  as  long  as  the  current 
of  blood  takes  its  natural  course ;  if,  however,  any  regurgitation  takes  place,  the 
valves  become  distended,  their  opposed  edges  are  brought  into  contact,  and  the 
current  is  intercepted.  Most  commonly  two  such  valves  are  found,  placed  opposite 
one  another,  more  especially  in  the  smaller  veins,  or  in  the  larger  trunks  at  the 
point  where  they  are  joined  by  small  branches ;  occasionally  there  are  three,  and 
sometimes  only  one.  The  wall  of  the  vein,  immediately  above  the  point  of  attach- 
ment of  each  segment  of  the  valve,  is  expanded  into  a  pouch  or  sinus,  which 
gives  to  the  vessel,  when  injected  or  distended  with  blood,  a  knotted  appearance. 
The  valves  are  very  numerous  in  the  veins  of  the  extremities,  especially  the  lower 
ones,  these  vessels  having  to  conduct  the  blood  against  the  force  of  gravity. 
They  are  absent  in  the  very  small  veins,  also  in  the  venae  cavse,  the  hepatic  vein, 
portal  vein  and  its  branches,  the  renal,  uterine,  and  ovarian  veins.  A  few  valves 
are  found  in  the  spermatic  veins,  and  one  also  at  their  point  of  junction  with  the 
renal  vein  and  inferior  vena  cava  in  both  sexes.  The  cerebral  and  spinal  veins,  the 
veins  of  the  cancellated  tissue  of  bone,  the  pulmonary  veins,  and  the  umbilical 
vein  and  its  branches,  are  also  destitute  of  valves.  They  are  occasionally  found, 
few  in  number,  in  the  azygos  and  intercostal  veins. 

The  veins  are  supplied  with  nutrient  vessels,  vasa  vasorum,  like  the  arteries; 
but  nerves  are  not  generally  found  distributed  upon  them.  The  only  vessels  upon 
which  they  have  at  present  been  traced,  are  the  sinuses  of  the  dura  mater ;  on  the 
spinal  veins;  on  the  venae  cavae;  on  the  common  jugular,  iliac,  and  crural  veins; 
and  on  the  hepatic  veins.     (Kolliker.) 

The  veins  may  be  arranged  into  three  groups:  1.  Those  of  the  head  and  neck, 
upper  extremity,  and  thorax,  which  terminate  in  the  superior  vena  cava.  2.  Those 
of  the  lower  extremity,  pelvis,  and  abdomen,  which  terminate  in  the  inferior  vena 
cava.   3.  The  cardiac  veins,  which  open  directly  into  the  right  auricle  of  the  heart. 

VEINS  OF  THE  HEAD  AND  NECK,  UPPER  EXTREMITY,  AND 

THORAX. 

Veins  of  the  Head  and  Neck. 

The  veins  of  the  head  and  neck  may  be  subdivided  into  three  groups.  1.  The 
veins  of  the  exterior  of  the  head.  2.  The  veins  of  the  neck.  3.  The  veins  of 
the  diploe  and  interior  of  the  cranium. 

1.  Veins  of  the  Exterior  of  the  Head. 
The  Veins  of  the  Exterior  of  the  Head  are  the 

Facial.  Temporo-m  axillary. 

Temporal.  Posterior  auricular. 

Internal  Maxillary.  Occipital. 


458 


VEINS. 


The  Facial  Vein  passes  obliquely  across  the  side  of  the  face,  extending  from 
the  inner  angle  of  the  orbit,  downwards  and  outwards,  to  the  anterior  margin  of 
the  Masseter  muscle.  It  lies  to  the  outer  side  of  the  facial  artery,  and  is  not  so 
tortuous  as  that  vessel.  It  commences  in  the  frontal  region,  where  it  is  called  the 
frontal  vein;  at  the  inner  angle  of  the  eye  it  has  received  the  name  of  the  angular 
vein;  and  from  this  point  to  its  termination,  the  facial  vein. 


Fig.  236.*- Veins  of  the  Head  and  Neck. 


Lingual 

laryngeal 


The  frontal  vein  commences  on  the  anterior  part  of  the  skull,  by  a  venous 
plexus,  which  communicates  with  the  anterior  branches  of  the  temporal  vein  ;  the 
veins  converge  to  form  a  single  trunk,  which  descends  along  the  middle  line  of  the 
forehead  parallel  with  the  vein  of  the  opposite  side,  and  unites  with  it  at  the  root 
of  the  nose  by  a  transverse  trunk,  called  the  nasal  arch.  Occasionally  the  frontal 
veins  join  to  form  a  single  trunk  which  bifurcates  at  the  root  of  the  nose  into  the 
two  angular  veins.  At  the  nasal  arch  the  branches  diverge,  and  run  along  the  side 
of  the  root  of  the  nose.  The  frontal  vein,  as  it  descends  upon  the  forehead, 
receives  the  supra-orbital  vein ;  the  dorsal  veins  of  the  nose  terminate  in  the  nasal 


OF   THE   HEAD.  459 

arch ;  and  the  angular  vein  receives,  on  its  inner  side,  the  veins  of  the  ala  nasi, 
on  its  outer  side  the  superior  palpebral  veins ;  it  moreover  communicates  with 
the  ophthalmic  vein,  which  establishes  an  important  anastomosis  between  this 
vessel  and  the  cavernous  sinus. 

The  facial  vein  commences  at  the  inner  angle  of  the  orbit,  being  a  continuation 
of  the  angular  vein.  It  passes  obliquely  downwards  and  outwards,  beneath  the 
great  Zygomatic  muscle,  descends  along  the  anterior  border  of  the  Masseter,  crosses 
over  the  body  of  the  lower  jaw,  with  the  facial  artery,  and,  passing  obliquely  out- 
wards and  backwards,  beneath  the  Platysma  and  cervical  fascia,  unites  with  a 
branch  of  communication  from  the  temporo-maxillary  vein,  to  form  a  trunk  of 
large  size  which  enters  the  internal  jugular. 

Branches.  The  facial  vein  receives,  near  the  angle  of  the  mouth,  communica- 
ting branches  from  the  pterygoid  plexus.  It  is  also  joined  by  the  inferior  pal- 
pebral, the  superior  and  inferior  labial  veins,  the  buccal  veins  from  the  cheek,  and 
the  masseteric  veins.  Below  the  jaw,  it  receives  the  submental,  the  inferior 
palatine,  which  returns  the  blood  from  the  plexus  around  the  tonsil  and  soft 
palate,  the  submaxillary  vein,  which  commences  in  the  submaxillary  gland,  and, 
lastly,  the  ranine  vein. 

The  Temporal  Vein  commences  by  a  minute  plexus  on  the  side  and  vertex  of 
the  skull,  which  communicates  with  the  frontal  vein  in  front,  the  corresponding 
vein  of  the  opposite  side,  and  the  posterior  auricular  and  occipital  veins  behind. 
From  this  network,  anterior  and  posterior  branches  are  formed  which  unite  above 
the  zygoma,  forming  the  trunk  of  the  vein.  This  trunk  is  joined  in  this  situation 
by  a  large  vein,  the  middle  temporal,  which  receives  the  blood  from  the  substance 
of  the  Temporal  muscle  and  pierces  the  fascia  at  the  upper  border  of  the  zygoma. 
The  temporal  vein  then  descends  between  the  external  auditory  meatus  and  the 
condyle  of  the  jaw,  enters  the  substance  of  the  parotid  gland,  and  unites  with  the 
internal  maxillary  vein,  to  form  the  temporo-maxillary. 

Branches.  The  temporal  vein  receives  in  its  course  some  parotid  veins,  an 
articular  branch  from  the  articulation  of  the  jaw,  anterior  auricular  veins  from 
the  external  ear,  and  a  vein  of  large  size,  the  transverse  facial,  from  the  side  of 
the  face. 

The  Internal  Maxillary  Vein  is  a  vessel  of  considerable  size,  receiving  branches 
which  correspond  with  those  derived  from  the  internal  maxillary  artery.  Thus 
it  receives  the  middle  meningeal  veins,  the  deep  temporal,  the  pterygoid,  masse- 
teric, buccal,  some  palatine  veins,  and  the  inferior  dental.  These  branches 
form  a  large  plexus,  the  pterygoid,  which  is  placed  between  the  Temporal  and 
External  pterygoid,  and  partly  between  the  Pterygoid  muscles.  This  plexus 
communicates  very  freely  with  the  facial  vein,  and  with  the  cavernous  sinus,  by 
branches  through  the  base  of  the  skull.  The  trunk  of  the  vein  then  passes 
backwards,  behind  the  neck  of  the  lower  jaw,  and  unites  with  the  temporal  vein, 
forming  the  temporo-maxillary. 

The  Temporo-maxillary  Vein,  formed  by  the  union  of  the  temporal  and  in- 
ternal maxillary  vein,  descends  in  the  substance  of  the  parotid  gland,  between 
the  ramus  of  the  jaw  and  the  Sterno-mastoid  muscle,  and  divides  into  two 
branches,  one  of  which  passes  inwards  to  join  the  facial  vein,  the  other  is  con- 
tinuous with  the  external  jugular.  It  receives  near  its  termination  the  posterior 
auricular  vein. 

The  Posterior  Auricular  Vein  commences  upon  the  side  of  the  head,  by  a  plexus 
which  communicates  with  the  branches  of  the  temporal  and  occipital  veins ;  de- 
scending behind  the  external  ear,  it  joins  the  temporo-maxillary,  just  before  that 
vessel  terminates  in  the  external  jugular.  This  vessel  receives  the  stylo-mastoid 
vein,  and  some  branches  from  the  back  part  of  the  external  ear. 

The  Occipital  Vein  commences  at  the  back  part  of  the  vertex  of  the  skull,  by 
a  plexus  in  a  similar  manner  with  the  other  veins.  It  follows  the  course  of  the 
occipital  artery,  passing  deeply  beneath  the  muscles  of  the  back  part  of  the  neck, 
and  terminates  in  the  internal  jugular,  occasionally  in  the  external  jugular.     As 


4G0  VEINS. 


this  vein  passes  opposite  the  mastoid  process,  it  receives  the  mastoid  vein,  which 
establishes  a  communication  with  the  lateral  sinus. 


2.  Yeins  of  the  Neck. 

The  Veins  of  the  Neck,  which  return  the  blood  from  the  head  and  face,  are 
the 

External  jugular.  Anterior  jugular. 

Posterior  external  jugular.  Internal  jugular. 

Vertebral. 

The  External  Jugular  Vein  receives  the  greater  part  of  the  blood  from  the 
exterior  of  the  cranium  and  deep  parts  of  the  face,  being  a  continuation  of  the 
temporo-maxillary  and  posterior  auricular  veins.  It  commences  in  the  substance 
of  the  parotid  gland,  on  a  level  with  the  angle  of  the  lower  jaw,  and  runs  perpen- 
dicularly down  the  neck,  in  the  direction  of  a  line  drawn  from  the  angle  of  the 
jaw  to  the  middle  of  the  clavicle.  In  its  course,  it  crosses  the  Sterno-mastoid 
muscle,  and  runs  parallel  with  its  posterior  border  as  far  as  its  attachment  to  the 
clavicle,  where  it  perforates  the  deep  fascia,  and  terminates  in  the  subclavian 
vein,  on  the  outer  side  of  the  internal  jugular.  As  it  descends  the  neck,  it  is 
separated  from  the  Sterno-mastoid  by  the  anterior  layer  of  the  deep  cervical 
fascia,  and  is  covered  by  the  Platysma,  the  superficial  fascia,  and  the  integument. 
This  vein  is  crossed  about  its  centre  by  the  superficial  cervical  nerve,  and  its 
upper  half  is  accompanied  by  the  auricularis  magnus  nerve.  The  external  jugular 
vein  varies  in  size,  bearing  an  inverse  proportion  to  that  of  the  other  veins  of  the 
neck ;  it  is  occasionally  double.  It  is  provided  with  two  pairs  of  valves,  the 
lower  pair  being  placed  at  its  entrance  into  the  subclavian  vein,  the  upper  pair  in 
most  cases  about  an  inch  and  a  half  above  the  clavicle.  These  valves  do  not  prevent 
the  regurgitation  of  the  blood,  or  the  passage  of  injection  from  below  upwards.1 

Branches.  This  vein  receives  the  occipital,  the  posterior  external  jugular,  and, 
near  its  termination,  the  supra-scapular  and  transverse  cervical  veins.  It  com- 
municates with  the  anterior  jugular,  and,  in  the  substance  of  the  parotid,  receives 
a  large  branch  of  communication  from  the  internal  jugular. 

The  Posterior  External  Jugular  Vein  returns  the  blood  from  the  integument 
and  superficial  muscles  in  the  upper  and  back  part  of  the  neck,  lying  between 
the  Splenius  and  Trapezius  muscles.  It  descends  the  back  part  of  the  neck,  and 
opens  into  the  external  jugular  just  below  the  middle  of  its  course. 

The  Anterior  Jugular  Vein  collects  the  blood  from  the  integument  and  muscles 
in  the  middle  of  the  anterior  region  of  the  neck.  It  passes  down  between  the 
median  line  and  the  anterior  border  of  the  Sterno-mastoid,  and,  at  the  lower  part 
of  the  neck,  passes  beneath  that  muscle  to  open  into  the  subclavian  vein,  near  the 
termination  of  the  external  jugular.  This  vein  varies  considerably  in  size,  bear- 
ing almost  always  an  inverse  proportion  to  the  external  jugular.  Most  frequently 
there  are  two  anterior  jugulars,  a  right  and  left;  but  occasionally -only  one.  This 
vein  receives  some  laryngeal  branches,  and  occasionally  an  inferior  thyroid  vein. 
Just  above  the  sternum,  the  two  anterior  jugular  veins  communicate  by  a  trans- 
verse trunk,  which  receives  branches  from  the  inferior  thyroid  veins.  It  also 
communicates  with  the  external  and  with  the  internal  jugular.  There  are  no 
valves  in  this  vein. 

The  Internal  Jugular  Vein  collects  the  blood  from  the  interior  of  the  cra- 
nium, from  the  superficial  parts  of  the  face,  and  from  the  neck.  It  commences 
at  the  jugular  foramen,  in  the  base  of  the  skull,  being  formed  by  the  coalescence 
of  the  lateral  and  inferior  petrosal  sinuses.     At  its  origin  it  is  somewhat  dilated, 

1  The  student  may  refer  to  an  interesting  paper  by  Dr.  Struthers,  "On  Jugular  Venesection 
in  Asphyxia,  Anatomically  and  Experimentally  Considered,  including  the  Demonstration  of 
Valves  in  the  Veins  of  the  Neck,"  in  the  Edinburgh  Medical  Journal,  for  November,  1856. 


OF   THE    NECK.  4G1 

and  this  dilatation  is  called  the  sinus,  or  gulf  of  the  internal  jugular  vein.  It 
runs  down  the  side  of  the  neck  in  a  vertical  direction,  lying  at  first  on  the  outer 
side  of  the  internal  carotid,  and  then  on  the  outer  side  of  the  common  carotid, 
and  at  the  root  of  the  neck  unites  with  the  subclavian  vein,  to  form  the  vena  in- 
nomiuata.  The  internal  jugular  vein,  at  its  commencement,  lies  upon  the  Rectus 
lateralis,  behind,  and  at  the  outer  side  of  the  internal  carotid,  and  the  eighth  and 
ninth  pairs  of  nerves ;  lower  down,  the  vein  and  artery  lie  upon  the  same  plane, 
the  glosso-pharyngeal  and  hypoglossal  nerves  passing  forwards  between  them ; 
the  pneumogastric  descends  between  and  behind  them,  in  the  same  sheath,  and 
the  spinal  accessory  passes  obliquely  outwards,  behind  the  vein.  At  the  root  of 
the  neck,  the  vein  of  the  right  side  is  placed  at  a  little  distance  from  the  artery ; 
on  the  left  side,  it  usually  crosses  it  at  its  lower  part.  The  vein  is  of  considera- 
ble size,  but  it  varies  in  different  individuals,  the  left  one  being  usually  the 
smallest.  It  is  provided  with  a  pair  of  valves,  which  are  placed  at  its  point  of 
termination,  or  from  half  to  three-quarters  of  an  inch  above  it. 

Branches.  This  vein  receives  in  its  course  the  facial,  lingual,  pharyngeal, 
superior  and  middle  thyroid  veins,  and  the  occipital.  At  its  point  of  junction 
with  the  branch  common  to  the  temporal  and  facial  veins,  it  becomes  greatly 
increased  in  size. 

The  lingual  veins  commence  on  the  dorsum,  sides,  and  under  surface  of  the 
tongue,  and  passing  backwards,  following  the  course  of  the  lingual  artery  and  its 
branches,  terminate  in  the  internal  jugular. 

The  pharyngeal  vein  commences  in  a  minute  plexus,  the  pharyngeal,  at  the 
back  part  and  sides  of  the  pharynx,  and  after  receiving  meningeal  branches,  and 
the  Vidian  and  spheno-palatine  veins,  terminates  in  the  internal  jugular.  It  occa- 
sionally opens  into  the  facial,  lingual,  or  superior  thyroid  vein. 

The  superior  thyroid  vein  commences  in  the  substance  and  on  the  surface  of  the 
thyroid  gland,  by  branches  corresponding  with  those  of  the  superior  thyroid  artery, 
and  terminates  in  the  upper  part  of  the  internal  jugular  vein. 

The  middle  thyroid  vein  collects  the  blood  from  the  lower  part  of  the  lateral  lobe 
of  the  thyroid  gland,  and,  being  joined  by  some  branches  from  the  larynx  and 
trachea,  terminates  in  the  lower  part  of  the  internal  jugular  vein. 

The  Vertebral  Vein  commences  by  numerous  small  branches  in  the  occipital 
region,  from  the  deep  muscles  at  the  upper  and  back  part  of  the  neck,  passes  out- 
wards, and  enters  the  foramen  in  the  transverse  process  of  the  atlas,  and  descends 
by  the  side  of  the  vertebral  artery,  in  the  canal  formed  by  the  transverse  processes 
of  the  cervical  vertebras.  Emerging  from  the  foramen  in  the  transverse  process  of 
the  sixth  cervical,  it  terminates  at  the  root  of  the  neck  in  the  back  part  of  the 
innominate  vein  near  its  origin,  its  mouth  being  guarded  by  a  pair  of  valves. 
This  vein,  in  the  lower  part  of  its  course,  occasionally  divides  into  two  branches ; 
one  emerges  with  the  artery  at  the  sixth  cervical  vertebra,  the  other  escapes 
through  the  foramen  in  the  seventh  cervical. 

Branches.  This  vein  receives  in  its  course  the  posterior  condyloid  vein,  mus- 
cular branches  from  the  muscles  in  the  prevertebral  region ;  dorsi-spinal  veins, 
from  the  back  part  of  the  cervical  portion  of  the  spine ;  meningo-rachidian  veins, 
from  the  interior  of  the  spinal  canal ;  and,  lastly,  the  ascending  and  deep  cervical 
veins. 

3.  Veins  of  the  Diploe  and  Interior  of  the  Cranium. 

Veins  of  the  Diploe. 

The  diploe  of  the  cranial  bones  is  channelled,  in  the  adult,  with  a  number  of 
tortuous  canals,  which  are  lined  by  a  more  or  less  complete  layer  of  compact 
tissue.  The  veins  they  contain  are  large  and  capacious,  their  walls  being  thin, 
and  formed  only  of  epithelium,  resting  upon  a  layer  of  elastic  tissue,  and  they 
present,  at  irregular  intervals,  pouch-like  dilatations  or  culs-de-sac,  which  serve 


462  VEINS. 

as  reservoirs  for  the  blood.     These  are  the  veins  of  the  diploe ;  they  can  only  be 
displayed  by  removing  the  outer  table  of  the  skull. 

In  adult  life,  as  long  as  the  cranial  bones  are  distinct  and  separable,  these  veins 
are  confined  to  the  particular  bones ;  but  in  old  age,  when  the  sutures  are  united, 
they  communicate  with  each  other,  and  increase  in  size.  These  vessels  commu- 
nicate, in  the  interior  of  the  cranium,  with  the  meningeal  veins,  and  with  the 
sinuses  of  the  dura  mater,  and,  on  the  exterior  of  the  skull,  with  the  veins  of  the 
pericranium.     They  are  divided  into  the  frontal,  which  opens  into  the  supra-orbital 

Fig.  237. — Veins  of  the  Diploe,  as  displayed  \>j  the  Removal  of  the 
Outer  Table  of  the  Skull. 


vein,  by  an  aperture  at  the  supra-orbital  notch ;  the  anterior  temporal,  which  is 
confined  chiefly  to  the  frontal  bone,  and  opens  into  one  of  the  deep  temporal  veins, 
after  escaping  by  an  aperture  in  the  great  wing  of  the  sphenoid ;  the  posterior 
temporal,  which  is  confined  to  the  parietal  bone,  and  terminates  in  the  lateral  sinus 
by  an  aperture  at  the  posterior  inferior  angle  of  the  parietal  bone ;  and  the  occipital, 
which  is  confined  to  the  occipital  bone,  and  opens  either  into  the  occipital  vein, 
or  the  occipital  sinus. 

Cerebral  Veins. 

The  Cerebral  Veins  are  remarkable  for  the  extreme  thinness  of  their  coats,  from 
the  muscular  tissue  in  them  being  wanting,  and  for  the  absence  of  valves.  They 
may  be  divided  into  two  sets,  the  superficial,  which  are  placed  on  the  surface,  and 
the  deep  veins,  which  occupy  the  interior  of  the  organ. 

The  Superficial  Cerebral  Veins  ramify  upon  the  surface  of  the  brain,  being 
lodged  in  the  sulci,  between  the  convolutions,  a  few  running  across  the  convolu- 
tions. They  receive  branches  from  the  substance  of  the  brain,  and  terminate  in 
the  sinuses.  They  are  named  from  the  position  they  occupy,  superior,  inferior, 
internal,  and  external. 

The  Superior  Cerebral  Veins,  seven  or  eight  in  number  on  each  side,  pass 
forwards  and  inwards  towards  the  great  longitudinal  fissure,  where  they  receive 
the  internal  cerebral  veins,  which  return  the  blood  from  the  convolutions  of  the 
flat  surface  of  the  corresponding  hemisphere ;  passing  obliquely  forwards,  they 
become  invested  with  a  tubular  sheath  of  the  arachnoid  membrane,  and  open  into 


CEREBRAL.  4G3 

the  superior  longitudinal  sinus,  in  the  opposite  direction  to  the  course  of  the 
blood. 

The  Inferior  Anterior  Cerebral  Veins  commence  on  the  under  surface  of  the 
anterior  lobes  of  the  brain,  and  terminate  in  the  cavernous  sinuses. 

The  Inferior  Lateral  Cerebral  Veins  commence  on  the  lateral  parts  of  the 
hemispheres  and  at  the  base  of  the  brain :  they  unite  to  form  from  three  to  five 
veins,  which  open  into  the  lateral  sinus  from  before  backwards. 

The  Inferior  Median  Cerebral  Veins,  which  are  very  large,  commence  at  the 
fore  part  of  the  under  surface  of  the  cerebrum,  and  from  the  convolutions  of  the 
posterior  lobe,  and  terminate  in  the  straight  sinus  behind  the  venae  Galeni. 

The  Deep  Cerebral  or  Ventricular  Veins  (venae  Galeni)  are  two  in  number, 
one  from  the  right  ventricle,  the  other  from  the  left.  They  are  each  formed 
by  two  veins,  the  vena  corporis  striati  and  the  choroid  vein.  They  pass  back- 
wards, parallel  with  one  another,  inclosed  within  the  velum  interpositum,  and 
pass  out  of  the  brain  at  the  great  transverse  fissure,  between  the  under  surface 
of  the  corpus  callosum  and  the  tubercula  quadrigemina,  and  enter  the  straight 
sinus. 

The  vena  corporis  striati  commences  in  the  groove  between  the  corpus  striatum 
and  thalamus  opticus,  receives  numerous  veins  from  both  of  these  parts,  and 
unites  behind  the  anterior  pillar  of  the  fornix  with  the  choroid  vein,  to  form  one 
of  the  venae  Galeni. 

The  choroid  vein  runs  along  the  whole  length  of  the  outer  border  of  the 
choroid  plexus,  receiving  veins  from  the  hippocampus  major,  the  fornix  and 
corpus  callosum,  and  unites;  at  the  anterior  extremity  of  the  choroid  plexus, 
with  the  vein  of  the  corpus  striatum. 

The  Cerebellar  Veins  occupy  the  surface  of  the  cerebellum,  and  are  disposed  in 
three  sets,  superior,  inferior,  and  lateral.  The  superior  pass  forwards  and  inwards, 
across  the  superior  vermiform  process,  and  terminate  in  the  straight  sinus ;  some 
open  into  the  venae  Galeni.  The  inferior  cerebellar  veins,  of  large  size,  run 
transversely  outwards,  and  terminate  by  two  or  three  trunks  in  the  lateral  sinuses. 
The  lateral  anterior  cerebellar  veins  terminate  in  the  superior  petrosal  sinuses. 

Sinuses  of  the  Dura  Mater. 

The  sinuses  of  the  dura  mater  are  venous  channels,  analogous  to  the  veins, 
their  outer  coat  being  formed  by  the  dura  mater ;  their  inner,  by  a  continuation 
of  the  serous  membrane  of  the  veins.  They  are  twelve  in  number,  and  are 
divided  into  two  sets: — 1.  Those  situated  at  the  upper  and  back  part  of  the  skull. 
2.  The  sinuses  at  the  base  of  the  skull. 

1.  The  sinuses  of  the  upper  and  back  part  are  the 

Superior  longitudinal.  Straight  sinus. 

Inferior  longitudinal.  Lateral  sinuses. 

Occipital  sinuses. 

The  Superior  Longitudinal  Sinus  occupies  the  attached  margin  of  the  falx 
cerebri.  Commencing  at  the  crista  Galli,  it  runs  from  before  backwards,  groov- 
ing the  inner  surface  of  the  frontal,  the  adjacent  margins  of  the  two  parietal 
and  the  superior  division  of  the  crucial  ridge  of  the  occipital  bone,  and  terminates 
by  dividing  into  the  two  lateral  sinuses.  This  sinus  is  triangular  in  form, 
narrow  in  front,  and  gradually  increasing  in  size  as  it  passes  backwards.  On 
examining  its  inner  surface,  it  presents  the  internal  openings  of  the  cerebral 
veins :  these  vessels  are,  for  the  most  part,  directed  from  behind  forwards,  and 
chiefly  open  at  the  back  part  of  the  sinus,  their  orifices  being  concealed  by  fibrous 
areolae;  numerous  fibrous  bands,  chordse  Willisii,  are  also  seen,  which  extend 
transversely  across  its  inferior  angle ;  and  lastly,  some  small,  white,  projecting 
bodies,  the  glandulae  Pacchioni.     This  sinus  receives  the  superior  cerebral  veins. 


464 


VEINS. 


numerous  veins  from  the  diploe  and  dura  mater,  and,  at  the  posterior  extremity 
of  the  sagittal  suture,  the  parietal  veins  from  the  pericranium. 

The  point  where  the  superior  longitudinal  and  lateral  sinuses  are  continuous  is 
called  the  confluence  of  the  sinuses  or  the  torcular  Herophili.  It  presents  a  con- 
siderable dilatation,  of  very  irregular  form,  and  is  the  point  of  meeting  of  six 
sinuses,  the  superior  longitudinal,  the  two  lateral,  the  two  occipital,  and  the 
straight. 

The  Inferior  Longitudinal  Sinus,  more  correctly  described  as  the  inferior 
longitudinal  vein,  is  contained  in  the  posterior  part  of  the  free  margin  of  the  falx 
cerebri.  It  is  of  a  circular  form,  increases  in  size  as  it  passes  backwards,  and 
terminates  in  the  straight  sinus.  It  receives  several  veins  from  the  falx  cerebri, 
and  occasionally  a  few  from  the  flat  surface  of  the  hemispheres. 

The  Straight  Sinus  is  situated  at  the  line  of  junction  of  the  falx  cerebri  with 
the  tentorium.  It  is  triangular  in  form,  increases  in  size  as  it  proceeds  back- 
wards, and  runs  obliquely  downwards  and  backwards  from  the  termination  of  the 
inferior  longitudinal  sinus  to  the  torcular  Herophili.  Besides  the  inferior  lon- 
gitudinal sinus,  it  receives  the  venae  Galeni,  the  inferior  median  cerebral  veins, 
and  the  superior  cerebellar.     A  few  transverse  bands  cross  its  interior. 

Fig.  238. — Vertical  Section  of  the  Skull,  showing  the  Sinuses  of  the  Dura  Mater. 


Toreular_ 
Herophili 


The  Lateral  Sinuses  are  of  large  size,  and  situated  in  the  attached  margin  of 
the  tentorium  cerebelli.  They  commence  at  the  torcular  Herophili,  and,  passing 
horizontally  outwards  to  the  base  of  the  petrous  portion  of  the  temporal  bone, 
curve  downwards  and  inwards  on  each  side  to  reach  the  jugular  foramen,  where 
they  terminate  in  the  internal  jugular  vein.  Each  sinus  rests,  in  its  course,  upon 
the  inner  surface  of  the  occipital  bone,  the  posterior  inferior  angle  of  the  parietal,  the 
mastoid  portion  of  the  temporal,  and  on  the  occipital  again  just  before  its  termi- 
nation. These  sinuses  are  of  unequal  size,  the  right  being  the  larger,  and  they 
increase  in  size  as  they  proceed  from  behind  forwards.  The  horizontal  portion  is 
of  a  triangular  form,  the  curved  portion  semi -cylindrical ;  their  inner  surface  is 
smooth,  and  not  crossed  by  the  fibrous  bands  found  in  the  other  sinuses.  These 
sinuses  receive  blood  from  the  superior  longitudinal,  the  straight,  and  the  occipital 
sinuses ;  and  in  front  they  communicate  with  the  superior  and  inferior  petrosal. 
They  communicate  with  the  veins  of  the  pericranium  by  means  of  the  mastoid 
and  posterior  condyloid  veins,  and  they  receive  the  inferior  cerebral  and  inferior 
cerebellar  veins,  and  some  from  the  diploe. 

The  Occipital  are  the  smallest  of  the  cranial  sinuses.  They  are  usually  two  in 
ruimber,  and  situated  in  the  attached  margin  of  the  falx  cerebelli.   They  commence 


SINUSES   OF   THE   DURA   MATER. 


46( 


by  several  small  veins  around  the  posterior  margin  of  the  foramen  magnum,  which 
communicate  with  the  posterior  spinal  veins,  and  terminate  by  separate  openings 
(sometimes  by  a  single  aperture)  in  the  torcular  Herophili. 
2.  The  sinuses  at  the  base  of  the  skull  are  the 


Cavernous. 
Circular. 


Transverse. 


Inferior  petrosal. 
Superior  petrosal. 


The  Cavernous  Sinuses  are  named  from  their  presenting  a  reticulated  structure. 
They  are  two  in  number,  of  large  size,  and  placed  one  on  each  side  of  the  sella 
Turcica,  extending  from  the  sphenoidal  fissure  to  the  apex  of  the  petrous  portion 

Fig.  239.— The  Sinuses  at  the  Base  of  the  Skull. 


of  the  temporal  bone :  they  receive  anteriorly  the  ophthalmic  vein  through  the 
sphenoidal  fissure,  communicate  behind  with  the  petrosal  sinuses,  and  with  each 
other  by  the  circular  and  transverse  sinuses.  On  the  inner  wall  of  each  sinus  is 
found  the  internal  carotid  artery,  accompanied  by  filaments  of  the  carotid  plexus 
and  by  the  sixth  nerve ;  and  on  its  outer  wall,  the  third,  fourth,  and  ophthalmic 
nerves.  These  parts  are  separated  from  the  blood  flowing  along  the  sinus  by  the 
lining  membrane,  which  is  continuous  with  the  inner  coat  of  the  veins.  The 
cavity  of  the  sinus,  which  is  larger  behind  than  in  front,  is  intersected  by  filaments 
of  fibrous  tissue  and  small  vessels.  The  cavernous  sinuses  receive  the  inferior 
anterior  cerebral  veins;  they  communicate  with  the  lateral  sinuses  by  means 
of  the  superior  and  inferior  petrosal,  and  with  the  facial  vein  through  the 
ophthalmic. 

The  ophthalmic  is  a  large  vein,  which  connects  the  frontal  vein  at  the  inner 
angle  of  the  orbit  with  the  cavernous  sinus ;  it  pursues  the  same  course  as  the 
ophthalmic  artery,  and  receives  branches  corresponding  to  those  derived  from  that 
vessel.  Forming  a  short  single  trunk,  it  passes  through  the  inner  extremity  of 
the  sphenoidal  fissure,  and  terminates  in  the  cavernous  sinus. 

The  Circular  Sinus  completely  surrounds  the  pituitary  body,  and  communicates 
on  each  side  with  the  cavernous  sinuses.  Its  posterior  half  is  larger  than  the 
30 


466 


VEINS, 


Fig.  240.— The  Superficial  Veins  of  the 
Upper  Extremity. 


anterior ;  and  in  old  age  it  is  more  capacious  than  at  an  early  period  of  life.  It 
receives  veins  from  the  pituitary  body,  and  from  the  adjacent  bone  and  dura  mater. 

The  Inferior  Petrosal  Sinus  is  situated  in 
the  groove  formed  by  the  junction  of  the 
inferior  border  of  the  petrous  portion  of  the 
temporal  with  the  basilar  process  of  the 
occipital.  It  commences  in  front  at  the 
termination  of  the  cavernous  sinus,  and  opens 
behind  into  the  jugular  foramen,  forming 
with  the  lateral  sinus  the  commencement  of 
the  internal  jugular  vein.  These  sinuses 
are  semi-cylindrical  in  form. 

The  Transverse  Sinus  is  placed  trans- 
versely across  the  fore  part  of  the  basilar 
process  of  the  occipital  bone,  serving  to 
connect  the  two  inferior  petrosal  and  cavern- 
ous sinuses.  A  second  is  occasionally  found 
opposite  the  foramen  magnum. 

The  Superior  Petrosal  Sinus  is  situated 
along  the  upper  border  of  the  petrous  por- 
tion of  the  temporal  bone,  in  the  front  part 
of  the  attached  margin  of  the  tentorium.  It 
is  small  and  narrow,  and  connects  together 
the  cavernous  and  lateral  sinuses  at  each 
side.  It  receives  a  cerebral  vein  (inferior 
lateral  cerebral)  from  the  under  part  of  the 
middle  lobe,  and  a  cerebellar  vein  (anterior 
lateral  cerebellar)  from  the  anterior  border 
of  the  cerebellum. 


IZeitanCejjXaJt'c, 


External , 

CulaMCoutNi  rwt 


Veins  of  the  Upper  Extremity 
and  Thorax. 

The  veins  of  the  upper  extremity  are 
divided  into  two  sets:  1.  The  superficial 
veins.     2.  The  deep  veins. 

The  Superficial  Veins  are  placed  imme- 
diately beneath  the  integument  between  the 
two  layers  of  superficial  fascia ;  they  com- 
mence in  the  hand  chiefly  on  its  dorsal 
aspect,  where  they  form  a  more  or  less  com- 
plete arch. 

The  Deep  Veins  accompany  the  arteries, 
and  constitute  the  venas  comites  of  those 
vessels. 

Both  sets  of  vessels  are  provided  with 
valves,  which  are  more  numerous  in  the  deep 
than  in  the  superficial. 

1.  The  Superficial  Veins  of  the  Upper 
Extremity  are  the 


Anterior  ulnar. 

Posterior  ulnar. 

Basilic. 

Eaclial. 

The  Anterior   Ulnar 


Cephalic. 
Median. 
Median  basilic. 
Median  cephalic. 
Vein  commences  on 


the  anterior  surface  of  the  wrist  and  ulnar 
side  of  the  hand,  and  ascends   along  the 


• 


OF   THE   UPPER  EXTREMITY.  467 

inner  side  of  the  forearm  to  the  bend  of  the  elbow,  where  it  joins  with  the  posterior 
ulnar  vein  to  form  the  basilic.  It  communicates  with  branches  of  the  median 
vein  in  front,  and  with  the  posterior  ulnar  behind. 

The  Posterior  Ulnar  Vein  commences  on  the  posterior  surface  of  the  ulnar 
side  of  the  hand,  and  from  the  vein  of  the  little  finger  (vena  salvatella),  situated 
over  the  fourth  metacarpal  space.  It  ascends  on  the  posterior  surface  of  the  ulnar 
side  of  the  forearm,  and  just  below  the  elbow  unites  with  the  anterior  ulnar  vein 
to  form  the  basilic. 

The  Basilic  is  a  vein  of  considerable  size,  formed  by  the  coalescence  of  the 
anterior  and  posterior  ulnar  veins ;  ascending  along  the  inner  side  of  the  elbow,  it 
receives  the  median  basilic  vein,  and,  passing  upwards  along  the  inner  side  of  the 
arm,  pierces  the  deep  fascia,  and  ascends  in  the  course  of  the  brachial  artery,  ter- 
minating either  in  one  of  the  venae  comites  of  that  vessel,  or  in  the  axillary  vein. 

The  Radial  Vein  commences  from  the  dorsal  surface  of  the  thumb,  index  finger, 
and  radial  side  of  the  hand,  by  branches  which  communicate  with  the  vena  salva- 
tella. They  form  by  their  union  a  large  vessel,  which  ascends  along  the  radial 
side  of  the  forearm,  receiving  numerous  branches  from  both  its  surfaces.  At  the 
bend  of  the  elbow  it  receives  the  median  cephalic,  when  it  becomes  the  cephalic 
vein. 

The  Cephalic  Vein  ascends  along  the  outer  border  of  the  Biceps  muscle,  to  the 
upper  third  of  the  arm  ;  it  then  passes  in  the  interval  between  the  Pectoralis  major 
and  Deltoid  muscles,  accompanied  by  the  descending  branch  of  the  thoracica  acro- 
mialis  artery,  and  terminates  in  the  axillary  vein  just  below  the  clavicle.  This 
vein  is  occasionally  connected  with  the  external  jugular  or  subclavian,  by  a  branch 
which  passes  from  it  upwards  in  front  of  the  clavicle. 

The  Median  Vein  collects  the  blood  from  the  superficial  structures  in  the  palmar 
surface  of  the  hand  and  middle  line  of  the  forearm,  communicating  with  the 
anterior  ulnar  and  radial  veins.  At  the  bend  of  the  elbow,  it  receives  a  branch  of 
communication  from  the  deep  veins,  accompanying  the  brachial  artery,  and  divides 
into  two  branches, -the  median  cephalic  and  median  basilic,  which  diverge  from 
each  other  as  they  ascend. 

The  Median  Cephalic,  the  smaller  of  the  two,  passes  outwards  in  the  groove 
between  the  Supinator  longus  and  Biceps  muscles,  and  joins  with  the  cephalic 
vein.     The  branches  of  the  external  cutaneous  nerve  pass  behind  this  vessel. 

The  Median  Basilic  vein  passes  obliquely  inwards,  in  the  groove  between  the 
Biceps  and  Pronator  radii  teres,  and  joins  with  the  basilic.  This  vein  passes 
in  front  of  the  brachial  artery,  from  which  it  is  separated  by  a  fibrous  expansion, 
given  off  from  the  tendon  of  the  Biceps  to  the  fascia  covering  the  Flexor  muscles 
of  the  forearm.  Filaments  of  the  internal  cutaneous  nerve  pass  in  front  of  as  well 
as  behind  this  vessel. 

2.  The  Deep  Veins  of  the  Upper  Extremity  follow  the  course  of  the  arteries, 
forming  their  vena3  comites.  They  are  generally  two  in  number,  one  lying  on 
each  side  of  the  corresponding  artery,  and  they  are  connected  at  intervals  by 
short  transverse  branches. 

There  are  two  digital  veins,  accompanying  each  artery  along  the  sides  of  the 
fingers ;  these,  uniting  at  their  base,  pass  along  the  interosseous  spaces  in  the  palm, 
and  terminate  in  the  two  superficial  palmar  veins.  Branches  from  these  vessels 
on  the  radial  side  of  the  hand  accompany  the  superficialis  vola3,  and  on  the  ulnar 
side  terminate  in  the  deep  ulnar  veins.  The  deep  ulnar  veins,  as  they  pass  in 
front  of  the  wrist,  communicate  with  the  interosseous  and  superficial  veins,  and 
unite  at  the  elbow  with  the  deep  radial  veins,  to  form  the  vense  comites  of  the 
brachial  artery. 

The  Interosseous  Veins  accompany  the  anterior  and  posterior  interosseous 
arteries.  The  anterior  interosseous  veins  commence  in  front  of  the  wrist,  where 
they  communicate  with  the  deep  radial  and  ulnar  veins ;  at  the  upper  part  of  the 
forearm  they  receive  the  posterior  interosseous  veins,  and  terminate  in  the  venoa 
comites  of  the  ulnar  artery. 


4G8  VEINS. 

The  Deep  Palmar  Veins  accompany  the  deep  palmar  arch,  being  formed  bv 
branches  which  accompany  the  ramifications  of  this  vessel.  They  communicate 
with  the  superficial  palmar  veins  at  the  inner  side  of  the  hand ;  and,  on  the  outer 
side,  terminate  in  the  venaa  comites  of  the  radial  artery.  At  the  wrist,  they  receive 
a  dorsal  and  a  palmar  branch  from  the  thumb,  and  unite  with  the  deep  radial 
veins.  Accompanying  the  radial  artery,  these  vessels  terminate  in  the  vense 
comites  of  the  brachial  artery. 

The  Brachial  Veins  are  placed  one  on  each  side  of  the  brachial  artery,  receiving 
branches  corresponding  with  those  given  off  from  this  vessel ;  at  the  lower  margin 
of  the  axilla  they  unite  with  the  basilic  to  form  the  axillary  vein. 

The  deep  veins  have  numerous  anastomoses,  not  only  with  each  other,  but  also 
with  }he  superficial  veins. 

The  Axillary  Yein  is  of  large  size  and  formed  by  the  continuation  upwards 
of  the  basilic  vein.  It  commences  at  the  lower  part  of  the  axillary  space,  and 
increasing  in  size  as  it  ascends,  by  receiving  branches  corresponding  with  those  of 
the  axillary  artery,  terminates  immediately  beneath  the  clavicle  at  the  outer  mar- 
gin of  the  first  rib,  and  becomes  the  subclavian  vein.  This  vessel  is  covered  in 
front  by  the  Pectoral  muscles  and  costo-coracoid  membrane,  and  lies  on  the  thoracic 
side  of  the  axillary  artery.  Opposite  the  Subscapularis,  it  is  joined  by  a  large 
vein,  formed  by  the  junction  of  the  vense  comites  of  the  brachial ;  and  near  its 
termination  it  receives  the  cephalic  vein.  This  vein  is  provided  with  a  pair  of 
valves  opposite  the  lower  border  of  the  Subscapularis  muscle ;  valves  are  also 
found,  at  the  termination  of  the  cephalic  and  subscapular  veins. 

The  Subclavian  Yein,  the  continuation  of  the  axillary,  extends  from  the  outer 
margin  of  the  first  rib  to  the  inner  end  of  the  sterno-clavicular  articulation,  where 
it  unites  with  the  internal  jugular,  to  form  the  vena  innominata.  It  is  in  relation, 
in  front,  with  the  clavicle  and  Subclavius  muscle ;  behind,  with  the  subclavian 
artery,  from  which  it  is  separated  internally  by  the  Scalenus  anticus  and  phrenic 
nerve.  Below,  it  rests  in  a  depression  on  the  first  rib  and  upon  the  pleura. 
Above,  it  is  covered  by  the  cervical  fascia  and  integument. 

The  subclavian  vein  occasionally  rises  in  the  neck  to  a  level  with  the  third  part 
of  the  subclavian  artery,  and,  in  two  instances,  has  been  seen  passing  with  the 
latter  behind  the  Scalenus  anticus.  This  vessel  is  provided  with  valves  about  an 
inch  from  its  termination  in  the  innominate,  just  external  to  the  entrance  of  the 
external  jugular  vein. 

Branches.  It  receives  the  external  and  anterior  jugular  veins  and  a  small  branch 
from  the  cephalic,  outside  the  Scalenus;  and  on  the  inner  side  of  this  muscle,  the 
internal  jugular  veins. 

The  YENiE  Innominate  (fig.  241)  are  two  large  trunks,  placed  one  on  each 
side  of  the  root  of  the  neck,  and  formed  by  the  union  of  the  internal  jugular  and 
subclavian  veins  of  the  corresponding  side. 

The  Bight  Vena  Innominata  is  a  short  vessel,  about  an  inch  and  a  half  in  length, 
which  commences  at  the  inner  end  of  the  clavicle,  and,  passing  almost  vertically 
downwards,  joins  with  the  left  vena  innominata  just  below  the  cartilage  of  the  first 
rib,  to  form  the  superior  vena  cava.  It  lies  superficial  and  external  to  the  arteria 
innominata ;  on  its  right  side  the  pleura  is  interposed  between  it  and  the  apex  of 
the  lung.  This  vein,  at  its  angle  of  junction  with  the  subclavian,  receives  the 
right  vertebral  vein,  and  right  lymphatic  duct ;  and,  lower  down,  the  right  internal 
mammary,  right  inferior  thyroid,  and  right  superior  intercostal  veins. 

The  Left  Vena  Innominata,  about  three  inches  in  length,  and  larger  than  the 
right,  passes  obliquely  from  right  to  left  across  the  upper  and  front  part  of  the 
chest,  to  unite  with  its  fellow  of  the  opposite  side,  forming  the  superior  vena  cava. 
It  is  in  relation,  in  front,  with  the  sternal  end  of  the  left  clavicle,  the  left  sterno- 
clavicular articulation,  and  with  the  first  piece  of  the  sternum,  from  which  it  is 
separated  by  the  Sterno-hyoid  and  Sterno-thyroid.  muscles,  the  thymus  gland  or 
its  remains,  and  some  loose  areolar  tissue.     Behind,  it  lies  across  the  roots  of  the 


INNOMINATE. 


469 


three  large  arteries  arising  from  the  arch  of  the  aorta.     This  vessel  is  joined  "by 
the  left  vertebral,  left  inferior  thyroid,  left  internal  mammary,  and  the  left  supe- 
rior intercostal  veins,  and 
occasionally  some  thymic 
and      pericardiac     veins.  Fis-  241--TJ1Ie  7e"ffi  Ca™  a"d  AzP°9  Veins' 

"  ,  "  ...  with  their  Formative  Branches. 

There  are  no  valves  in  the  '„     A  T     / 

\\3.~-^AnUrior  Jugular* 

venas  mnominatoe. 


Peculiarities.  Sometimes 
the  innominate  veins  open  se- 
parately into  the  right  auri- 
cle ;  in  such  cases  the  right 
vein  takes  the  ordinary  course 
of  the  superior  vena  cava,  but 
the  left  vein,  after  communi- 
cating by  a  small  branch  with 
the  right  one,  passes  in  front 
of  the  root  of  the  left  lung, 
and,  turning  to  the  back  of 
the  heart,  receives  the  cardiac 
veins,  and  terminates  in  the 
back  of  the  right  auricle. 
This  occasional  condition  of 
the  veins  in  the  adult  is  a 
regular  one  in  the  foetus  at  an 
early  period,  and  the  two  ves- 
sels are  persistent  in  birds 
and  some  mammalia.  The 
subsequent  changes  which 
take  place  in  these  vessels  are 
the  following  :  The  communi- 
cating branch  between  the  two 
trunks  enlarges  and  forms  the 
future  left  innominate  vein ; 
the  remaining  part  of  the  left 
trunk  is  obliterated  as  far 
as  the  heart,  where  it  remains 
pervious,  and  forms  the  coro- 
nary sinus ;  a  remnant  of  the 
obliterated  vessel  is  seen  in 
adult  life  as  a  fibrous  band 
passing  along  the  back  of  the 
left  auricle  and  in  front  of  the 
root  of  the  left  lung,  called,  by 
Mr.  Marshall,  the  vestigial  fold 
of  the  pericardium. 

The  internal  mammary 
veins,  two  in  number  to 
each  artery,  follow  the 
course  of  that  vessel,  and 
receive  branches  corre- 
sponding with  those  de- 
rived from  it.  The  two 
veins  unite  into  a  single 
trunk,  which  terminates 
in  the  innominate  vein. 

The  inferior  thyroid 
veins,  two,  frequently  three 
or  four  in  number,  arise 
in  the  venous  plexus,  on 
the  thyroid  body,  commu- 
nicating with  the  middle 
and  superior  thyroid  veins. 
The  left  one  descends  in 


Superior  Thyroid 


WLJJlt 


'vntal  Jugular 


4T0  VEINS. 

front  of  the  trachea,  behind  the  Sterno-thyroid  muscles,  communicating  with  ita 
fellow  by  transverse  branches,  and  terminates  in  the  left  vena  innominata.  The 
right  one,  which  is  placed  a  little  to  the  right  of  the  median  line,  opens  into  the 
right  vena  innominata,  just  at  its  junction  with  the  superior  cava.  These  veins 
receive  tracheal  and  inferior  laryngeal  branches,  and  are  provided  with  valves  at 
their  termination  in  the  innominate  veins. 

The  Superior  Intercostal  Veins  return  the  blood  from  the  upper  intercostal 
spaces. 

The  rigid  superior  intercostal,  much  smaller  than  the  left,  closely  corresponds 
with  the  superior  intercostal  artery,  receiving  the  blood  from  the  first,  or  first  and 
second  intercostal  spaces,  and  terminates  in  the  right  vena  innominata.  Some- 
times it  passes  down,  and  opens  into  the  vena  azygos  major. 

The  left  superior  intercostal  is  always  larger  than  the  right,  but  varies  in  size  in 
different  subjects,  being  small  when  the  left  upper  azygos  vein  is  large,  and  vice 
versa.  It  is  usually  formed  by  branches  from  the  two  or  three  upper  intercostal 
spaces,  and,  passing  across  the  arch  of  the  aorta,  terminates  in  the  left  vena  inno- 
minata.    The  left  bronchial  vein  opens  into  it. 

The  Superior  Vena  Cava  receives  the  blood  which  is  conveyed  to  the  heart 
from  the  whole  of  the  upper  half  of  the  body.  It  is  a  short  trunk,  varying 
from  two  inches  and  a  half  to  three  inches  in  length,  formed  by  the  junction  of 
the  two  venae  innominatae.  It  commences  immediately  below  the  cartilage  of  the 
first  rib  on  the  right  side,  and,  descending  vertically  downwards,  enters  the  peri- 
cardium about  an  inch  and  a  half  above  the  heart,  and  terminates  in  the  upper 
part  of  the  right  auricle.  In  its  course,  it  describes  a  slight  curve,  the  convexity  of 
which  is  turned  to  the  right  side. 

Relations.  In  front,  with  the  thoracic  fascia,  which  separates  it  from  the  thymus 
gland,  and  from  the  sternum ;  behind,  with  the  root  of  the  right  lung.  On  its 
right  side,  with  the  phrenic  nerve  and  the  pleura  of  the  right  side ;  on  its  left 
side,  with  the  ascending  part  of  the  aorta.  The  portion  contained  within  the 
pericardium  is  covered  by  the  serous  layer  of  that  membrane,  in  its  anterior 
three-fourths.  It  receives  the  vena  azygos  major,  just  before  it  enters  the  peri- 
cardium, and  several  small  veins  from  the  pericardium  and  parts  in  the  medias- 
tinum.    The  superior  vena  cava  has  no  valves. 

The  Azygos  Veins  connect  together  the  superior  and  inferior  venae  cavae, 
supplying  the  place  of  these  vessels  in  that  part  of  the  trunk  in  which  they  are 
deficient,  on  account  of  their  connection  with  the  heart. 

The  larger,  the  right  azygos  vein,  commences  opposite  the  first  or  second  lumbar 
vertebra,  by  receiving  a  branch  from  the  right  lumbar  veins ;  sometimes  by  a 
branch  from  the  renal  vein,  or  from  the  inferior  vena  cava.  It  enters  the  thorax 
through  the  aortic  opening  in  the  Diaphragm,  and  passes  along  the  right  side  of 
the  vertebral  column  to  the  third  dorsal  vertebra,  where  it  arches  forward,  over 
the  root  of  the  right  lung,  and  terminates  in  the  superior  vena  cava,  just  before 
that  vessel  enters  the  pericardium.  Whilst  passing  through  the  aortic  opening 
of  the  Diaphragm,  it  lies  with  the  thoracic  duct  on  the  right  side  of  the  aorta ; 
and  in  the  thorax,  it  lies  upon  the  intercostal  arteries,  on  the  right  side  of  the 
aorta  and  thoracic  duct,  covered  by  the  pleura. 

Branches.  It  receives  nine  or  ten  lower  intercostal  veins  of  the  right  side,  the 
vena  azygos  minor,  several  oesophageal,  mediastinal,  and  vertebral  veins ;  near  its 
termination,  the  right  bronchial  vein ;  and  it  is  occasionally  connected  with  the 
right  superior  intercostal  vein.  A  few  imperfect  valves  are  found  in  this  vein ; 
but  its  branches  are  provided  with  complete  valves. 

The  intercostal  veins  on  the  left  side,  below  the  two  or  three  upper  intercostal 
spaces,  usually  form  two  trunks,  named  the  left  lower,  and  the  left  upper,  azygos 
veins. 

The  left  lower  or  smaller  azygos  vein  commences  in  the  lumbar  region,  by  a 
branch  from  one  of  the  lumbar  veins,  or  from  the  left  renal.  It  passes  into  the 
thorax,  through  the  left  crus  of  the  Diaphragm,  and,  ascending  on  the  left  side  of 


AZYGOS— SPINAL.  471 

the  spine,  as  high  as  the  sixth  or  seventh  vertebra,  passes  across  the  column, 
behind  the  aorta  and  thoracic  duct,  to  terminate  in  the  right  azygos  vein.  It 
Teceives  the  four  or  five  lower  intercostal  veins  of  the  left  side,  and  some  oesopha- 
geal and  mediastinal  veins. 

The  left  upper  azygos  vein  varies  according  to  the  size  of  the  left  superior 
intercostal.  It  receives  veins  from  the  intercostal  spaces  between  the  left  superior 
intercostal  vein,  and  highest  branch  of  the  left  lower  azygos.  They  are  usually 
two  or  three  in  number,  and  join  to  form  a  trunk  which  ends  in  the  right  azygos 
vein,  or  in  the  left  lower  azygos.  When  this  vein  is  small,  or  altogether  wanting, 
the  left  superior  intercostal  vein  will  extend  as  low  as  the  fifth  or  sixth  intercostal 
space. 

The  bronchial  veins  return  the  blood  from  the  substance  of  the  lungs ;  that  of 
the  right  side  opens  into  the  vena  azygos  major,  near  its  termination ;  that  of  the 
left  side,  in  the  left  superior  intercostal  vein. 

The  Spinal  Veins. 

The  numerous  venous  plexuses  placed  upon  and  within  the  spine  may  be 
arranged  into  four  sets : — 

1.  Those  placed  on  the  exterior  of  the  spinal  column  (dorsi-spinal  veins). 

2.  Those  situated  in  the  interior  of  the  spinal  canal,  between  the  vertebrae  and 
the  theca  vertebralis  {meningo-rachidian  veins). 

3.  The  veins  of  the  bodies  of  the  vertebrae  {vense  basis  vertebrarum). 

4.  The  veins  of  the  spinal  cord  {medulli- spinal  veins). 

1.  The  Dorsi-spinal  Veins  commence  by  small  branches,  which  receive  their 
blood  from  the  integument  of  the  back  of  the  spine,  and  from  the  muscles  in  the 
vertebral  grooves.  They  form  a  complicated  network,  which  surrounds  the 
spinous  processes,  laminae,  and  the  transverse  and  articular  processes  of  all  the 
vertebrae.  At  the  bases  of  the  transverse  processes,  they  communicate,  by  means 
of  ascending  and  descending  branches,  with  the  veins  surrounding  the  contiguous 
vertebrae,  and  they  join  with  the  veins  in  the  spinal  canal  by  branches  which  per- 
forate the  ligamenta  subflava;  in  the  intervals  between  the  arches  of  the  vertebrae, 
they  terminate  in  the  vertebral  veins  in  the  neck,  in  the  intercostal  veins  in  the 
thorax,  in  the  lumbar  and  sacral  veins  in  the  loins  and  pelvis. 

2.  The  veins  contained  in  the  spinal  canal  are  situated  between  the  theca 
vertebralis  and  the  vertebrae.  They  consist  of  two  longitudinal  plexuses,  one 
of  which  runs  along  the  posterior  surface  of  the  bodies  of  the  vertebrae, 
throughout  the  entire  length  of  the  spinal  canal  {anterior  longitudinal  spinal  veins), 
receiving  the  veins  belonging  to  the  bodies  of  the  vertebrae  (venae  basis  verte- 
brarum). The  other  plexus  {posterior  longitudinal  spinal  veins)  is  placed  on  the 
inner  or  anterior  surface  of  the  laminae  of  the  vertebrae,  and  extends  also  along 
the  entire  length  of  the  spinal  canal. 

The  Anterior  Longitudinal  Spinal  Veins  consist  of  two  large,  tortuous  venous 
canals,  which  extend  along  the  whole  length  of  the  vertebral  column,  from  the 
foramen  magnum  to  the  base  of  the  coccyx,  being  placed  one  on  each  side  of  the 
posterior  surface  of  the  bodies  of  the  vertebrae,  external  to  the  posterior  common 
ligament.  These  veins  communicate  together  opposite  each  vertebra,  by  transverse 
trunks,  which  pass  beneath  the  ligament,  and  receive  the  large  venae  basis  verte- 
brarum, from  the  interior  of  the  body  of  each  vertebra.  The  anterior  longitudinal 
spinal  veins  are  least  developed  in  the  cervical  and  sacral  regions.  They  are  not 
of  uniform  size  throughout,  being  alternately  enlarged  and  constricted.  At  the 
intervertebral  foramina,  they  communicate  with  the  dorsi-spinal  veins,  and  with 
the  vertebral  veins  in  the  neck,  with  the  intercostal  veins  in  the  dorsal  region, 
and  with  the  lumbar  and  sacral  veins  in  the  corresponding  regions. 

The  Posterior  Longitudinal  Spinal  Veins,  smaller  than  the  anterior,  are  situated 
one  on  either  side,  between  the  inner  surface  of  the  laminae  and  the  theca  verte- 
bralis.  They  communicate,  like  the  anterior,  opposite  each  vertebra,  by  transverse 


472 


VEINS. 


trunks ;  and  with  the  anterior  longitudinal  veins,  by  lateral  transverse  branches 
which  pass  from  behind  forwards.  These  veins,  at  the  intervertebral  foramina, 
join  with  the  dorsi-spinal  veins. 

Fig.  242. — Transverse  Section  of  a  Dorsal  Vertebra,  showing  the  Spinal  Veins. 


3.  The  Veins  of  the  Bodies  of  the  Vertebrse  (venae  basis  vertebrarum)  emerge 
from  the  foramina  on  their  posterior  surface,  and  join  the  transverse  trunk 
connecting  the  anterior  longitudinal  spinal  veins.  They  are  contained  in  large, 
tortuous  channels,  in  the  substance  of  the  bones,  similar  in  every  respect  to  those 
found  in  the  diploe  of  the  cranial  bones.  These  canals  lie  parallel  to  the  upper  and 
lower  surface  of  the  bones,  arise  from  the  entire  circumference  of  the  vertebra, 
communicate  with  veins  which  enter  through  the  foramina,  on  the  anterior  surface 
of  the  bodies,  and  converge  to  the  principal  canal,  which  is  sometimes  double 
towards  its  posterior  part.     They  become  greatly  developed  in  advanced  age. 

Fig.  243. — Vertical  Section  of  two  Dorsal  Vertebrje,  showing  the  Spinal  Veins.  . 


4.  The  Veins  of  the  Spinal  Cord  (medulli-spinal)  consist  of  a  minute  tortuous 
venous  plexus,  which  covers  the  entire  surface  of  the  cord,  being  situated  between 
the  pia  mater  and  arachnoid.  These  vessels  emerge  chiefly  from  the  posterior 
median  furrow,  and  are  largest  in  the  lumbar  region.  Near  the  base  of  the  skull 
they  unite,  and  form  two  or  three  small  trunks,  which  communicate  with  the  ver- 
tebral veins,  and  then  terminate  in  the  inferior  cerebellar  veins,  or  in  the  petrosal 
sinuses.  Each  of  the  spinal  nerves  is  accompanied  by  a  branch  as  far  as  the  in- 
tervertebral foramina,  where  they  join  the  other  veins  from  the  spinal  canal. 
There  are  no  valves  in  the  spinal  veins. 


OF   THE   LOWER  EXTREMITY. 


IVi 


VEINS  OF  THE  LOWER  EXTREMITY. 


Fig.  244.— The  Internal  or 

Long  Saphenous  Vein 

and  its  Branches. 

\ 


-r\4 


The  veins  of  the  lower  extremity  are  subdivided,  like  those  of  the  upper,  into 
two  sets,  superficial  and  deep ;  the  superficial  veins  being  placed  beneath  the  integu- 
ment, between  the  two  layers  of  superficial  fascia, 
the  deep  veins  accompanying  the  arteries,  and  form- 
ing the  vena?  comites  of  those  vessels.  Both  sets  of 
veins  are  provided  with  valves,  which  are  more  nu- 
merous in  the  deep  than  in  the  superficial  set.  These 
valves  are  also  more  numerous  in  the  lower  than  in 
the  upper  limbs. 

The  Superficial  Veins  of  the  lower  extremity 
are  the  internal  or  long  saphenous,  and  the  external 
or  short  saphenous. 

The  internal  saphenous  vein  (fig.  244)  com- 
mences from  a  minute  plexus,  which  covers  the 
dorsum  and  inner  side  of  the  foot;  it  ascends  in 
front  of  the  inner  ankle,  and  along  the  inner  side 
of  the  leg,  behind  the  inner  margin  of  the  tibia, 
accompanied  by  the  internal  saphenous  nerve. 
At  the  knee,  it  passes  backwards  behind  the  inner 
condyle  of  the  femur,  ascends  along  the  inside  of 
the  thigh,  and,  passing  through  the  saphenous 
opening  in  the  fascia  lata,  terminates  in  the  femoral 
vein,  an  inch  and  a  half  below  Poupart's  ligament. 
This  vein  receives  in  its  course  cutaneous  branches 
from  the  leg  and  thigh,  and,  at  the  saphenous  open- 
ing, the  superficial  epigastric,  superficial  circumflex 
iliac,  and  external  pudic  veins.  The  veins  from 
the  inner  and  back  part  of  the  thigh  frequently 
unite  to  form  a  large  vessel,  which  enters  the .  main 
trunk  near  the  saphenous  opening,  and  sometimes 
those  on  the  outer  side  of  the  thigh  join  to  form  a 
large  branch ;  so  that  occasionally  three  large  veins 
are  seen  converging  from  different  parts  of  the  thigh 
towards  the  saphenous  opening.  The  internal 
saphenous  vein  communicates  in  the  foot  with  the 
internal  plantar  vein  ;  in  the  leg,  with  the  posterior 
tibial  veins,  by  branches  which  perforate  the  tibial 
origin  of  the  Soleus  muscle,  and  also  with  the  ante- 
rior tibial  veins ;  at  the  knee,  with  the  articular 
veins ;  in  the  thigh,  with  the  femoral  vein  by  one  or 
more  branches.  The  valves  in  this  vein  vary  from 
two  to  six  in  number ;  they  are  more  numerous  in 
the  thigh  than  in  the  leg. 

The  external  or  short  saphenous  vein  is  formed 
by  branches  which  collect  the  blood  from  the 
dorsum  and  outer  side  of  the  foot ;  it  ascends  behind 
the  outer  ankle,  and  along  the  outer  border  of  the 
tendo  Achillis,  across  which  it  passes  at  an  acute 
angle  to  reach  the  middle  line  of  the  posterior 
aspect  of  the  leg.  Ascending  directly  upwards, 
it  perforates  the  deep  fascia  in  the  lower  part  of 
the  popliteal  space,  and  terminates  in  the  popliteal 
vein,  between  the  heads  of  the  Gastrocnemius  muscle. 
It  is  accompanied  by  the  external  saphenous  nerve. 


m 


474 


VEINS. 


Fig.  245. 


-External  or  Short  Saphe- 
nous Vein. 


It  receives  numerous  large  branches  from  the  back  part  of  the  leg,  and  communicatee 

with  the  deep  veins  on  the  dorsum  of  the  foot,  and 
behind  the  outer  malleolus.  This  vein  has  only 
two  valves,  one  of  which  is  always  found  near  its 
termination  in  the  popliteal  vein. 

The  Deep  Veins  of  the  lower  extremity  accom- 
pany the  arteries  and  their  branches,  and  are  called 
the  vense  comites  of  those  vessels. 

The  external  and  internal  plantar  veins  unite  to 
form  the  posterior  tibial.  They  accompany  the 
posterior  tibial  artery,  and  are  joined  by  the  pero- 
neal veins. 

The  anterior  tibial  veins  are  formed  by  a  continua- 
tion upwards  of  the  venae  dorsales  pedis.  They 
perforate  the  interosseous  membrane  at  the  upper 
part  of  the  leg,  and  form,  by  their  junction  with  the 
posterior  tibial,  the  popliteal  vein. 

The  valves  in  the  deep  veins  are  very  nume- 
rous. 

The  Popliteal  Vein"  is  formed  by  the  junction 
of  the  venae  comites  of  the  anterior  and  posterior 
tibial  vessels;  it  ascends  through  the  popliteal 
space  to  the  tendinous  aperture  in  the  Adductor 
magnus,  where  it  becomes  the  femoral  vein.  In  the 
lower  part  of  its  course,  it  is  placed  internal  to  the 
artery;  between  the  heads  of  the  Gastrocnemius, 
it  is  superficial  to  that  vessel ;  but  above  the  knee- 
joint,  it  is  close  to  its  outer  side.  It  receives  the 
sural  veins  from  the  Gastrocnemius  muscle,  the 
articular  veins,  and  the  external  saphenous.  The 
valves  in  this  vein  are  usually  four  in  number. 

The  Femoral  Yein  accompanies  the  femoral 
artery  through  the  upper  two-thirds  of  the  thigh. 
In  the  lower  part  of  its  course,  it  lies  external  to 
the  artery ;  higher  up,  it  is  behind  it ;  and  beneath 
Poupart's  ligament,  it  lies  to  its  inner  side,  and  on 
the  same  plane  as  that  vessel.  It  receives  numerous 
muscular  branches;  the  profunda  femoris  joins  it 
about  an  inch  and  a  half  below  Poupart's  ligament, 
and  near  its  termination  the  internal  saphenous  vein.  The  valves  in  this  vein  are 
four  or  five  in  number. 

The  External  Iliac  Vein  commences  at  the  termination  of  the  femoral,  be- 
neath the  crural  arch,  and,  passing  upwards  along  the  brim  of  the  pelvis,  terminates 
opposite  the  sacro-iliac  symphysis,  by  uniting  with  the  internal  iliac  to  form  the 
common  iliac  vein.  On  the  right  side,  it  lies  at  first  along  the  inner  side  of  the 
external  iliac  artery,  but,  as  it  passes  upwards,  gradually  inclines  behind  it.  On 
the  left  side,  it  lies  altogether  on  the  inner  side  of  the  artery.  It  receives,  imme- 
diately above  Poupart's  ligament,  the  epigastric  and  circumflex  iliac  veins.  It 
has  no  valves. 

The  Internal  Iliac  Vein  is  formed  by  the  venae  comites  of  the  branches  of 
the  internal  iliac  artery,  the  umbilical  arteries  excepted.  It  receives  the  blood 
from  the  exterior  of  the  pelvis  by  the  gluteal,  sciatic,  internal  pudic,  and  obturator 
veins ;  and  from  the  organs  in  the  cavity  of  the  pelvis  by  the  hemorrhoidal  and 
vesico-prostatic  plexuses  in  the  male,  and  the  uterine  and  vaginal  plexuses  in  the 
female.  The  vessels  forming  these  plexuses  are  remarkable  for  their  large  size, 
their  frequent  anastomoses,  and  the  number  of  valves  which  they  contain.  The 
internal  iliac  vein  lies  at  first  on  the  inner  side  and  then  behind  the  internal  iliac 


ILIAC— INFERIOR   VENA   CAVA.  475 

artery,  and  terminates  opposite  the  sacro-iliac  articulation,  by  uniting  with  the 
external  iliac,  to  form  the  common  iliac  vein.     This  vessel  has  no  valves. 

The  hemorrhoidal  plexus  surrounds  the  lower  end  of  the  rectum,  being  formed 
by  the  superior  hemorrhoidal  veins,  branches  of  the  inferior  mesenteric,  and  the 
middle  and  inferior  hemorrhoidal,  which  terminate  in  the  internal  iliac.  The 
portal  and  general  venous  systems  have  a  free  communication  by  means  of  the 
branches  composing  this  plexus. 

The  vesico-prostatic  plexus  surrounds  the  neck  and  base  of  the  bladder  and 
prostate  gland.  It  communicates  with  the  hemorrhoidal  plexus  behind,  and 
receives  the  dorsal  vein  of  the  penis,  which  enters  the  pelvis  beneath  the  sub- 
pubic ligament.  This  plexus  is  supported  upon  the  sides  of  the  bladder  by  a 
reflection  of  the  pelvic  fascia.  The  veins  composing  it  are  very  liable  to  become 
varicose,  and  often  contain  hard  earthy  concretions,  called  phlebolites. 

The  dorsal  vein  of  the  penis  is  a  vessel  of  large  size,  which  returns  the  blood 
from  the  body  of  this  organ.  At  first  it  consists  of  two  branches,  which  are  con- 
tained in  the  groove  on  the  dorsum  of  the  penis,  and  receives  veins  from  the 
glans,  the  corpus  spongiosum,  and  numerous  superficial  veins ;  these  unite  near 
the  root  of  the  penis  into  a  single  trunk,  which  pierces  the  triangular  ligament 
beneath  the  pubic  arch,  and  divides  into  two  branches,  which  enter  the  prostatic 
plexus. 

The  vaginal  plexus  surrounds  the  mucous  membrane  of  the  vagina,  being  espe- 
cially developed  at  the  orifice  of  this  canal ;  it  communicates  with  the  vesical 
plexus  in  front,  and  with  the  hemorrhoidal  plexus  behind. 

The  uterine  plexus  is  situated  along  the  sides  and  superior  angles  of  the  uterus, 
receiving  large  venous  canals  (the  uterine  sinuses)  from  its  substance.  The  veins 
composing  this  plexus  anastomose  frequently  with  each  other  and  with  the  ovarian 
veins.     They  are  not  tortuous  like  the  arteries. 

Each  Common  Iliac  Vein  is  formed  by  the  union  of  the  external  and  internal 
iliac  veins  in  front  of  the  sacro-vertebral  articulation ;  passing  obliquely  upwards 
towards  the  right  side,  they  terminate  upon  the  intervertebral  substance  between 
the  fourth  and  fifth  lumbar  vertebrae,  where  they  unite  at  an  acute  angle  to  form 
the  inferior  vena  cava.  The  right  common  iliac  is  shorter  than  the  left,  nearly 
vertical  in  its  direction,  and  ascends  behind  and  then  to  the  outer  side  of  its 
corresponding  artery.  The  left  common  iliac,  longer  and  more  oblique  in  its  course, 
is  at  first  situated  at  the  inner  side  of  the  corresponding  artery,  and  then  behind 
the  right  common  iliac.  Each  common  iliac  receives  the  ilio-lumbar,  and  some- 
times the  lateral  sacral  veins.  The  left  one  receives,  in  addition,  the  middle  sacral 
vein.     No  valves  are  found  in  these  veins. 

The  middle  sacral  vein  accompanies  its  corresponding  artery  along  the  front  of 
the  sacrum,  and  terminates  in  the  left  common  iliac  vein;  occasionally  in  the 
commencement  of  the  inferior  vena  cava. 

Peculiarities.  The  left  common  iliac  vein,  instead  of  joining  with  the  right  one  in  its  usual 
position,  occasionally  ascends  on  the  left  side  of  the  aorta  as  high  as  the  kidney,  where,  after 
receiving  the  left  renal  vein,  it  crosses  over  the  aorta,  and  then  joins  with  the  right  vein  to  form 
the  vena  cava.  In  these  cases,  the  two  common  iliacs  are  connected  by  a  small  communicating 
branch  at  the  spot  where  they  are  usually  united. 

The  Inferior  Vena  Cava  returns  to  the  heart  the  blood  from  all  the  parts  below 
the  Diaphragm.  It  is  formed  by  the  junction  of  the  two  common  iliac  veins  on 
the  right  side  of  the  intervertebral  substance,  between  the  fourth  and  fifth  lumbar 
vertebras.  It  passes  upwards  along  the  front  of  the  spine,  on  the  right  side  of  the 
aorta,  and,  having  reached  the  under  surface  of  the  liver,  is  contained  in  a  groove 
in  its  posterior  border.  It  then  perforates  the  tendinous  centre  of  the  Diaphragm, 
enters  the  pericardium,  where  it  is  covered  by  its  serous  layer,  and  terminates  in 
the  lower  and  back  part  of  the  right  auricle.  At  its  termination  in  the  auricle, 
it  is  provided  with  a  valve,  the  Eustachian,  which  is  of  large  size  during  fcetal  life. 

Relations.     In  front,  from  below  upwards,  with  the  mesentery,  transverse  por- 


476  VEINS. 

tion  of  the  duodenum,  the  pancreas,  portal  vein,  and  the  posterior  border  of  th? 
liver,  which  partly  and  occasionally  completely  surrounds  it ;  behind,  it  rests  upon 
the  vertebral  column,  the  right  crus  of  the  Diaphragm,  the  right  renal  and  lumbar 
arteries ;  on  the  left  side,  it  is  in  relation  with  the  aorta.  It  receives  in  its  course 
the  following  branches : — 

Lumbar.  Supra-renal. 

Eight  spermatic.  Phrenic. 

Renal.  Hepatic. 

Peculiarities  of  Position.  This  vessel  is  sometimes  placed  on  the  left  side  of  the  aorta,  as 
high  as  the  left  renal  vein,  after  receiving  which  it  crosses  over  to  its  usual  position  on  the  right 
side ;  or  it  may  be  placed  altogether  on  the  left  side  of  the  aorta,  as  far  upwards  as  its  termination 
in  the  heart :  in  such  cases,  the  abdominal  and  thoracic  viscera,  together  with  the  great  vessels, 
are  all  transposed. 

Peculiarities  of  Termination.  Occasionally  the  inferior  vena  cava  joins  the  right  azygos  vein, 
which  is  then  of  large  size.  In  such  cases,  the  superior  cava  receives  the  whole  of  the  blood  from 
the  body  before  transmitting  it  to  the  right  auricle,  the  blood  from  the  hepatic  veins  excepted, 
these  vessels  terminating  directly  in  the  right  auricle. 

The  lumbar  veins,  three  or  four  in  number  on  each  side,  collect  the  blood  by 
dorsal  branches  from  the  muscles  and  integument  of  the  loins,  and  by  abdominal 
branches  from  the  walls  of  the  abdomen,  where  they  communicate  with  the 
epigastric  veins.  At  the  spine,  they  receive  branches  from  the  spinal  plexuses,  and 
they  pass  forwards  round  the  sides  of  the  bodies  of  the  vertebras  beneath  the  Psoas 
magnus,  and  terminate  at  the  back  part  of  the  inferior  cava.  The  left  lumbar  veins 
are  longer  than  the  right,  and  pass  behind  the  aorta.  The  lumbar  veins  commu- 
nicate with  each  other  by  branches  which  pass  in  front  of  the  transverse  processes. 
Occasionally  two  or  more  of  these  veins  unite  to  form  a  single  trunk,  the  ascending 
lumbar,  which  serves  to  connect  the  common  iliac,  ilio-lumbar,  lumbar,  and  azygos 
veins  of  the  corresponding  side  of  the  body. 

The  spermatic  veins  emerge  from  the  back  of  the  testis,  and  receive  branches 
from  the  epididymis ;  they  form  a  branched  and  convoluted  plexus,  called  the 
spermatic  plexus  or  plexus  pampiniformis,  below  the  abdominal  ring.  The  vessels 
composing  this  plexus  are  very  numerous,  and  ascend  along  the  cord  in  front  of 
the  vas  deferens ;  having  entered  the  abdomen,  they  coalesce  to  form  two  branches, 
which  ascend  on  the  Psoas  muscle,  behind  the  peritoneum,  lying  one  on  each  side 
of  the  spermatic  artery,  and  unite  to  form  a  single  vessel,  which  opens  on  the  right 
side  in  the  inferior  vena  cava,  piercing  this  vessel  obliquely;  on  the  left  side  in  the 
left  renal  vein,  terminating  at  right  angles  with  this  vein.  The  spermatic  veins 
are  provided  with  valves.  The  left  spermatic  vein  passes  behind  the  sigmoid 
flexure  of  the  colon ;  this  circumstance,  as  well  as  the  indirect  communication  of 
•  the  vessel  with  the  inferior  vena  cava,  may  serve  to  explain  the  more  frequent 
occurrence  of  varicocele  on  the  left  side. 

The  ovarian  veins  are  analogous  to  the  spermatic  in  the  male ;  they  form  a 
plexus  near  the  ovary,  and  in  the  broad  ligament  and  Fallopian  tube,  communi- 
cating with  the  uterine  plexus.  They  terminate  as  in  the  male.  Valves  are 
occasionally  found  in  these  veins.  These  vessels,  like  the  uterine  veins,  become 
much  enlarged  during  pregnancy. 

The  renal  veins  are  of  large  size,  and  placed  in  front  of  the  divisions  of  the 
renal  arteries.  The  left  is  longer  than  the  right,  and  passes  in  front  of  the  aorta, 
just  below  the  origin  of  the  superior  mesenteric  arter}'-.  It  receives  the  left 
spermatic  and  left  inferior  phrenic  veins.  It  usually  opens  into  the  vena  cava,  a 
little  higher  than  the  right. 

The  supra-renal  vein  terminates,  on  the  right  side,  in  the  vena  cava ;  on  the  left 
side,  in  the  left  renal  or  phrenic  vein. 

The  phrenic  veins  follow  the  course  of  the  phrenic  arteries.  The  two  superior, 
of  small  size,  accompany  the  corresponding  nerve  and  artery;  the  right  terminating 


PORTAL   SYSTEM.  47T 

opposite  the  junction  of  the  two  venae  innominate,  the  left  in  the  left  superior 
intercostal  or  left  internal  mammary.  The  two  inferior  phrenic  veins  follow  the 
course  of  the  inferior  phrenic  arteries,  and  terminate,  the  right  in  the  inferior  vena 
cava,  the  left  in  the  left  renal  vein. 

The  hepatic  veins  commence  in  the  substance  of  the  liver,  in  the  capillary  ter- 
minations of  the  vena  portae ;  these  branches,  gradually  uniting,  form  three  large 
veins,  which  converge  towards  the  posterior  border  of  the  liver,  and  open  into  the 
inferior  vena  cava,  whilst  that  vessel  is  situated  in  the  groove  at  the  back  part  of 
this  organ.  Of  these  three  veins,  one  from  the  right  and  another  from  the  left 
lobes  open  obliquely  into  the  vena  cava;  that  from  the  middle  of  the  organ  and 
lobus  Spigelii  having  a  straight  course.  The  hepatic  veins  run  singly,  and  are 
in  direct  contact  with  the  hepatic  tissue.     They  are  destitute  of  valves. 


PORTAL  SYSTEM  OF  VEINS. 

The  portal  venous  system  is  composed  of  four  large  veins,  which  collect  the 
venous  blood  from  the  viscera  of  digestion.  The  trunk  formed  by  their  union, 
the  vena  portae,  enters  the  liver,  ramifies  throughout  its  substance,  and  its  branches, 
again  emerging  from  that  organ  as  the  hepatic  veins,  terminate  in  the  inferior 
vena  cava.  The  branches  of  this  vein  are  in  all  cases  single,  and  destitute  of 
valves. 

The  veins  forming  the  portal  system  are  the 

Inferior  mesenteric.  Splenic. 

Superior  mesenteric.  Gastric. 

The  inferior  mesenteric  vein  returns  the  blood  from  the  rectum,  sigmoid  flexure, 
and  descending  colon,  corresponding  with  the  ramifications  of  the  branches  of  the 
inferior  mesenteric  artery.  Ascending  beneath  the  peritoneum  in  the  lumbar 
region,  it  passes  behind  the  transverse  portion  of  the  duodenum  and  pancreas,  and 
terminates  in  the  splenic  vein.  Its  hemorrhoidal  branches  inosculate  with  those 
of  the  internal  iliac,  and  thus  establish  a  communication  between  the  portal  and 
the  general  venous  system. 

The  superior  mesenteric  vein  returns  the  blood  from  the  small  intestines,  and 
from  the  caecum  and  ascending  and  transverse  portions  of  the  colon,  correspond- 
ing with  the  distribution  of  the  branches  of  the  superior  mesenteric  artery.  The 
large  trunk  formed  by  the  union  of  these  branches  ascends  along  the  right  side 
and  in  front  of  the  corresponding  artery,  passes  in  front  of  the  transverse  portion 
of  the  duodenum,  and  unites  behind  the  upper  border  of  the  pancreas  with  the 
splenic  vein,  to  form  the  vena  portae. 

The  splenic  vein  commences  by  five  or  six  large  branches,  which  return  the 
blood  from  the  substance  of  the  spleen.  These  uniting  form  a  single  vessel,  which 
passes  from  left  to  right  behind  the  upper  border  of  the  pancreas,  and  terminates 
at  its  greater  end  by  uniting  at  a  right  angle  with  the  superior  mesenteric  to  form 
the  vena  portae.  The  splenic  vein  is  of  large  size,  and  not  tortuous  like  the 
artery.  It  receives  the  vasa  brevia  from  the  left  extremity  of  the  stomach,  the 
left  gastro-epiploic  vein,  pancreatic  branches  from  the  pancreas,  the  pancreatico- 
duodenal vein,  and  the  inferior  mesenteric  vein. 

The  gastric  is  a  vein  of  small  size,  which  accompanies  the  gastric  artery  from 
left  to  right  along  the  lesser  curvature  of  the  stomach,  and  terminates  in  the  vena 
portae. 

The  Portal  Vein  is  formed  by  the  junction  of  the  superior  mesenteric  and  splenic 
veins,  their  union  taking  place  in  front  of  the  vena  cava,  and  behind  the  upper 
border  of  the  great  end  of  the  pancreas.  Passing  upwards  through  the  right 
border  of  the  lesser  omentum  to  the  under  surface  of  the  liver,  it  enters  the 
transverse  fissure,  where  it  is  somewhat  enlarged,  forming  the  sinus  of  the  portal 
vein,  and  divides  into  two  branches,  which  accompany  the  ramifications  of  the 


41S 


VEINS. 


hepatic  artery  and  hepatic  duct  throughout  its  substance.  Of  these  two  branches 
the  right  is  the  larger  but  the  shorter  of  the  two.  The  portal  vein  is  about  four 
inches  in  length,  and,  whilst  contained  in  the  lesser  omentum,  lies  behind  and 
between  the  hepatic  duct  and  artery,  the  former  being  to  the  right,  the  latter  to 
the  left.  These  structures  are  accompanied  by  filaments  of  the  hepatic  plexus 
and  numerous  lymphatics,  surrounded  by  a  quantity  of  loose  areolar  tissue,  the 


Fig.  246.— Portal  Vein  aud  its  Branches. 


capsule  of  Glisson,  and  placed  between  the  layers  of  the  lesser  omentum.  The 
vena  portae  receives  the  gastric  and  cystic  veins ;  the  latter  vein  sometimes  ter- 
minates in  the  right  branch  of  the  vena  porta?.  Within  the  liver,  the  portal  vein 
receives  the  blood  from  the  branches  of  the  hepatic  artery. 


CARDIAC— PULMONARY.  479 


CARDIAC  VEINS. 

The  veins  which  return  the  blood  from  the  substance  of  the  heart  are  the 

Great  cardiac  vein.  Anterior  cardiac  veins. 

Posterior  cardiac  vein.  Venae  Thebesii. 

The  Great  Cardiac  Vein  is  a  vessel  of  considerable  size,  which  commences  at 
the  apex  of  the  heart,  and  ascends  along  the  anterior  interventricular  groove  to 
the  base  of  the  ventricles.  It  then  curves  to  the -left  side,  around  the  auriculo- 
ventricular  groove,  between  the  left  auricle  and  ventricle,  to  the  back  part  of 
the  heart,  and  opens  into  the  coronary  sinus,  its  aperture  being  guarded  by  two 
valves.  It  receives  the  posterior  cardiac  vein,  and  the  left  cardiac  veins  from 
the  left  auricle  and  ventricle,  one  of  which,  ascending  along  the  left  margin  of 
the  ventricle,  is  of  large  size.  The  branches  joining  it  are  provided  with 
valves. 

The  Posterior  Cardiac  Vein  commences,  by  small  branches,  at  the  apex  of  the 
heart,  communicating  with  those  of  the  preceding.  It  ascends  along  the  posterior 
interventricular  groove  to  the  base  of  the  heart,  and  terminates  in  the  coronary 
sinus,  its  orifice  being  guarded  by  a  valve.  It  receives  the  veins  from  the  posterior 
surface  of  both  ventricles. 

The  Anterior  Cardiac  Veins  are  three  or  four  small  branches,  which  collect 
the  blood  from  the  anterior  surface  of  the  right  ventricle.  One  of  these,  the 
vein  of  Galen,  larger  than  the  rest,  runs  along  the  right  border  of  the  heart. 
They  open  separately  into  the  lower  part  of  the  right  auricle. 

The  Vense  Thebesii  are  numerous  minute  veins,  which  return  the  blood 
directly  from  the  muscular  substance,  without  entering  the  venous  current. 
They  open,  by  minute  orifices,  foramina  Thebesii,  on  the  inner  surface  of  the  right 
auricle. 

The  Coronary  Sinus  is  that  portion  of  the  great  cardiac  vein  which  is  situated 
in  the  posterior  part  of  the  left  auriculo-ventricular  groove.  It  is  about  an  inch 
in  length,  presents  a  considerable  dilatation,  and  is  covered  by  the  muscular  fibres 
of  the  left  auricle.  It  receives  the  great  cardiac  vein,  the  posterior  cardiac  vein, 
and  an  oblique  vein  from  the  back  part  of  the  left  auricle,  the  remnant  of  the 
obliterated  left  innominate  trunk  of  the  foetus,  described  by  Mr.  Marshall.  The 
coronary  sinus  terminates  in  the  right  auricle,  between  the  inferior  vena  cava 
and  the  auriculo-ventricular  aperture,  its  orifice  being  guarded  by  a  semilunar 
fold  of  the  lining  membrane  of  the  heart,  the  coronary  valve.  All  the  branches 
joining  this  vessel,  excepting  the  oblique  vein  above  mentioned,  are  provided 
with  valves. 


THE  PULMONARY  VEINS. 

The  Pulmonary  Veins  return  the  arterial  blood  from  the  lungs  to  the  left 
auricle  of  the  heart.  They  are  four  in  number,  two  for  each  lung.  The  pul- 
monary differ  from  other  veins  in  several  respects: — 1.  They  carry  arterial 
instead  of  venous  blood.  2.  They  are  destitute  of  valves.  3.  They  are  only 
slightly  larger  than  the  arteries  they  accompany.  4.  They  accompany  those 
vessels  singly.  They  commence  in  a  capillary  network,  upon  the  parietes  of  the 
bronchial  cells,  where  they  are  continuous  with  the  ramifications  of  the  pulmonary 
artery,  and,  uniting  together,  form  a  single  trunk  for  each  lobule.  These  branches, 
successively  uniting,  form  a  single  trunk  for  each  lobe,  three  for  the  right,  and  two 
for  the  left,  lung.  The  vein  of  the  middle  lobe  of  the  right  lung  unites  with  that 
from  the  upper  lobe,  in  most  cases,  forming  two  trunks  on  each  side,  which  open 


480  VEINS. 

separately  into  the  left  auricle.  Occasionally  they  remain  separate ;  there  are  then 
three  veins  on  the  right  side.  Not  unfrequently,  the  two  left  pulmonary  veins 
terminate  by  a  common  opening. 

Within  the  lung,  the  branches  of  the  pulmonary  artery  are  in  front,  the  veins 
behind,  and  the  bronchi  between  the  two. 

At  the  root  of  the  lung,  the  veins  are  in  front,  the  artery  in  the  middle,  and  the 
bronchus  behind. 

Within  the  pericardium,  their  anterior  surface  is  invested  by  the  serous  layer 
of  this  membrane,  the  right  pulmonary  veins  pass  behind  the  right  auricle  and 
ascending  aorta,  the  left  pass  in  front  of  the  thoracic  aorta,  with  the  left  pul- 
monary artery. 


Of  the  Lymphatics. 


The  Lymphatics  have  derived  their  name  from  the  appearance  of  the  fluid 
contained  in  their  interior  (lympha,  water).  They  are  also  called  absorbents,  from 
the  property  they  possess  of  absorbing  certain  materials  for  the  replenishing  of 
the  blood,  and  conveying  them  into  the  circulation. 

The  lymphatic  system  includes  not  only  the  lymphatic  vessels  and  the  glands 
through  which  they  pass,  but  also  the  lacteal  or  chyliferous  vessels.  The  lacteals 
are  the  lymphatic  vessels  of  the  small  intestine,  and  differ  in  no  respect  from  the 
lymphatics  generally,  excepting  that  they  contain  a  milk-white  fluid,  the  chyle, 
during  the  process  of  digestion,  and  convey  it  into  the  blood  through  the  thoracic 
duct. 

The  lymphatics  are  exceedingly  delicate  vessels,  the  coats  of  which  are  so 
transparent  that,  the  fluid  they  contain  is  readily  seen  through  them.  They  retain 
a  nearly  uniform  size,  being  interrupted  at  intervals  by  constrictions,  which  give 
to  them  a  knotted  or  beaded  appearance.  These  constrictions  correspond  to  the 
presence  of  valves  in  their  interior.  Lymphatics  are  found  in  nearly  every  texture 
and  organ  of  the  body,  with  the  exception  of  the  substance  of  the  brain  and 
spinal  cord,  the  eyeball,  cartilage,  tendon,  membranes  of  the  ovum,  the  placenta, 
and  umbilical  cord,  the  nails,  cuticle,  and  hair.  Their  existence  in  the  substance 
of  bone  is  doubtful. 

The  lymphatics  are  arranged  into  a  superficial  and  deep  set.  The  superficial 
lymphatics,  on  the  surface  of  the  body,  are  placed  immediately  beneath  the  integu- 
ment, accompanying  the  superficial  veins ;  they  join  the  deep  lymphatics  in  certain 
situations  by  perforating  the  deep  fascia.  In  the  interior  of  the  body,  they  lie  in 
the  submucous  areolar  tissue,  throughout  the  whole  length  of  the  gastro-pulmonary 
and  genito- urinary  tracts ;  or  in  the  subserous  areolar  tissue,  beneath  the  serous 
membrane  covering  the  various  organs  in  the  cranial,  thoracic,  and  abdominal 
cavities.  These  vessels  probably  arise  in  the  form  of  a  dense  plexiform  network 
interspersed  among  the  proper  elements  and  bloodvessels  of  the  several  tissues; 
the  vessels  composing  which,  as  well  as  the  meshes  between  them,  are  much  larger 
than  those  of  the  capillary  plexus.  From  these  networks  small  vessels  emerge, 
which  pass,  either  to  a  neighboring  gland,  or  to  join  some  larger  lymphatic  trunk. 
The  deep  lymphatics,  fewer  in  number,  and  larger  than  the  superficial,  accompany 
the  deep  bloodvessels.  Their  mode  of  origin  is  not  known;  it  is,  however, 
probably  similar  to  that  of  the  superficial  vessels.  The  lymphatics  of  any  part 
or  organ  exceed,  in  number,  the  veins;  but  in  size,  they  are  much  smaller. 
Their  anastomoses  also,  especially  of  the  large  trunks,  are  more  frequent,  and  are 
effected  by  vessels  equal  in  diameter  to  those  which  they  connect,  the  continuous 
trunks  retaining  the  same  diameter. 

The  lymphatic  vessels,  like  arteries  and  veins,  are  composed  of  three  coats. 

The  internal  is  an  epithelial  and  elastic  coat ;  it  is  thin,  transparent,  slightly 
elastic,  and  ruptures  sooner  than  the  other  coats.  It  is  composed  of  a  layer  of 
elongated  epithelial  cells,  supported  on  a  simple  network  of  elastic  fibres. 

The  middle  coat  is  composed  of  smooth  muscular  and  fine  elastic  fibres  disposed 
in  a  transverse  direction. 

The  external  or  areolo-fibrous  coat  consists  of  filaments  of  areolar  tissue, 
intermixed  with  smooth  muscular  fibres,  longitudinally  or  obliquely  disposed.  It 
forms  a  protective  covering  to  the  other  coats,  and  serves  to  connect  the  vessel 
with  the  neighboring  structures. 

31  481 


482  LYMPHATICS. 

The  lymphatics  are  supplied  by  nutrient  vessels,  which  are  distributed  to 
their  outer  and  middle  coats ;  but  no  nerves  have  at  present  been  traced  into 
them. 

The  lymphatics  are  very  generally  provided  with  valves,  which  assist  materially 
in  effecting  the  circulation  of  the  fluid  they  contain.  They  are  formed  of  a  thin 
layer  of  fibrous  tissue,  lined  on  both  surfaces  with  scaly  epithelium.  Their  form 
is  semilunar ;  they  are  attached  by  their  convex  edge  to  the  sides  of  the  vessel, 
the  concave  edge  being  free,  and  directed  in  the  course  of  the  contained  current. 
Usually,  two  such  valves,  of  equal  size,  are  found  placed  opposite  one  another ; 
but  occasionally  exceptions  occur,  especially  at  or  near  the  anastomoses  of  lymphatic 
vessels.  Thus  one  valve  may  be  of  very  rudimentary  size,  the  other  increased  in 
proportion.  In  other  cases,  the  semilunar  flaps  have  been  found  directed  trans- 
versely across  the  vessel,  instead  of  obliquely,  so  as  to  impede  the  circulation  in 
both  directions,  but  not  to  completely  arrest  it  in  either ;  or  the  semilunar  flaps, 
taking  the  same  direction,  have  been  united  on  one  side,  so  that  they  formed,  by 
their  union,  a  transverse  septum,  having  a  partial  transverse  slit ;  and  sometimes 
the  flap  was  constituted  of  a  circular  fold,  attached  to  the  entire  circumference  of 
the  vessel,  and  having  in  its  centre  a  circular  or  elliptical  aperture,  the  arrange- 
ments of  the  flaps  being  similar  to  those  composing  the  ileo-ceecal  valve. 

The  valves  in  the  lymphatic  vessels  are  placed  at  much  shorter  intervals  than 
in  the  veins.  They  are  most  numerous  near  the  lymphatic  glands,  and  they  are 
found  more  frequently  in  the  lymphatics  of  the  neck  and  upper  extremity,  than  in 
the  lower.  The  wall  of  the  lymphatics,  immediately  above  the  point  of  attachment 
of  each  segment  of  a  valve,  is  expanded  into  a  pouch  or  sinus,  which  gives  to 
these  vessels,  when  distended,  the  knotted  or  beaded  appearance  which  they  present. 
Valves  are  wanting  in  the  vessels  composing  the  plexiform  network  in  which  the 
lymphatics  originate. 

There  is  no  satisfactory  evidence  to  prove  that  any  natural  communication  exists 
between  the  lymphatics  of  glandular  organs  and  their  ducts,  or  between  the 
lymphatics  and  the  capillary  vessels. 

The  lymphatic  or  absorbent  glands,  named  also  conglobate  glands,  are  small 
solid  glandular  bodies,  situated  in  the  course  of  the  lymphatic  and  lacteal  vessels. 
They  are  found  in  the  neck  and  on  the  external  parts  of  the  head ;  in  the  upper 
extremity,  in  the  axilla  and  front  of  the  elbow ;  in  the  lower  extremity,  in  the 
groin  and  popliteal  space.  In  the  abdomen,  they  are  found  in  large  numbers  in 
the  mesentery,  and  along  the  side  of  the  aorta,  vena  cava,  and  iliac  vessels ;  and  in 
the  thorax,  in  the  anterior  and  posterior  mediastina.  They  are  somewhat  flattened, 
and  of  a  round  or  oval  form.  In  size,  they  vary  from  a  hempseed  to  an  almond, 
and  their  color,  on  section,  is  of  a  pinkish-gray  tint,  excepting  the  bronchial 
glands  which  in  the  adult  are  mottled  with  black.  Each  gland  has  a  layer  of 
cellular  tissue  investing  it,  forming  a  capsule,  from  which  prolongations  dip  into 
its  substance  forming  partitions.  The  lymphatic  and  lacteal  vessels  pass  through 
these  bodies  in  their  passage  to  the  thoracic  and  lymphatic  ducts.  A  lymphatic 
or  lacteal,  previous  to  its  entering  a  gland,  divides  into  several  small  branches,  which 
are  named  afferent  vessels.  As  they  enter,  their  external  coat  becomes  continuous 
with  the  capsule  of  the  gland,  and  the  vessels,  much  thinned,  and  consisting  only 
of  their  internal  coat  and  epithelium,  pass  into  the  gland,  where,  subdividing, 
they  pursue  a  tortuous  course ;  and  finally  anastomosing  form  a  plexus.  The 
vessels  composing  this  plexus  unite  to  form  two  or  more  efferent  vessels,  which 
on  emerging  from  the  gland  are  again  invested  with  their  external  coat.  Within 
the  lymphatic  vessels,  as  supposed  by  Kolliker,  Goodsir,  and  others,  or  lying 
between  them,  grouped  in  cells,  like  the  acini  of  secreting  glands,  is  a  large 
number  of  minute  dotted  corpuscles.  They  are  spheroidal  or  disk-shaped  pellucid 
particles,  about  -g^Vtr  of  an  inch  in  diameter,  having  two  or  three  minute  dark 
particles  in  their  interior.  It  is  probable  that  they  play  an  important  part  in  the 
more  complete  elaboration  of  the  lymph  or  chyle  traversing  the  glands.  Capillary 
vessels  are  abundantly  distributed  on  the  walls  of  the  lymphatics  in  the  glands. 


THORACIC   DUCT. 


483 


Thoracic  Duct. 

The  Thoracic  Duct  (fig.  247)  conveys  the  great  mass  of  the  lymph  and  chyle 
into  the  blood.     It  is  the  common  trunk  of  all  the  lymphatic  vessels  of  the  body, 
excepting  those  of  the  right 
Side    of   the    head,    neck,   and  &S-  247.-The  Thoracic  and  Right  Lymphatic  Ducts. 

thorax,  and  right  upper  ex- 
tremity, the  right  lung,  right 
side  of  the  heart,  and  the 
convex  surface  of  the  liver. 
It  varies  from  eighteen  to 
twenty  inches  in  length  in 
the  adult,  and  extends  from 
the  second  lumbar  vertebra 
to  the  root  of  the  neck.  It 
commences  in  the  abdomen 
by  a  triangular  dilatation,  the 
receptaculum  chyli  (reservoir 
or  cistern  of  Pecquet),  which 
is  situated  upon  the  front  of 
the  body  of  the  second  lumbar 
vertebra,  to  the  right  side  of 
and  behind  the  aorta,  by  the 
side  of  the  right  crus  of  the 
Diaphragm.  It  ascends  into 
the  thorax  through  the  aortic 
opening  in  the  Diaphragm, 
and  is  placed  in  the  posterior 
mediastinum  in  front  of  the 
vertebral  column,  lying  be- 
tween the  aorta  and  vena 
azygos.  Opposite  the  fourth 
dorsal  vertebra  it  inclines  to- 
wards the  left  side  and  ascends 
behind  the  arch  of  the  aorta, 
on  the  left  side  of  the  oeso- 
phagus, and  behind  the  first 
portion  of  the  left  subclavian 
artery,  to  the  upper  orifice  of 
the  thorax.  Opposite  the 
upper  border  of  the  seventh 
cervical  vertebra  it  curves 
downwards  above  the  sub- 
clavian artery,  and  in  front 
of  the  Scalenus  muscle,  so  as 
to  form  an  arch ;  and  ter- 
minates near  the  angle  of 
junction  of  the  left  internal 
jugular  and  subclavian  veins. 
The  thoracic  duct,  at  its  com- 
mencement, is  about  equal  in 
size  to  the  diameter  of  a  goose- 
quill,  diminishes  considerably 
in  its  calibre  in  the  middle 
of  the  thorax,  and  is  again  dilated  just  before  its  termination.  It  is  generally 
flexuous  in  its  course,  and  constricted  at  intervals  so  as  to  present  a  varicose 


484  LYMPHATICS. 

appearance.  The  thoracic  duct  not  unfrequently  divides  in  the  middle  of  its 
course  into  two  branches  of  unequal  size  which  soon  reunite,  or  into  several 
branches  which  form  a  plexiform  interlacement.  It  occasionally  bifurcates,  at 
its  upper  part,  into  two  branches,  the  left  one  terminating  in  the  usual  manner,  the 
right  one  opening  into  the  right  subclavian  vein,  in  connection  with  the  right 
lymphatic  duct.  The  thoracic  duct  has  numerous  halves  throughout  its  whole 
course,  but  they  are  more  numerous  in  the  upper  than  in  the  lower  part ;  at  its 
termination  it  is  provided  with  a  pair  of  valves,  the  free  borders  of  which  are 
turned  towards  the  vein,  so  as  to  prevent  the  regurgitation  of  venous  blood  into 
the  duct. 

Branches.  The  thoracic  duct  at  its  commencement  receives  four  or  five  large 
trunks  from  the  abdominal  lymphatic  glands,  and  also  the  trunk  of  the  lacteal 
vessels.  Within  the  thorax,  it  is  joined  by  the  lymphatic  vessels  from  the  left 
half  of  the  wall  of  the  thoracic  cavity,  the  lymphatics  from  the  sternal  and 
intercostal  glands,  those  of  the  left  lung,  left  side  of  the  heart,  trachea,  and  oeso- 
phagus ;  and,  just  before  its  termination,  receives  the  lymphatics  of  the  left  side 
of  the  head  and  neck,  and  left  upper  extremity. 

Structure.  The  thoracic  duct  is  composed  of  three  coats,  which  differ  in  some 
respects  from  those  of  the  lymphatic  vessels.  The  internal  coat  consists  of  a 
layer  of  epithelium,  resting  upon  some  striped  lamellae,  and  an  elastic  fibrous  coat, 
the  fibres  of  which  run  in  a  longitudinal  direction.  The  middle  coat  consists 
of  a  layer  of  connective  tissue,  beneath  which  are  several  laminae  of  muscular 
tissue,  the  fibres  of  which  are  disposed  transversely,  and  intermixed  with  fine 
elastic  fibres.  The  external  coat  is  composed  of  areolar  tissue,  with  elastic  fibres 
and  isolated  fasciculi  of  muscular  fibres. 

The  Right  Lymphatic  Duct  is  a  short  trunk,  about  an  inch  in  length,  and  a 
line  or  a  line  and  a  half  in  diameter,  which  receives  the  lymph  from  the  right  side 
of  the  head  and  neck,  the  right  upper  extremity,  the  right  side  of  the  thorax,  the 
right  lung  and  right  side  of  the  heart,  and  from  the  convex  surface  of  the  liver, 
and  terminates  at  the  angle  of  union  of  the  right  subclavian  and  right  internal 
jugular  veins.  Its  orifice  is  guarded  by  two  semilunar  valves,  which  prevent  the 
entrance  of  blood  from  the  veins. 

Lymphatics  of  the  Head,  Face,  and  Neck. 

The  Superficial  Lymphatic  Glands  of  the  Head  (fig.  248)  are  of  small  size, 
few  in  number,  and  confined  to  its  posterior  region.  They  are  the  occipital,  placed 
at  the  back  of  the  head  along  the  attachment  of  the  Occipito-frontalis ;  and  the 
posterior  auricular,  near  the  upper  end  of  the  Sterno-mastoid.  These  glands 
become  considerably  enlarged  in  cutaneous  affections  and  other  diseases  of  the 
scalp.  In  the  face,  the  superficial  lymphatic  glands  are  more  numerous :  they 
are  the  parotid,  some  of  which  are  superficial  and  others  deeply  placed  in  its 
substance ;  the  zygomatic,  situated  under  the  zygoma ;  the  buccal,  on  the  surface 
of  the  Buccinator  muscle ;  and  the  submaxillary,  the  largest,  beneath  the  body  of 
the  lower  jaw. 

The  superficial  lymphatics  of  the  head  are  divided  into  an  anterior  and  a 
posterior  set,  which  follow  the  course  of  the  temporal  and  occipital  vessels.  The 
temporal  set  accompany  the  temporal  artery  in  front  of  the  ear,  to  the  parotid 
lymphatic  glands,  from  which  they  proceed  to  the  lymphatic  glands  of  the  neck. 
The  occipital  set  follow  the  course  of  the  occipital  artery,  descend  to  the  occipital 
and  posterior  auricular  lymphatic  glands,  and  from  thence  join  the  cervical 
glands. 

The  superficial  lymphatics  of  the  face  are  more  numerous  than  those  of  the 
head.  They  commence  over  its  entire  surface,  those  from  the  frontal  region  accom- 
panying the  frontal  vessels;  they  then  pass  obliquely  across  the  face,  accompanying 
the  facial  vein,  pass  through  the  buccal  glands  on  the  surface  of  the  Buccinator 
muscle,   and  join  the  submaxillary  lymphatic   glands.     The  latter    receive  the 


OF  THE  HEAD,  FACE,  AND  NECK. 


485 


lymphatic  vessels  from  the  lips,  and  are  often  found  enlarged  in  cases  cf  malignant 
disease  of  these  parts. 

The  deep  lymphatics  of  the  face  are  derived  from  the  pituitary  membrane  of  the 
nose,  the  mucous  membrane  of  the  mouth  and  pharynx,  and  the  contents  of  the 
temporal  aud  orbital  fossae;  they  accompany  the  branches  of  the  internal 
maxillary  artery,  and  terminate  in  the  deep  parotid  and  cervical  lymphatic 
glands. 

The  deep  lymphatics  of  the  cranium  consist  of  two  sets,  the  meningeal  and  cere- 
bral. The  meningeal  lymphatics  accompany  the  meningeal  vessels,  escape  through 
foramina  at  the  base  of  the  skull,  and  join  the  deep  cervical  lymphatic  glands. 


Fig.  248. — The  Superficial  Lymphatics  and  Glands  of  the  Head,  Face  and  Neck. 


The  cerebral  tymphatics  are  described  by  Fohmann  as  being  situated  between  the 
arachnoid  and  pia  mater,  as  well  as  in  the  choroid  plexuses  of  the  lateral  ven. 
tricles ;  they  accompany  the  trunks  of  the  carotid  and  vertebral  arteries,  and  pro- 
bably pass  through  foramina  at  the  base  of  the  skull,  to  terminate  in  the  deep 
cervical  glands.  They  have  not  at  present  been  demonstrated  in  the  dura  mater, 
or  in  the  substance  of  the  brain. 

The  Lymphatic  Glands  of  the  Neck  are  divided  into  two  sets,  superficial  and  deep. 

The  superficial  cervical  glands  are  placed  in  the  course  of  the  external  jugular 
vein,  between  the  Platysma  and  Sterno-mastoid.  They  are  most  numerous  at  the 
root  of  the  neck,  in  the  triangular  interval  between  the  clavicle,  the   Sterno- 


486 


LYMPHATICS 


mastoid,  and  the  Trapezius,  where  they  are  continuous  with  the  axillary  glands. 
A  few  small  glands  are  also  found  on  the  front  and  sides  of  the  larynx. 

The  deep  cervical  glands  (fig.  249)  are  numerous  and  of  large  size ;  they  form 
an  uninterrupted  chain  along  the  sheath  of  the  carotid  artery  and  internal  jugular 
vein,  lying  by  the  side  of  the  pharynx,  oesophagus,  and  trachea,  and  extending 
from  the  base  of  the  skull  to  the  thorax,  where  they  communicate  with  the  lym- 
phatic glands  in  this  cavity. 

Fig.  249. — The  Deep  Lymphatics  and  Glands  of  the  Neck  and  Thorax. 


The  superficial  and  deep  cervical  lymphatics  are  a  continuation  of  those  already 
described  on  the  cranium  and  face.  After  traversing  the  glands  in  those  regions, 
they  pass  through  the  chain  of  glands  which  lie  along  the  sheath  of  the  carotid 
vessels,  being  joined  by  the  lymphatics  from  the  pharynx,  oesophagus,  larynx., 
trachea,  and  thyroid  gland.  At  the  lower  part  of  the  neck,  after  receiving 
some  lymphatics  from  the  thorax,  they  unite  into  a  single  trunk,  which  termi- 
nates on  the  left  side,  in  the  thoracic  duct ;  on  the  right  side,  in  the  right  lym- 
phatic duct. 

Lymphatics  of  the  Upper  Extremity. 

The  Lymphatic  Glands  of  the  upper  extremity  (fig.  250)  may  be  subdivided 
into  two  sets,  superficial  and  deep. 


OF   THE   UPPER   EXTREMITY. 


481 


The  superficial  lymphatic  glands  are  few,  and.  of  small  size.  There  are  occa- 
sionally two  or  three  in  front  of  the  elbow,  and  one  or  two  above  the  internal 
condyle  of  the  humerus,  near  the  basilic  vein. 

The  deep  lymphatic  glands  are  also  few  in  number.  In  the  forearm  a  few 
small  ones  are  occasionally  found  in  the  course  of  the  radial  and  ulnar  vessels  ; 
and  in  the  arm,  there  is  a  chain  of  small  glands  along  the  inner  side  of  the  brachial 
artery. 

Fig.  250. — The  Superficial  Lymphatics  and  Glands  of  the  Upper  Extremity. 


The  axillary  glands  are  of  large  size,  and  usually  ten  or  twelve  in  number. 
A  chain  of  these  glands  surrounds  the  axillary  vessels,  imbedded  in  a  quantity  of 
loose  areolar  tissue ;  they  receive  the  lymphatic  vessels  from  the  arm ;  others  are 
dispersed  in  the  areolar  tissue  of  the  axilla :  the  remainder  are  arranged  in  two 
series,  a  small  chain  running  along  the  lower  border  of  the  Pectoralis  major,  as 
far  as  the  mammary  gland,  receiving  the  lymphatics  from  the  front  of  the  chest 
and  mamma ;  others  are  placed  along  the  lower  margin  of  the  posterior  wall  of 


488  LYMPHATICS. 

the  axilla,  which  receive  the  lymphatics  from  the  integument  of  the  back.  Two 
or  three  subclavian  lymphatic  glands  are  placed  immediately  beneath  the  clavicle; 
it  is  through  these  that  the  axillary  and  deep  cervical  glands  communicate  with 
each  other.  One  is  figured  by  Mascagni  near  the  umbilicus.  In  malignant  diseases, 
tumors,  or  other  affections  implicating  the  upper  part  of  the  back  and  shoulder^ 
the  front  of  the  chest  and  mamma,  the  upper  part  of  the  front  and  side  of  the 
abdomen,  or  the  hand,  forearm,  and  arm,  the  axillary  glands  are  usually  found 
enlarged. 

The  superficial  lymphatics  of  the  upper  extremity  arise  from  the  skin  of  the 
hand,  and  run  along  the  sides  of  the  fingers  chiefly  on  the  dorsal  surface  of  the 
hand ;  they  then  pass  up  the  forearm,  and  subdivide  into  two  sets,  which  take  the 
course  of  the  subcutaneous  veins.  Those  from  the  inner  border  of  the  hand  accom- 
pany the  ulnar  veins  along  the  inner  side  of  the  forearm  to  the  bend  of  the  elbow, 
where  they  join  with  some  lymphatics  from  the  outer  side  of  the  forearm ;  they 
then  follow  the  course  of  the  basilic  vein,  communicate  with  the  glands  immediately 
above  the  elbow,  and  terminate  in  the  axillary  glands,  joining  with  the  deep 
lymphatics.  The  superficial  lymphatics  from  the  outer  and  back  part  of  the  hand 
accompany  the  radial  veins  to  the  bend  of  the  elbow,  being  less  numerous  than  the 
preceding.  Here  the  greater  number  join  the  basilic  group  ;  the  rest  ascend  with 
the  cephalic  vein  on  the  outer  side  of  the  arm,  some  crossing  obliquely  the  upper 
part  of  the  Biceps  to  terminate  in  the  axillary  glands,  whilst  one  or  two  accompany 
the  cephalic  vein  in  the  cellular  interval  between  the  Pectoralis  major  and  Deltoid, 
and  enter  the  subclavian  lymphatic  glands. 

The  deep  lymphatics  of  the  upper  extremity  accompany  the  deep  bloodvessels. 
In  the  forearm,  they  consist  of  three  sets,  corresponding  with  the  radial,  ulnar, 
and  interosseous  arteries ;  they  pass  through  the  glands  occasionally  found  in  the 
course  of  these  vessels,  and  communicate  at  intervals  with  the  superficial  lymphatics. 
In  their  ascent  upwards,  some  of  them  pass  through  the  glands  which  lie  upon  the 
brachial  artery ;  they  then  enter  the  axillary  and  subclavian  glands,  and  at  the  root 
of  the  neck  terminate,  on  the  left  side  in  the  thoracic  duct,  and  on  the  right  side 
in  the  right  lymphatic  duct. 

Lymphatics  of  the  Lower  Extremity. 

The  Lymphatic  Glands  of  the  lower  extremity  may  be  subdivided  into  two  sets, 
superficial  and  deep. 

The  superficial  lymphatic  glands  are  confined  to  the  inguinal  region. 

The  superficial  inguinal  glands,  placed  immediately  beneath  the  integument, 
are  of  large  size,  and  vary  from  eight  to  ten  in  number.  They  are  divisible  into 
two  groups ;  an  upper,  disposed  irregularly  along  Poupart's  ligament,  receiving 
the  lymphatic  vessels  from  the  integument  of  the  scrotum,  penis,  parietes  of  the 
abdomen,  perineum,  and  gluteal  regions ;  and  an  inferior  group,  which  surrounds 
the  saphenous  opening  in  the  fascia  lata,  a  few  being  sometimes  continued  along 
the  saphenous  vein  to  a  variable  extent.  The  latter  receive  the  superficial  lymphatic 
vessels  from  the  lower  extremity.  These  glands  frequently  become  enlarged  in 
diseases  implicating  the  parts  from  which  their  efferent  lymphatics  originate. 
Thus,  in  malignant  or  syphilitic  affections  of  the  prepuce  and  penis,  the  labia 
majora  in  the  female,  in  cancer  scroti,  in  abscess  in  the  perineum,  or  in  any  other 
disease  affecting  the  integument  and  superficial  structures  in  these  parts,  or  the 
sub-umbilical  part  of  the  abdomen  or  gluteal  region,  the  upper  chain  of  glands  is 
almost  invariably  enlarged,  the  lower  chain  being  implicated  in  diseases  affecting 
the  lower  limb. 

The  deep  lymphatic  glands  are  the  anterior  tibial,  popliteal,  deep  inguinal, 
gluteal,  and  ischiatic. 

The  anterior  tibial  gland  is  not  constant  in  its  existence.  It  is  generally  found 
by  the  side  of  the  anterior  tibial  artery,  upon  the  interosseous  membrane  at  the 
upper  part  of  the  leg.     Occasionally,  two  glands  are  found  in  this  situation. 


OF   THE   LOWER   EXTREMITY. 


489 


The  deep  popliteal  glands,  four  or  five 
in  number,  are  of  small  size;  they  sur- 
round the  popliteal  vessels,  imbedded  in 
the  cellular  tissue  and  fat  of  the  popliteal 
space. 

The  deep  inguinal  glands  are  placed 
beneath  the  deep  fascia  around  the  femoral 
artery  and  vein.  They  are  of  small  size, 
and  communicate  with  the  superficial 
inguinal  glands  through  the  saphenous 
opening. 

The  gluteal  and  ischiatic  glands  are 
placed,  the  former  above,  the  latter  below, 
the  Pyriformis  muscle,  resting  on  their 
corresponding  vessels  as  they  pass  through 
the  great  sacro -sciatic  foramen. 

The  Lymphatics  of  the  lower  extremity, 
like  the  veins,  may  be  divided  into  two 
sets,  superficial  and  deep. 

The  superficial  lymphatics  are  placed 
between  the  integument  and  superficial 
fascia,  and  are  divisible  into  two  groups, 
an  internal  group,  which  follow  the  course 
of  the  internal  saphenous  vein;  and  an 
external  group,  which  accompany  the 
external  saphenous. 

The  internal  group,  the  largest,  com- 
mence on  the  inner  side  and  dorsum  of 
the  foot ;  they  pass,  some  in  front  of,  and 
some  behind,  the  inner  ankle,  ascend  the 
leg  with  the  internal  saphenous  vein,  pass 
with  it  behind  the  inner  condyle  of  the 
femur,  and  accompany  it  to  the  groin, 
where  they  terminate  in  the  group  of  in- 
guinal glands  which  surround  the  saphe- 
nous opening.  Some  of  the  efferent  vessels 
from  these  glands  pierce  the  cribriform 
fascia  and  sheath  of  the  femoral  vessels, 
and  terminate  in  a  lymphatic  gland 
contained  in  the  femoral  canal,  thus 
establishing  a  communication  between 
the  lymphatics  of  the  lower  extremity 
and  those  of  the  trunk ;  others  pierce  the 
fascia  lata,  and  join  the  deep  inguinal 
glands. 

The  external  group  arise  from  the  outer 
side  of  the  foot,  ascend  in  front  of  the  leg, 
and,  just  below  the  knee,  cross  the  tibia 
from  without  inwards,  to  join  the  lym- 
phatics on  the  inner  side  of  the  thigh. 
Others  commence  on  the  outer  side  of  the 
foot,  pass  behind  the  outer  malleolus,  and 
accompany  the  external  saphenous  vein 
along  the  back  of  the  leg,  where  they 
enter  the  popliteal  glands. 

The  deep  lymphatics  of  the  lower  ex- 
tremity are  few  in  number,  and  accompany 


Fig.  251. — The  Superficial  Lymphatics  and 
Glands  of  the  Lower  Extremity. 


Superficia 


490  LYMPHATICS. 

the  deep  bloodvessels.  In  the  leg,  they  consist  of  three  sets,  the  anterior  tibial, 
peroneal,  and  posterior  tibial,  which  accompany  the  corresponding  vessels,  being 
two  or  three  in  number  to  each ;  they  ascend  with  the  bloodvessels,  and  enter  the 
lymphatic  glands  in  the  popliteal  space.  The  efferent  vessels  from  these  glands 
accompany  the  femoral  vein,  and  join  the  deep  inguinal  glands ;  from  these,  the 
vessels  pass  beneath  Poupart's  ligament,  and  communicate  with  the  chain  of 
glands  surrounding  the  external  iliac  vessels. 

The  deep  lymphatics  of  the  gluteal  and  ischiatic  regions  follow  the  course  of 
the  bloodvessels,  and  join  the  gluteal  and  ischiatic  glands  at  the  great  sacro-sciatic 
foramen. 

Lymphatics  of  the  Pelvis  and  Abdomen. 

The  Deep  Lymphatic  Glands  in  the  Pelvis  are,  the  external  iliac,  the  internal 
iliac,  and  the  sacral.     Those  of  the  abdomen  are  the  lumbar  glands. 

The  external  iliac  glands  form  an  uninterrupted  chain  round  the  external  iliac 
vessels,  three  being  placed  round  the  commencement  of  the  vessel  just  behind  the 
crural  arch.  They  communicate  below  with  the  femoral  lymphatics,  and  above 
with  the  lumbar  glands. 

The  internal  iliac  glands  surround  the  internal  iliac  vessels ;  they  receive  the 
lymphatics  corresponding  to  the  branches  of  the  internal  iliac  artery,  and  com- 
municate with  the  lumbar  glands. 

The  sacral  glands  occupy  the  sides  of  the  anterior  surface  of  the  sacrum,  some 
being  situated  in  the  mesorectal  fold.  These  and  the  internal  iliac  glands  become 
greatly  enlarged  in  malignant  disease  of  the  bladder,  rectum,  or  uterus. 

The  lumbar  glands  are  very  numerous ;  they  are  situated  on  the  front  of  the 
lumbar  vertebras,  surrounding  the  common  iliac  vessels,  the  aorta,  and  vena  cava ; 
they  receive  the  lymphatic  vessels  from  the  lower  extremities  and  pelvis,  as  well 
as  from  the  testes  and  some  of  the  abdominal  viscera.  The  efferent  vessels  from 
these  glands  unite  into  a  few  large  trunks,  which,  with  the  lacteals,  form  the  com- 
mencement of  the  thoracic  duct.  In  some  cases  of  malignant  disease,  these  glands 
become  enormously  enlarged,  completely  surrounding  the  aorta  and  vena  cava, 
and  occasionally  greatly  contracting  the  calibre  of  these  vessels.  In  all  cases  of 
malignant  disease  of  the  testis,  and  in  malignant  disease  of  the  lower  limb,  before 
any  operation  is  attempted,  careful  examination  of  the  abdomen  should  be  made, 
in  order  to  ascertain  if  any  enlargement  exists ;  and  if  any  should  be  detected, 
all  operative  measures  are  fruitless. 

The  lymphatics  of  the  pelvis  and  abdomen  may  be  divided  into  two  sets,  superficial 
and  deep. 

The  superficial  lymphatics  of  the  walls  of  the  abdomen  and  pelvis  follow  the  course 
of  the  superficial  bloodvessels.  Those  derived  from  the  integument  of  the  lower 
part  of  the  abdomen  below  the  umbilicus  follow  the  course  of  the  superficial 
epigastric  vessels,  and  converge  to  the  superior  group  of  the  superficial  inguinal 
glands ;  the  deep  set  accompany  the  deep  epigastric  vessels,  and  communicate  with 
the  external  iliac  glands.  The  superficial  lymphatics  from  the  sides  and  lumbar  part 
of  the  abdominal  wall  wind  round  the  crest  of  the  ilium,  accompanying  the  super- 
ficial circumflex  iliac  vessels,  to  join  the  superior  group  of  the  superficial  inguinal 
glands;  the  greater  number,  however,  accompany  the  ilio-lumbar  and  lumbar 
vessels  backwards,  to  join  the  lumbar  glands. 

The  superficial  lymphatics  of  the  gluteal  region  turn  horizontally  round  the  outer 
side  of  the  nates,  and  join  the  superficial  inguinal  glands. 

The  superficial  lymphatics  of  the  scrotum  and  perinseum  follow  the  course  of  the 
external  pudic  vessels,  and  terminate  in  the  superficial  inguinal  glands. 

The  superficial  lymphatics  of  the  penis  occupy the  sides  and  dorsum  of  the  organ, 
the  latter  receiving  the  lymphatics  from  the  skin  covering  the  glans  penis;  they 
all  converge  to  the  upper  chain  of  the  superficial  inguinal  glands.  The  deep 
lymphatic  vessels  of  the  penis  follow  the  course  of  the  internal  pudic  vessels,  and 
join  the  internal  iliac  glands. 


OF   THE   PELVIS   AND   ABDOMEN 


491 


In  the  female,  the  lymphatic  vessels  of  the  mucous  membrane  of  the  labia, 
nymphae,  and  clitoris,  terminate  in  the  upper  chain  of  the  inguinal  lymphatic 
glands. 

The  deep  lymphatics  of  the  pelvis  and  abdomen  take  the  course  of  the  principal 
bloodvessels.  Those  of  the  parietes  of  the  pelvis,  which  accompany  the  gluteal, 
ischiatic,  and  obturator  vessels,  follow  the  course  of  the  internal  iliac  artery,  and 
ultimately  join  the  lumbar  lymphatics. 


Fig.  252. — The  Deep  Lymphatic  Vessels  and  Glands  of  the  Abdomen  and  Pelvis. 


Sxttrnal 
Ilia*  daul* 


Clanrti 


Sacral  G//z>/ch 


Internal 
\lliae  Glands 


Deej}  Lymphati.es 
of   PeM3 


The  efferent  vessels  from  the  inguinal  glands  enter  the  pelvis  beneath  Poupart's 
ligament,  where  they  lie  in  close  relation  with  the  femoral  vein ;  they  then  pass 
through  the  chain  of  glands  surrounding  the  external  iliac  vessels,  and  finally 
terminate  in  the  lumbar  glands.  They  receive  the  deep  epigastric,  circumflex 
iliac,  and  ilio-lumbar  lymphatics. 


492  LYMPHATICS. 

The  lymphatics  of  the  Madder  arise  from  the  entire  surface  of  the  organ ;  the 
greater  number  run  beneath  the  peritoneum  on  its  posterior  surface,  and,  after 
passing  through  the  lymphatic  glands  in  this  situation,  join  with  the  lymphatics 
from  the  prostate  and  vesicular  seminales,  and  enter  the  internal  iliac  glands. 

The  lymphatics  of  the  rectum  are  of  large  size ;  after  passing  through  some  small 
glands  that  lie  upon  its  outer  wall  and  in  the  mesorectum,  they  pass  to  the  sacral 
or  lumbar  glands. 

The  lymphatics  of  the  uterus  consist  of  two  sets,  superficial  and  deep;  the 
former  being  placed  beneath  the  peritoneum,  the  latter  in  the  substance  of  the 
organ.  The  lymphatics  of  the  cervix  uteri,  together  with  those  from  the  vagina, 
enter  the  internal  iliac  and  sacral  glands ;  those  from  the  body  and  fundus  of  the 
uterus  pass  outwards  in  the  broad  ligaments,  and,  being  joined  by  the  lymphatics 
from  the  ovaries,  broad  ligaments,  and  Fallopian  tubes,  ascend  with  the  ovarian 
vessels  to  open  into  the  lumbar  glands.  In  the  unimpregnated  uterus,  they  are 
small ;  but  during  gestation  they  become  very  greatly  enlarged. 

The  lymphatics  of  the  testicle  consist  of  two  sets,  superficial  and  deep;  the 
former  commence  on  the  surface  of  the  tunica  vaginalis,  the  latter  in  the  epidi- 
dymis and  body  of  the  testis.  They  form  several  large  trunks,  which  ascend  with 
the  spermatic  cord,  and,  accompanying  the  spermatic  vessels  into  the  abdomen, 
open  into  the  lumbar  glands ;  hence  the  enlargement  of  these  glands  in  malignant 
disease  of  the  testis. 

The  lymphatics  of  the  kidney  arise  on  the  surface,  and  also  in  the  interior  of  the 
organ;  they  join  at  the  hilus,  and,  after  receiving  the  lymphatic  vessels  from  the 
ureter  and  supra-renal  capsule,  open  into  the  lumbar  glands. 

The  lymphatics  of  the  liver  are  divisible  into  two  sets,  superficial  and  deep. 
The  former  arise  in  the  sub-peritoneal  areolar  tissue  over  the  entire  surface  of  the 
organ.  Those  on  the  convex  surface  may  be  divided  into  four  groups : — 1.  Those 
which  pass  from  behind  forwards,  consisting  of  three  or  four  branches,  which 
ascend  in  the  longitudinal  ligament,  and  unite  to  form  a  single  trunk,  which  passes 
up  between  the  fibres  of  the  Diaphragm,  behind  the  ensiform  cartilage,  to  enter 
the  anterior  mediastinal  glands,  and  finally  ascends  to  the  root  of  the  neck,  to 
terminate  in  the  right  lymphatic  duct.  2.  Another  group,  which  also  incline 
from  behind  forwards,  are  reflected  over  the  anterior  margin  of  the  liver  to  its 
under  surface,  and  from  thence  pass  along  the  longitudinal  fissure  to  the  glands 
in  the  gastro-hepatic  omentum.  3.  A  third  group  incline  outwards  to  the  right 
lateral  ligament,  and,  uniting  into  one  or  two  large  trunks,  pierce  the  Diaphragm, 
and  run  along  its  upper  surface  to  enter  the  anterior  mediastinal  glands;  or, 
instead  of  entering  the  thorax,  turn  inwards  across  the  crus  of  the  Diaphragm, 
and  open  into  the  commencement  of  the  thoracic  duct.  4.  The  fourth  group 
incline  outwards  from  the  surface  of  the  left  lobe  of  the  liver  to  the  left  lateral 
ligament,  pierce  the  Diaphragm,  and,  passing  forwards,  terminate  in  the  glands  in 
the  anterior  mediastinum. 

The  superficial  lymphatics  on  the  under  surface  of  the  liver  are  divided  into  three 
sets: — 1.  Those  on  the  right  side  of  the  gall-bladder  enter  the  lumbar  glands.  2. 
Those  surrounding  the  gall-bladder  form  a  remarkable  plexus,  which  accompanies 
the  hepatic  vessels,  and  open  into  the  glands  in  the  gastro-hepatic  omentum.  3. 
Those  on  the  left  of  the  gall-bladder  pass  to  the  oesophageal  glands,  and  to  those 
placed  along  the  lesser  curvature  of  the  stomach. 

The  deep  lymphatics  accompany  the  branches  of  the  portal  vein  and  the  hepatic 
artery  and  duct  through  the  substance  of  the  liver ;  passing  out  at  the  transverse 
fissure,  they  enter  the  lymphatic  glands  along  the  lesser  curvature  of  the  stomach 
and  behind  the  pancreas,  or  join  with  one  of  the  lacteal  vessels  previous  to  its 
termination  in  the  thoracic  duct. 

The  lymphatic  glands  of  the  stomach  are  of  small  size ;  they  are  placed  along 
the  lesser  and  greater  curvatures,  some  within  the  gastro-splenic  omentum,  whilst 
others  surround  its  cardiac  and  pyloric  orifices. 

The  lymphatics  of  the  stomach  consist  of  two  sets,  superficial  and  deep ;  the 


OF   THE   INTESTINES   AND   THORAX.  493 

former  originating  in  the  subserous,  and  the  latter  in  the  submucous  coat.  They 
follow  the  course  of  the  bloodvessels,  and  may  consequently  be  arranged  into 
three  groups.  The  first  group  accompany  the  coronary  vessels  along  the  lesser 
curvature,  receiving  branches  from  both  surfaces  of  the  organ,  and  pass  to  the 
glands  around  the  pylorus.  The  second  group  pass  from  the  great  end  of  the 
stomach,  accompany  the  vasa  brevia,  and  enter  the  splenic  lymphatic  glands. 
The  third  group  run  along  the  greater  curvature  with  the  right  gastro-epiploic 
vessels,  and  terminate  at  the  root  of  the  mesentery  in  one  of  the  principal  lacteal 
vessels. 

The  lymphatic  glands  of  the  spleen  occupy  the  hilus.  Its  lymphatic  vessels  consist 
of  two  sets,  superficial  and  deep ;  the  former  are  placed  beneath  its  peritoneal 
covering,  the  latter  in  the  substance  of  the  organ :  they  accompany  the  blood- 
vessels, passing  through  a  series  of  small  glands,  and,  after  receiving  the  lymphatics 
from  the  pancreas,  ultimately  pass  into  the  thoracic  duct. 

The  Lymphatic  System  of  the  Intestines. 

The  lymphatic  glands  of  the  small  intestine  are  placed  between  the  layers  of  the 
mesentery,  occupying  the  meshes  formed  by  the  superior  mesenteric  vessels, 
and  hence  called  mesenteric  glands.  They  vary  in  number  from  a  hundred  to  a 
hundred  and  fifty ;  and  in  size,  from  that  of  a  pea  to  that  of  a  small  almond.  These 
glands  are  most  numerous,  and  largest,  superiorly  near  the  duodenum,  and  inferiorly 
opposite  the  termination  of  the  ileum  in  the  colon.  The  latter  group  become 
greatly  enlarged  and  infiltrated  with  deposit  in  cases  of  fever  accompanied  with 
ulceration  of  the  intestines. 

The  lymphatic  glands  of  the  large  intestine  are  much  less  numerous  than  the 
mesenteric  glands ;  they  are  situated  along  the  vascular  arches  formed  by  the 
arteries  previous  to  their  distribution,  and  even  sometimes  upon  the  intestine  itself. 
They  are  fewest  in  number  along  the  transverse  colon,  where  they  form  an  unin- 
terrupted chain  with  the  mesenteric  glands. 

The  lymphatics  of  the  small  intestine  are  called  lacteals,  from  the  milk-white 
fluid  they  usually  contain ;  they  consist  of  two  sets,  superficial  and  deep ;  the 
former  lie  beneath  the  peritoneal  coat,  taking  a  longitudinal  course  along  the 
outer  side  of  the  intestine ;  the  latter  occupy  the  submucous  tissue,  and  course 
transversely  round  the  intestine,  accompanied  by  the  branches  of  the  mesenteric 
vessels:  they  pass  between  the  layers  of  the  mesentery,  enter  the  mesenteric 
glands,  and  finally  unite  to  form  two  or  three  large  trunks,  which  terminate  in 
the  thoracic  duct. 

The  lymphatics  of  the  large  intestine  consist  of  two  sets:  those  of  the  caecum, 
ascending  and  transverse  colon,  which,  after  passing  through  their  proper  glands, 
enter  the  mesenteric  glands ;  and  those  of  the  descending  colon  and  rectum,  which 
pass  to  the  lumbar  glands. 

The  Lymphatics  of  the  Thorax. 

The  deep  lymphatic  glands  of  the  thorax  are  the  intercostal,  internal  mammary, 
anterior  mediastinal,  and  posterior  mediastinal. 

The  intercostal  glands  are  small,  irregular  in  number,  and  situated  on  each  side 
of  the  spine,  near  the  costo-vertebral  articulations,  some  being  placed  between  the 
two  planes  of  intercostal  muscles. 

The  internal  mammary  glands  are  placed  at  the  anterior  extremity  of  each 
intercostal  space,  by  the  side  of  the  internal  mammary  vessels. 

The  anterior  mediastinal  glands  are  placed  in  the  loose  areolar  tissue  of  the 
anterior  mediastinum,  some  lying  upon  the  Diaphragm  in  front  of  the  pericardium, 
and  others  round  the  great  vessels  at  the  base  of  the  heart. 

The  posterior  mediastinal  glands  are  situated  in  the  areolar  tissue  in  the  posterior 
mediastinum,  forming  a  continuous  chain  by  the  side  of  the  aorta  and  oesophagus; 


494  LYMPHATICS. 

they  communicate  on  each  side  with  the  intercostal,  below  with  the  lumbar  glands, 
and  above  with  the  deep  cervical. 

The  superficial  lymphatics  of  the  front  of  the  thorax  run  across  the  great  Pectoral 
muscle,  and  those  on  the  back  part  of  this  cavity  lie  upon  the  Trapezius  and 
Latissimus  dorsi;  they  all  converge  to  the  axillary  glands.  The  lymphatics  from 
the  mamma  run  along  the  lower  border  of  the  Pectoralis  major,  through  a  chain 
of  small  lymphatic  glands,  and  communicate  with  the  axillary  glands. 

The  deep  lymphatics  of  the  thorax  are  the  intercostal,  internal  mammary,  and 
diaphragmatic. 

The  intercostal  lymphatics  follow  the  course  of  the  intercostal  vessels,  receiving 
lymphatics  from  the  Intercostal  muscles  and  pleura ;  they  pass  backwards  to  the 
spine,  and  unite  with  lymphatics  from  the  back  part  of  the"  thorax -and  spinal  canal. 
After  traversing  the  intercostal  glands,  they  incline  down  the  spine,  and  terminate  • 
in  the  thoracic  duct. 

The  internal  mammary  lymphatics  follow  the  course  of  the  internal  mammary 
vessels ;  they  commence  in  the  muscles  of  the  abdomen  above  the  umbilicus, 
communicating  with  the  epigastric  lymphatics,  ascend  between  the  fibres  of  the 
Diaphragm  at  its  attachment  to  the  ensiform  appendix,  and  in  their  course  behind 
the  costal  cartilages  are  joined  by  the  intercostal  lymphatics,  terminating  on  the 
right  side  in  the  right  lymphatic  duct,  on  the  left  side  in  the  thoracic  duct. 

The  lymphatics  of  the  Diaphragm  follow  the  course  of  their  corresponding 
vessels,  and  terminate,  some  in  front  in  the  anterior  mediastinal  and  internal 
mammary  glands,  some  behind  in  the  intercostal  and  hepatic  lymphatics. 

The  bronchial  glands  are  situated  round  the  bifurcation  of  the  trachea  and 
roots  of  the  lungs.  They  are  ten  or  twelve  in  number,  the  largest  being  placed 
opposite  the  bifurcation  of  the  trachea,  the  smallest  round  the  bronchi  and  their 
primary  divisions  for  some  little  distance  within  the  substance  of  the  lungs.  In 
infancy,  they  present  the  same  appearance  as  lymphatic  glands  in  other  situations; 
in  the  adult  they  assume  a  brownish  tinge,  and  in  old  age  a  deep  black  color. 
Occasionally  they  become  sufficiently  enlarged  to  compress  and  narrow  the  canal 
of  the  bronchi ;  and  they  are  often  the  seat  of  tubercle  or  deposits  of  phosphate 
of  lime. 

The  lymphatics  of  the  lung  consist  of  two  sets,  superficial  and  deep :  the  former 
are  placed  beneath  the  pleura,  forming  a  minute  plexus,  which  covers  the  outer 
surface  of  the  lung;  the  latter  accompany  the  bloodvessels,  and  run  along  the 
bronchi :  they  both  terminate  at  the  root  of  the  lungs  in  the  bronchial  glands. 
The  efferent  vessels  from  these  glands,  two  or  three  in  number,  ascend  upon  the 
trachea  to  the  root  of  the  neck,  traverse  the  tracheal  and  oesophageal  glands, 
and  terminate  on  the  left  side  in  the  thoracic  duct,  and  on  the  right  side  in  the 
right  lymphatic  duct. 

The  cardiac  lymphatics  consist  of  two  sets,  superficial  and  deep  ;  the  former 
arise  in  the  subserous  areolar  tissue  of  the  surface,  and  the  latter  beneath  the 
internal  lining  membrane  of  the  heart ;  they  follow  the  course  of  the  coronary 
vessels.  Those  of  the  right  side  unite  into  a  trunk  at  the  root  of  the  aorta,  which, 
ascending  across  the  arch  of  that  vessel,  passes  backwards  to  the  trachea,  upon 
which  it  ascends,  to  terminate  at  the  root  of  the  neck  in  the  right  lymphatic  duct; 
those  of  the  left  side  unite  into  a  single  vessel  at  the  base  of  the  heart,  which 
passing  along  the  pulmonary  artery,  and  traversing  some  glands  at  the  root  of  the 
aorta,  ascends  on  the  trachea  to  terminate  in  the  thoracic  duct. 

The  thymic  lymphatics  arise  from  the  spinal  surface  of  the  thymus  gland,  and 
terminate  on  each  side  in  the  internal  jugular  veins. 

The  thyroid  lymphatics  arise  from  either  lateral  lobe  of  the  thyroid  gland ;  they 
converge  to  form  a  short  trunk,  which  terminates  on  the  right  side  in  the  right 
lymphatic  duct,  on  the  left  side  in  the  thoracic  duct. 

The  lymphatics  of  the  oesophagus  form  a  plexus  round  that  tube,  traverse  the 
glands  in  the  posterior  mediastinum,  and,  after  communicating  with  the  pulmonary 
lymphatic  vessels  near  the  roots  of  the  lungs,  terminate  in  the  thoracic  duct. 


Nervous  System. 


The  Nervous  System  consists  of  a  series  of  connected  central  organs,  called 
collectively,  the  cerebrospinal  centre  or  axis,  of  the  ganglia,  and  of  the  nerves. 

The  cerebrospinal  portion  of  the  nervous  system  includes  the  brain  and  spinal 
cord,  with  the  nerves  connected  with  them,  and  the  ganglia  seated  upon  these 
nerves.  It  was  distinguished,  by  Bichat,  as  the  nervous  system  of  animal  life. 
It  includes  those  nervous  organs  in  and  through  which  the  several  functions  of 
the  mind  are  more  immediately  connected ;  the  nerves  of  the  senses,  and  those 
relating  to  volition  and  common  sensation,  are  connected  with  it,  as  well  as  those 
concerned  in  many  nervous  actions,  with  which  the  mind  has  no  connection. 

The  ganglionic  or  sympathetic  system  consists  of  a  double  chain  of  ganglia 
connected  by  nervous  cords,  situate  along  the  spinal  column;  and  from  which 
nerves  with  ganglia  developed  upon  them  proceed  to  the  viscera  in  the  thoracic, 
abdominal  and  pelvic  cavities.  It  was  distinguished,  by  Bichat,  as  the  nervous 
system  of  organic  life.  This  system  is  less  immediately  connected  with  the  mind, 
appearing  to  be  more  closely  concerned  than  the  cerebro-spinal  system  with  the 
processes  of  organic  life. 

The  several  organs  of  the  nervous  system  are  composed  of  two  different 
substances,  which  differ  from  each  other  in  density,  color,  in  their  minute  struc- 
ture, and  in  their  chemical  composition.  They  are  called  the  vesicular  nervous 
matter  and  the  fibrous  nervous  matter.  The  former  is  often  called  the  gray  or 
cineritious  substance ;  and  the  latter,  the  white  or  medullary. 

The  fibrous  nervous  matter  is  most  extensively  diffused  throughout  the  body. 
It  forms  a  large  portion  of  the  nervous  centres,  either  alone,  or  mixed  with 
vesicular  matter ;  and  is  the  principal  constituent  of  the  nerves  which  connect 
them  with  the  various  tissues  and  organs. 

The  vesicular  nervous  matter  is  usually  known  by  its  soft  consistence,  and  dark 
reddish-gray  color ;  it  is  generally  collected  into  masses  intermingled  with  the 
fibrous  structure,  in  various  parts  of  the  brain  and  spinal  cord,  and  in  the  several 
ganglia. 

Chemical  Composition.  The  following  analysis  by  Lassaighe  represents  the 
relative  proportion  of  the  different  constituents  composing  the  gray  and  white 
matter  of  the  brain : — 


Gray. 

White 

Water         .... 

.    85.2 

.      73.0 

Albuminous  matter     . 

.     7.5 

.      9.9 

Colorless  fat 

.     1.0 

.     13.9 

Red  fat        ...         . 

.     3.7 

0.9 

Osmazome  and  lactates 

.     1.4 

1.0 

Phosphates 

.      1.2 

1.3 

100.0        100.0 

It  appears  from  this  analysis  that  the  cerebral  substance  consists  of  albumen, 
dissolved  in  water,  combined  with  fatty  matters  and  salts.  The  fatty  matters, 
according  to  Fremy,  consist  of  cerebric  acid,  which  is  most  abundant,  cholesterin, 
oleophosphoric  acid,  and  olein,  margarin,  and  traces  of  their  acids.  The  same 
analyst  states,  that  the  fat  contained  in  the  brain  is  confined  almost  exclusively  to 
the  white  substance,  and  that  its  color  becomes  lost  when  the  fatty  matters  are 
removed.     According  to  Vauquelin,  the  cord  contains  a  larger  proportion  of  fat 

495 


496  NERVOUS   SYSTEM. 

than  tlie  brain ;  and,  according  to  L'Heritier,  the  nerves  contain  more  albumen 
and  more  soft  fat  than  the  brain. 

Microscopic  Structure.  The  fibrous  nervous  matter  consists  of  two  different 
kinds  of  nerve  fibres,  which  are  distinguished  as  the  tubular  fibre  and  the  gela- 
tinous fibre.  In  most  nerves  these  two  kinds  are  intermingled;  the  tubular 
fibres  being  more  numerous  in  the  nerves  of  the  cerebro-spinal  system,  the  gela- 
tinous predominating  in  the  nerves  of  the  sympathetic  system.  • 

The  tubular  fibres  appear  to  consist  of  tubules  of  simple  membrane,  homogeneous 
in  structure,  and  analogous  to  the  sarcolemma  of  striped  muscle.  Within  is  the 
proper  nerve  substance,  composed  apparently  of  two  different  materials ;  the  central 
part,  which  occupies  the  axis  of  the  nerve  tube,  is  a  transparent  material,  termed 
the  axis  cylinder  ;  while  the  outer  portion,  which  forms  a  tube  within  the  tubular 
membrane,  inclosing  the  axis-cylinder,  is  usually  opaque  and  dimly  granular,  as 
if  from  a  kind  of  coagulation,  and  is  generally  known  as  the  white  substance 
of  Schwann.  The  peculiar  white  appearance  of  the  cerebro-spinal  nerves  is 
principally  due  to  the  large  amount  of  the  white  substance  of  Schwann  which  they 
contain.  It  is  probable  that  the  essential  element  of  the  nerve  tube  is  the  axis 
cylinder,  the  tubular  membrane  and  white  substance  of  Schwann  affording  me- 
chanical protection  to  this  substance,  insulating  it  from  the  constituent  parts  of 
the  neighboring  fibres. 

In  a  perfectly  fresh  state,  the  nerve  tubes  present  the  appearance  of  simple 
membranous  tubes,  perfectly  cylindrical,  and  containing  a  transparent  and  ap- 
parently homogeneous  material ;  but  shortly  after  death,  when  pressed  or  separated 
by  coarse  manipulation,  they  undergo  changes  which  render  it  probable  that  their 
contents  are  composed  of  the  two  materials  above  mentioned,  for  the  fine  outline 
of  the  previously  cylindrical  tube  is  exchanged  for  a  dark  double  contour,  the 
outer  line  being  formed  by  the  tubular  sheath,  the  inner  by  the  white  substance  of 
Schwann,  at  the  same  time  the  granular  material  collects  into  small  masses  which 
distend  the  tubular  membrane  at  irregular  intervals,  while  the  intermediate  spaces 
collapse,  giving  the  fibres  a  varicose  or  beaded  appearance.  In  the  brain,  spinal 
cord,  and  nerves  of  special  sense,  the  tubes  are  very  apt  to  exhibit  this  change, 
owing  to  extreme  thinness  of  the  tubular  membrane  and  to  a  diminished  con- 
sistence of  the  contained  nervous  matter.  The  contents  of  the  nerve  tubes  are 
extremely  soft,  for  when  subjected  to  slight  pressure  they  readily  pass  from  one 
part  of  the  canal  to  another,  and  often  cause  a  bulging  at  the  side  of  the  tube. 
The  contents,  also,  readily  escape  on  pressure  from  the  extremities  of  the  tube, 
assuming  the  appearance  and  form  of  globules,  consisting  of  a  transparent  central 
part,  surrounded  by  a  layer  of  the  white  substance  of  Schwann,  marked  by  its 
double  contour. 

The  nerve  fibres  vary  in  size ;  they  are  largest  within  the  trunk  and  branches 
of  the  nerves,  measuring  from  tj^Vtt  to  35VTT  of  an  inch.  They  become  gradually 
smaller  as  they  approach  the  brain  and  spinal  cord,  and  usually  also  in  the  tissues 
in  which  they  are  distributed.  In  the  gray  matter  of  the  brain  and  spinal  cord, 
they  seldom  measure  more  than  TTj^t  to  y^^u  of  an  inch. 

The  gelatinous  fibres  constitute  the  main  part  of  the  trunk  and  branches 
of  the  sympathetic  nerve,  and  are  intermingled  in  various  proportions  in  the 
cerebro-spinal  nerves.  When  collected  together  in  great  numbers,  they  exhibit 
a  yellowish-gray  color.  They  are  flattened,  soft,  and  homogeneous  in  appearance, 
containing  nuclei,  of  a  round  or  oval  form,  arranged  at  nearly  equal  distances, 
and  frequently  presenting  nucleoli.  They  vary  in  diameter,  from  ^^  to  -^^ 
of  an  inch,  and  resemble  much  the  fibres  of  unstriped  muscle.  They  differ  from 
the  tubular  fibres  in  their  smaller  size,  being  only  one-half  or  one-third  their  size, 
in  the  absence  of  the  double  contour,  their  apparently  uniform  structure,  and  their 
yellowish-gray  color.  It  appears  probable  that  these  nerves  are  composed  ex- 
clusively of  the  substance  which  corresponds  with  the  axis  cylinder  of  the  tubular 
nerves,  and  differs  from  them  in  not  possessing  the  tubular  membrane,  and  white 
substance  of  Schwann. 


GENERAL   ANATOMY.  491 

The  vesicular  nervous  substance  is  distinguished  by  its  dark  reddish-gray 
color,  and  soft  consistence.  It  is  found  in  the  brain,  spinal  cord,  and  various 
ganglia,  intermingled  with  the  fibrous  nervous  substance,  but  is  never  found  in  the 
nerves.  It  is  composed,  as  its  name  implies,  of  vesicles  or  corpuscles,  commonly 
called  nerve  or  ganglion  corpuscles,  containing  nuclei  and  nucleoli ;  the  vesicles 
being  imbedded  either  in  a  finely  granular  substance,  as  in  the  brain,  or  in  a 
capsule  of  nucleated  cells,  as  in  the  ganglia.  Each  vesicle  consists  of  an  exceed- 
ingly  delicate  membranous  wall,  inclosing  a  finely  granular  material,  part  of 
which  is  occasionally  of  a  coarser  kind,  and  of  a  reddish  or  yellowish-brown 
color.  The  nucleus  is  vesicular,  much  smaller  than  the  vesicle,  and  adherent  t<  > 
some  part  of  its  interior.  The  nucleolus,  which  is  inclosed  within  the  nucleus,  is 
vesicular  in  form,  of  minute  size,  and  peculiarly  clear  and  brilliant.  The  nerve 
corpuscles  vary  in  shape  and  size;  some  are  small,  spherical,  or  ovoidal,  with  an 
uninterrupted  outline ;  these  forms  being  most  numerous  in  the  ganglia  of  the 
sympathetic.  Others,  called  caudate  or  stellate  nerve  corpuscles,  are  characterized 
by  their  larger  size,  and  from  having  one  or  more  tail-like  processes  issuing  from 
them,  which  occasionally  divide  and  subdivide  into  numerous  branches.  These 
processes  are  very  delicate,  apparently  tubular,  and  contain  a  similar  granular 
material  to  that  found  within  the  corpuscle.  Some  of  the  processes  terminate 
in  fine  transparent  fibres,  which  become  lost  among  the  other  elements  of  the 
nervous  tissue;  others  may  be  traced  until,  after  losing  their  granular  appearance, 
they  become  continuous  with  an  ordinary  nerve  fibre. 

The  Ganglia  may  be  regarded  as  separate  and  independent  nervous  centres,  of 
smaller  size  and  less  complex  structure  than  the  brain,  connected  with  each  other, 
with  the  cerebro-spinal  axis,  and  with  the  nerves  in  various  situations.  They  are 
found  on  the  posterior  root  of  each  of  the  spinal  nerves ;  on  the  posterior  or 
sensory  root  of  the  fifth  cranial  nerve;  on  the  facial  nerve;  on  the  glosso- 
pharyngeal and  pneumogastric  nerves ;  in  a  connected  series  along  each  side  of 
the  vertebral  column,  forming  the  trunk  of  the  sympathetic ;  on  the  branches  of 
that  nerve  in  the  head,  neck,  thorax,  and  abdomen ;  or  at  the  point  of  junction 
of  branches  of  that  nerve  with  the  cerebro-spinal  nerves.  On  section,  they  an; 
seen  to  consist  of  a  reddish-gray  substance,  traversed  by  numerous  white  nerve 
fibres :  they  vary  considerably  in  form  and  size,  the  largest  being  those  found  in 
the  cavity  of  the  abdomen;  the  smallest,  the  microscopic  ganglia,  which  exist 
in  considerable  numbers  upon  the  nerves  distributed  to  the  different  viscera. 
The  ganglia  are  invested  by  a  smooth  and  firm  closely-adhering  membranous 
envelope,  consisting  of  dense  areolar  tissue  and  continuous  with  the  neurilemma 
of  the  nerves.  It  sends  numerous  processes  into  the  interior  of  the  ganglia, 
which  support  the  bloodvessels  supplying  its  substance. 

In  structure,  all  ganglia  are  essentially  similar,  consisting  of  the  same 
structural  elements  as  the  other  nervous  centres,  viz.,  a  collection  of  vesicular 
nervous  matter,  traversed  by  tubular  and  gelatinous  nerve  fibres.  The  vesicular 
nervous  matter  consists  of  nerve  cells  or  ganglion -globules,,  most  of  which  appear 
free,  and  of  a  round  or  oval  form,  being  more  especially  seated  near  the 
surface  of  the  ganglion ;  others  have  caudate  processes,  and  give  origin  to  nerve 
fibres.  In  the  ganglia,  the  nerve  cells  are  usually  inclosed  in  a  capsule  of 
granular  corpuscles  and  fibres.  The  tubular  nerve  fibres  run  through  the 
ganglion,  some  being  collected  into  bundles ;  others,  separating  from  each  other, 
take  a  circuitous  course  among  the  nerve  cells  before  leaving  the  ganglia. 

The  Nerves  are  round  or  flattened  cords,  communicating,  on  the  one  hand,  with 
the  cerebro-spinal  centre  or  the  ganglia,  and,  by  the  other,  distributed  to  the 
various  textures  of  the  body,  forming  the  medium  of  communication  between 
the  two. 

The  nerves  are  subdivided  into  two  great  classes,  the  cerebro-spinal,  which 

proceed  from  the  cerebro-spinal  axis,  and  the  sympathetic  or  ganglionic  nerves, 

which  proceed  from  the  ganglia  of  the  sympathetic ;  the  cerebro-spinal  are  the 

nerves  of  animal  life,  being  distributed  to  the  organs  of  the  senses,  the  skin,  and 

32 


498  NERVOUS   SYSTEM. 

to  the  active  organs  of  locomotion,  the  muscles.  The  sympathetic  or  ganglionic 
nerves  are  distributed  chiefly  to  the  viscera  and  bloodvessels,  and  are  termed  the 
nerves  of  organic  life. 

The  Cerebrospinal  nerves  consist  of  numerous  nerve  fibres,  collected  together  and 
inclosed  in  a  membranous  sheath.  A  small  bundle  of  primitive  fibres,  inclosed 
in  a  tubular  sheath,  is  called  a  funiculus:  if  the  nerve  is  of  small  size,  it  may 
consist  only  of  a  single  funiculus,  but,  if  large,  the  funiculi  are  collected  together 
into  larger  bundles  or  fasciculi;  and  are  bound  together  in  a  common  membranous 
investment,  termed  the  sheath.  In  structure,  the  common  sheath  investing  the 
whole  nerve,  as  well  as  the  septa  given  off  from  it,  which  separate  the  fasciculi, 
consist  of  areolar  tissue,  composed  of  white  and  yellow  elastic  fibres,  the  latter 
existing  in  greatest  abundance.  The  tubular  sheath  of  the  funiculi,  the  neurilemma, 
consists  of  a  fine,  smooth,  transparent  membrane,  which  may  be  easity  separated, 
in  the  form  of  a  tube,  from  the  fibres  it  incloses;  in  structure,  it  is,  for  the 
most  part,  a  simple  and  homogeneous  transparent  film,  occasionally  composed  of 
numerous  minute  reticular  fibres. 

The  cerebro-spinal  nerves  consist  almost  exclusively  of  the  tubular  nerve  fibres, 
the  gelatinous  fibres  existing  in  very  small  proportion. 

The  bloodvessels  supplying  a  nerve  terminate  in  a  minute  capillary  plexus, 
the  vessels  composing  which  run,  for  the  most  part,  parallel  with  the  funiculi ; 
they  are  connected  together  by  short  transverse  vessels,  forming  narrow  oblong 
meshes,  similar  to  the  capillary  system  of  muscle. 

The  nerve  fibres,  as  far  as  is  at  present  known,  do  not  coalesce,  but  pursue  an 
uninterrupted  course  from  the  centre  to  the  periphery.  In  dissecting  a  nerve, 
however,  into  its  component  funiculi,  it  may  be  seen  that  they  do  not  pursue  a 
perfectly  insulated  course,  but  occasionally  join  at  a  very  acute  angle  with  other 
funiculi  proceeding  in  the  same  direction ;  from  these,  again,  branches  are  given 
off,  which  join  again  in  like  manner  with  other  funiculi.  It  must  be  remembered, 
however,  that  in  these  communications  the  nerve  fibres  do  not  coalesce,  but  merely 
pass  into  the  sheath  of  the  adjacent,  nerve,  become  intermixed  with  the  nerve 
fibres,  and  again  pass  on  to  become  blended  with  the  nerve  fibres  in  some  adjoining 
fasciculus. 

Nerves,  in  their  course,  subdivide  into  branches,  and  these  frequently  commu- 
nicate with  branches  of  a  neighboring  nerve.  In  the  subdivision  of  a  nerve,  the 
filaments  of  which  it  is  composed  are  continued  from  the  trunk  into  the  branches, 
and  at  their  junction  with  the  branches  of  neighboring  nerves  the  filaments  pass 
to  become  intermixed  with  those  of  the  other  nerve  in  their  further  progress ;  in 
no  instance,  however,  do  the  separate  nerve  fibres  inosculate. 

The  communications  which  take  place  between  two  or  more  nerves  form  what 
is  called  a  plexus.  Sometimes  a  plexus  is  formed  by  the  primary  branches  of  the 
trunks  of  the  nerves,  as  the  cervical,  brachial,  lumbar,  and  sacral  plexuses,  and 
occasionally  by  the  terminal  fasciculi,  as  in  the  plexuses  formed  at  the  periphery 
of  the  body.  In  the  formation  of  a  plexus,  the  component  nerves  divide,  then 
join,  and  again  subdivide  in  such  a  complex  manner  that  the  individual  fasciculi 
become  interlaced  most  intricately ;  so  that  each  branch  leaving  a  plexus  may 
contain  filaments  from  each  of  the  primary  nervous  trunks  which  form  it.  In  the 
formation  also  of  the  smaller  plexuses  at  the  periphery  of  the  body,  there  is  a  free 
interchange  of  the  fasciculi  and  primitive  fibrils.  In  each  case,  however,  the 
individual  filaments  remain  separate  and  distinct,  and  do  not  inosculate  with  each 
other. 

It  is  probable,  that,  through  this  interchange  of  fibres,  the  different  branches 
passing  off  from  a  plexus  have  a  more  extensive  connection  with  the  spinal  cord 
than  if  each  of  them  had  proceeded  to  be  distributed  without  such  connection  with 
other  nerves.  Consequently,  the  parts  supplied  by  these  nerves  have  more  ex- 
tended relations  with  the  nervous  centres ;  by  this  means,  also,  groups  of  muscles 
may  be  associated  for  combined  action. 

The  termination  of  nerve  fibres  signifies  their  mode  of  distribution  and  con- 


GENERAL   ANATOMY.  499 

nection  in  the  nerve  centres,  and  in  the  different  organs  and  tissues  they  supply ; 
the  former  are  called  their  central,  the  latter  their  peripheral  terminations. 

As  to  the  mode  in  which  the  nerve  fibres  are  disposed  in  the  nervous  centres,  it 
is  probable  that  many  originate  from  nerve  corpuscles,  in  the  manner  before  men- 
tioned; others  probably  form  simple  loops.  As  to  the  more  exact  mode  of 
connection  of  the  nerve  fibres  with  the  nerve  corpuscles,  it  appears  that  more 
commonly  as  the  fibre  approaches  the  vesicle,  the  white  substance  of  Schwann 
gradually  disappears,  and  the  tubular  membrane  expands,  so  as  to  envelope  the 
corpuscle ;  the  sheath,  contracting  at  the  opposite  side  of  the  corpuscle,  is  again 
continuous  with  the  tubular  sheath  of  the  nerve  fibre,  a  prolongation  from  the 
granular  substance  of  the  corpuscle  extending  for  some  distance  along  each,  part 
of  the  nerve  tube,  and  taking  the  place  of  the  usual  elements  of  the  nerve  fibre. 
"Whether  this  relation  of  nerve  fibres  to  ganglion-corpuscles  is  common  to  all 
kinds  of  nerve  fibre's,  has  yet  to  be  determined. 

In  the  peripheral  distribution  of  the  nerves,  small  bundles  of  nerve  fibres  com- 
monly form  delicate  plexuses ;  these,  dividing,  give  off  the  primitive  fibres,  which 
are  disposed  of  in  various  ways  in  different  tissues. — 1.  Occasionally  the  elemen- 
tary fibres  are  disposed  in  hops,  as  has  been  found  in  the  internal  ear,  in  the 
papiike  of  the  tongue  and  of  the  skin,  in  the  tooth  pulp,  and  in  striped  muscular 
tissue ;  each  fibre,  after  issuing  from  a  branch  in  a  terminal  plexus,  runs  over  or 
through  the  substance  of  the  tissue,  and,  turning  back,  joins  the  same  or  a  neigh- 
boring branch,  in  which  it  probably  passes  back  to  a  nervous  centre.  2.  Some- 
times each  ultimate  nerve  fibre  divides  into  several  branches,  which  spread  out  in 
the  substance  of  the  tissue,  as  is  seen  in  the  retina,  in  the  muscular  tissue  of  the 
frog  and  lower  vertebrata.  3.  Sometimes  the  ultimate  nerve  fibres  form  minute 
plexuses,  as  in  certain  serous  membranes,  viz.,  the  peritoneum,  and  in  the  pia  mater 
of  the  brain  and  cord.  4.  Not  uncommonly  the  nerve  fibres  terminate  by  free 
ends,  as  is  seen  in  the  Pacinian  corpuscles,  and  in  some  of  the  papiike  of  the  skin. 
5.  Occasionally,  the  nerve  fibres  are  brought  into  direct  connection  with  nerve- 
corpuscles,  as  in  the  retina  and  in  the  lamina  spiralis  of  the  internal  ear. 

Some  nerve  fibres  have  no  peripheral  termination.  Gerber  has  shown,  that 
nerve  fibres  occasionally  form  loops,  by  their  j  unction  with  a  neighboring  fibre  in 
the  same  fasciculus,  and  return  to  the  cerebro-spinal  centre  without  having  any 
peripheral  termination.  These  he  considers  to  be  sentient  nerves,  appropriated 
exclusively  to  the  nerve  itself,  the  nervi  nervorum,  upon  which  the  sensibility  of 
the  nerve  depends,  and  quite  exclusive  of  the  sensation  produced  by  an  impression 
made  at  the  peripheral  end  of  the  nerve.  These  fibres  bear  some  analogy  to  those 
met  with  in  the  back  part  of  the  optic  commissure,  where  a  set  of  fibres  passes 
from  one  optic  tract  across  the  commissure  to  the  opposite  tract,  having  no  com- 
munication with  the  optic  nerve ;  also  in  the  communications  formed  between  the 
cervical  nerves  and  spinal  accessory  and  descendens  noni,  the  nerve  fibres  forming 
an  arch  connected  by  each  extremity  with  the  cerebro-spinal  centre,  and  having 
no  peripheral  termination. 

Again,  some  nerve  fibres  would  appear  to  have  no  central  connection  with  the 
cerebro-spinal  centre,  as  those  forming  the  most  anterior  part  of  the  optic  con> 
missure.  These  inter-retinal  fibres,  as  they  are  called,  commence  in  the  retina, 
pass  along  the  optic  nerve,  and  across  the  commissure  to  the  optic  nerve  and 
retina  of  the  opposite  side. 

The  point  of  connection  of  a  nerve  with  the  brain  or  spinal  cord  is  called,  for 
convenience  of  description,  its  origin  or  root.  If  the  fasciculi  of  which  the  nerve 
is  composed  should  all  arise  at  or  near  one  point,  or  along  one  tract,  the  root  is 
called  single.  If,  on  the  contrary,  the  fasciculi  divide  into  two  separate  bundles, 
which  are  connected  at  two  different  points  with  any  part  of  the  cerebro-spinal 
centre,  such  nerve  is  said  to  have  a  double  origin,  or  to  arise  by  two  roots,  each  of 
which  may  have  a  separate  function,  as  in  the  spinal  nerves.  The  point  where 
the  separate  fasciculi  of  a  nerve  are  connected  to  the  surface  of  the  cerebro-spinai 


500  NERVOUS   SYSTEM. 

centre,  is  called  the  apparent  origin  of  a  nerve  ;  the  term,  real  or  deep  origin,  being 
given  to  that  part  of  the  centre  from  which  a  nerve  actually  springs. 

The  Sympjathetic  nerve  consists  of  tubular  and  gelatinous  fibres,  intermixed 
with  a  varying  proportion  of  filamentous  areolar  tissue,  and  inclosed  in  a  sheath 
formed  of  fibro-areolar  tissue.  The  tubular  fibres  are,  for  the  most  part,  smaller 
than  those  composing  the  cerebro-spinal  nerves;  their  double  contour  is  less 
distinct,  and,  according  to  Eemak,  they  present  nuclei  similar  to  those  found  in 
the  gelatinous  nerve  fibres.  Those  branches  of  the  sympathetic  which  present  a 
well-marked  gray  color  are  composed  more  especially  of  gelatinous  nerve  fibres, 
intermixed  with  few  tubular  fibres ;  whilst  those  of  a  white  color  contain  more 
of  the  tubular  fibres,  and  few  gelatinous.  Occasionally  the  gray  and  white  cords 
run  together  in  a  single  nerve,  without  any  intermixture,  as  in  the  branches  of 
communication  between  the  sympathetic  ganglia  and  the  spinal  nerves,  or  in  the 
communicating  cords  between  the  ganglia. 

The  nerve  fibres  both  of  the  cerebro-spinal  and  sympathetic  system  convey 
impressions  of  a  twofold  kind.  The  sensitive  nerves,  called  also  centripetal  or 
afferent  nerves,  transmit  impressions  made  upon  their  peripheral  extremities  to  the 
nervous  centres,  and  in  this  way  the  mind,  through  the  medium  of  the  brain, 
becomes  conscious  of  external  objects.  The  motor  nerves,  called  also  centrifugal 
or  efferent  nerves,  transmit  impressions  from  the  nervous  centres  to  the  parts  to 
which  the  nerves  are  distributed,  these  impressions  either  exciting  muscular  con- 
tractions, or  influencing  the  processes  of  nutrition,  growth,  and  secretion. 

The  Cerebro-spinal  Centre  consists  of  two  parts,  the  spinal  cord  and  the  ence- 
phalon :  the  latter  may  be  subdivided  into  the  cerebrum,  the  cerebellum,  the  pons 
Varolii,  and  the  medulla  oblongata. 

THE'  SPINAL  COED  AND  ITS  MEMBRANES. 

Dissection.  To  dissect  the  cord  and  its  membranes,  it  will  be  necessary  to  lay  open  the  whole 
length  of  the  spinal  canal.  For  this  purpose  the  muscles  must  be  separated  from  the  vertebral 
grooves,  so  as  to  expose  the  spinous  processes  and  laminae  of  the  vertebrae ;  and  the  hitter 
must  be  sawn  through  on  each  side,  close  to  the  roots  of  the  transverse  processes,  from  the  third 
or  fourth  cervical  vertebra,  above,  to  the  sacrum  below.  The  vertebral  arches  haviDg  been  dis- 
placed, by  means  of  a  chisel,  and  the  separate  fragments  removed,  the  dura  mater  will  be 
exposed,  covered  by  a  plexus  of  veins  and  a  quantity  of  loose  areolar  tissue,  often  infiltrated 
with  a  serous  fluid.  The  arches  of  the  upper  vertebrae  are  best  divided  by  means  of  a  strong 
pair  of  forceps. 

Membeanes  of  the  Cord. 

The  membranes  which  envelop  the  spinal  cord  are  three  in  number.  The 
most  external  is  the  dura  mater,  a  strong  fibrous  membrane,  which  forms  a  loose 
sheath  around  the  cord.  The  most  internal  is  the  pia  mater,  a  cellulo- vascular 
membrane,  which  closely  invests  the  entire  surface  of  the  cord.  Between  the 
two,  is  the  arachnoid  membrane,  an  intermediate  serous  sac,  which  envelopes  the 
cord,  and  is  then  reflected  on  the  inner  surface  of  the  dura  mater. 

The  Dura  Mater  of  the  cord,  continuous  with  that  which  invests  the  brain, 
is  a  loose  sheath  which  surrounds  it,  being  separated  from  the  bony  walls  of  the 
spinal  canal  by  a  quantity  of  loose  areolar  adipose  tissue,  and  a  plexus  of  veins. 
It  is  attached  to  the  circumference  of  the  foramen  magnum,  and  to  the  posterior 
common  ligament,  throughout  the  whole  length  of  the  spinal  canal,  by  fibrous 
tissue ;  and  extends,  below,  as  far  as  the  top  of  the  sacrum ;  but,  beyond  this 
point,  it  is  impervious,  being  continued,  in  the  form  of  a  slender  cord,  to  the  back 
of  the  coccyx,  where  it  blends  with  the  periosteum.  This  sheath  is  much  larger 
tnan  is  necessary  for  its  contents,  and  its  size  is  greater  in  the  cervical  and  lumbar 
regions,  than  in  the  dorsal.  Its  inner  surface  is  smooth,  and  covered  by  a  layer  of 
polygonal  cells ;  and  on  each  side  may  be  seen  the  double  openings  which  trans- 
mit the  two  roots  of  the  corresponding  spinal  nerve,  the  fibrous  layer  of  the  dura 


/J~U* 


C^<K^    »*< 


MEMBRANES   OF   THE    CORD. 


501 


l'ii 


253.— The  Spinal  Cord  and 
its  Membranes. 


mater  being  continued  in  the  form,  of  a  tubular  prolongation  on  them  as  they  issue 
from  these  apertures.  These  prolongations  of  the  dura  mater  are  short  in  the 
upper  part  of  the  spine,  but  become  gradually  longer  below,  forming  a  number 
of  tubes  of  fibrous  membrane,  which  inclose  the  sacral  nerves,  and  are  contained 
in  the  spinal  canal. 

The  chief  peculiarities  of  the  dura  mater  of  the  cord,  as  compared  with  that 
investing  the  brain,  are  the  following : — 

The  dara  mater  of  the  cord  is  not  adherent  to  the 
bones  of  the  spinal  canal,  which  have  an  independent 
periosteum. 

It  does  not  send  partitions  into  the  fissures  of  the 
cord,  as  in  the  brain. 

Its  fibrous  laminse  do  not  separate,  to  form  venous 
sinuses,  as  in  the  brain. 

Structure.  The  dura  mater  consists  of  white  fibrous 
tissue,  arranged  in  bands  which  intersect  one  another. 
It  is  sparingly  supplied  with  vessels ;  and  no  nerves 
have  as  yet  been  traced  into  it. 

The  Arachnoid  is  exposed  by  slitting  up  the  dura 
mater,  and  reflecting  this  membrane  on  either  side 
(fig.  253).  It  is  a  thin,  delicate,  serous  membrane, 
which  invests  the  outer  surface  of  the  cord,  and  is 
then  reflected  upon  the  inner  surface  of  the  dura 
mater,  to  which  it  is  intimately  adherent.  That 
portion  which  surrounds  the  cord  is  called  the  vis- 
ceral layer  of  the  arachnoid;  and  that  which  lines 
the  inner  surface  of  the  dura  mater,  the  parietal 
layer;1  the  interval  between  the  two  is  called  the 
cavity  of  the  arachnoid.  The  visceral  layer  forms 
a  loose  sheath  around  the  cord,  so  as  to  leave  a  con- 
siderable interval  between  the  two  which  is  called 
the  sub-arachnoidean  space.  This  space  is  largest 
at  the  lower  part  of  the  spinal  canal,  and  incloses 
the  mass  of  nerves  which  fbrm  the  cauda  equina.    It 

contains  an  abundant  serous  secretion,  the  cerebro-spinal  fluid,  and  usually  com- 
municates with  the  general  ventricular  cavity  of  the  brain,  by  means  of  an  opening 
in  the  fibrous  layer  of  the  inferior  boundary  of  the  fourth  ventricle.  This 
secretion  is  sufficient  in  amount  to  ex- 
pand the  arachnoid  membrane,  so  as  to 
completely  fill  up  the  whole  of  the  space 
included  in  the  dura  mater.  The  sub- 
arachnoidean  space  is  crossed,  at  the  back 
part  of  the  cord,  by  numerous  fibrous 
bands,  which  stretch  from  the  arachnoid 
to  the  pia  mater,  especially  in  the  cervi- 
cal region,  and  is  partially  subdivided 
by  a  longitudinal  membranous  partition, 
which  serves  to  connect  the  arachnoid 
with  the  pia  mater,  opposite  the  posterior 
median  fissure.  This  partition  is  incom- 
plete, and  cribriform  in  structure,  consisting  of  bundles  of  white  fibrous  tissue, 
interlacing  with  each  other.  The  visceral  layer  of  the  arachnoid  surrounds  the 
spinal  nerves  where  they  arise  from  the  cord,  and  in  ploses  them  in  a  tubular 


Fig. 


254. — Transverse  Section  of  the  Spinal 
Cord  and  its  Membranes. 


1  Kcilliker  denies  that  the  inner  surface  of  the  dura  mater  is  covered  by  an  outer  layer  of  the 
arachnoid,  and  states,  that  nothing  is  found  here  except  an  epithelial  layer,  no  trace  of  a  special 
membrane  existing. 


502  NERYOTTS   SYSTEM. 

sheath  as  far  as  their  point  of  exit  from  the  dura  mater,  where  it  becomes  con- 
tinuous with  the  parietal  layer. 

The  arachnoid  is  destitute  of  vessels.  No  nerves  have  as  yet  been  traced  into 
this  membrane. 

The  Pia  Mater  of  the  cord  is  exposed  on  the  removal  of  the  arachnoid  (fig.  253). 
It  is  less  vascular  in  structure  than  the  pia  mater  of  the  brain,  with  which  it  is 
continuous,  being  thicker,  more  dense  in  structure,  and  composed  of  fibrous  tissue, 
arranged  in  longitudinal  bundles.  It  covers  the  entire  surface  of  the  cord,  to 
which  it  is  very  intimately  adherent,  forming  its  neurilemma,  and  sends  a  process 
downwards  into  its  anterior  fissure,  and  another,  extremely  delicate,  into  the 
posterior  fissure.  It  also  forms  a  sheath  for  each  of  the  filaments  of  the  spinal 
nerves,  and  invests  the  nerves  themselves.  A  longitudinal  fibrous  band  extends 
along  the  middle  line  on  its  anterior  surface,  called  by  Haller,  the  linea  splendens ; 
and  a  somewhat  similar  band,  the  ligamentum  denticulatum,  is  situated  on  each 
side.  At  the  point  where  the  cord  terminates,  the  pia  mater  becomes  contracted, 
and  is  continued  down  as  a  long,  slender  filament  {filum  terminale),  which 
descends  through  the  centre  of  the  mass  of  nerves  forming  the  cauda  equina,  and 
is  blended  with  the  impervious  sheath  of  dura  mater,  on  a  level  with  the  top  of 
the  sacral  canal.  It  assists  in  maintaining  the  cord  in  its  position  during  the 
movements  of  the  trunk,  and  is,  from  this  circumstance,  called  the  central 
ligament  of  the  spinal  cord.  It  contains  a  little  nervous  substance,  which  may 
be  traced  for  some  distance  into  its  upper  part,  and  is  accompanied  by  a  small 
artery  and  vein. 

Structure.  The  pia  mater  of  the  cord,  though  less  vascular  than  that  which 
invests  the  brain,  contains  a  network  of  delicate  vessels  in  its  substance.  It  is 
also  supplied  with  nerves,  which  are  derived  from  the  sympathetic,  and  from  the 
posterior  roots  of  the  spinal  nerves.  At  the  upper  part  of  the  cord,  the  pia 
mater  presents  a  grayish,  mottled  tint,  which  is  owing  to  yellowish  or  brown 
pigment  cells  being  scattered  within  its  tissue. 

The  Liyamentum  Denticulatum  (fig.  253)  is  a  narrow,  fibrous  band,  situated  on 
each  side  of  the  spinal  cord,  throughout  its  entire  length,  and  separating  the 
anterior  from  the  posterior  roots  of  the  spinal  nerves,  having  received  its  name 
from  the  serrated  appearance  which  it  presents.  Its  inner  border  is  continuous 
with  the  pia  mater,  at  the  side  of  the  cord.  Its  outer'border  presents  a  series  of 
triangular,  dentated  serrations,  the  points  of  which  are  fixed,  at  intervals,  to  the 
dura  mater,  serving  to  unite  together  the  two  layers  of  the  arachnoid  membrane. 
These  serrations  are  about  twenty  in  number,  on  each  side,  the  first  being  attached 
to  the  dura  mater,  opposite  the  margin  of  the  foramen  magnum,  between  the 
vertebral  artery  and  the  hypoglossal  nerve;  and  the  last  corresponds  to  nearly  the 
lower  end  of  the  cord.  Its  use  is  to  support  the  cord  in  the  fluid  by  which  it  is 
surrounded. 

The  Spinal  Cord. 

The  spinal  cord  {medulla  spinalis)  is  the  cylindrical  elongated  part  of  the  cerebro- 
spinal axis,  which  is  contained  in  the  spinal  canal.  Its  length  is  usually  about 
sixteen  or  seventeen  inches,  and  its  weight,  when  divested  of  its  membranes  and 
nerves,  about  one  ounce  and  a  half,  its  proportion  to  the  encephalon  being  about 
1  to  33.  It  does  not  nearly  fill  the  canal  in  which  it  is  contained,  its  investing 
membranes  being  separated  from  the  surrounding  walls  by  areolar  tissue  and 
a  plexus  of  veins.  It  occupies,  in  the  adult,  the  upper  two-thirds  of  the  spinal 
canal,  extending  from  the  foramen  magnum  to  the  lower  border  of  the  body  of 
the  first  lumbar  vertebra,  where  it  terminates  in  a  slender  filament  of  gray 
substance,  the  filum  terminale,  which  lies  concealed  among  the  leash  of  nerves 
forming  the  cauda  equina.  In  the  foetus,  before  the  third  month,  it  extends  to  the 
bottom  of  the  sacral  canal;  but,  after  this  period,  it  gradually  recedes  from 
below,  as  the  growth  of  the  bones  composing  the  canal  is  more  rapid  in  proportion 


SPINAL   COED. 


503 


Fi|T.  255.— Spinal  Cord,  Side 
View.  Plan  of  the  Fissures 
and  Columns. 


Posterior 
Lateral  Fissure 


than  the  cord ;  so  that,  in  the  child  at  birth,  it  extends  as  far  as  the  third  lumbar 
vertebra.  Its  position  varies  also  according  to  the  degree  of  curvature  of  the 
spinal  column,  being  raised  somewhat  in  flexion  of  the  spine.  On  examining 
its  surface  it  presents  a  difference  in  its  diameter  in  different  parts,  being  marked 
by  two  enlargements,  an  upper  or  cervical,  and  a  lower  or  lumbar.  The  cervical 
enlargement,  which  is  the  larger,  extends  from  the  third  cervical  to  the  first  dorsal 
vertebra :  its  greatest  diameter  is  in  the  transverse  direction,  and  it  corresponds 
with  the  origin  of  the  nerves  which  supply  the  upper  extremities.  The  lower 
or  lumbar  enlargement  is  situated  opposite  the  last  dorsal  vertebra,  its  greatest 
diameter  being  from  before  backwards.  It  corresponds  with  the  origin  of  the 
nerves  which  supply  the  lower  extremities.  In  form,  the  spinal  cord  is  a  flattened 
cylinder.  Its  anterior  surface  presents,  along  the  middle  line,  a  longitudinal 
fissure,  the  anterior  median  fissure ;  and,  on  its  posterior  surface,  another  fissure 
exists,  which  also  extends  along  the  entire  length  of  the  cord,  the  posterior  median 
fissure.  These  fissures  serve  to  divide  the  cord  into  two  symmetrical  halves, 
which  are  united  in  the  middle  line,  throughout  their  entire  length,  by  a  transverse 
band  of  nervous  substance,  the  commissure. 

The  Anterior  median  fissure  is  wider,  but  of  less 
depth,  than  the  posterior,  extending  into  the  cord  for 
about  one-third  of  its  thickness,  and  is  deepest  at 
the  lower  part  of  the  cord.  It  contains  a  prolonga- 
tion from  the  pia  mater ;  and  its  floor  is  formed  by 
the  anterior  white  commissure,  which  is  perforated  by 
numerous  bloodvessels,  which  pass  to  the  centre  of 
the  cord. 

The  Posterior  median  fissure  is  much  more  deli- 
cate than  the  anterior,  and  most  distinct  at  the  upper 
and  lower  parts  of  the  cord.  It  extends  into  the 
cord  to  about  one-half  of  its  depth.  It  contains  a 
very  slender  process  of  the  pia  mater  and  numerous 
bloodvessels,  and  its  floor  is  formed  by  a  thin  layer 
of  white  substance,  the  posterior  white  commissure. 
Some  anatomists  state,  that  the  bottom  of  this  fissure 

corresponds  to  the  gray  matter,  except  in  the  cervical  region,  and  at  a  point 
corresponding  to  the  enlargement  in  the  lumbar  region. 

Lateral  Fissures.  On  either  side  of  the  anterior  median  fissure,  a  linear  series 
of  foramina  may  be  observed,  indicating  the  points  where  the  anterior  roots  of 
the  spinal  nerves  emerge  from  the  cord.  This  is  called,  by  some  anatomists,  the 
anterior  lateral  fissure  of  the  cord,  although  no  actual  fissure  exists  in  this 
situation.  On  either  side  of  the  posterior  median  fissure,  along  the  line  of 
attachment  of  the  posterior  roots  of  the  nerves,  a  delicate  fissure  may  be  seen, 
leading  down  to  the  gray  matter  which  approaches  the  surface  in  this  situation : 
this  is  called  the  posterior  lateral  fissure  of  the  spinal  cord.  On  the  posterior 
surface  of  the  spinal  cord,  on  either  side  of  the  posterior  median  fissure,  is  a  slight 
longitudinal  furrow,  marking  off  two  slender  tracts,  the  posterior  median  columns. 
These  are  most  distinct  in  the  cervical  region,  but  are  stated  by  Foville  to  exist 
throughout  the  whole  length  of  the  cord. 

Columns  of  the  Cord.  The  fissures  divide  each  half  of  the  spinal  cord  into 
four  columns,  an  anterior  column,  a  lateral  column,  a  posterior  column  and  a 
posterior  median  column. 

The  anterior  column  includes  all  the  portion  of  the  cord  between  the  anterior 
median  fissure  and  the  anterior  lateral  fissure,  from  which  the  anterior  roots  of 
the  nerves  arise.  It  is  continuous  with  the  anterior  pyramid  of  the  medulla 
oblongata. 

The  lateral  column,  the  largest  segment  of  the  cord,  includes  all  the  portion 
between  the  anterior  and  posterior  lateral  fissures.  It  is  continuous  with  the 
lateral  column  of  the  medulla.     By  some  anatomists,  the  anterior  and  lateral 


504  NERVOUS   SYSTEM. 

columns  are  included  together,  under  the  name  of  the  antero-lateral  column, 
which  forms  rather  more  than  two-thirds  of  the  entire  circumference  of  the 
cord. 

The  posterior  column  is  situated  between  the  posterior  median  and  posterior 
lateral  fissures.     It  is  continuous  with  the  restiform  body  of  the  medulla. 

The  posterior  median  column  is  that  narrow  segment  of  the  cord  which  is  seen 
on  each  side  of  the  posterior  median  fissure,  usually  included  with  the  preceding, 
as  the  posterior  column. 

Structure  of  the  Cord.  If  a  transverse  section  of  the  spinal  cord  be  made,  it 
will  be  seen  to  consist  of  white  and  gray  nervous  substance.  The  white  matter 
is  situated  externally,  and  constitutes  its  chief  portion.  The  gray  substance 
occupies  its  centre,  and  is  so  arranged  as  to  present  on  the  surface  of  the  section 
two  crescentic  masses  placed  one  in  each  lateral  half  of  the  cord,  united  together 
by  a  transverse  band  of  gray  matter,  the  gray  commissure.  Each  crescentic  mass 
has  an  anterior  and  posterior  horn.  The  posterior  horn  is  long  and  narrow,  and 
approaches  the  surface  at  the  posterior  lateral  fissure,  near  which  it  presents  a 
slight  enlargement.  The  anterior  horn  is  short  and  thick,  and  does  not  quite 
reach  the  surface,  but  extends  towards  the  point  of  attachment  of  the  anterior 
roots  of  the  nerves.  Its  margin  presents  a  dentate  or  stellate  appearance.  Owing 
to  this  peculiar  arrangement  of  the  gray  matter,  the  anterior  and  posterior  horns 
projecting'  towards  the  surface,  each  half  of  the  cord  is  divided,  more  or  less 
completely,  into  three  columns,  anterior,  middle,  and  posterior ;  the  anterior  and 
middle  being  joined  to  form  the  antero-lateral  column,  as  the  anterior  horn  does 
not  quite  reach  the  surface. 

The  gray  commissure,  which  connects  the  two  crescentic  masses  of  gray  matter, 
is  separated  from  the  bottom  of  the  anterior  median  fissure  by  the  anterior  white 
commissure ;  and,  from  the  bottom  of  the  posterior  fissure  by  the  posterior  white 
commissure.  The  gray  commissure  consists  of  a  transverse  band  of  gray  matter, 
and  of  white  fibres,  derived  from  the  opposite  half  of  the  cord  and  the  posterior 

roots  of  the   nerves.     The  anterior   commissure   is 
Fig.  256.— -Transverse  Sections     formed,  partly  of  fibres  from  the  anterior  column, 
of  the  Cord.  an(j  partiy  from  ^  fiDrils  of  the  anterior  roots  of 

the  spinal  nerves,  which  decussate  as  they  pass  across 
from  one  to  the  other  side. 

The  mode  of  arrangement  of  the  gray  matter,  and 
Opposite  Middle  of  Cervical  re$s     its  amount  in  proportion  to  the  white,  vary  in  different 

parts  of  the  cord.  Thus,  the  posterior  horns  are 
long  and  narrow,  in  the  cervical  region;  short  and 
narrower,  in  the  dorsal;  short,  but  wider,  in  the 
lumbar  region.  In  the  cervical  region,  the  crescentic 
portions  are  small,  the  white  matter  more  abundant 
opposite  Middle.  <$•  Dorsal  ret*         than  in  any  other  region  of  the  cord.     In  the  dorsal 

region,  the  gray  matter  is  least  developed,  the  white 
matter  being  also  small  in  quantity.  In  the  lumbar 
region,  the  gray  matter  is  more  abundant  than  in 
any  other  region  of  the  cord.  Towards  the  lower 
cpposit*  zumiar  rryion,  end  of  the  cord,  the  white  matter  gradually  ceases. 

The  crescentic  portions  of  the  gray  matter  soon  blend 
into  a  single  mass,  which  forms  the  only  constituent  of  its  extreme  point. 

The  white  substance  of  the  cord  consists  of  transverse,  oblique,  and  longitudinal  fibres,  with 
oloodvessels  and  connective  tissue. 

rYhz  transverse  fibres  proceed  from  the  gray  substance,  and  form  with  each  other  a  kind  of 
plexus  between  the  bundles  of  longitudinal  fibres  with  which  many  are  continuous  ;  while  others 
reach  the  surface  of  the  cord  through  fissures  containing  connective  tissue.  Within  the  gray 
substance  thev  are  continuous  with  the  roots  of  the  nerves,  the  processes  of  the  nerve  cells,  and 
with  the  anterior  and  posterior  commissures.  The  oblique  fibres  proceed  from  the  gray  substance 
both  upwards  and  downwards  :  they  form  the  deep  strata  of  the  white  columns,  and,  after  running 


SPINAL   CORD. 


505 


Fig.  257. — Transverse  Section  of  the  gray  substance 
of  the  spinal  cord,  near  the  middle  of  the 
dorsal  region.     Magnified  13  diameters. 


g,t  ^>* 


a  variable  length  become  superficial.     The  longitudinal  fibres  are  more  superficial,  run  nearly 
parallel  with  each  other,  and  form  the  greater  portion  of  the  white  columns. 

The  gray  substance  of  the  cord  con- 
sists of,  1.  Nerve  fibres  of  variable,  but 
smaller,  average  diameter  than  those  of 
the  columns.  2.  Nerve  cells  of  various 
shapes  and  sizes,  with  from  two  to  eight 
processes.  3.  Bloodvessels  and  con- 
nective tissue. 

Each  lateral  half  of  the  gray  sub- 
stance is  divided  into  an  anterior  and 
posterior  horn,  and  the  tractus  inter- 
medio  lateralis,  or  lateral  part  of  the 
gray  substance  between  the  anterior 
aud  posterior  cornua. 

The  posterior  horn  consists  of  two 
parts,  the  caput  cornu,  or  expanded  ex- 
tremity of  the  horn  (fig.  257),  round 
which  is  the  lighter  space  or  lamina, 
the  gelatinous  substance;  and  the  cervix 
cornu,  or  remaining  narrow  portion  of 
the  horn,  as  far  forwards  as  the  central 
canal. 

The  gelatinous  substance  contains 
along  its  border  a  series  of  large  nerve 
cells  ;  but  more  internally  consists  of  a 
stratum  of  small  cells  traversed  by 
transverse,  oblique,  and  longitudinal 
fibres  (figs.  258  and  259). 


Fig.  258. — Transverse  Section  of  the  gray  substance  of  the  spinal  cord  through  the  middle  of  the 
lumbar  enlargement.  On  the  left  side  the  groups  of  large  cells  are  seen  ;  on  the  right  side 
the  course  of  the  fibres  without  the  cells.     Magnified  13  diameters. 


i.fc.ftr&SV'f 


Nearly  the  whole  inner  half  of  the  cervix  is  occupied  by  a  remarkable  and  important  column 
of  nerve  cells,  called  the  posterior  vesicular  column  (fig.  257),  which  varies  in  size  and  appearance 
in  different  regions  of  the  cord,  and  is  intimatelv  connected  with  the  posterior  roots  of  the 
nerves. 


506 


NERVOUS   SYSTEM. 


Fig.  259.— Longitudinal  Section  of  the 
white  and  gray  substance  of  the 
spinal  cord,  through  the  middle  of  the 
lambar  enlargement.   Mag.  14  diam. 


Within  and  along  the  outer  border  of  the  cervix  are  several  thick  bundles  of  longitudinal 
fibres,  represented  in  the  adjoining  figure  by  the  dark  spots ;  other  bundles  of  the  same  kind 
may  be  seen  in  the  gray  substance  along  the  line  of  junction  of  the  caput  with  the  cervix  cornu 
(fig.  258). 

The  anterior  horn  of  the  gray  substance  in  the  cervical  and  lumbar  swellings,  where  it  gives 
origin  to  the  nerves  of  the  extremities,  is  much  larger  than  in  any  other  region,  and  contains 
several  distinct  groups  of  large  and  variously  shaped  cells.  This  is  well  shown  on  comparing 
the  above  figures. 

The  tractus  intermedia  lateralis  (fig.  257)  extends 
from  the  upper  part  of  the  lumbar  to  the  lower  part 
of  the  cervical  enlargement,  and  consists  of  variously 
shaped  cells,  which  are  smaller  than  those  of  the 
anterior  cornu.  In  the  neck  above  the  cervical  en- 
largement, a  similar  tract  reappears,  and  is  traversed 
by  the  lower  part  of  the  spinal  accessory  nerve. 

Origin  of  the  Spinal  Nerves.  The  posterior  roots 
are  larger  than  the  anterior;  but  their  component 
filaments  are  finer  and  more  delicate.  They  are  all 
attached  immediately  to  the  posterior  columns  only, 
and  decussate  with  each  other  in  all  directions  through 
the  columns;  but  some  of  them  pass  through  the 
gray  substance  into  both  the  lateral  and  anterior 
columns.  Within  the  gray  substance,  they  run  lon- 
gitudinally upwards  and  downwards ;  transversely 
through  the  posterior  commissure  to  the  opposite 
side ;  and  into  the  anterior  cornu  of  their  own  side 
(figs.  258  and  259). 

The  anterior  roots  are  attached  exclusively  to  the 
anterior  columns,  or  rather  to  the  anterior  part  of  ihe 
antero-lateral  columns ;  for  there  is  no  antero-lateral 
fissure  dividing  the  anterior  from  the  lateral  column. 
Within  the  gray  substance,  the  fibrils  cross  each  other, 
and  diverge  in  all  directions  like  the  expanded  hairs 
of  abrush  (figs.  258  and  259),  some  of  them  running  more 
or  less  longitudinally  upwards  and  downwards ;  and 
others  decussating  with  those  of  the  opposite  side 
through  the  anterior  commissure  in  front  of  the  cen- 
tral canal. 

All  the  fibres  of  both  roots  of  the  nerves  proceed 
through  the  white  columns  into  the  gray  substance, 
with,  perhaps,  the  exception  of  some  which  appear  to 
run  longitudinally  in  the  posterior  columns ;  but 
whether  these  latter  fibres  of  the  posterior  roots  ulti- 
mately enter  the  gray  substance  of  the  cord  after  a 
very  oblique  course,  or  whether  they  proceed  upwards 
to  the  brain,  is  uncertain.' 


6e(at 
Salsl'ctnce 


Grey 

Substance 


MtT  Boots 


The  Central  Canal. 

In  the  foetus,  until  after  the  sixth  month,  a  canal,  continuous  with  the  general 
ventricular  cavity  of  the  brain,  extends  throughout  the  entire  length  of  the  spinal 
cord,  formed  by  the  closing-in  of  a  previously  open  groove. 

In  the  adult,  this  canal  can  only  be  seen  at  the  upper  part  of  the  cord,  extending 
from  the  point  of  the  calamus  scriptorius,  in  the  floor  of  the  fourth  ventricle,  for 
about  half  an  inch  down  the  centre  of  the  cord,  where  it  terminates  in  a  cul-de- 
sac  ;  the  remnant  of  the  canal  being  just  visible  in  a  section  of  the  cord,  as  a 
small,  pale  spot,  corresponding  to  the  centre  of  the  gray  commissure,  its  cavity 
being  lined  with  a  layer  of  cylindrical  ciliated  epithelium.  In  some  cases,  this 
canal  remains  pervious  throughout  the  whole  length  of  the  cord. 


1  The  above  description,  and  accompanying  illustrations,  kindly  furnished  me  by  my  friend, 
Mr.  Lockhart  Clarke,  embodies  a  condensed  account  of  his  laborious  and  extensive  observations 
on  the  structure  of  the  spinal  cord.  For  further  information  on  this  subject,  vide  Phil.  Traus. 
iS51— 1853,  Part  iii. ;  1858,  Part  i. ;  1859,  Part  i. 


DURA   MATER.  50? 


THE  BRAIN  AND  ITS  MEMBRANES. 

Dissection.  To  examine  the  brain  with  its  membranes,  the  skull-cap  should  first  be  removed. 
This  may  be  effected  by  sawing  through  the  external  table,  commencing,  in  front,  about  an  inch 
above  the  margin  of  the  orbit,  and  extending,  behind,  to  a  level  with  the  occipital  protuberance. 
The  internal  table  must  then  be  broken  through  with  the  chisel  and  hammer,  to  prevent  injury 
to  the  investing  membranes  or  brain,  and,  after  having  been  loosened,  it  should  be  forcibly  detached, 
when  the  dura  mater  will  be  exposed.  The  adhesion  between  the  bone  and  the  dura  mater  is 
very  intimate,  and  much  more  so  in  the  young  subject  than  in  the  adult. 

The  membranes  of  the  brain  are,  the  dura  mater,  arachnoid  membrane,  and  pia 
mater. 

Dura  Matee. 

The  dura  mater  is  a  thick  and  dense  inelastic  fibrous  membrane,  which  lines 
the  interior  of  the  skull.  Its  outer  surface  is  rough  and  fibrillated,  and  adheres 
closely  to  the  inner  surface  of  the  bones,  forming  their  internal  periosteum,  this 
adhesion  being  more  intimate  opposite  the  sutures  and  at  the  base  of  the  skull ; 
at  the  margin  of  the  foramen  magnum  it  becomes  continuous  with  the  dura 
mater  lining  the  spinal  canal.  Its  inner  surface  is  smooth  and  epitheliated, 
being  lined  by  the  parietal  layer  of  the  arachnoid.  The  dura  mater  is,  therefore, 
a  fibro-serous  membrane,  composed  of  an  external  fibrous  lamella,  and  an  internal 
serous  layer.  It  sends  numerous  processes  inwards,  into  the  cavity  of  the  skull, 
for  the  support  and  protection  of  the  different  parts  of  the  brain  ;  it  is  also  pro- 
longed to  the  outer  surface  of  the  skull,  through  the  various  foramina  which 
exist  at  its  base,  where  it  is  continuous  with  the  pericranium;  and  its  fibrous  layer 
forms  sheaths  for  the  nerves  which  pass  through  these  apertures.  At  the  base 
of  the  skull,  it  sends  a  fibrous  prolongation  into  the  foramen  caecum ;  it  lines  the 
olfactory  groove,  and  sends  a  series  of  tubular  prolongations  round  the  filament; 
of  the  olfactory  nerves  as  they  pass  through  the  cribriform  foramina ;  a  prolonga- 
tion is  also  continued  through  the  sphenoidal  fissure  into  the  orbit,  and  another 
is  continued  into  the  same  cavity  through  the  optic  foramen,  forming  a  sheath  for 
the  optic  nerve,  which  is  continued  as  far  as  the  eyeball.  In  certain  situations  in 
the  skull  already  mentioned,  the  fibrous  layers  of  this  membrane  subdivide,  to 
form  sinuses  for  the  passage  of  venous  blood.  Upon  the  upper  surface  of  the 
dura  mater,  in  the  situation  of  the  longitudinal  sinus,  may  be  seen  numerous 
small  whitish  bodies,  the  gland ul®  Pacchioni. 

Structure.  The  dura  mater  consists  of  white  fibrous  and  elastic  tissues,  arranged 
in  flattened  laminae,  which  intersect  one  another  in  every  direction.     , 

Its  arteries  are  very  numerous,  but  are  chiefly  distributed  to  the  bones.  Those 
found  in  the  anterior  fossa  are  the  anterior  meningeal,  from  the  anterior  and 
posterior  ethmoidal,  and  internal  carotid.  In  the  middle  fossa  are  the  middle  and 
small  meningeal,  from  the  internal  maxillary,  and  a  third  branch  from  the 
ascending  pharyngeal,  which  enters  the  skull  through  the  foramen  lacerum  basis 
cranii.  In  the  posterior  fossa,  are  the  posterior  meningeal  branch  of  the  occipital, 
which  enters  the  skull  through  the  jugular  foramen;  the  posterior  meningeal,  from 
the  vertebral ;  and  occasionally  meningeal  branches  from  the  ascending  pharyn- 
geal, which  enter  the  skull,  one  at  the  jugular  foramen,  the  other  at  the  anterior 
condyloid  foramen. 

The  veins,  which  return  the  blood  from  the  dura  mater,  and  partly  from  the 
bones,  anastomose  with  the  diploic  veins.  These  vessels  terminate  in  the  various 
sinuses,  with  the  exception  of  two  which  accompany  the  middle  meningeal  artery; 
these  pass  from  the  skull  at  the  foramen  spinosum. 

The  nerves  of  the  dura  mater  are,  the  recurrent  branch  of  the  fourth,  and  fila- 
ments from  the  Casserian  ganglion,  the  ophthalmic  nerve,  and  sympathetic. 

The  so-called  glandulae  Pacchioni  are  numerous  small  whitish  granulations, 
usually  collected  into  clusters  of  variable  size,  which  are  found  in  the  following 
situations :     1.  Upon  the  outer  surface  of  the  dura  mater,  in  the  vicinity  of  the 


508  NERVOUS    SYSTEM. 

superior  longitudinal  sinus,  being  received  into  little  depressions  on  the  inner 
surface  of  the  calvarium.  2.  On  the  inner  surface  of  the  dura  mater.  3.  In  the 
superior  longitudinal  sinus.  4.  On  the  pia  mater  near  the  margin  of  the 
hemispheres. 

These  bodies  are  not  glandular  in  structure,  but  consist  of  a  fibro-cellular  matrix 
originally  developed  from  the  pia  mater ;  by  their  growth,  they  produce  absorption 
or  separation  of  the  fibres  of  the  dura  mater;  in  a  similar  manner  they  make  their 
way  into  the  superior  longitudinal  sinus,  where  they  are  covered  by  the  lining 
membrane.  The  cerebral  layer  of  the  arachnoid  in  the  situation  of  these  growths 
is  usually  thickened  and  opaque,  and  adherent  to  the  parietal  portion. 

These  bodies  are  not  found  in  infancy,  and  very  rarely  until  the  third  year. 
They  are  usually  found  after  the  seventh  year ;  and  from  this  period  they  increase 
in  number  as  age  advances.     Occasionally  they  are  wanting. 

Processes  of  the  Dura  Mater. 

The  processes  of  the  dura  mater,  sent  inwards  into  the  cavity  of  the  skull,  are 
three  in  number,  the  falx  cerebri,  the  tentorium  cerebelli,  and  the  falx  cerebelli. 

The  falx  cerebri,  so  named  from  its  sickle-like  form,  is  a  strong  arched  process 
of  the  dura  mater,  which  descends  vertically  in  the  longitudinal  fissure  between  the 
two  hemispheres  of  the  brain.  It  is  narrow  in  front,  where  it  is  attached  to  the 
crista  galli  process  of  the  ethmoid  bone ;  and  broad  behind,  where  it  is  connected 
with  the  upper  surface  of  the  tentorium.  Its  upper  margin  is  convex,  and  attached 
to  the  inner  surface  of  the  skull  as  far  back  as  the  internal  occipital  protuberance. 
In  this  situation,  it  is  broad,  and  contains  the  superior  longitudinal  sinus.  Its 
lower  margin  is  free,  concave,  and  presents  a  sharp  curved  edge  which  contains 
the  inferior  longitudinal  sinus. 

The  tentorium  cerebelli,  so  named  from  its  tent-like  form,  is  an  arched  lamina  of 
dura  mater,  elevated  in  the  middle,  and  inclining  downwards  towards  its  cir- 
cumference. It  covers  the  upper  surface  of  the  cerebellum,  supporting  the  posterior 
lobes  of  the  brain,  and  preventing  their  pressure  upon  it.  It  is  attached,  behind, 
by  its  convex  border,  to  the  transverse  ridges  upon  the  inner  surface  of  the  occi- 
pital bone,  and  there  incloses  the  lateral  sinuses ;  in  front,  to  the  superior  margin 
of  the  petrous  portion  of  the  temporal  bone,  inclosing  the  superior  petrosal  sinuses, 
and  from  the  apex  of  this  bone,  on  each  side,  is  continued  to  the  anterior  and 
posterior  clinoid  processes.  Along  the  middle  line  of  its  upper  surface,  the  pos- 
terior border  of  the  falx  cerebri  is  attached,  the  straight  sinus  being  placed  at 
their  point  of  junction.  Its  anterior  border  is  free  and  concave,  and  presents  a 
large  oval  opening  for  the  transmission  of  the  crura  cerebri. 

The  falx  cerebelli  is  a  small  triangular  process  of  dura  mater,  received  into  the 
indentation  between  the  two  lateral  lobes  of  the  cerebellum  behind.  Its  base  is 
attached,  above,  to  the  under  and  back  part  of  the  tentorium ;  its  posterior  margin, 
to  the  lower  division  of  the  vertical  crest  on  the  inner  surface  of  the  occipital  bone. 
As  it  descends,  it  sometimes  divides  into  two  smaller  folds,  which  are  lost  on  the 
sides  of  the  foramen  magnum. 

Arachnoid  Membrane. 

The  arachnoid  (apa^,  fZSoj,  like  a  spider's  web),  so  named  from  its  extreme 
thinness,  is  the  serous  membrane  which,  envelops  the  brain,  and  is  then  reflected 
on  the  inner  surface  of  the  dura  mater.  Like  other  serous  membranes,  it  is  a 
shut  sac,  and  consists  of  a  parietal  and  a  visceral  layer. 

The  parietal  layer  covers  the  inner  surface  of  the  dura  mater,1  and  gives  this 
membrane  the  smooth  and  polished  surface  which  it  presents ;  it  is  also  reflected 
over  those  processes  which  separate  the  hemispheres  of  the  brain  and  cerebellum. 

1  Kolliker  denies  this ;  and  states,  that  the  inner  surface  of  the  dura  mater  is  covered  with 
pavement  epithelium,  but  has  no  other  investment  which  can  be  regarded  as  a  parietal  layer  of 
the  arachnoid. 


PIA   MATER.  509 

The  visceral  layer  invests  the  brain  more  loosely,  being  separated  from  direct 
contact  with  the  cerebral  substance  by  the  pia  mater,  and  a  quantity  of  loose  areolar 
tissue,  the  sub-arachnoidean.  On  the  upper  surface  of  the  cerebrum,  the  arachnoid 
is  thin  and  transparent,  and  may  be  easily  demonstrated  by  injecting  a  stream  of 
air  beneath  it  by  means  of  a  blowpipe ;  it  passes  over  the  convolutions  without 
dipping  down  into  the  sulci  between  them.  At  the  base  of  the  brain,  the  arachnoid 
is  thicker,  and  slightly  opaque  towards  the  central  part ;  it  covers  the  anterior 
lobes,  is  extended  across  between  the  two  middle  lobes,  so  as  to  leave  a  considerable 
interval  between  it  and  the  brain,  the  anterior  sub-arachnoidean  spiace;  it  is  closely 
adherent  to  the  pons  and  under  surface  of  the  cerebellum ;  but  between  the  hemi- 
spheres of  the  cerebellum  and  the  medulla  oblongata,  another  considerable  interval 
is  left  between  it  and  the  brain,  called  the  posterior  sub-arachnoidean  space.  These 
two  spaces  communicate  together  across  the  crura  cerebri.  The  arachnoid  mem- 
brane surrounds  the  nerves  which  arise  from  the  brain,  and  incloses  them  in  loose 
sheaths  as  far  as  their  point  of  exit  from  the  skull,  where  it  becomes  continuous 
with  the  parietal  layer. 

The  sub-arachnoid  space  is  the  interval  between  the  arachnoid  and  pia  mater : 
this  space  is  narrow  on  the  surface  of  the  hemispheres ;  but  at  the  base  of  the 
brain,  a  wide  interval  is  left  between  the  two  middle  lobes,  and  behind,  between 
the  hemispheres  of  the  cerebellum  and  the  medulla  oblongata.  This  space  is  the 
seat  of  an  abundant  serous  secretion,  the  cerebro-spinal  fluid,  which  fills  up  the 
interval  between  the  arachnoid  and  pia  mater.  The  sub-arachnoid  space  usually 
communicates  with  the  general  ventricular  cavity  of  the  brain,  by  means  of  an 
opening  in  the  inferior  boundary  of  the  fourth  ventricle. 

The  sac  of  the  arachnoid  also  contains  serous  fluid ;  this  is,  however,  small  in 
quantity  compared  with  the  cerebro-spinal  fluid. 

Structure.  The  arachnoid  consists  of  bundles  of  white  fibrous  and  elastic  tissues 
intimately  blended  together.  Its  outer  surface  is  covered  with  a  layer  of  scaly 
epithelium.  It  is  destitute  of  vessels,  and  the  existence  of  nerves  in  it  has  not 
been  satisfactorily  demonstrated. 

The  cerebro-spinal  fluid  fills  up  the  sub-arachnoid  space,  keeping  the  opposed 
surfaces  of  the  arachnoid  membrane  in  contact.  It  is  a  clear,  limpid  fluid,  having 
a  saltish  taste,  and  a  slightly  alkaline  reaction.  According  to  Lassaigne,  it  con- 
sists of  98.5  parts  of  water,  the  remaining  1.5  per  cent,  being  solid  matters,  animal 
and  saline.  It  varies  in  quantity,  being  most  abundant  in  old  persons,  and  is 
quickly  reproduced.  Its  chief  use  is  probably  to  afford  mechanical  protection  to 
the  nervous  centres,  and  to  prevent  the  effects  of  concussions  communicated  from 
without. 

Pia  Mater. 

The  Pia  Mater  is  a  vascular  membrane,  and  derives  its  blood  from  the  internal 
carotid  and  vertebral  arteries.  It  consists  of  a  minute  plexus  of  bloodvessels, 
held  together  by  an  extremely  fine  areolar  tissue.  It  invests  the  entire  surface 
of  the  brain,  dipping  down  between  the  convolutions  and  laminae,  and  is  prolonged 
iuto  the  interior,  forming  the  velum  interpositum  and  choroid  plexuses  of  the 
fourth  ventricle.  Upon  the  surface  of  the  hemispheres,  where  it  covers  the  gray 
matter  of  the  convolutions,  it  is  very  vascular,  and  gives  off  from  its  inner  surface 
a  multitude  of  minute  vessels,  which  extend  perpendicularly  for  some  distance 
into  the  cerebral  substance.  At  the  base  of  the  brain,  in  the  situation  of  the 
substantia  perforata  and  locus  perforatus,  a  number  of  long  straight  vessels  are 
given  off,  which  pass  through  the  white  matter  to  reach  the  gray  substance  in 
the  interior.  On  the  cerebellum,  the  membrane  is  more  delicate,  and  the  vessels 
from  its  inner  surface  are  shorter.  Upon  the  crura  cerebri  and  pons  Varolii,  its 
characters  are  altogether  changed;  it  here  presents  a  dense  fibrous  structure, 
marked  only  by  slight  traces  of  vascularity. 

According  to  Fohmann  and  Arnold,  this  membrane  contains  numerous  lym- 
phatic vessels.     Its  nerves  are  derived  from  the  sympathetic,  and  also  from  the 


510  NERVOUS   SYSTEM. 

third,  sixth,  seventh,  eighth,  and  spinal  accessory.   They  accompany  the  branches 
of  the  arteries. 

The  Brain. 

The  brain  {encephalon)  is  that  portion  of  the  cerebro-spinal  axis  that  is  con- 
tained in  the  cranial  cavity.  It  is  divided  into  fonr  principal  parts,  viz :  the 
cerebrum,  the  cerebellum,  the  pons  Varolii,  and  medulla  oblongata. 

The  cerebrum  forms  the  largest  portion  of  the  encephalic  mass,  and  occupies  a 
considerable  part  of  the  cavity  of  the  cranium,  resting  in  the  anterior  and  middle 
fossas  of  the  base  of  the  skull,  and  separated  posteriorly  from  the  cerebellum  by 
the  tentorium  cerebelli.  About  the  middle  of  its  under  surface,  is  a  narrow  con- 
stricted portion,  part  of  which,  the  crura  cerebri,  is  continued  onwards  into  the 
pons  Varolii  below,  and  through  it  to  the  medulla  oblongata  and  spinal  cord ; 
whilst  another  portion,  the  crura  cerebelli,  passes  down  into  the  cerebellum. 

The  cerebellum  (little  brain  or  after-brain)  is  situated  in  the  inferior  occipital 
fossse,  being  separated  from  the  under  surface  of  the  posterior  lobes  of  the  cere- 
brum by  the  tentorium  cerebelli.  It  is  connected  to  the  rest  of  the  encephalic 
mass  by  means  of  connecting  bands,  called  crura;  of  these,  two  ascend  to  the 
cerebrum,  two  descend  to  the  medulla  oblongata,  and  two  blend  together  in  front, 
forming  the  pons  Varolii. 

Therms  Varolii  is  that  portion  of  the  encephalic  mass  which  rests  upon  the 
upper  part  of  the  basilar  process.  It  constitutes  the  bond  of  union  of  the  various 
segments  above-named,  receiving,  above,  the  crura  from  the  cerebrum ;  at  the 
sides,  the  crura  from  the  cerebellum;  and  being  connected,  below,  with  the 
medulla  oblongata. 

The  medulla  oblongata  extends  from  the  lower  border  of  the  pons  Varolii  to 
the  upper  part  of  the  spinal  cord.  It  lies  beneath  the  cerebellum,  resting  on  the 
lower  part  of  the  basilar  groove  of  the  occipital  bone. 

Weight  of  the  encephalon.  The  average  weight  of  the  brain,  in  the  adult  male, 
is  49  \  oz.,  or  a  little  more  than  3  lbs.  avoirdupois;  that  of  the  female,  44  oz.;  the 
average  difference  between  the  two  being  from  5  to  6  oz.  The  prevailing  weight 
of  the  brain,  in  the  male,  ranges  between  46  oz.  and  53  oz. ;  and  in  the  female, 
between  41  oz.  and  47  oz.  In  the  male,  the  maximum  weight  out  of  278  cases 
was  65  oz.,  and  the  minimum  weight  34  oz.  The  maximum  weight  of  the  adult 
female  brain,  out  of  191  cases,  was  56  oz.,  and  the  minimum  weight  31  oz.  It 
appears  that  the  weight  of  the  brain  increases  rapidly  up  to  the  seventh  year, 
more  slowly  to  the  period  between  sixteen  and  twenty,  and  still  more  slowly  to 
that  between  thirty  and  forty,  when  it  reaches  its  maximum.  Beyond  this  period, 
as  age  advances  and  the  mental  faculties  decline,  the  brain  diminishes  slowly  in 
weight,  about  an  ounce  for  each  subsequent  decennial  period.  These  results  apply 
alike  to  both  sexes. 

The  size  of  the  brain  appears  to  bear  a  general  relation  to  the  intellectual 
capacity  of  the  individual.  Cuvier's  brain  weighed  rather  more  than  64  oz.,  that 
of  the  late  Dr.  Abercrombie  63  oz.,  and  that  of  Dupuytren  62  J  oz.  On  the  other 
hand,  the  brain  of  an  idiot  seldom  weighs  more  than  23  oz. 

The  human  brain  is  heavier  than  that  of  all  the  lower  animals  excepting 
the  elephant  and  whale.  The  brain  of  the  former  weighs  from  8  lbs.  to  10  lbs.; 
and  that  of  the  whale,  in  a  specimen  seventy-five  feet  long,  weighed  rather  more 
than  5  lbs. 

Medulla  Oblongata. 

The  medulla  oblongata  is  the  upper  enlarged  part  of  the  spinal  cord,  and  extends 
Crom  the  upper  border  of  the  atlas  to  the  lower  border  of  the  pons  Varolii.  It  is 
directed  obliquely  downwards  and  backwards,  its  anterior  surface  resting  on  the 
basilar  groove  of  the  occipital  bone,  its  posterior  surface  being  received  into  the 
fossa  between  the  hemispheres  of  the  cerebellum,  forming  the  floor  of  the  fourth 


MEDULLA   OBLONGATA. 


511 


ventricle.  It  is  pyramidal  in  form,  its  broad,  extremity  directed  upwards,  its 
lower  end  being  narrow  at  its  point  of  connection  with  the  cord.  It  measures  an 
inch  and  a  quarter  in  length,  three-quarters  of  an  inch  in  breadth  at  its  widest 
part,  and  half  an  inch  in  thickness.  Its  surface  is  marked,  in  the  median  line,  in 
front  and  behind,  by  an  anterior  and  posterior  median  fissure,  which  are  con- 
tinuous with  those  of  the  spinal  cord.  The  anterior  fissure  contains  a  fold  of 
pia  mater,  and  terminates  just  below  the  pons  in  a  cul-de-sac,  the  foramen  ca?cum. 
The  posterior  is  a  deep  but  narrow  fissure,  continued  upwards  along  the  floor  of 
the  fourth  ventricle,  where  it  is  finally  lost.  These  two  fissures  divide  the 
medulla  into  two  symmetrical  halves,  each  lateral  half  being  subdivided  by 
minor  grooves  into  four  columns,  which,  from  before  backwards,  are  named,  the 
anterior  pyramid,  lateral  tract  and  olivary  body,  the  restiform  body,  and  the  posterior 
pyramid. 

The  anterior  pyramids  or  corpora  pyramidalia  are  two  pyramidal-shaped 
bundles  of  white  matter,  placed  one  on  either  side  of  the  anterior  median  fissure, 
and  separated  from  the  olivary  body, 

Which  is  external   to  them,  by  a  slight     FiS-  260.— Medulla  Oblongata  and  Pods  Varolii. 
j  •  A  ,  ,1      i  i        i  n?i  Anterior  Surtace. 

depression.  At  the  lower  border  ot  the 
pons  they  are  somewhat  constricted; 
they  then  become  enlarged,  and  taper 
slightly  as  they  descend,  being  con- 
tinuous below  with  the  anterior  co- 
lumns of  the  cord.  On  separating  the 
pyramids  below,  it  will  be  observed 
that  the  innermost  fibres  of  the  two 
form  from  four  to  five  bundles  on  each 
side,  which  decussate  with  one  another ; 
this  decussation,  however,  is  not  formed 
entirely  of  fibres  from  the  pyramids, 
but  mainly  from  the  deep  portion  of 
the  lateral  columns  of  the  cord  which 
pass  forwards  to  the  surface  between 
the  diverging  anterior  columns.  The 
outermost  fibres  do  not  decussate ;  they 
are  derived  from  the  anterior  columns 
of  the  cord,  and  are  continued  directly 
upwards  through  the  pons  Varolii. 

Lateral  tract  and  olivary  body.  The  lateral  tract  is  continuous  with  the  lateral 
column  of  the  cord.  Below,  it  is  broad,  and  includes  that  part  of  the  medulla 
between  the  anterior  pyramid  and  restiform  body ;  but,  above,  it  is  pushed  a  little 
backwards,  and  narrowed  by  the  projection  forwards  of  the  olivary  body. 

The  olivary  bodies  are  two  prominent,  oval  masses,  situated  behind  the  anterior 
pyramids,  from  which  they  are  separated  by  slight  grooves.  They  equal,  in 
breadth,  the  anterior  pyramids,  are  a  little  broader  above  than  below,  and  are 
about  half  an  inch  in  length,  being  separated,  above,  from  the  pons  "Varolii,  by  a 
slight  depression.  Numerous  white  fibres,  fibrse  arciformes,  are  seen  winding 
round  the  lower  end  of  each  body ;  sometimes  crossing  their  surface. 

The  restiform  bodies  are  the  largest  columns  of  the  medulla,  and  continuous, 
below,  with  the  posterior  columns  of  the  cord.  They  are  two  rounded,  cord-like 
eminences,  placed  between  the  lateral  tracts,  in  front,  and  the  posterior  pyramids, 
behind;  from  both  of  which  they  are  separated  by  slight  grooves.  As  they 
ascend,  they  diverge  from  each  other,  assist  in  forming  the  lateral  boundaries  of 
the  fourth  ventricle,  and  then  enter  the  corresponding  hemisphere  of  the  cere- 
bellum, forming  its  inferior  peduncle,  from  which  it  is  probable  that  some  fibres 
are  continued  from  them  into  the  cerebrum. 

The  posterior  pyramids  or  fasciculi  graciles  are  two  narrow,  white  cords,  placed 
one  on  each  side  of  the  posterior  median  fissure,  and  separated  from  the  restiform 


512 


NERVOUS   SYSTEM. 


Fig.  2G1. — Posterior  Surface  of  Medulla 
Oblongata. 


bodies  by  a  narrow  groove.     They  consist  entirely  of  white  fibres,  and  are  con 
tinuous  with  the  posterior  median  columns  of  the  spinal  cord.     These  bodies  lie 

at  first  in  close  contact.  Opposite  the 
apex  of  the  fourth  ventricle,  they  form 
an  enlargement,  the  processus  clavatus,  and 
then,  diverging,  are  lost  in  the  correspond- 
ing restiform  body.  The  upper  part  of 
the  posterior  pyramids  forms  the  lateral 
boundaries  of  the  calamus  scriptorius. 

The  posterior  surface  of  the  medulla 
oblongata  forms  part  of  the  floor  of  the 
fourth  ventricle.  It  is  of  a  triangular 
form,  bounded  on  each  side  by  the  di- 
verging posterior  pyramids,  and  is  that 
part  of  the  ventricle  which,  from  its 
resemblance  to  the  point  of  a  pen,  is 
called  the  calamus  scriptorius.  The  di- 
vergence of  the  posterior  pyramids  and 
the  restiform  bodies  opens  to  view  the 
gray  matter  of  the  medulla,  which  is  con- 
tinuous, below,  with  the  gray  commissure 
of  the  cord.  In  the  middle  line  is  seen  a 
longitudinal  furrow,  continuous  with  the 
posterior  median  fissure  of  the  cord,  ter- 
minating, below,  at  the  point  of  the  ven- 
tricle, in  a  cul-de-sac,  the  ventricle  of 
Arantius,  which  descends  into  the  medulla 
for  a  slight  extent.  It  is  the  remains  of  a  canal,  which,  in  the  foetus,  extends 
throughout  the  entire  length  of  the  cord. 

Structure.  The  columns  of  the  cord  are  directly  continuous  with  those  of  the 
medulla  oblongata,  below;  but,  higher  up,  both  the  white  and  gray  constituents 
are  re-arranged  before  they  are  continued  upwards  to  the  cerebrum  and  cere- 
bellum. 

The  anterior  pyramid  is  composed  of  fibres  derived  from  the  anterior  column 
of  the  cord  of  its  own  side,  and  from  the  lateral  column  of  the  opposite  half  of 
the  cord,  and  is  continued  upwards  into  the  cerebrum  and  cerebellum.  The 
cerebellar  fibres  form  a  superficial  and  deep  layer,  which  pass  beneath  the  olive 
to  the  restiform  body,  and  spread  out  into  the  structure  of  the  cerebellum.  A 
deeper  fasciculus  incloses  the  olivary  body,  and,  receiving  fibres  from  it,  enters 

the  pons  as  the  olivary  fasciculus  or 
Fir.  2b2. — Transverse  Section  of  Medulla  .en    .     t     ,  ,i        i  •    r.  o n-\  n 

Oblongata.  fillet;  but  the  cbiei  mass  01  fibres  trom 

the  pyramid,  the  cerebral  fibres,  enter 
the  pons  in  their  passage  upwards  to 
the  cerebrum.  The  anterior  pyramids 
contain  no  gray  matter. 

The  lateral  tract  is  continuous,  be- 
low, with  the  lateral  column  of  the  cord. 
Its  fibres  pass  in  three  different  direc- 
tions. The  most  external  join  the 
restiform  body,  and  pass  to  the  cerebellum.  The  internal,  more  numerous,  pass 
forwards,  pushing  aside  the  fibres  of  the  anterior  column,  and  form  part  of  the 
opposite  anterior  pyramid.  The  middle  fibres  ascend,  beneath  the  olivary  body, 
to  the  cerebrum,  passing  along  the  back  of  the  pons,  and  form,  together  with 
fibres  from  the  restiform  body,  the  fasciculi  teretes,  in  the  floor  of  the  fourth 
ventricle. 

Olivary  hody.  If  a  transverse  section  is  made  through  either  olivary  body,  it 
will  be  found  to  consist  of  a  small  ganglionic  mass,  deeply  imbedded  in  the  medulla, 


Tntcrior  Tietare- 


Fasciculi  Terete! 


JUstrjvrm  ~Bo3tf 
Olivary  Body 
A ntrriar  Pyramid. 


STRUCTURE  OF  THE  MEDULLA  OBLONGATA. 


513 


partly  appearing  on  the  surface  as  a  smooth,  olive-shaped  eminence  (fig.  262).  It 
consists,  externally,  of  white  substance ;  and,  internally,  of  a  gray  nucleus,  the 
corpus  dentatum.  The  gray  matter  is  arranged  in  the  form  of  a  hollow  capsule, 
open  at  its  upper  and  inner  part,  and  presenting  a  zig-zag  or  dentated  outline. 
White  fibres  pass  into  or  from  the  interior  of  this  body,  by  the  aperture  in  the 
posterior  part  of  the  capsule.  They  join  with  those  fibres  of  the  anterior  column 
which  ascend  on  the  outer  side,  and  beneath  the  olive,  to  form  the  olivary  fasci- 
culus, which  ascends  to  the  cerebrum. 

Fig.  2G3. — The  Columns  of  the  Medulla  Oblongata,  and  their  Connection  with  the 
Cerebrum  and  Cerebellum. 


Medulla    Oblongata 


The  restiform  body  is  formed  chiefly  of  fibres  from  the  posterior  column  of  the 
cord ;  but  it  receives  some  from  the  lateral  column,  and  a  fasciculus  from  the 
anterior,  and  is  continued,  upwards,  to  the  cerebrum  and  cerebellum.  On  entering 
the  pons,  it  divides  into  two  fasciculi,  above  the  point  of  the  fourth  ventricle. 
The  most  external  one  enters  the  cerebellum ;  the  inner  one  joins  the  posterior 
pyramid,  is  continued  up  along  the  fourth  ventricle,  and,  joining  the  fasciculi 
teretes,  passes  up  to  the  cerebrum. 

Septum  of  the  medulla  oblongata.  Above  the  decussation  of  the  anterior 
pyramids,  numerous  white  fibres  extend,  from  behind  forwards,  in  the  median 
line,  forming  a  septum,  which  subdivides  the  medulla  into  two  lateral  halves. 
Some  of  these  fibres  emerge  at  the  anterior  median  fissure  and  form  a  band  which 
curves  round  the  lower  border  of  the  olivary  body,  or  passes  transversely  across 
it,  and  round  the  sides  of  the  medulla,  forming  the  arc/form  fibres  of  Rolando. 
Others  appear  in  the  floor  of  the  fourth  ventricle,  issuing  from  the  posterior 
median  fissure,  and  form  the  white  striae  in  that  situation. 

Gray  matter  of  the  medulla  oblongata.  The  gray  matter  of  the  medulla  is  a 
continuation  of  that  contained  in  the  interior  of  the  spinal  cord,  besides  a  series 
of  special  deposits  or  nuclei. 

In  the  lower  part  of  the  medulla,  the  gray  matter  is  arranged  as  in  the  cord, 
but,  at  the  upper  part,  it  becomes  more  abundant,  and  is  disposed  with  less 
apparent  regularity,  becoming  blended  with  all  the  white  fibres,  except  the 
anterior  pyramids.  The  part  corresponding  to  the  transverse  gray  commissure 
of  the  cord  is  exposed  to  view  in  the  floor  of  the  medulla  oblongata,  by  the 


514  NERVOUS    SYSTEM. 

divergence  of  the  restiform  bodies,  and  posterior  pyramids,  becoming  blended  with 
the  ascending  fibres  of  the  lateral  column,  and  thus  forming  the  fasciculi  teretes. 
The  lateral  crescentic  portions,  but  especially  the  posterior  horns,  become  enlarged, 
blend  with  the  fibres  of  the  restiform  bodies,  and  form  the  tuberculo  cinereo  of 
Rolando. 

Special  deposits  of  gray  matter  are  found  both  in  the  anterior  and  posterior 
parts  of  the  medulla;  in  the  former  situation,  forming  the  corpus  dentatum 
within  the  olivary  body,  and,  in  the  latter,  a  series  of  special  masses,  or  nuclei, 
connected  with  the  roots  of  origin  of  the  spinal  accessory,  vagus,  glosso-pharyn- 
geal,  and  hypoglossal  nerves.  It  thus  appears  that  the  closest  analogy  in 
structure,  and  also  probably  in  general  endowments,  exists  between  the  medulla 
oblongata  and  the  spinal  cord.  The  larger  size  and  peculiar  form  of  the  medulla 
depending  on  the  enlargement,  divergence,  and  decussation  of  the  various 
columns ;  and  also  from  the  addition  of  special  deposits  of  gray  matter  in  the 
olivary  bodies  and  other  parts,  evidently  in  adaptation  to  the  more  extended  range 
of  function  which  this  part  of  the  cerebro-spinal  axis  possesses. 


PONS  VAROLII. 

The  pons  Varolii  (mesocephale,  Chaussier)  is  the  bond  of  union  of  the  various 
segments  of  the  encephalon,  connecting  the  cerebrum  above,  the  medulla  oblongata 
below,  and  the  cerebellum  behind.  It  is  situated  above  the  medulla  oblongata, 
below  the  crura  cerebri,  and  between  the  hemispheres  of  the  cerebellum. 

Its  under  surface  presents  a  broad  transverse  band  of  white  fibres,  which  arches 
like  a  bridge  across  the  upper  part  of  the  medulla,  extending  between  the  two 
hemispheres  of  the  cerebellum.  This  surface  projects  considerably  beyond  the 
level  of  these  parts,  is  of  a  quadrangular  form,  rests  upon  the  basilar  groove  of 
the  occipital  bone,  and  is  limited  before  and  behind  by  very  prominent  margins. 
It  presents  along  the  middle  line  a  longitudinal  groove,  wider  in  front  than  behind, 
which  lodges  the  basilar  artery ;  numerous  transverse  striae  are  also  observed  on 
each  side,  which  indicate  the  course  of  its  superficial  fibres. 

Its  upper  surface  forms  part  of  the  floor  of  the  fourth  ventricle,  and  at  each  side 
it  becomes  contracted  into  a  thick  rounded  cord,  the  crus  cerebelli,  which  enters 
the  substance  of  the  cerebellum,  constituting  its  middle  peduncle. 
•    Structure.     The  pons  Varolii  consists  of  alternate  layers  of  transverse  and  longi- 
tudinal fibres  intermixed  with  gray  matter  (fig.  263). 

The  transverse  fibres  connect  together  the  two  lateral  hemispheres  of  the 
cerebellum,  and  constitute  its  great  transverse  commissure.  They  consist  of  a 
superficial  and  a  deep  layer.  The  superficial  layer  passes  uninterruptedly  across 
the  surface  of  the  pons,  forming  a  uniform  layer,  consisting  of  fibres  derived  from 
the  crus  cerebelli  on  each  side,  which  meet  in  the  median  line.  The  deep  layer 
of  transverse  fibres  decussates  with  the  longitudinal  fibres  continued  up  from  the 
medulla,  and  contains  much  gray  matter  between  its  fibres. 

The  longitudinal  fibres  are  continued  up  through  the  pons.  1.  From  the 
anterior  pyramidal  body.  2.  From  the  olivary  body.  3.  From  the  lateral  and 
posterior  columns  of  the  cord,  receiving  special  fibres  from  the  gray  matter  of  the 
pons  itself. 

1.  The  fibres  from  the  anterior  pyramid  ascend  through  the  pons,  imbedded 
between  two  layers  of  transverse  fibres,  being  subdivided  in  their  course  into 
smaller  bundles ;  at  the  upper  border  of  the  pons  they  enter  the  crus  cerebri, 
forming  its  fasciculated  portion. 

2.  The  olivary  fasciculus  divides  in  the  pons  into  two  bundles,  one  of  which 
ascends  to  the  corpora  quadrigemina ;  the  other  is  continued  to  the  cerebrum  with 
the  fibres  of  the  lateral  column. 

3.  The  fibres  from  the  lateral  and  posterior  columns  of  the  cord,  with  a  bundle 
from  the  olivary  fasciculus,  are  intermixed  with  much  gray  matter,  and  appear  in 


CEREBRUM.  515 

the  floor  of  the  fourth  ventricle  as  the  fasciculi  teretes;  they  ascend  to  the  deep  or 
cerebral  part  of  the  crus  cerebri. 

Foville  considers  that  a  few  fibres  from  each  of  the  longitudinal  tracts  of  the 
medulla  turn  forwards,  and  are  continuous  with  the  transverse  fibres  of  the  pons. 

Septum.  The  pons  is  subdivided  into  two  lateral  halves  by  a  median  septum, 
which  extends  through  its  posterior  half.  The  septum  consists  of  antero-posterior 
and  transverse  fibres.  The  former  are  derived  from  the  floor  of  the  fourth  ven- 
tricle and  from  the  transverse  fibres  of  the  pons,  which  bend  backwards  before 
passing  across  to  the  opposite  side.  The  latter  are  derived  from  the  floor  of  the 
fourth  ventricle ;  they  pierce  the  longitudinal  fibres,  and  are  then  continued  across 
from  one  to  the  other  side  of  the  medulla,  piercing  the  antero-posterior  fibres. 
The  two  halves  of  the  pons,  in  front,  are  connected  together  by  transverse  com- 
missural fibres. 

CEREBRUM. 

Upper  Surface. 

The  Cerebrum,  in  man,  constitutes  the  largest  portion  of  the  encephalon.  Its 
upper  surface  is  of  an  ovoidal  form,  broader  behind  than  in  front,  convex  in  its 
general  outline,  and  divided  into  two  lateral  halves  or  hemispheres,  right  and  left, 
by  the  great  longitudinal  fissure.  This  fissure  extends  throughout  the  entire 
length  of  the  cerebrum  in  the  middle  line,  reaching  down  to  the  base  of  the 
brain  in  front  and  behind,  but  interrupted  in  the  middle  by  a  broad  transverse 
commissure  of  white  matter,  the  corpus  callosum,  which  connects  the  two  hemi- 
spheres together.  This  fissure  lodges  the  falx  cerebri,  and  indicates  the  original 
development  of  the  brain  by  two  lateral  halves. 

Each  hemisphere  presents  an  outer  surface,  which  is  convex,  to  correspond 
with  the  vault  of  the  cranium ;  an  inner  surface,  flattened,  and  in  contact  with  the 
opposite  hemisphere,  the  two  inner  surfaces  forming  the  sides  of  the  longitudinal 
fissure ;  and  an  under  surface  or  base,  of  more  irregular  form,  which  rests,  in 
front,  on  the  anterior  and  middle  fossae  at  the  base  of  the  skull,  and,  behind,  upon 
the  tentorium. 

Convolutions.  If  the  pia  mater  is  removed  with  the  forceps,  the  entire  surface 
of  each  hemisphere  will  present  a  number  of  convoluted  eminences,  the  convolu- 
tions, separated  from  each  other  by  depressions  {sulci)  of  various  depths.  The 
outer  surface  of  each  convolution,  as  well  as  the  sides  and  bottom  of  the  sulci 
between  them,  are  composed  of  gray  matter,  which  is  here  called  the  cortical  sub- 
stance. The  interior  of  each  convolution  is  composed  of  white  matter,  and  white 
fibres  also  blend  with  the  gray  matter  at  the  sides  and  bottom  of  the  sulci.  By 
this  arrangement  the  convolutions  are  admirably  adapted  to  increase  the  amount 
of  gray  matter  without  occupying  much  additional  space,  and  also  afford  a  greater 
extent  of  surface,  for  the  fibres  to  terminate  in  it.  On  closer  examination,  how- 
ever, the  gray  matter  of  the  cortical  substance  is  found  subdivided  into  four 
layers,  two  of  which  are  composed  of  gray  and  two  of  white  substance.  The 
most  external  is  an  outer  white  stratum,  not  equally  thick  over  all  parts  of  the 
brain,  being  most  marked  on  the  convolutions  in  the  longitudinal  fissure  and  on 
the  under  part  of  the  brain,  especially  on  the  middle  lobe,  near  the  descending 
horn  of  the  lateral  ventricle.  Beneath  the  latter  is  a  thick  reddish  gray  lamina, 
and  then  another  thin  white  stratum ;  lastly,  a  thin  stratum  of  gray  matter,  which 
lies  in  close  contact  with  the  white  fibres  of  the  hemispheres ;  consequently  white 
and  gray  laminae  alternate  with  one  another  in  the  gray  matter  of  the  convolu- 
tions. In  certain  convolutions,  however,  the  cortical  substance  consists  of  no  less 
than  six  layers,  three  gray  and  three  white,  an  additional  white  stratum  dividing 
the  most  superficial  gray  one  into  two ;  this  is  especially  marked  in  those  convo- 
lutions which  are  situated  near  the  corpus  callosum. 

A  perfect  resemblance  between  the  convolutions  does  not  exist  in  all  brains, 


516 


NERVOUS    SYSTEM. 


nor  are  they  symmetrical  on  the  two  sides  of  the  same  brain.  Occasionally  the 
free  borders  or  the  sides  of  a  deep  convolution  present  a  fissured  or  notched 
appearance. 

The  sulci  are  generally  an  inch  in  depth,  but  they  vary  in  different  brains,  and 
in  different  parts  of  the  same  brain,  being  usually  deepest  on  the  outer  convex 
surface  of  the  hemispheres ;  the  deepest  is  situated  on  the  inner  surface  of  the 
hemisphere,  on  a  level  with  the  corpus  callosum,  and  corresponds  to  the  projection 
in  the  posterior  horn  of  the  lateral  ventricle,  the  hippocampus  minor. 

The  number  and  extent  of  the  convolutions,  as  well  as  their  depth,  appear  to 
bear  a  close  relation  to  the  intellectual  power  of  the  individual,  as  is  shown  in 
their  increasing  complexity  of  arrangement  as  we  ascend  from  the  lowest  mam- 
malia up  to  man.  Thus  they  are  absent  in  some  of  the  lower  orders  of  mammalia, 
and  they  increase  in  number  and  extent  through  the  higher  orders.  In  man  they 
present  the  most  complex  arrangement.     Again,  in  the  child  at  birth  before  the 


Fig.  264. — Upper  Surface  of  the  Brain,  the  Pia  Mater  having  been  removed. 
Great  Xonyi'lua'ixcl  Fissurs 


intellectual  faculties  are  exercised,  the  convolutions  have  a  very  simple  arrange- 
ment, presenting  few  undulations ;  and  the  sulci  between  them  are  less  deep  than 
in  the  adult.  In  old  age,  when  the  mental  faculties  have  diminished  in  activity, 
the  convolutions  become  much  less  prominently  marked. 

Those  convolutions  which  are  the  largest  and  most  constantly  present  are  the 
convolution  of  the  corpus  callosum,  the  convolution  of  the  longitudinal  fissure, 
the  supra-orbital  convolution,  and  the  convolutions  of  the  outer  surface  of  the 
hemisphere. 


BASE   OF   THE   BRAIN.  517 

The  convolution  of  the  corpus  calhsum  {gyrus  fornicatus)  is  always  well 
marked.  It  lies  parallel  with  the  upper  surface  of  the  corpus  callosura,  com- 
mencing on  the  under  surface  of  the  brain  in  front  of  the  anterior  perforated 
space ;  it  winds  round  the  curved  border  of  the  corpus  callosum,  and  passes 
along  its  upper  surface  as  far  as  its  posterior  extremity,  where  it  is  connected 
with  the  convolutions  of  the  posterior  lobe ;  it  then  curves  downwards  and 
forwards,  embracing  the  cerebral  peduncle,  passes  into  the  middle  lobe,  forming 
the  hippocampus  major,  and  terminates  just  behind  the  point  from  whence  it 
arose. 

The  supra-orbital  convolution  on  the  under  surface  of  the  anterior  lobe  is  well 
marked. 

The  convolution  of  the  longitudinal  fissure  bounds  the  margin  of  the  fissure 
on  the  upper  surface  of  the  hemisphere.  It  commences  on  the  under  surface  of 
the  brain,  at  the  anterior  perforated  space,  passes  forwards  along  the  inner  margin 
of  the  anterior  lobe,  being  here  divided  by  a  deep  sulcus,  in  which  the  olfactory 
nerve  is  received ;  it  then  curves  over  the  anterior  and  upper  surface  of  the  hemi- 
sphere, along  the  margin  of  the  longitudinal  fissure,  to  its  posterior  extremity, 
where  it  curves  forwards  along  the  under  surface  of  the  hemisphere  as  far  as  the 
middle  lobe. 

The  convolutions  on  the  outer  convex  surface  of  the  hemisphere,  the  general 
direction  of  which  is  more  or  less  oblique,  are  the  largest  and  the  most  complicated 
convolutions  of  the  brain,  frequently  becoming  branched  like  the  letter  Yin  their 
course  upwards  and  backwards  towards  the  longitudinal  fissure :  these  convolutions 
attain  their  greatest  development  in  man,  and  are  especially  characteristic  of  the 
human  brain.     They  are  seldom  symmetrical  on  the  two  sides. 

Under  Surface  or  Base. 

The  under  surface  of  each  hemisphere  presents  a  subdivision,  as  already 
mentioned,  into  three  lobes,  named,  from  their  position,  anterior,  middle,  and 
posterior. 

The  anterior  lobe,  of  a  triangular  form,  with  its  apex  backwards,  is  somewhat 
concave,  and  rests  upon  the  convex  surface  of  the  roof  of  the  orbit,  being  separated 
from  the  middle  lobe  by  the  fissure  of  Sylvius.  The  middle  lobe,  which  is  more 
prominent,  is  received  into  the  middle  fossa  of  the  base  of  the  skull.  The  posterior 
lobe  rests  upon  the  tentorium,  its  extent  forwards  being  limited  by  the  anterior 
margin  of  the  cerebellum. 

The  various  objects  exposed  to  view  on  the  under  surface  of  the  cerebrum  in 
the  middle  line  are  here  arranged  in  the  order  in  which  they  are  met  with  from 
before  backwards. 

Longitudinal  fissure.  Tuber  cinereum. 

Corpus  callosum  and  its  peduncles.  Infundibulum. 

Lamina  cinerea.  Pituitary  body. 

Olfactory  nerve.  Corpora  albicantia. 

Fissure  of  Sylvius.  Posterior  perforated  space. 

Anterior  perforated  space.  Crura  cerebri. 
Optic  commissure. 

The  longitudinal  fissure  partially  separates  the  two  hemispheres  from  one 
another ;  it  divides  the  two  anterior  lobes  in  front,  and,  on  raising  the  cerebellum 
and  pons,  it  will  be  seen  completely  separating  the  two  posterior  lobes,  the  inter- 
mediate portion  of  the  fissure  being  arrested  by  the  great  transverse  band  of  white 
matter,  the  corpus  callosum.  Of  these  two  portions  of  the  longitudinal  fissure, 
that  which  separates  the  posterior  lobes  is  the  longest.  In  the  fissure  between 
the  two  anterior  lobes  the  anterior  cerebral  arteries  may  be  seen  ascending  to  the 
corpus  callosum ;  and  at  the  back  part  of  this  portion  of  the  fissure,  the  anterior 
curved  portion  of  the  corpus  callosum  descends  to  the  base  of  the  brain. 


518 


NERVOUS   SYSTEM. 


The  corpus  callosum  terminates  at  the  base  of  the  brain  by  a  concave  margin, 
which  is  connected  with  the  tuber  cinereum  through  the  intervention  of  a  thin 
layer  of  gray  substance,  the  lamina  cinerea.  This  may  be  exposed  by  gently 
raising  and  drawing  back  the  optic  commissure.  A  broad  white  band  may  be 
observed  on  each  side,  passing  from  the  under  surface  of  the  corpus  callosum 
backwards  and  outwards,  to  the  commencement  of  the  fissure  of  Sylvius ;  these 
bands  are  called  the  peduncles  of  the  corpus  callosum.  Laterally,  the  corpus 
callosum  extends  into  the  anterior  lobe.  « 

The  lamina  cinerea  is  a  thin  layer  of  gray  substance,  extending  backwards 
from  the  termination  of  the  corpus  callosum  above  the  optic  commissure  to  the 
tuber  cinereum ;  it  is  continuous  on  either  side  with  the  gray  matter  of  the  anterior 
perforated  space,  and  forms  the  anterior  part  of  the  inferior  boundary  of  the  third 
ventricle. 

Fig.  265.— Base  of  the  Brain. 

M 


The  olfactory  nerve,  with  its  bulb,  is  seen  on  either  side  of  the  longitudinal 
fissure,  upon  the  under  surface  of  each  anterior  lobe. 

The  fissure  of  Sylvius  separates  the  anterior  and  middle  lobes,  and  lodges  the 
middle  cerebral  artery.  At  its  entrance  is  seen  a  point  of  medullary  substance, 
corresponding  to  a  subjacent  band  of  white  fibres,  connecting  the  anterior  and 
middle  lobes,  and  called  the  fasciculus  unciformis  ;  on  following  this  fissure  out- 
wards, it  divides  into  two  branches,  which  inclose  a  triangular-shaped  prominent 
cluster  of  isolated  convolutions,  the  island  of  Reil.  These  convolutions,  from 
being  covered  in  by  the  sides  of  the  fissure,  are  called  the  gyri  operti. 


BASE    OF   THE   BRAIN.  519 

The  anterior  perforated  space  is  situated  at  the  inner  side  of  the  fissure  of 
Sylvius.  It  is  of  a  triangular  shape,  bounded  in  front  by  the  convolution  of  the 
anterior  lobe  and  roots  of  the  olfactory  nerve ;  behind,  by  the  optic  tract ;  externally, 
by  the  middle  lobe  and  commencement  of  the  fissure  of  Sylvius ;  internally,  it  is 
continuous  with  the  lamina  cinerea,  and  crossed  by  the  peduncle  of  the  corpus 
callosum.  It  is  of  a  grayish  color,  and  corresponds  to  the  under  surface  of  the 
corpus  striatum,  a  large  mass  of  gray  matter,  situated  in  the  interior  of  the  brain ; 
it  has  received  its  name  from  being  perforated  by  numerous  minute  apertures  for 
the  transmission  of  small  straight  vessels  into  the  substance  of  the  corpus  striatum. 

The  optic  commissure  is  situated  in  the  middle  line,  immediately  behind  the 
lamina  cinerea.     It  is  the  point  of  junction  between  the  two  optic  nerves. 

Immediately  behind  the  diverging  optic  tracts,  and  between  them  and  the 
peduncles  of  the  cerebrum  [crura  cerebri)  is  a  lozenge-shaped  interval,  the  inter- 
peduncular space,  in  which  are  found  the  following  parts,  arranged  in  the  following 
order  from  before  backwards :  the  tuber  cinereum,  infundibulum,  pituitary  body, 
corpora  albicantia,  and  the  posterior  perforated  space. 

The  tuber  cinereum  is  an  eminence  of  gray  substance,  situated  between  the 
optic  tracts  and  the  corpora  albicantia ;  it  is  connected  with  the  surrounding  parts 
of  the  cerebrum,  forms  part  of  the  floor  of  the  third  ventricle,  and  is  continuous 
with  the  gray  substance  in  that  cavity.  From  the  middle  of  its  under  surface, 
a  conical  tubular  process  of  gray  matter,  about  two  lines  in  length,  is  continued 
downwards  and  forwards  to  be  attached  to  the  posterior  lobe  of  the  pituitary  body ; 
this  is  the  infundibulum.  Its  canal,  funnel-shaped  in  form,  communicates  with 
the  third  ventricle.     :, 

The  pituitary  body  is  a  small,  reddish-gray,  vascular  mass,  weighing  from  five 
to  ten  grains,  and  of  an  oval  form,  situated  in  the  sella  Turcica,  in  connection  with 
which  it  is  retained  by  the  dura  mater  which  forms  the  inner  wall  of  the  cavernous 
sinus.  It  is  very  vascular,  and  consists  of  two  lobes,  separated  from  one  another 
by  a  fibrous  lamina.  Of  these,  the  anterior  is  the  larger,  of  an  oblong  form,  and 
somewhat  concave  behind,  where  it  receives  the  posterior  lobe,  which  is  round. 
The  anterior  lobe  consists  externally  of  firm  yellowish-gray  substance,  and  inter- 
nally of  a  soft  pulpy  substance  of  a  yellowish-white  color.  The  posterior  lobe  is 
darker  than  the  anterior.  In  the  foetus  it  is  larger  proportionally  than  in  the 
adult,  and  contains  a  cavity  which  communicates  through  the  infundibulum  with 
the  third  ventricle.  In  the  adult  it  is  firmer  and  more  solid,  and  seldom  "contains 
any  cavity.  Its  structure,  especially  the  anterior  lobe,  is  similar  to  that  of  the 
ductless  glands. 

The  corpora  albicantia  are  two  small  round  white  masses,  each  about  the  size  of 
a  pea,  placed  side  by  side  immediately  behind  the  tuber  cinereum.  They  are  formed 
by  the  anterior  crura  of  the  fornix,  hence  called  the  bulbs  of  the  fornix,  which, 
after  descending  to  the  base  of  the  brain,  are  folded  upon  themselves,  before  passing 
upwards  to  the  thalami  optici.  They  are  composed  externally  of  white  substance, 
and  internally  of  gray  matter ;  the  gray  matter  of  the  two  being  connected  by  a 
transverse  commissure  of  the  same  material.  At  an  early  period  of  foetal  life 
they  are  blended  together  into  one  large  mass,  but  become  separated  about  the 
seventh  month*. 

The  posterior  perforated  space  or  pons  Tarini  corresponds  to  a  whitish-gray 
substance,  placed  between  the  corpora  albicantia  in  front,  the  pons  Varolii  behind, 
and  the  crura  cerebri  on  either  side.  It  forms  the  back  part  of  the  floor  of  the 
third  ventricle,  and  is  perforated  by  numerous  small  orifices  for  the  passage  of 
bloodvessels  to  the  thalami  optici. 

The  crura  cerebri  or  peduncles  of  the  cerebrum  are  two  thick  cylindrical  bundles 
of  white  matter,  which  emerge  from  the  anterior  border  of  the  pons,  and  diverge 
as  they  pass  forwards  and  outwards  to  enter  the  under  part  of  either  hemisphere. 
Each  crus  is  about  three-quarters  of  an  inch  in  length,  and  somewhat  broader  in 
front  than  behind.  They  are  marked  upon  their  surface  with  longitudinal  stria?, 
and  each  is  crossed,  just  before  entering  the  hemisphere,  by  a  flattened  white  band. 


520  NERYOUS   SYSTEM. 

the  optic  tract,  which  is  adherent  by  its  upper  border  to  the  peduncle.  In  its 
interior  is  contained  a  mass  of  dark-gray  matter,  called  the  locus  niger.  The  third 
nerves  may  be  seen  emerging  from  the  inner  side  of  either  crus  ;  and  the  fourth 
nerve  winding  around  its  outer  side  from  above. 

Each  crus  consists  of  a  superficial  and  deep  layer  of  longitudinal  white  fibres, 
continued  upwards  from  the  pons,  separated  by  a  mass  of  gray  matter,  the  locus 
niger. 

The  superficial  longitudinal  fibres  are  continued  upwards,  from  the  anterior 
pyramids  to  the  cerebrum.  They  consist  of  coarse  fasciculi,  which  form  the  free 
part  of  the  crus,  and  have  received  the  name  of  the  fasciculated  portion  of  the 
peduncle  or  crus. 

The  deep  layer  of  longitudinal  fibres  is  continued  upwards,  to  the  cerebrum, 
from  the  lateral  and  posterior  columns  of  the  medulla,  and  from  the  olivary  fasci- 
culus, these  fibres  consisting  of  some  derived  from  the  same,  and  others  from  the 
opposite  lateral  tract  of  the  medulla.  More  deeply,  is  a  layer  of  finer  fibres, 
mixed  with  gray  matter,  derived  from  the  cerebellum,  blended  with  the  former. 
The  cerebral  surface  of  the  crus  cerebri  is  formed  of  these  fibres,  and  is  named 
the  tegumentum. 

The  locus  niger  is  a  mass  of  gray  matter,  situated  between  the  superficial  and 
deep  layer  of  fibres  above  described.  It  is  placed  nearer  the  inner  than  the  outer 
side  of  this  body. 

The  posterior  lobes  of  the  cerebrum  are  concealed  from  view  by  the  upper 
surface  of  the  cerebellum,  and  pons  Yarolii.  When  these  parts  are  removed,  the 
two  hemispheres  are  seen  to  be  separated  by  the  great  longitudinal  fissure,  this 
fissure  being  arrested,  in  front,  by  the  posterior  rounded  border  of  the  corpus 
callosum. 

Geneeal  Aeeangement  of  the  Paets  composing  the  Ceeebeum. 

As  the  peduncles  of  the  cerebrum  enter  the  hemispheres,  they  diverge  from  one 
another,  so  as  to  leave  an  interval  between  them,  the  interpeduncular  space.  As 
they  ascend,  the  component  fibres  of  each  pass  through  two  large  masses  of  gray 
matter,  the  ganglia  of  the  brain,  called  the  thalaini  optici  and  corpora  striata, 
which  project  as  rounded  eminences  from  the  upper  and  inner  side  of  each 
peduncle.  The  hemispheres  are  connected  together,  above  these  masses,  by  the 
great  transverse  commissure,  the  corpus  callosum,  and  the  interval  left  between 
its  under  surface,  the  upper  surface  of  the  ganglia,  and  the  parts  closing  the 
interpeduncular  space,  forms  the  general  ventricular  cavity.  The  upper  part  of 
this  cavity  is  subdivided  into  two  by  a  vertical  septum,  the  septum  luciclum :  and 
thus  the  two  lateral  ventricles  are  formed.  The  lower  part  of  this  cavity  forms 
the  third  ventricle,  which  communicates  with  the  lateral  ventricles,  above,  and 
with  the  fourth  ventricle,  behind.  The  fifth  ventricle  is  the  interval  left  between 
the  two  layers  composing  the  septum  lucidum. 

'  Inteeioe  of  the  Ceeebeum. 

If  the  upper  part  of  either  hemisphere  is  removed  with  a  scalpel,  about  half 
an  inch  above  the  level  of  the  corpus  callosum,  its  internal  white  matter  will  be 
exposed.  It  is  an  oval-shaped  centre,  of  white  substance,  surrounded  on  all  sides 
by  a  narrow,  convoluted  margin  of  gray  matter  which  presents  an  equal  thickness 
in  nearly  every  part.  This  white  central  mass  has  been  called  the  centrum  ovale 
minus.  Its  surface  is  studded  with  numerous  minute  red  dots,  the  puncta  vasculosa, 
produced  by  the  escape  of  blood  from  divided  bloodvessels.  In  inflammation,  or 
great  congestion  of  the  brain,  these  are  very  numerous,  and  of  a  dark  color.  If 
the  remaining  portion  of  one  hemisphere  is  slightly  separated  from  the  other,  a 
broad  band  of  white  substance  will  be  observed  connecting  them,  at  the  bottom 
of  the  longitudinal  fissure :   this  is  the  corpus  callosum.     The  margins  of  the 


CORPUS   CALLOSUM. 


521 


hemispheres,  which  overlap  this  portion  of  the  brain,  are  called  the  labia  cerebri. 
Each  labium  is  part  of  the  convolution  of  the  corpus  callosum  (gyrus  fornicatus), 
already  described ;  and  the  space  between  it  and  the  upper  surface  of  the  corpus 
callosum  has  been  termed  the  ventricle  of  the  corpus  callosum. 

The  hemispheres  should  now  be  sliced  off;  to  a  level  with  the  corpus  callosum, 
when  the  white  substance  of  that  structure  will  be  seen  connecting  together  both 
hemispheres.  The  large  expanse  of  medullary  matter  now  exposed,  surrounded 
by  the  convoluted  margin  of  gray  substance,  is  called  the  centrum  ovale  majus  of 
Vieussens. 

The  corpus  callosum  is  a  thick  stratum  of  transverse  fibres,  exposed  at  the 
bottom  of  the  longitudinal  fissure.  It  connects  the  two  hemispheres  of  the  brain, 
forming  their  great  transverse  commissure  ;  and  forms  the  roof  of  a  space  in  the 

Fig.  266.— Section  of  the  Brain.     Made  on  a  level  with  the  Corpus  Callosum. 


interior  of  each  hemisphere,  the  lateral  ventricle.  It  is  about  four  inches  in 
length,  extending  to  within  an  inch  and  a  half  of  the  anterior,  and  to  within  two 
inches  and  a  half  of  the  posterior,  part  of  the  brain.  It  is  somewhat  broader 
behind  than  in  front,  and  is  thicker  at  either  end  than  in  its  central  part,  being 
thickest  behind.  It  presents  a  somewhat  arched  form,  from  before  backwards, 
terminating  anteriorly  in  a  rounded  border,  which  curves  downwards  and  back- 
wards, between  the  anterior  Jobes  to  the  base  of  the  brain.  In  its  course,  it  forms 
a  distinct  bend,  named  the  knee  or  genu,  and  the  reflected  portion,  named  the 
beak  or  rostrum,  becoming  gradually  narrower,  is  attached  to  the  anterior  cerebral 
lobe,  and  is  connected,  through  the  lamina  cinerea,  with  the  optic  commissure. 
The  reflected  portion  of  th,e  corpus  callosum  gives  off,  near  its  termination,  two 


522 


NERVOUS   SYSTEM. 


bundles  of  white  substance,  which,  diverging  from  one  another,  pass  backwards, 
across  the  anterior  perforated  space,  to  the  entrance  of  the  fissure  of  Sylvius. 
They  are  called  the  peduncles  of  the  corpus  callosum.  Posteriorly,  the  corpus 
callosum  forms  a  thick,  rounded  fold,  which  is  free  for  a  little  distance,  as  it 
curves  forwards,  and  is  then  continuous  with  the  fornix.  On  its  upper  surface, 
its  fibrous  structure  is  very  apparent  to  the  naked  eye,  being  collected  into  coarse, 
transverse  bundles.  Along  the  middle  line,  is  a  linear  depression,  the  raphe,  bounded 
laterally  by  two  or  more  slightly  elevated  longitudinal  bands,  called  the  striae 
longitudinales  or  nerves  of  Lancisi ;  and,  still  more  externally,  other  longitudinal 
stria?  are  seen,  beneath  the  convolutions,  which  rest  on  the  corpus  callosum.  These 
are  the  strioe  longitudinales  laterales.     The  under  surface  of  the  corpus  callosum 


Fig.  267.— The  Lateral  Ventricles  of  the  Brain. 


is  continuous  behind  with  the  fornix,  being  separated  from  it  in  front  by  the 
septum  lucidum,  which  forms  a  vertical  partition  between  the  two  ventricles.  On 
either  side,  the  fibres  of  the  corpus  callosum  penetrate  into  the  substance  of  the 
hemispheres,  and  connect  together  the  anterior,  middle,  and  part  of  the  posterior 
lobes.  It  is  the  large  number  of  fibres  derived  from  the  anterior  and  posterior 
lobes,  which  explains  the  great  thickness  of  the  two  extremities  of  this  commissure. 

An  incision  should  now  be  made  through  the  corpus  callosum,  on  either  side  of  the  raphe, 
when  two  large  irregular  cavities  will  be  exposed,  which  extend  throughout  the  entire  length  of 
each  hemisphere.     These  are  the  lateral  ventricles. 

The  lateral  ventricles  are  serous  cavities,  formed  by  the  upper  part  of  the 
general  ventricular  space  in  the  interior  of  the  brain.  They  are  lined  by  a  thin 
diaphanous  lining  membrane,  covered  with  ciliated  epithelium,  and  moistened  by  a 


LATERAL   VENTRICLES.  523 

serous  fluid,  which  is  sometimes,  even  in  health,  secreted  in  considerable  quantity. 
These  cavities  are  two  in  number,  one  in  each  hemisphere,  and  they  are  separated 
from  each  other  by  a  vertical  septum,  the  septum  lucidum. 

Each  lateral  ventricle  consists  of  a  central  cavity  or  body,  and  three  smaller 
cavities  or  cornua,  which  extend  from  it  in  different  directions.  The  anterior 
cornu  curves  forwards  and  outwards,  into  the  substance  of  the  anterior  lobe.  The 
posterior  cornu,  called  the  digital  cavity,  curves  backwards  into  the  posterior  lobe. 
The  middle  cornu  descends  into  the  middle  lobe. 

The  central  cavity  or  body  of  the  lateral  ventricle  is  triangular  in  form.  It 
is  bounded,  above,  by  the  under  surface  of  the  corpus  callosum,  which  forms  the 
roof  of  the  cavity.  Internally,  is  a  vertical  partition,  the  septum  lucidum,  which 
separates  it  from  the  opposite  ventricle,  and  connects  the  under  surface  of  the 
corpus  callosum  with  the  fornix.  Its  floor  is  formed  by  the  following  parts, 
enumerated  in  their  order  of  position,  from  before  backwards,  the  corpus  striatum, 
taenia  semicircularis,  thalamus  opticus,  choroid  plexus,  corpus  fimbriatum,  and 
fornix. 

The  anterior  cornu  is  triangular  in  form,  passing  outwards  into  the  anterior 
lobe,  and  curving  round  the  anterior  extremity  of  the  corpus  striatum.  It  is 
bounded,  above  and  in  front,  by  the  corpus  callosum;  behind,  by  the  corpus 
striatum. 

The  posterior  cornu  or  digital  cavity  curves  backwards  into  the  substance  of 
the  posterior  lobe,  its  direction  being  backwards  and  outwards,  and  then  inwards. 
On  its  floor  is  seen  a  longitudinal  eminence,  which  corresponds  with  a  deep  sulcus 
between  two  convolutions ;  this  is  called  the  hippocampus  minor.  Between  the 
middle  and  posterior  horns,  a  smooth  eminence  is  observed,  which  varies  consi- 
derably in  size  in  different  subjects.     It  is  called  the  eminentia  collateralis. 

The  corpus  striatum  has  received  its  name  from  the  striated  appearance  which 
its  section  presents,  from  white  fibres  diverging  through  its  substance.  The  intra- 
ventricular portion  is  a  large  pear-shaped  mass,  of  a  gray  color  externally ;  its 
broad  extremity  is  directed  forwards,  into  the  forepart  of  the  body,  and  anterior 
cornu  of  the  lateral  ventricle ;  its  narrow  end  is  directed  outwards  and  backwards, 
being  separated  from  its  fellow  by  the  thalami  optici ;  it  is  covered  by  the  serous 
lining  of  the  cavity,  and  crossed  by  some  veins  of  considerable  size.  The  extra- 
ventricular  portion  is  imbedded  in  the  white  substance  of  the  hemisphere. 

The  tsenia  semicircularis  is  a  narrow,  whitish,  semitransparent  band  of  medul- 
lary substance,  situated  in  the  depression  between  the  corpus  striatum  and  thala- 
mus opticus.  Anteriorly,  it  descends  in  connection  with  the  anterior  pillar  of  the 
fornix ;  behind,  it  is  continued  into  the  descending  horn  of  the  ventricle,  where 
it  becomes  lost.  Its  surface,  especially  at  its  forepart,  is  transparent,  and  dense 
in  structure,  and  was  called  by  Tarinus  the  horny  band.  It  consists  of  longitu- 
dinal white  fibres,  the  deepest  of  which  run  between  the  corpus  striatum  and 
thalamus  opticus.  Beneath  it  is  a  large  vein,  the  vena  corporis  striati,  which 
receives  numerous  smaller  veins  from  the  surface  of  the  corpus  striatum,  and 
thalamus  opticus,  and  terminates  in  the  venae  Galeni. 

The  choroid  plexus  is  a  highly  vascular,  fringe-like  membrane,  occupying  the 
margin  of  the  fold  of  pia  mater  (velum  interpositum),  in  the  interior  of  the  brain. 
It  extends,  in  a  curved  direction,  across  the  floor  of  the  lateral  ventricle.  In  front, 
where  it  is  small  and  tapering,  it  communicates  with  the  choroid  plexus  of  the 
opposite  side,  through  a  large  oval  aperture,  the  foramen  of  Monro.  Posteriorly, 
it  descends  into  the  middle  horn  of  the  lateral  ventricle,  where  it  joins  with  the 
pia  mater  through  the  transverse  fissure.  In  structure,  it  consists  of  minute  and 
highly  vascular  villous  processes,  the  villi  being  covered  by  a  single  layer  of 
epithelium,  composed  of  large  round  corpuscles,  containing,  besides  a  central 
nucleus,  a  bright  yellow  spot.  The  arteries  of  the  choroid  plexus  enter  the  ven- 
tricle, at  the  descending  cornu,  and,  after  ramifying  through  its  substance,  send 
branches  into  the  substance  of  the  brain.  The  veins  of  the  choroid  plexus  ter- 
minate in  the  venae  Galeni. 


524 


NERVOUS    SYSTEM. 


The  corpus  fimbriatum,  called  also  the  tsenia  hippocampi,  is  a  narrow,  white, 
tape-like  band,  situated  immediately  behind  the  choroid  plexus.  It  is  the  lateral 
edge  of  the  posterior  pillar  of  the  fornix,  and  is  attached  along  the  inner  border  of 
the  hippocampus  major  as  it  descends  into  the  middle  horn  of  the  lateral  ventricle. 
It  may  be  traced  as  far  as  the  pes  hippocampi. 

The  thalami  optici  and  fornix  will  be  described  when  more  completely  exposed, 
in  a  later  stage  of  the  dissection  of  the  brain. 

The  middle  cornu  should  now  be  exposed,  throughout  its  entire  extent,  by  introducing  the 
little  finger  gently  into  it,  and  cutting  through  the  hemisphere,  between  it  and  the  surface,  in  the 
direction  of  the  cavity. 

The  middle  or  descending  cornu,  the  largest  of  the  three,  traverses  the  middle 
lobe  of  the  brain,  forming  in  its  course  a  remarkable  curve  round  the  back  of  the' 


Fig. 


268. — The  Fornix,  Velum  Interpositum,  and  Middle  or  Descending  Cornu  of 
the  Lateral  Ventricle. 


optic  thalamus.  It  passes,  at  first,  backwards,  outwards,  and  downwards,  and 
then  curves  around  the  crus  cerebri,  forwards  and  inwards,  nearly  to  the  point  of 
the  middle  lobe,  close  to  the  fissure  of  Sylvius.  Its  upper  boundary  is  formed 
by  the  medullary  substance  of  the  middle  lobe,  and  the  under  surface  of  the 
thalamus  opticus.  Its  lower  boundary  presents  for  examination  the  following 
parts :  The  hippocampus  major,  pes  hippocampi,  pes  accessorius,  corpus  fimbria- 
tum, choroid  plexus,  fascia  dentata,  transverse  fissure. 

The  hippocampus  major  or  cornu  ammonis,  so  called  from   its  resemblance  to 
a  ram's  horn,  is  a  white  eminence,  of  a  curved  elongate  form,  extending  along  the 


LATERAL   VENTRICLE  — MIDDLE    CORNU.  525 

entire  length  of  the  floor  of  the  middle  horn  of  the  lateral  ventricle.  At  its  lower 
extremity  it  becomes  enlarged,  and  presents  a  number  of  rounded  elevations  with 
intervening  depressions,  which,  from  presenting  some  resemblance  to  the  claw  of 
an  animal,  is  called  the  pes  hippocampi.  If  a  transverse  section  is  made  through 
the  hippocampus  major,  it  will  be  seen  that  this  eminence  is  the  inner  surface  of 
the  convolution  of  the  corpus  callosum,  doubled  upon  itself  like  a  horn,  the  white 
convex  portion  projecting  into  the  cavity  of  the  ventricle ;  the  gray  portion  being 
on  the  surface  of  the  cerebrum,  the  edge  of  which,  slightly  indented,  forms  the 
fascia  dentata.  The  white  matter  of  the  hippocampus  major  is  continuous  through 
the  corpus  fimbriatum,  with  the  fornix  and  corpus  callosum. 

The  pes  accessor  ius  or  eminentia  collateralis  has  been  already  mentioned,  as  a 
white  eminence,  varying  in  size,  placed  between  the  hippocampus  major  and 
minor,  at  the  junction  of  the  posterior  with  the  descending  cornu.  Like  the  hippo- 
campi, it  is  formed  of  white  matter  corresponding  to  one  of  the  sulci,  between 
two  convolutions  protruding  into  the  cavity  of  the  ventricle. 

The  corpus  fimbriatum  is  a  continuation  of  the  posterior  pillar  of  the  fornix, 
prolonged,  as  already  mentioned,  from  the  central  cavity  of  the  lateral  ventricle. 

Fascia  dentata.  On  separating  the  inner  border  of  the  corpus  fimbriatum  from 
the  choroid  plexus,  and  raising  the  edge  of  the  former,  a  serrated  band  of  gray 
substance,  the  edge  of  the  gray  substance  of  the  middle  lobe,  will  be  seen  beneath 
it;  this  is  the  fascia  dentata.  Correctly  speaking,  it  is  placed  external  to  the 
cavity  of  the  descending  cornu. 

The  transverse  fissure  is  seen  on  separating  the  corpus  fimbriatum  from  the  thal- 
amus opticus.  It  is  situated  beneath  the  fornix,  extending  from  the  middle  line 
behind,  downwards  on  either  side,  to  the  end  of  the  descending  cornu,  being 
bounded  on  one  side  by  the  fornix  and  the  hemisphere,  and  on  the  other  by  the 
thalamus  opticus.  Through  this  fissure  the  pia  mater  passes  from  the  exterior  of 
the  brain  into  the  ventricles,  to  form  the  choroid  plexuses.  Where  the  pia  mater 
projects  into  the  lateral  ventricle,  beneath  the  edge  of  the  fornix,  it  is  covered  by 
a  prolongation  of  the  lining  membrane,  which  excludes  it  from  the  cavity. 

The  septum  lucidum  forms  the  internal  boundary  of  the  lateral  ventricle.  It 
is  a  thin,  semi-transparent  septum,  attached,  above,  to  the  under  surface  of  the 
corpus  callosum ;  below,  to  the  anterior  part  of  the  fornix ;  and,  in  front  of  this, 
to  the  prolonged  portion  of  the  corpus  callosum.  It  is  triangular  in  form,  broad 
in  front,  and  narrow  behind,  its  surfaces  looking  towards  the  cavities  of  the  ven- 
tricles. The  septum  consists  of  two  laminae,  separated  by  a  narrow  interval,  the 
fifth  ventricle. 

Each  lamina  consists  of  an  internal  layer  of  white  substance,  covered  by  the 
lining  membrane  of  the  fifth  ventricle ;  and  an  outer  layer  of  gray  matter,  covered 
by  the  lining  membrane  of  the  lateral  ventricle.  The  cavity  of  the  ventricle  is 
lined  by  a  serous  membrane,  covered  with  epithelium,  and  contains  fluid.  In  the 
foetus,  and  in  some  animals,  this  cavity  communicates,  below,  with  the  third 
ventricle,  but  in  the  adult,  it  forms  a  separate  cavity.  In  cases  of  serous  effusion 
into  the  ventricles,  the  septum  is  often  found  softened  and  partially  broken 
down. 

The  fifth  ventricle  may  be  exposed  by  cutting  through  the  septum  and  attached  portion  of  the 
corpus  callosum,  with  the  scissors ;  after  examining  which,  the  corpus  callosum  should  be  cut 
across,  towards  its  anterior  part,  and  the  two  portions  carefully  dissected,  the  one  forwards,  the 
other  backwards,  when  the  fornix  will  be  exposed. 

The  fornix  is  a  longitudinal  lamella,  of  fibrous  matter,  situated  beneath  the 
corpus  callosum,  with  which  it  is  continuous  behind,  but  separated  from  it  in  front 
by  the  septum  lucidum.  It  may  be  described  as  consisting  of  two  symmetrical 
halves,  one  for  either  hemisphere.  These  two  portions  are  joined  together  in  the 
middle  line,  where  they  form  the  body,  but  are  separated  from  one  another  in 
front  and  behind ;  in  front,  forming  the  anterior  crura,  and  behind,  the  posterior 
crura. 


526  NERVOUS   SYSTEM. 

The  body  of  the  fornix  is  triangular  in  form ;  narrow  in  front,  broad  behind. 
Its  upper  surface  is  connected,  in  the  median  line,  to  the  septum  lucidum  in  front, 
and  the  corpus  callosum  behind.  Its  under  surface  rests  upon  the  velum  interpo- 
situm,  which  separates  it  from  the  third  ventricle,  and  the  inner  portion  of  the 
optic  thalami.  Its  lateral  edges  form,  on  each  side,  part  of  the  floor  of  the  lateral 
ventricles,  and  are  in  contact  with  the  choroid  plexuses. 

The  anterior  crura  arch  downwards  towards  the  base  of  the  brain,  separated 
from  each  other  by  a  narrow  interval.  They  are  composed  of  white  fibres,  which 
descend  through  a  quantity  of  gray  matter  in  the  lateral  walls  of  the  third  ven- 
tricle, and  are  placed  immediately  behind  the  anterior  commissure.  At  the  base 
of  the  brain,  the  white  fibres  of  each  crus  form  a  sudden  curve  upon  themselves, 
spread  out  and  form  the  outer  part  of., the  corresponding  corpus  albicans,  from 
which  point  they  may  be  traced  upwards  into  the  substance  of  the  corresponding 
thalamus  opticus.  The  anterior  crura  of  the  fornix  are  connected  in  their  course 
with  the  optic  commissure,  the  white  fibres  covering  the  optic  thalamus,  the 
peduncle  of  the  pineal  gland,  and  the  superficial  fibres  of  the  taenia  semicircu- 
laris. 

The  posterior  crura,  at  their  commencement,  are  intimately  connected  by  their 
upper  surfaces  with  the  corpus  callosum ;  diverging  from  one  another,  they  pass 
downwards  into  the  descending  horn  of  the  lateral  ventricle,  being  continuous 
with  the  concave  border  of  the  hippocampus  major.  The  lateral  thin  edges  of 
the  posterior  crura  have  received  the  name  corpus  fimbriatum,  already  described. 
On  the  under  surface  of  the  fornix,  towards  its  posterior  part,  between  the  diverg- 
ing posterior  crura,  may  be  seen  some  transverse  lines,  and  others  longitudinal  or 
oblique.  This  appearance  has  been  termed  the  lyra,  from  the  fancied  resemblance 
it  bears  to  the  strings  of  a  harp. 

Between  the  anterior  pillars  of  the  fornix  and  the  anterior  extremities  of  the 
thalami  optici,  an  oval  aperture  is  seen  on  each  side,  the  foramen  of  Monro.  The 
two  openings  descend  towards  the  middle  line,  and,  joining  together,  lead  into  the 
upper  part  of  the  third  ventricle.  These  openings  communicate  with  the  lateral 
ventricles  on  each  side,  and  below  with  the  third  ventricle. 

Divide  the  fornix  across  anteriorly,  and  reflect  the  two  portions,  the  one  forwards,  the  other 
backwards,  when  the  velum  interpositum  will  be  exposed. 

The  velum  interpositum  is  a  vascular  membrane,  reflected  from  the  pia  mater 
into  the  interior  of  the  brain  through  the  transverse  fissure,  passing  beneath  the 
posterior  rounded  border  of  the  corpus  callosum  and  fornix,  and  above  the  corpora 
quadrigemina,  pineal  gland,  and  optic  thalami.  It  is  of  a  triangular  form,  and 
separates  the  under  surface  of  the  body  of  the  fornix  from  the  cavity  of  the  third 
ventricle.  Its  posterior  border  forms  an  almost  complete  investment  for  the  pineal 
gland.  Its  anterior  extremity,  or  apex,  is  bifid ;  each  bifurcation  being  continued 
into  the  corresponding  lateral  ventricle,  behind  the  anterior  crura  of  the  fornix, 
forming  the  anterior  extremity  of  the  choroid  plexus.  On  its  under  surface  are 
two  vascular  fringes,  which  diverge  from  each  other  behind,  and  project  into  the 
cavity  of  the  third  ventricle.  These  are  the  choroid  plexuses  of  the  third  ventricle. 
To  its  lateral  margins  are  connected  the  choroid  plexuses  of  the  lateral  ventricles. 
The  arteries  of  the  velum  interpositum  enter  from  behind,  beneath  the  corpus 
callosum.  Its  veins,  the  venee  Galeni,  two  in  number,  run  along  its  under  sur- 
face ;  they  are  formed  by  the  venee  corporis  striati,  and  the  venaa  plexus  choroidis ; 
the  ven&e  Galeni  unite  posteriorly  into  a  single  trunk,  which  terminates  in  the 
straight  sinus. 

The  velum  interpositum  should  now  be  removed.  This  must  be  effected  carefully,  especially  at 
its  posterior  part,  where  it  invests  the  pineal  gland ;  the  thalami  optici  will  then  be  exposed  with 
the  cavity  of  the  third  ventricle  between  them  (fig.  269). 

The  thalami  optici  are  two  large  oblong  masses,  placed  between  the  diverging 
portions  of  the  corpora  striata ;  they  are  of  a  white  color,  superficially ;  internally, 


THIRD   VENTRICLE. 


52T 


they  are  composed  of  white  fibres  intermixed  with  gray  matter.  Each  thalamus 
rests  upon  its  corresponding  crus  cerebri,  which  it  embraces.  Externally,  it  is 
bounded  by  the  corpus  striatum,  and  taania  semicircularis ;  and  is  continuous  with 
the  hemisphere.  Internally,  it  forms  the  lateral  boundary  of  the  third  ventricle ; 
and  running  along  its  upper  border  is  seen  the  peduncle  of  the  pineal  gland.  Its 
upper  surface  is  free,  being  pa#ly  seen  in  the  lateral  ventricle ;  it  is  partly  covered 
by  the  fornix,  and  marked  in  front  by  an  eminence,  the  anterior  tubercle.  Its 
under  surface  forms  the  roof  of  the  descending  cornu  of  the  lateral  ventricle ;  into 
it  the  crus  cerebri  passes.  Its  posterior  and  inferior  part,  which  projects  into  the 
descending  horn  of  the  lateral  ventricle,  presents  two  small  round  eminences,  the 
internal  and  external  geniculate  bodies.  Its  anterior  extremity,  which  is  narrow, 
forms  the  posterior  boundary  of  the  foramen  of  Monro. 


Fig.  269.— The  Third  and  Fourth  Ventricles. 


The  third  ventricle  is  the  narrow  oblong  fissure  placed  between  the  thalami 
optici,  and  extending  to  the  base  of  the  brain.  It  is  bounded,  above,  by  the  under 
surface  of  the  velum  interpositum,  from  which  are  suspended  the  choroid  plexuses 
of  the  third  ventricle ;  and,  laterally,  by  two  white  tracts,  one  on  either  side,  the 
peduncles  of  the  pineal  gland.  Its  floor,  somewhat  oblique  in  its  direction,  is 
formed,  from  before  backwards,  by  the  parts  which  close  the  interpeduncular  space, 
viz.,  the  iamma  cinerea,  the  tuber  cinereum  and  infundibulum,  the  corpora  albicantia, 
and  the  locus  perforatus ;  its  sides,  by  the  optic  thalami ;  in  front,  by  the  anterior 


528  NERVOUS    SYSTEM. 

crura  of  the  fornix,  and  part  of  the  anterior  commissure ;  behind,  by  the  posterior 
commissure,  and  the  iter  e  tertio  ad  quartum  venlriculum. 

The  cavity  of  the  third  ventricle  is  crossed  by  three  commissures,  named,  from 
their  position,  anterior,  middle,  and  posterior. 

The  anterior  commissure  is  a  rounded  cord  of  white  fibres,  placed  in  front  of  the 
anterior  crura  of  the  fornix.  It  perforates  the  corpus  striatum  on  either  side,  and 
spreads  out  into  the  substance  of  the  hemispheres,  over  the  roof  of  the  descending 
horn  of  each  lateral  ventricle. 

The  middle  or  soft  commissure  consists  almost  entirely  of  gray  matter.  It 
connects  together  the  thalami  optici.  and  is  continuous  with  the  gray  matter  lining 
the  anterior  part  of  the  third  ventricle. 

The  posterior  commissure,  smaller  than  the  anterior,  is  a  flattened  white  band  of 
fibres,  connecting  together  the  two  thalami  optici  posteriorly.  It  bounds  the  third 
ventricle  posteriorly,  and  is  placed  in  front  of  and  beneath  the  pineal  gland,  above 
the  opening  leading  to  the  fourth  ventricle. 

The  third  ventricle  has  four  openings  connected  with  it.  In  front  are  two  oval 
apertures,  one  on  either  side,  the  foramina  of  Monro,  through  which  the  third 
communicates  with  the  lateral  ventricles.  Behind,  is  a  third  opening  leading  into 
the  fourth  ventricle  by  a  canal,  the  aqueduct  of  Sylvius  or  iter  e  tertio  ad  quartum 
ventriculum.  The  fourth,  situated  in  the  anterior  part  of  the  floor  of  the  ventricle, 
is  a  deep  pit,  which  leads  downwards  to  the  funnel-shaped  cavity  of  the  infundi- 
bulum,  the  iter  ad  infundibulum. 

The  lining  membrane  of  the  lateral  ventricles  is  continued  through  the  foramina 
of  Monro  into  the  third  ventricle,  and  extends  along  the  iter  a  tertio  into  the 
fourth  ventricle ;  at  the  bottom  of  the  iter  ad  infundibulum,  it  ends  in  a  cul- 
de-sac. 

Gray  matter  of  the  third  ventricle.  A  layer  of  gray  matter  covers  the  greater 
part  of  the  surface  of  the  third  ventricle.  In  the  floor  of  this  cavity  it  exists  in 
great  abundance,  and  is  prolonged  upwards  on  the  sides  of  the  thalami,  extending 
across  the  cavity  as  the  soft  commissure ;  below,  it  enters  into  the  corpora  albi- 
cantia,  and  surrounds  in  part  the  anterior  pillars  of  the  fornix. 

Behind  the  third  ventricle,  and  in  front  of  the  cerebellum,  are  the  corpora 
quadrigemina ;  and  resting  upon  these,  the  pineal  gland. 

The  jmieal  gland,  so  named  from  its  peculiar  shape  (pinus,  the  fruit  of  the  fir), 
called  also  the  conarium,  is  a  small  reddish-gray  body,  conical  in  form,  placed 
immediately  behind  the  posterior  commissure,  and  between  the  nates,  upon  which 
it  rests.  It  is  retained  in  its  position  by  a  duplicature  of  pia  mater,  derived  from 
the  under  surface  of  the  velum  interpositum,  which  almost  completely  invests  it. 
The  pineal  gland  is  about  four  lines  in  length,  and  from  two  to  three  in  width  at 
its  base,  and  is  said  to  be  larger  in  the  child  than  in  the  adult,  and  in  the  female 
than  in  the  male.  Its  base  is  connected  with  the  cerebrum  by  some  transverse 
commissural  fibres,  derived  from  the  posterior  commissure ;  and  by  four  slender 
peduncles,  formed  of  medullary  fibres.  Of  these,  the  two  superior  pass  forwards 
upon  the  upper  and  inner  margin  of  the  optic  thalami  to  the  anterior  crura  of  the 
fornix,  with  which  they  become  blended.  The  inferior  peduncles  pass  vertically 
downwards  from  the  base  of  the  pineal  gland,  along  the  back  part  of  the  inner 
surface  of  the  thalami,  and  are  only  seen  on  a  vertical  section  through  the  gland. 
The  pineal  gland  is  very  vascular,  and  consists  chiefly  of  gray  matter,  with  a  few 
medullary  fibres.  In  its  base  is  a  small  cavity,  said  by  some  to  communicate  with 
that  of  the  third  ventricle.  It  contains  a  transparent  viscid  fluid,  and  occasionally 
a  quantity  of  sabulous  matter,  named  acervulus  cerebri,  composed  of  phosphate 
and  carbonate  of  lime,  phosphate  of  magnesia  and  ammonia,  with  a  little  animal 
matter.  These  concretions  are  almost  constant  in  their  existence,  and  are  found 
at  all  periods  of  life.  When  this  body  is  solid,  the  sabulous  matter  is  found  upon 
its  surface,  and  occasionally  upon  its  peduncles. 

On  the  removal  of  the  pineal  gland  and  adjacent  portion  of  pia  mater,  the  corpora  quadri- 
gemina are  exposed. 


CORPORA    QUADRIGEMINA  — VALVE    OF   VIEUSSENS.     529 

The  corpora  or  iubercula  quadrigemina — the  optic  lobes — are  four  rounded  emi- 
nences placed  in  pairs,  two  in  front  and  two  behind,  separated  from  another  by  a 
crucial  depression.  They  are  situated  immediately  behind  the  third  ventricle 
and  posterior  commissure,  beneath  the  posterior  border  of  the  corpus  callosum, 
and  above  the  iter  e  tertio  ad  quartum  ventriculum.  The  anterior  pair,  the  nates, 
are  the  larger,  oblong  from  before  backwards,  and  of  a  gray  color.  The  posterior 
pair,  the  testes,  are  hemispherical  in  form,  and  lighter  in  color  than  the  preceding. 
They  are  connected  on  each  side  with  the  thalamus  opticus,  and  commencement 
of  the  optic  tracts,  by  means  of  two  white  prominent  bands,  termed  brachia.  Those 
connecting  the  nates  with  the  thalamus  {brachia  anteriora)  are  the  larger,  and  pass 
obliquely  outwards.  Those  connecting  the  testes  with  the  thalamus  are  called  the 
brachia  posteriora.  Both  pairs,  in  the  adult,  are  quite  solid,  being  composed  of  white 
matter  externally,  and  gray  matter  within.  These  bodies  are  larger  in  the  lower, 
animals  than  in  man.  In  fishes,  reptiles,  and  birds,  they  are  only  two  in  number, 
are  called  the  optic  lobes,  from  their  connection  with  the  optic  nerves,  and  are 
hollow  in  their  interior ;  but  in  mammalia,  they  are  four  in  number,  as  in  man,  and 
quite  solid.  In  the  human  foetus,  they  are  developed  at  a  very  early  period,  and 
form  a  large  proportion  of  the  cerebral  mass ;  at  first,  they  are  only  two  in  number, 
as  in  the  lower  mammalia,  and  hollow  in  their  interior. 

These  bodies,  from  below,  receive  white  fibres  from  the  olivary  fasciculus  or  fillet; 
they  are  also  connected  with  the  cerebellum,  by  means  of  a  large  white  cord  on 
each  side,  the  processus  ad  testes  or  superior  peduncles  of  the  cerebellum,  which 
pass  up  to  the  thalami  from  the  tubercula  quadrigemina. 

The  valve  of  Vieussens  is  a  thin  translucent  lamina  of  medullary  substance, 
stretched  between  the  two  processus  e  cerebello  ad  testes ;  it  covers  in  the  canal 
leading  from  the  third  to  the  fourth  ventricle,  forming  part  of  the  roof  of  the  latter 
cavity.  It  is  narrow  in  front,  where  it  is  connected  with  the  testes ;  and  broader 
behind,  at  its  connection  with  the  vermiform  process  of  the  cerebellum.  A  slight 
elevated  ridge,  the  frenulum,  descends  upon  the  upper  part  of  the  valve  from  the 
corpora  quadrigemina,  and  on  either  side  of  it  may  be  seen  the  fibres  of  origin  of 
the  fourth  nerve.  Its  lower  half  is  covered  by  a  thin  transversely  grooved  lobule 
of  gray  matter  prolonged  from  the  anterior  border  of  the  cerebellum  ;  this  is  called 
the  linguetta  laminosa. 

The  corpora  geniculata  are  two  small,  flattened,  oblong  masses,  placed  on  the 
outer  side  of  the  corpora  quadrigemina,  and  on  the  under  and  back  part  of  each 
optic  thalamus,  and  named,  from  their  position,  corpus  geniculatum  externum  and 
corpus  geniculatum  internum.  They  are  placed  one  on  the  outer  and  one  on  the 
inner  side  of  each  optic  tract.  In  this  situation,  the  optic  tract  may  be  seen 
dividing  into  two  bands,  one  of  which  is  connected  with  the  external  geniculate  body 
and  nates,  the  other  being  connected  with  the  internal  geniculate  body  and  testis. 

Structure  of  the  cerebrum.  The  white  matter  of  each  hemisphere  consists  of 
three  kinds  of  fibres.  1.  Diverging  or  peduncular  fibres,  which  connect  the 
hemisphere  with  the  cord  and  medulla  oblongata.  2.  Transverse  commissural 
fibres  which  connect  together  the  two  hemispheres.  3.  Longitudinal  commissural 
fibres,  which  connect  distant  parts  of  the  same  hemisphere. 

The  diverging  or  peduncular  fibres  consist  of  a  main  body,  and  of  certain  accessory 
fibres.  The  main  body  of  fibres  originates  in  the  columns  of  the  cord  and  medulla 
oblongata,  and  enters  the  cerebrum  through  the  crus  cerebri,  where  they  are 
arranged  in  two  bundles,  separated  by  the  locus  niger.  Those  fibres  which  form 
the  inferior  or  fasciculated  portion  of  the  crus  are  derived  from  the  anterior 
pyramid,  and,  ascending,  pass  mainly  through  the  centre  of  the  striated  body ;  those 
on  the  opposite  surface  of  the  crus,  which  form  the  tegmentum,  are  derived  from 
the  posterior  pyramid  and  fasciculi  teretes ;  ascending,  they  pass,  some  through  the 
under  part  of  the  thalamus,  and  others  through  both  thalamus  and  corpus  striatum, 
decussating  in  these  bodies  with  each  other,  and  with  the  fibres  of  the  corpus 
callosum.  The  optic  thalami  also  receive  accessory  fibres  from  the  jwocessus  ad 
testes,  the  olivary  fasciculus,  the  corpora  quadrigemina,  and  corpora  geniculata 
34 


530  NERVOUS    SYSTEM. 

Some  of  the  diverging  fibres  end  in  the  cerebral  ganglia,  whilst  others  pass 
through  and  receive  additional  fibres  from  them,  and,  as  they  emerge,  radiate  into 
the  anterior,  middle,  and  posterior  lobes  of  the  hemisphere,  decussating  again  with 
the  fibres  of  the  corpus  cailosum,  before  passing  to  the  convolutions. 

The  transverse  commissural  fibres  connect  together  the  two  hemispheres  across 
the  middle  line.  They  are  formed  by  the  corpus  cailosum,  and  the  anterior  and 
posterior  commissures. 

The  longitudinal  commissural  fibres  connect  together  distant  parts  of  the  same 
hemisphere,  the  fibres  being  disposed  in  a  longitudinal  direction.  They  form  the 
fornix,  the  taenia  semicircularis,  and  peduncles  of  the  pineal  gland,  the  stria? 
longitudinales,  the  fibres  of  the  gyrus  fornicatus,  and  the  fasciculus  uncinatus. 


CEREBELLUM. 

The  Cerebellum  or  little  brain  is  that  portion  of  the  encephalon  which  is  con- 
tained in  the  inferior  occipital  fossee.  It  is  situated  beneath  the  posterior  lobes 
of  the  cerebrum,  from  which  it  is  separated  by  the  tentorium.  Its  average  weight 
in  the  male  is  5  oz.  4  drs.  It  attains  its  maximum  weight  between  the  twenty-fifth 
and  fortieth  years ;  its  increase  in  weight  after  the  fourteenth  year  being  relatively 
greater  in  the  female  than  in  the  male.  The  proportion  between  the  cerebellum 
and  cerebrum  is,  in  the  male,  as  1  to  8$  ;  and,  in  the  female,  as  1  to  8 J.  In  the 
infant,  it  is  proportionally  much  smaller  than  in  the  adult,  the  relation  between 
them  being,  according  to  Chaussier,  between  1  to  13  and  1  to  26 ;  by  Cruveilhier 
it  was  found  to  be  1  to  20.  In  form,  the  cerebellum  is  oblong,  flattened  from 
above  downwards,  its  greatest  diameter  being  from  side  to  side.  It  measures 
from  three  and  a  half  to  four  inches  transversely,  from  two  to  two  and  a  half 
inches  from  before  backwards,  being  about  two  inches  thick  in  the  centre,  and 
about  six  lines  at  its  circumference,  the  thinnest  part.  It  consists  of  gray  and 
white  matter :  the  former,  darker  than  that  of  the  cerebrum,  occupies  the  surface ; 
the  latter,  the  interior.  The  surface  of  the  cerebellum  is  not  convoluted  like  the 
cerebrutr^but  traversed  by  numerous  curved  furrows  or  sulci,  which  vary  in  depth 
at  different  parts,  and  correspond  to  the  intervals  between  the  laminae  of  which  its 
exterior  is  composed. 

Its  upper  surface  (fig.  270)  is  somewhat  elevated  in  the  median  line,  and  de- 


Upper  Surface  of  the  Cerebellum. 


[tressed  towards  its  circumference;  it  consists  of  two  lateral  hemispheres,  connected 
together  by  an  elevated  median  portion  or  lobe,  the  superior  vermiform  process. 


CEREBELLUM. 


531 


The  median  lobe  is  the  fundamental  part,  and  in  some  animals,  as  fishes  and  reptiles, 
the  only  part  which  exists ;  the  hemispheres  being  additions,  and  attaining  their 
maximum  in  man.  The  hemispheres  are  separated,  in  front,  by  a  deep  notch,  the 
incisura  cerebelli  anterior,  which  encircles  the  corpora  quadrigemina  behind ;  they 
are  also  separated  by  a  similar  notch  behind,  the  incisura  cerebelli  posterior,  in 
which  is  received  the  upper  part  of  the  falx  cerebelli.  The  superior  vermiform 
process  (upper  part  of  the  median  lobe  of  the  cerebellum),  extends  from  the  notch 
on  the  anterior  to  that  on  the  posterior  border.  It  is  divided  into  three  lobes :  the 
lobulus  centralis,  a  small  lobe,  situated  in  the  incisura  anterior ;  the  monticulus  cere- 
belli, the  central  projecting  part  of  the  process;  and  the  commissura  simplex,  a 
small  lobe  near  the  incisura  posterior. 

The  under  surface  of  the  cerebellum  (fig.  271)  is  subdivided  into  two  lateral 
hemispheres  by  a  depression,  the  valley,  which  extends  from  before  backwards  in 
the  middle  line.  The  lateral  hemispheres  are  lodged  in  the  inferior  occipital  fossae ; 
the  median  depression,  or  valley,  receives  the  back  part  of  the  medulla  oblongata, 
is  broader  in  the  centre  than  at  either  extremity,  and  has,  projecting  from  its  floor, 
part  of  the  median  lobe  of  the  cerebellum,  called  the  inferior  vermiform  process. 
The  parts  entering  into  the  composition  of  this  body  are,  from  behind  forwards,  the 

Fig.  271. — Under  Surface  of  che  Cerebellum. 


commissura  brevis,  situated  in  the  incisura  posterior ;  in  front  of  this,  a  laminated 
conical  projection,  the  pyramid;  more  anterior,  is  a  larger  eminence,  the  uvula, 
placed  between  the  two  rounded  lobes  which  occupy  the  sides  of  the  valley,  the 
amygdalae,  and  connected  with  them  by  a  commissure  of  gray  matter,  indented 
on  the  surface,  called  the  furrowed  band.  In  front  of  the  uvula  is  the  nodule; 
it  is  the  anterior  pointed  termination  of  the  inferior  vermiform  process,  and  projects 
into  the  cavity  of  the  fourth  ventricle;  it  has  been  named  by  Malacarne  the 
laminated  tubercle.  On  each  side  of  the  nodule  is  a  thin  layer  of  white  substance, 
attached  externally  to  the  flocculus,  and  internally  to  the  nodule,  and  to  a  corre- 
sponding part  on  the  opposite  side ;  they  form  together  the  posterior  medullary 
velum  or  commissure  of  the  flocculus.  It  is  usually  covered  in  and  concealed  by 
the  amygdalae,  and  cannot  be  seen  until  these  are  drawn  aside.  This  band  is 
of  a  semilunar  form  on  each  side,  its  anterior  margin  being  free  and  concave,  its 
posterior  being  attached  just  in  front  of  the  furrowed  band.  Between  it  and  the 
nodulus  and  uvula  behind,  is  a  deep  fossa,  called  the  swallow's  nest  {nidus  hirun- 
dinis). 

Lobes  of  the  cerebellum.  Each  hemisphere  is  divided  into  an  upper  and  a  lower 
portion  by  the  great  horizontal  fissure,  which  commences  in  front  at  the  pons,  and 
passes  horizontally  round  the  free  margin  of  either  hemisphere,  backwards  to  the 
middle  line.  From  this  primary  fissure  numerous  secondary  fissures  proceed,  which 
separate  the  cerebellum  into  lobes. 


532  NERVOUS   SYSTEM. 

Upon  the  upper  surface  of  either  hemisphere  there  are  two  lobes,  separated  from 
each  other  by  a  fissure.  These  are  the  anterior  or  square  lobe,  which  extends 
as  far  back  as  the  posterior  edge  of  the  vermiform  process,  and  the  posterior  or 
semilunar  lobe,  which  passes  from  the  termination  of  the  preceding  to  the  great 
horizontal  fissure. 

Upon  the  under  surface  of  either  hemisphere  there  are  five  lobes,  separated  by 
sulci ;  these  may  be  described  from  before  backwards.  The  flocculus  or  sub-pedun- 
cular lobe  is  a  prominent  tuft,  situated  behind  and  below  the  middle  peduncle  of  the 
cerebellum ;  its  surface  is  composed  of  gray  matter,  subdivided  into  a  few  small 
laminae ;  it  is  sometimes  called  the  pneumo gastric  lobule,  from  being  situated  be- 
hind the  pneumogastric  nerve.  The  amygdala  or  tonsil  is  situated  on  either  side 
of  the  great  median  fissure  or  valley,  and  projects  into  the  fourth  ventricle.  The 
digastric  lobe  is  situated  on  the  outside  of  the  tonsil,  being  connected  in  part  with 
the  pyramid.  Behind  the  digastric  is  the  slender  lobe,  which  is  connected  with 
the  back  part  of  the  pyramid  and  the  commissura  brevis ;  and  more  posteriorly 
is  the  inferior  posterior  lobe,  which  also  joins  the  commissura  brevis  in  the  valley. 

Fourth  Ventricle. 

The  fourth  ventricle  or  ventricle  of  the  cerebellum  is  the  space  between  the  pos- 
terior surface  of  the  medulla  oblongata  and  pons  in  front,  and  the  cerebellum 
behind.  It  is  lozenge-shaped,  being  contracted  above  and  below,  and  broadest 
across  its  central  part.  It  is  bounded  laterally  by  the  processus  e  cerebello  ad  testes 
above,  and  by  the  diverging  posterior  pyramids  and  restiform  bodies  below. 

The  roof  is  arched;  it  is  formed  by  the  valve  of  Vieussens  and  the  under  surface 
of  the  cerebellum,  which  presents  in  this  situation  four  small  eminences  or  lobules, 
two  occupying  the  median  line,  the  nodulus  and  uvula,  the  remaining  two,  the 
amygdalae,  being  placed  on  either  side  of  the  uvula 

The  anterior  boundary  or  floor  is  formed  by  the  posterior  surface  of  the  medulla 
oblongata  and  pons.  In  the  median  line  is  seen  the  posterior  median  fissure ;  it 
becomes  gradually  obliterated  above,  and  terminates  below  in  the  point  of  the 
calamus  scriptorius,  formed  by  the  convergence  of  the  posterior  pyramids.  At  this 
point  is  the  orifice  of  a  short  canal  terminating  in  a  cul-de-sac,  the  remains  of  the 
canal  which  extends  in  fcetal  life  through  the  centre  of  the  cord:  On  each  side 
of  the  median  fissure  are  two  slightly  convex  longitudinal  eminences,  the  fasciculi 
teretes ;  they  extend  the  entire  length  of  the  floor,  being  indistinct  below,  and  of 
a  grayish  color,  but  well  marked  and  whitish  above.  Each  eminence  consists  of 
fibres  derived  from  the  lateral  tract  and  restiform  body,  which  ascend  to  the  cere- 
brum. Opposite  the  crus  cerebelli,  on  the  outer  side  of  the  fasciculi  teretes,  is  a 
small  eminence  of  dark  gray  substance,  which  presents  a  bluish  tint  through  the 
thin  stratum  covering  it ;  this  is  called  the  locus  cceruleus;  and  a  thin  streak  of  the 
same  color  continued  up  from  this  on  either  side  of  the  fasciculi  teretes,  as  far  as 
the  top  of  the  ventricle,  is  called  the  taenia  violacea.  The  lower  part  of  the  floor 
of  the  ventricle  is  crossed  by  several  white  transverse  lines,  linese  transversa ;  they 
emerge  from  the  posterior  median  fissure ;  some  enter  the  crus  cerebelli,  others 
enter  the  roots  of  origin  of  the  auditory  nerve,  whilst  some  pass  upwards  and 
outwards  on  the  floor  of  the  ventricle. 

The  lining  membrane  of  the  fourth  ventricle  is  continuous  with  that  of  the 
third,  through  the  aqueduct  of  Sylvius,  and  its  cavity  communicates  below  with 
the  sub-arachnoid  space  of  the  brain  and  cord  through  an  aperture  in  the  layer  of 
pia  mater,  extending  between  the  cerebellum  and  medulla  oblongata.  Laterally, 
this  membrane  is  reflected  outwards  a  short  distance  between  the  cerebellum  and 
medulla. 

The  choroid  plexuses  of  the  fourth  ventricle  are  two  in  number ;  they  are 
delicate  vascular  fringes,  which  project  into  the  ventricle  on  each  side,  passing 
from  the  point  of  the  inferior  vermiform  process  to  the  outer  margin  of  the  resti- 
form bodies. 


STRUCTURE    OF    CEREBELLUM. 


533 


The  gray  matter  in  the  floor  of  the  ventricle  consists  of  a  tolerably  thick 
stratum,  continuous  below  with  the  gray  commissure  of  the  cord,  and  extending 
up  as  high  as  the  aqueduct  of  Sylvius,  besides  some  special  deposits  connected 
with  the  roots  of  origin  of  certain  nerves.  In  the  upper  half  of  the  ventricle  is 
a  projection  situated  over  the  nucleus,  from  which  the  sixth  and  facial  nerves 
take  a  common  origin.  In  the  lower  half  are  three  eminences  on  each  side  for 
the  roots  of  origin  of  the  eighth  and  ninth  nerves. 

Structure.  If  a  vertical  section  is  made  through  either  hemisphere  of  the  cere- 
bellum, midway  between 

its  centre  and  the  superior  Fig.  272.— Vertical  Section  of  the  Cerebellum, 

vermiform  process ;  it  will 
be  found  to  consist  of  a 
central  stem  of  white  mat- 
ter, which  contains  in  its 
interior  a  dentate  body. 
From  the  surface  of  each 
hemisphere,  a  series  of 
plates  of  medullary  matter 
are  detached,  which,  co- 
vered with  gray  matter, 
form  the  laminae ;  and  from 
its  anterior  part  arise  three 
large  processes  or  pedun- 
cles, superior,  middle,  and 
inferior,  by  which  it  is  con- 
nected with  the  rest  of  the 
encephalon. 

The  laminae  are  about 
ten  or  twelve  in  number,  including  those  on  both  surfaces  of  the  cerebellum,  those 
in  front  being  detached  at  a  right  angle,  and  those  behind  at  an  acute  angle ;  as 
each  lamina  proceeds  outwards,  other  secondary  laminae  are  detached  from  it,  and, 
from  these,  tertiary  laminae.  The  arrangement  thus  described  gives  to  the  cut 
surface  of  the  organ  a  foliated  appearance,  to  which  the  name  arbor  vitse  has  been 
given.  Each  lamina  consists  of  white  matter,  covered  externally  by  a  layer  of 
gray  substance. 

The  white  matter  of  each  lamina  is  derived  partly  from  the  central  stem ;  in 
addition  to  which  white  fibres  pass  from  one  lamina  to  another. 

The  gray  matter  resembles  somewhat  the  cortical  substance  of  the  convolutions. 
It  consists  of  two  layers,  the  external  one,  soft  and  of  a  grayish  color,  the  internal 
one,  firmer  and  of  a  rust  color. 

The  corpus  dentatum.  or  ganglion  of  the  cerebellum  is  situated  a  little  to  the  inner 
side  of  the  centre  of  the  stem  of  white  matter.  It  consists  of  an  open  bag  or 
capsule  of  gray  matter,  the  section  of  which  presents  a  gray  dentated  outline, 
being  open  at  its  anterior  part.  It  is  surrounded  by  white  fibres ;  white  fibres 
are  also  contained  in  its  interior,  which  issue  from  it  to  join  the  superior  peduncles. 
The  peduncles  of  the  cerebellum,  superior,  middle,  and  inferior,  serve  to  connect 
it  with  the  rest  of  the  encephalon. 

The  superior  peduncles  (processus  e  cerebello  ad  testes)  connect  the  cerebellum  with 
the  cerebrum ;  they  pass  forwards  and  upwards  to  the  testes,  beneath  which  they 
ascend  to  the  crura  cerebri  and  optic  thalami,  forming  part  of  the  diverging  cere- 
bral fibres ;  each  peduncle  forms  part  of  the  lateral  boundary  of  the  fourth 
ventricle,  and  is  connected  with  its  fellow  of  the  opposite  side  by  the  valve  of 
Vieussens.  The  peduncles  are  continuous  behind  with  the  folia  of  the  inferior 
vermiform  process,  and  with  the  white  fibres  in  the  interior  of  the  corpus  den- 
tatum. Beneath  the  corpora  quadrigemina.  the  innermost  fibres  of  each  peduncle 
decussate  with  each  other,  so  that  some  fibres  from  the  right  half  of  the  cerebellum 
are  continued  to  the  left  half  of  the  cerebrum. 


534  NERVOUS   SYSTEM. 

The  inferior  peduncles  (processus  admedullam)  connect  the  cerebellum  with  the 
medulla  oblongata.  They  pass  downwards  to  the  back  part  of  the  medulla,  and 
form  part  of  the  restiform  bodies.  Above,  the  fibres  of  each  process  are  con- 
nected chiefly  with  the  laminae,  on  the  upper  surface  of  the  cerebellum;  and 
below,  they  are  connected  with  all  three  tracts  of  one  half  of  the  medulla,  and, 
through  these,  with  the  corresponding  half  of  the  cord,  excepting  the  posterior 
median  columns. 

The  middle  peduncles  (processiLS  ad  pontem),  the  largest  of  the  three,  connect 
together  the  two  hemispheres  of  the  cerebellum,  forming  their  great  transverse 
commissure.  They  consist  of  a  mass  of  curved  fibres,  which  arise  in  the  lateral 
parts  of  the  cerebellum,  and  pass  across  to  the  same  points  on  the  opposite  side. 
They  form  the  transverse  fibres  of  the  pons  Yarolii. 


On  the  General  Anatomy  of  the  Nerves  and  Nervous  Centres,  the  student  may  consult  the 
works  of  Kblliker,  and  Todd  and  Bowman,  before  alluded  to  ;  and  the  Articles  "  Nerve  and  Nerv- 
ous Centres,"  in  the  Cyclop,  of  Anat.  and  Physiol. — For  further  information  on  the  Descriptive 
Anatomy  of  the  Nervous  Centres,  consult: — Cruveilhier's  "  Anatomie  Descriptive ;"  Todd's 
"  Descriptive  Anatomy  of  the  Brain,  Spinal  Cord,  and  Ganglions ;"  Herbert  Mayo's  "  Plates  of 
the  Brain  and  Spinal  Cord;"  and  Arnold's  " Tabulae  Anatomical.  Fascic.  i.  Icones  Cerebri  et 
Medullar  Spinalis." 


Cranial  Nerves. 

The  Cranial  Nerves,  nine  in  number  on  each  side,  include  those  nerves  which 
arise  from  some  part  of  the  cerebro-spinal  centre,  and  are  transmitted  through 
foramina  in  the  base  of  the  cranium.  They  have  been  named  numerically, 
according  to  the  order  in  which  they  pass  out  of  this  cavity.  Their  names  are 
also  derived  from  the  part  to  which  each  is  distributed,  or  from  the  special 
function  appropriated  to  each.  Taken  in  their  order,  from  before  backwards, 
they  are  as  follows : — 

1st.  Olfactory.  ,_  ,     (  Facial  or  Portio  dura. 

2d.  Optic.  '  \  Auditory  or  Portio  mollis. 

3d.  Motor  oculi.  I  Glosso-pharyngeal. 

4th.  Pathetic.  8th.  <  Pneumogastric  or  Par  vagum. 

5th.  Trifacial  or  Trigemini.  (  Spinal  accessory. 

6th.  Abducens.  9th.      Hypoglossal. 

If,  however,  the  7th  pair  be  considered  as  two,  and  the  8th  pair  as  three  distinct 
nerves,  then  their  number  will  be  increased  to  twelve,  which  is  the  arrangement 
adopted  by  Sommering. 

The  cranial  nerves  may  be  subdivided  into  four  groups,  according  to  the 
peculiar  function  possessed  by  each,  viz.,  nerves  of  special  sense;  nerves  of 
common  sensation ;  nerves  of  motion ;  and  mixed  nerves.  These  groups  may 
be  thus  arranged : — 

1.  Nerves  of  Special  Sense.  2.  Nerves  of  Motion. 

Olfactory.  Motor  oculi- 

Optic  Pathetic. 

Auditorv  Part  of  third  division  of  fifth  (de- 

Part  of  giosso-pharyngeal  (described  scr^    under  the   fifth    nerve, 

under  the  eighth  pair,  p.  555).  P'  5  °)*     ' 

Lingual  branch  of  the  fifth  (described  Abducens. 

under  the  fifth  nerve,  p.  550).  facial. 

Hypoglossal. 

4.  Mixed  Nerves. 
3.  Nerves  of  Common  Sensation.  Pneumogastric  _  (described    under 

the  eighth  pair,  p.  557). 
Fifth  (greater  portion).  Spinal  accessory  (described  under 

Part  oi  glosso-pharyngeal.  the  eighth  pair,  p.  560). 

All  the  cranial  nerves  are  connected  to  some  part  of  the  surface  of  the  brain. 
This  is  termed  their  superficial  or  apparent  origin.  But  their  fibres  may,  in  all 
cases,  be  traced  deeply  into  the  substance  of  the  organ.  This  would  form  their 
deep  or  real  origin. 

1.  Nerves  o»  Special  Sense. 

Olfactory  Nerve. 

The  First  or  Olfactory  Nerve,  the  special  nerve  of  the  sense  of  smell,  may 
be  regarded  as  a  portion  of  the  cerebral  substance,  pushed  forwards  in  direct 
relation  with  the  organ  to  which  it  is  distributed.     It  arises  by  three  roots. 

The  external  or  long  root  is  a  narrow  white  medullary  band,  which  passes 
outwards  across  the  fissure  of  Sylvius,  into  the  substance  of  the  middle  lobe  of  the 
cerebrum.  Its  deep  origin  may  be  traced  to  the  corpus  striatum1,  the  superficial 
fibres  of  the  optic  thalamus2,  the  anterior  commissure3,  and  the  convolutions  of 
the  island  of  Eeil. 

1  Vicussens,  Winslow,  Monro,  Mayo.  a  Valentin.  «  Cruveilhier. 

535 


536 


CRANIAL   NERVES. 


The  middle  or  gray  root  arises  from  a  papilla  of  gray  matter,  the  caruncula 
mammillaris,  imbedded  in  the  anterior  lobe.  This  root  is  prolonged  into  the 
nerve  from  the  adjacent  part  of  the  brain,  and  contains  white  fibres  in  its  interior, 
which  are  connected  with  the  corpus  striatum. 

The  internal  or  short  root  is  composed  of  white  fibres,  which  arise  from  the 
inner  and  back  part  of  the  anterior  lobe,  being  connected,  according  to  Foville, 
with  the  longitudinal  fibres  of  the  gyrus  fornicatus. 

These  three  roots  unite,  and  form  a  flat  band,  narrower  in  the  middle  than  at 
either  extremity,  and  its  section  of  a  somewhat  prismoid  form.  It  is  soft  in  texture, 
and  contains  a  considerable  amount  of  gray  matter  in  its  substance.  As  it  passes 
forwards,  it  is  contained  in  a  deep  sulcus,  between  two  convolutions,  lying  on  the 
under  surface  of  the  anterior  lobe,  on  either  side  of  the  longitudinal  fissure,  and 
is  retained  in  position  by  the  arachnoid  membrane  which  covers  it.  On  reaching 
the  cribriform  plate  of  the  ethmoid  bone,  it  expands  into  an  oblong  mass  of  grayish- 
white  substance,  the  olfactory  bulb.  From  the  under  part  of  this  bulb  are  given 
off  numerous  filaments,  about  twenty  in  number,  which  pass  through  the  cribriform 
foramina,  and  are  distributed  to  the  mucous  membrane  of  the  nose.  Each  filament 
is  surrounded  by  a  tubular  prolongation  from  the  dura  mater  and  pia  mater;  the 
former  being  lost  on  the  periosteum  lining  the  nose ;  the  latter,  in  the  neurilemma 
of  the  nerve.  The  filaments,  as  they  enter  the  nares,  are  divisible  into  three 
groups :  an  inner  group,  larger  than  those  on  the  outer  Avail,  spread  out  over  the 
upper  third  of  the  septum ;  a  middle  set,  confined  to  the  roof  of  the  nose ;  and 
an  outer  set,  which  are  distributed  over  the  superior  and  middle  turbinated  bones, 
and  the  surface  of  the  ethmoid  in  front  of  them.  As  the  filaments  descend,  they 
unite  in  a  plexiform  network,  and  become  gradually  lost  in  the  lining  membrane. 
Their  mode  of  termination  is  unknown. 

The  olfactory  differs  in  structure  from  other  nerves,  in  containing  gray  matter 
in  its  interior,  and  being  soft  and  pulpy  in  structure.  Its  filaments  are  deficient 
in  the  white  substance  of  Schwann,  are  not  divisible  into  fibrillae,  and  resemble 
the  gelatinous  fibres  in  being  nucleated,  and  of  a  finely-granular  texture. 


Fig.  273.— The  Optic  Nerves  and  Optic  Tracts. 


Optic  Nerve. 

The  Second  or  Optic  Nerve,  the  special  nerve  of  the  sense  of  sight,  is 
distributed  exclusively  to  the  eyeball.  The  nerves  of  opposite  sides  are  connected 
together  at  the  commissure ;  and  from  the  back  of  the  commissure,  they  may  be 

traced  to  the  brain,  under  the  name  of  the 
optic  tracts. 

The  optic  tract,  at  its  connection  with 
the  brain,  divides  into  two  bands  which 
are  continued  into  the  optic  thalami,  the 
corpora  geniculata,  and  the  corpora 
quadrigemina.  The  fibres  of  origin  from 
the  thalamus  may  be  traced  partly  from 
its  surface,  and  partly  from  its  interior. 
From  this  origin,  the  tract  winds  obliquely 
across  the  under  surface  of  the  crus  cerebri, 
in  the  form  of  a  flattened  band,  destitute 
of  neurilemma,  and  is  attached  to  the  crus 
by  its  anterior  margin.  It  now  assumes  a 
cylindrical  form,  and,  as  it  passes  forwards, 
is  connected  with  the  tuber  cinereum,  and 
lamina  cinerea,  from  both  of  which  it 
receives  fibres.  According  to  Foville,  it 
is  also  connected  with  the  taenia  semi- 
circularis,  and  the  anterior  termination  of  the  gyrus  fornicatus.  It  finally  joins 
with  the  nerve  of  the  opposite  side,  to  form  the  optic  commissure. 


OPTIC  — AUDITORY  — MOTOR   OCULI.  537 

The  commissure,  somewhat  quadrilateral  in  form,  rests  upon  the  olivary  process 
of  the  sphenoid  bone,  being  bounded,  in  front,  by  .the  lamina  cinerea;  behind,  by 
the  tuber  cinereum ;  on  either  side,  by  the  anterior  perforated  space.  Within 
the  commissure,  the  optic  nerves  of  the  two  sides  undergo  a  partial  decussation. 
The  fibres  which  form  the  inner  margin  of  each  tract, 

are  continued  across  from  one  to  the  other  side  of  the  ^f^^SJLS^ 
brain,  and  have  no  connection  with  the  optic  nerves. 
These  may  be  regarded  as  commissural  fibres  (inter- 
cerebral)  between  the  thalami  of  opposite  sides. 
Some  fibres  are  continued  across  the  anterior  border 
of  the  chiasma,  and  connect  the  optic  nerves  of  the 

two  sides,  having  no  relation  with  the  optic  tracts.  "^     •/w"'*— *• 

They  may  be  regarded  as  commissural  fibres  between  the  two  retinas  (inter-retinal 
fibres).  The  outer  fibres  of  each  tract  are  continued  into  the  optic  nerve  of  the  same 
side.  The  central  fibres  of  each  tract  are  continued  into  the  optic  nerve  of  the 
opposite  side,  decussating  in  the  commissure  with  similar  fibres  of  the  opposite  tract.1 

The  optic  nerves  arise  from  the  fore  part  of  the  commissure,  and,  diverging  from 
one  another,  become  rounded  in  form,  firm  in  texture,  and  are  inclosed  in  a  sheath 
derived  from  the  arachnoid.  As  each  nerve  passes  through  the  corresponding 
optic  foramen,  it  receives  a  sheath  from  the  dura  mater ;  and  as  it  enters  the,orbit, 
this  sheath  subdivides  into  two  layers,  one  of  which  becomes  continuous  with  the 
periosteum  of  the  orbit ;  the  other  forms  a  sheath  for  the  nerve,  and  surrounds  it 
as  far  as  the  sclerotic.  The  nerve  passes  through  the  cavity  of  the  orbit,  pierces 
the  sclerotic  and  choroid  coats  at  the  back  part  of  the  eyeball,  a  little  to  the  nasal 
side  of  its  centre,  and  expands  into  the  retina.  A  small  artery,  the  arteria  cen- 
tralis retinas,  perforates  the  optic  nerve  a  little  behind  the  globe,  and  runs  along 
its  interior  in  a  tubular  canal  of  fibrous  tissue.  It  supplies  the  inner  surface  of 
the  retina,  and  is  accompanied  by  corresponding  veins. 

Auditory  Nerve. 

The  Auditory  Nerve,  the  portio  mollis  of  the  seventh  pair,  is  the  special  nerve 
of  the  sense  of  hearing,  being  distributed  exclusively  to  the  internal  ear.  The 
portio  dura  of  the  seventh  pair,  the  facial  nerve,  is  the  motor  nerve  of  the  muscles 
of  the  face.     It  will  be  described  with  the  motor  cranial  nerves. 

The  auditory  nerve  arises  from  numerous  white  striae,  the  lineae  transversae, 
which  emerge  from  the  posterior  median  fissure  in  the  anterior  wall,  or  floor,  of 
the  fourth  ventricle.  It  is  also  connected  with  the  gray  matter  of  the  medulla, 
which  corresponds  to  the  locus  caeruleus.  According  to  Foville,  the  roots  of  this 
nerve  are  connected,  on  the  under  surface  of  the  middle  peduncle,  with  the  gray 
substance  of  the  cerebellum,  with  the  flocculus,  and  with  the  gray  matter  at  the 
borders  of  the  calamus  scriptorius.  The  nerve  winds  round  the  restiform  body, 
from  which  it  receives  fibres,  and  passes  forwards  across  the  posterior  border  of 
the  eras  cerebelli,  in  company  with  the  facial  nerve,  from  which  it  is  partially 
separated  by  a  small  artery.  It  then  enters  the  meatus  auditorius,  in  company 
with  the  facial  nerve,  and,  at  the  bottom  of  the  meatus,  divides  into  two  branches, 
cochlear  and  vestibular,  which  are  distributed,  the  former  to  the  cochlea,  the 
latter  to  the  vestibule  and  semicircular  canals.  The  auditory  nerve  is  very  soft 
in  texture  (hence  the  name  portio  mollis),  destitute  of  neurilemma,  and,  within  the 
meatus,  receives  one  or  two  filaments  from  the  facial. 

2.  The  Motor  Cranial  Nerves. 

Third  or  Motor  Oculi  Nerve. 

The  Third  or  Motor  Oculi  Nerve  supplies  all  the  muscles  of  the  eyeball,  except 
the  Superior  oblique  and  External  rectus ;  it  also  sends  motor  filaments  to  the  iris. 

1  A  specimen  of  congenital  absence  of  the  optic  commissure  is  to  be  found  in  the  Museum  of 
the  Westminster  Hospital. 


538 


CRANIAL   NERVES. 


£  j  la.TroelileqgX. 


It  is  a  rather  large  nerve,  of  rounded  form  and  firm  texture,  having  its  apparent 
origin  from  the  inner  surface  of  the  crus  cerebri,  immediately  in  front  of  the  pons 
Varolii. 

The  deep  origin  may  be  traced  into  the  substance  of  the  crus,  where  some  of 
its  fibres  are  connected  with  the  locus  niger ;  others  run  downwards,  among  the 
longitudinal  fibres  of  the  pons,  whilst  others  ascend,  to  be  connected  with  the 
tubercula  quadrigemina  and  valve  of  Vieussens.  According  to  Stilling,  the 
fibres  of  the  nerve  pierce  the  peduncle  and  locus  niger,  and  arise  from  a  gray 
nucleus  in  the  floor  of  the  aqueduct  of  Sylvius.  On  emerging  from  the  brain,  it 
is  invested  in  a  sheath  of  pia  mater,  and  inclosed  in  a  prolongation  from  the 
arachnoid.  It  then  pierces  the  dura  mater  on  the  outer  side  of  the  anterior 
clinoid  process,  where  its  serous  covering  is  reflected  from  it,  and  passes  along 
the  outer  wall  of  the  cavernous  sinus,  above  the  other  orbital  nerves,  receiving 
in  its  course  one  or  two  filaments  from  the  cavernous  plexus  of  the  sympathetic. 
It  then  divides  into  two  branches,  which  enter  the  orbit  through  the  sphenoidal 

fissure,    between    the     two 
Fig.  275.— Nerves  of  the  Orbit.     Seen  from  above.  heads  of  the   External  rec- 

tus muscle.  On  passing 
through  the  fissure,  the 
nerve  is  placed  below  the 
fourth,  and  the  frontal  and 
lachrymal  branches  of  the 
ophthalmic  nerve. 

The  superior  division, 
the  smaller,  passes  inwards 
across  the  optic  nerve,  and 
supplies  the  Superior  rectus 
and  Levator  palpebral. 

The  inferior  division, 
the  larger,  divides  into 
three  branches.  One  passes 
beneath  the  optic  nerve  to 
the  Internal  rectus ;  another 
to  the  Inferior  rectus ;  and 
the  third,  the  largest  of  the 
three,  passes  forwards,  be- 
tween the  Inferior  and  Ex- 
ternal recti,  to  the  Inferior 
oblique.  From  the  latter,  a 
short,  thick  branch  is  given 
off  to  the  lower  part  of  the 
lenticular  ganglion,  forming 
its  inferior  root,  as  well  as 
two  filaments  to  the  Inferior 
rectus.  All  these  branches 
enter  the  muscles  on  their 
ocular  surface. 


(Hi 'current  Filamrni 

I      U  Aura-JIattr 


Fourth  Nerve. 

The  Fourth  or  Trochlear  nerve,  the  smallest  of  the  cranial  nerves,  supplies 
the  Superior  oblique  muscle.  It  arises  from  the  upper  part  of  the  valve  of 
Vieussens,  immediately  behind  the  testis,  and  divides,  beneath  the  corpora  quadri- 
gemina, into  two  fasciculi ;  the  anterior  one  arising  from  a  nucleus  of  gray  matter, 
close  to  the  middle  line  of  the  floor  of  the  Sylvian  aqueduct ;  the  posterior  one 
from  a  gray  nucleus,  at  the  upper  part  of  the  floor  of  the  fourth  ventricle,  close  to 
the  origin  of  the  fifth  nerve.     The  two  nerves  are  connected  together,  at  their 


FOURTH— SIXTH. 


539 


origin,  by  a  transverse  band  of  white  fibres,  which  crosses  the  surface  of  the  velum. 
The  nerve  winds  round  the  outer  side  of  the  crus  cerebri,  immediately  above  the 
pons  Varolii,  pierces  the  dura  mater  in  the  free  border  of  the  tentorium  cerebelli, 
near  the  posterior  clinoid  process,  above  the  oval  opening  for  the  fifth  nerve,  and 
passes  forwards  through  the  outer  wall  of  the  cavernous  sinus,  below  the  third ; 
but,  as  it  enters  the  orbit,  through  the  sphenoidal  fissure,  it  becomes  the  highest  of 
all  the  nerves.  In  the  orbit,  it  passes  inwards,  above  the  origin  of  the  Levator 
palpebrae,  and  finally  enters  the  orbital  surface  of  the  Superior  oblique  muscle. 

In  the  outer  wall  of  the  cavernous  sinus,  this  nerve  receives  some  filaments 
from  the  carotid  plexus  of  the  sympathetic.  It  is  not  unfrequently  blended  with 
the  ophthalmic  division  of  the  fifth ;  and  occasionally  gives  off'  a  branch  to  assist 
in  the  formation  of  the  lachrymal  nerve.  It  also  gives  off  a  recurrent  branch, 
which  passes  backwards  between  the  layers  of  the  tentorium,  dividing  into  two 
or  three  filaments,  which  may  be  traced  as  far  back  as  the  wall  of  the  lateral 
sinus. 

Fig.  276. — Nerves  of  the  Orbit  and  Ophthalmic  Ganglion.     Side  view. 


Internal  Cavatid  As. 
h  Carotid  Plaits. 


Hot/)* 
Hoot 


Sixth  or  Abducens  Nerve. 

The  Sixth  or  Abducens  Nerve  supplies  the  External  rectus  muscle.  Its 
apparent  origin  is  by  several  filaments  from  the  constricted  part  of  the  corpu3 
pyramidale,  close  to  the  pons,  or  from  the  lower  border  of  the  pons  itself. 

The  deep  origin  of  this  nerve  has  been  traced  by  Mayo,  between  the  fasciculi 
of  the  corpus  pyramidale,  to  the  posterior  part  of  the  medulla,  where  Stilling 
has  shown  its  connection  with  a  gray  nucleus  in  the  floor  of  the  fourth  ventricle. 
The  nerve  pierces  the  dura  mater,  immediately  below  the  posterior  clinoid  pro- 
cess, lying  in  a  groove  by  the  side  of  the  body  of  the  sphenoid  bone.  It  passes 
forwards  through  the  cavernous  sinus,  lying  on  the  outer  side  of  the  internal 
carotid  artery,  where  it  is  joined  by  several  filaments  from  the  carotid  plexus,  by 
one  from  Meckel's  ganglion  (Bock),  and  another  from  the  ophthalmic  nerve.  It 
enters  the  orbit  through  the  sphenoidal  fissure,  and  lies  above  the  ophthalmic 
vein,  from  which  it  is  separated  by  a  lamina  of  dura  rnater.  It  then  passes 
between  the  two  heads  of  the  External  rectus,  and  is  distributed  to  that  muscle 
on  its  ocular  surface. 

Relations  of  the  Orbital  Nerves. 

The  above-mentioned  nerves,  as  well  as  the  ophthalmic  division  of  the  fifth,  as 
they  pass  to  the  orbit,  bear  a  certain  relation  to  each  other  in  the  cavernous 


540  CRANIAL   NERVES. 

sinus,  at  the  sphenoidal  fissure,  and  in  the  cavity  of  the  orbit,  which  will  be  now 
described. 

In  the  cavernous  sinus,  the  third,  fourth,  and  ophthalmic  division  of  the  fifth. 
are  placed  in  the  dura  mater,  forming  the  outer  wall  of  the  sinus  in  numerical 
order,  both  from  above  downwards,  and  from  within  outwards.  The  sixth  nerve 
lies  at  the  outer  side  of  the  internal  carotid  artery.  As  these  nerves  pass  forwards 
to  the  sphenoidal  fissure,  the  third  and  fifth  nerves  become  divided  ;  and  the  sixth 
approaches  the  rest ;  so  that  their  relative  position  becomes  considerably  changed. 

In  the  sphenoidal  fissure,  the  fourth,  and  the  frontal  and  lachrymal  divisions 
of  the  ophthalmic,  lie  upon  the  same  plane,  the  former  being  most  internal,  the 
latter  external ;  and  they  enter  the  cavity  of  the  orbit  above  the  muscles.  The 
remaining  nerves  enter  the  orbit  between  the  two  heads  of  the  External  rectus. 
The  superior  division  of  the  third  is  the  highest ;  beneath  this,  the  nasal  branch 
of  the  fifth ;  then  the  inferior  division  of  the  third ;  and  the  sixth  lowest  of  all. 

In  the  orbit,  the  fourth,  and  the  frontal  and  lachrymal  divisions  of  the  ophthalmic, 
lie  on  the  same  plane  immediately  beneath  the  periosteum,  the  fourth  nerve  being 
internal  and  resting  on  the  Superior  oblique,  the  frontal  resting  on  the  Levator 
palpebral,  and  the  lachrymal  on  the  External  rectus.  Next  in  order  comes  the 
superior  division  of  the  third  nerve  lying  immediately  beneath  the  Superior  rectus, 
and  then  the  nasal  division  of  the  fifth  crossing  the  optic  nerve  from  the  outer  to 
the  inner  side  of  this  cavity.  Beneath  these  is  found  the  optic  nerve,  surrounded 
in  front  by  the  ciliary  nerves,  and  having  the  lenticular  ganglion  on  its  outer 
side,  between  it  and  the  External  rectus.  Below  the  optic  is  the  inferior  division 
of  the  third,  and  the  sixth,  which  lies  on  the  outer  side  of  the  cavity. 

Facial  Nerve. 

The  Facial  Nerve,  the  portio  dura  of  the  seventh  pair,  is  the  motor  nerve  of 
all  the  muscles  of  the  face,  the  Platysma  and  Buccinator.  It  supplies  also  the 
muscles  of  the  external  ear,  the  posterior  belly  of  the  Digastric  and  the  Stylo-hyoid. 
Through  the  chorda  tympani  it  supplies  the  Lingualis ;  by  its  tympanic  branch, 
the  Stapedius  and  Laxator  tympani;  through  the  otic  ganglion,  the  Tensor  tympani ; 
and  through  the  connection  of  its  trunk  with  the  Vidian  nerve,  by  the  petrosal 
nerves,  it  probably  supplies  the  Levator  palati  and  Azygos  uvulas.  It  arises  from 
the  lateral  tract  of  the  medulla  oblongata,  in  the  groove  between  the  olivary  and 
restiform  bodies.  Its  deep  origin  may  be  traced  to  the  floor  of  the  fourth  ventricle, 
where  it  is  connected  with  the  same  nucleus  as  the  sixth  nerve.  This  nerve  is 
situated  a  little  nearer  to  the  middle  line  than  the  portio  mollis,  close  to  the  lower 
border  of  the  pons  Varolii,  from  which  some  of  its  fibres  are  derived. 

Connected  with  this  nerve,  and  lying  between  it  and  the  portio  mollis,  is  a  small 
fasciculus,  the  portio  inter  duram  et  mollem  of  Wrisberg.  This  accessory  portion 
arises  from  the  lateral  column  of  the  cord. 

The  nerve  passes  forwards  and  outwards  upon  the  crus  cerebelli,  and  enters  the 

internal  auditory  meatus  with 

Fig.  277.— The  Course  and  Connections  of  the  Facial  the   auditory  nerve.      Within 

Nerve  in  the  Temporal  Bone.  the    meatus>   the    faeial    nerve 

tttv^      Jf.        .T>  lies  first  to  the  inner  side  of 

*****  Mr—i l^L^^r^^^^Sli^  tne  auditory,  and  then   in  a 

*«y'^Z^%f^SB|^OirmA  groove  upon  this  nerve,  and  is 

intumescnu*  Ca"^-"'-'^^^^^\T»'i  connected  to  it  by  one  or  two 

juj.r  f  '-««Kl8f^^R'l  At  tllc  bottom  of  the  mea- 

•   ■  {Audit™,         ^^ijJwjm      J.j  tus,  it  enters  the  aquasductus 

^^  Fallopii,  and  follows  the  ser- 

pentine course  of  that  canal 
through  the   petrous   portion 
of  the  temporal  bone,  from  its  commencement  at  the  internal  meatus  to  its  termina- 
tion at  the  stylo-mastoid  foramen.     It  is  at  first  directed  outwards  towards  the 


FACIAL. 


541 


hiatus  Fallopii,  where  it  forms  a  reddish  gangliform  swelling  (intumescentia 
gangliformis),  and  is  joined  by  several  nerves ;  bending  suddenly  backwards,  it 
runs  in  the  internal  wall  of  the  tympanum,  above  the  fenestra  ovalis,  and 
at  the  back  of  this  cavity  passes  vertically  downwards  to  the  stylo-mastoid 
foramen. 

On  emerging  from  this  aperture,  it  runs  forwards  in  the  substance  of  the  parotid 
gland,  crosses  the  external  carotid  artery,  and  divides  behind  the  ramus  of  the 
lower  jaw  into  two  primary  branches,  temporo-facial  and  cervico-facial,  from 
which  numerous  offsets  are  distributed  over  the  side  of  the  head,  face,  and  upper 
part  of  the  neck,  supplying  the  superficial  muscles  in  these  regions. 

The  communications  of  the  facial  nerve  may  be  thus  arranged : — 


In  the  internal  auditory  meatus 


In  the  aquaeductus  Fallopii 


At  its  exit  from  the  stylo-mastoid 
foramen        . 


On  the  face 


With  the  auditory  nerve. 

With  Meckel's  ganglion   by  the  large 

petrosal  nerve. 
With   the  otic  ganglion   by  the  small 

petrosal  nerve. 
With  the  sympathetic  on  the  middle  me- 
ningeal by  the  external  petrosal  nerve. 
With  the  pneumogastric. 
"        glossopharyngeal. 
"        carotid  plexus. 
"        auricularis  magnus. 
"        auriculotemporal. 
With  the  three  divisions  of  the  fifth. 


In  the  internal  auditory  meatus,  some  minute  filaments  pass  between  the  facial 
and  auditory  nerves. 

Opposite  the  hiatus  Fallopii,  the  gangliform  enlargement  on  the  facial  nerve 
communicates,  by  means  of  the  large  petrosal  nerve,  with  Meckel's  ganglion, 
forming  its  motor  root ;  by  a  filament  from  the  small  petrosal  with  the  otic 
ganglion ;  and  by  the  external  petrosal,  with  the  sympathetic  filaments  accom- 
panying the  middle  meningeal  artery  (Bidder).  From  the  gangliform  enlarge- 
ment, according  to  Arnold,  a  twig  is  sent  back  to  the  auditory  nerve. 

At  its  exit  from  the  stylo-mastoid  foramen,  it  sends  a  twig  to  the  pneumogastric, 
another  to  the  glossopharyngeal  nerve,  and  communicates  with  the  carotid  plexus 
of  the  sympathetic,  with  the  great  auricular  branch  of  the  cervical  plexus,  with 
the  auriculo-temporal  branch  of  the  inferior  maxillary  nerve  in  the  parotid  gland, 
and  on  the  face  with  the  terminal  branches  of  the  three  divisions  of  the  fifth. 


Branches  of  Distribution. 


Within  aquaeductus  Fallopii 

At  exit  from   stylo-mastoid 
foramen 


On  the  face 


Tympanic. 
Chorda  tympani. 
Posterior  auricular. 
Digastric. 
Stylo-hyoid. 

(  Temporal. 
Temporo-facial  <  Malar. 

(  Infra-orbital. 
(  Buccal. 

■!  Supra-maxillary. 
(  Infra-maxillary. 


Cervico-facial 


The  Tympanic  branch  arises  from  the  nerve  opposite  the  pyramid;  it  is  a  small 
filament,  which  supplies  the  Stapedius  and  Laxator  tympani  muscles. 


542 


CRANIAL   NERVES. 


The  Chorda  tympani  is  given  off  from  the  facial  as  it  passes  vertically  down- 
wards at  the  back  of  the  tympanum,  about  a  quarter  of  an  inch  before  its  exit 
from  the  stylo-mastoid  foramen.  It  ascends  from  below  upwards  in  a  distinct 
canal,  parallel  with  the  aquaeductus  Fallopii,  and  enters  the  cavity  of  the  tym- 
panum through  an  opening  between  the  base  of  the  pyramid  and  the  attachment 
of  the  membrana  tympani,  and  becomes  invested  with  mucous  membrane.  It 
passes  forwards  through  the  cavity  of  the  tympanum,  between  the  handle  of  the 
malleus  and  vertical  ramus  of  the  incus,  to  its  anterior  inferior  angle,  and  emerges 
from '  that  cavity  through  a  foramen  (the  canal  of  Huguier)  at  the  inner  side  of 


Fig.  278.— The  Nerves  of  the  Scalp,  Face,  and  Side  of  the  Neck. 


Terminations 
>f  Supra  -  trochlear 

tf  Infra  -trochlea* 
cf  Nasal 


the  Glaserian  fissure.  It  then  descends  between  the  two  Pterygoid  muscles,  and 
meets  the  gustatory  nerve  at  an  acute  angle,  after  communicating  with  which,  it 
accompanies  it  to  the  submaxillary  gland ;  it  then  joins  the  submaxillary  ganglion, 
and  terminates  in  the  Lingualis  muscle. 

The  Posterior  auricular  nerve  arises  close  to  the  stylo-mastoid  foramen,  and 
passes  upwards- in  front  of  the  mastoid  process,  where  it  is  joined  by  a  filament 


FACIAL.  543 

from  the  auricular  branch  of  the  pneumogastric,  and  communicates  with  the  deep 
branch  of  the  auricularis  magnus ;  as  it  ascends  between  the  meatus  and  mastoid 
process  it  divides  into  two  branches.  The  auricular  branch  supplies  the  Retra- 
hens  aurem,  and  the  integument  at  the  back  part  of  the  auricle.  The  occipital 
branch,  the  larger,  passes  backwards  along  the  superior  curved  line  of  the  occi- 
pital bone,  and  supplies  the  occipital  portion  of  the  Occipito-frontalis  and  the 
integument. 

The  Stylo-hyoid  is  a  long  slender  branch,  which  passes  inwards,  entering  the 
Stylo-hyoid  muscle  about  its  middle ;  it  communicates  with  the  sympathetic  fila- 
ments on  the  external  carotid  artery. 

The  Digastric  branch  usually  arises  by  a  common  trunk  with  the  preceding ;  it 
divides  into  several  filaments,  which  supply  the  posterior  belly  of  the  Digastric ; 
one  of  these  perforates  that  muscle  to  join  the  glosso-pharyngeal  nerve. 

The  Temporo-facial,  the  larger  of  the  two  terminal  branches,  passes  upwards 
and  forwards  through  the  parotid  gland,  crosses  the  neck  of  the  condyle  of  the 
jaw,  being  connected  in  this  situation  with  the  auriculo-temporal  branch  of  the 
inferior  maxillary  nerve,  and  divides  into  branches,  which  are  distributed  over 
the  temple  and  upper  part  of  the  face ;  these  may  be  divided  into  three  sets, 
temporal,  malar,  and  infra-orbital. 

The  temporal  branches  cross  the  zygoma  to  the  temporal  region,  supplying 
the  Attrahens  aurem  and  the  integument,  and  join  with  the  temporal  branch  of 
the  superior  maxillary,  and  with  the  auriculo-temporal  branch  of  the  inferior 
maxillary.  The  more  anterior  branches  supply  the  frontal  portion  of  the  Occipito- 
frontalis,  and  the  Orbicularis  palpebrarum  muscle,  joining  with  the  supra-orbital 
branch  of  the  ophthalmic. 

The  malar  brandies  pass  across  the  malar  bone  to  the  outer  angle  of  the  orbit, 
where  they  supply  the  Orbicularis  and  Corrugator  supercilii  muscles,  joining  with 
filaments  from  the  lachrymal  and  supra-orbital  nerves ;  others  supply  the  lower 
eyelid,  joining  with  filaments  of  the  malar  branches  of  the  superior  maxillary  nerve. 

The  infra-orbital,  of  larger  size  than  the  rest,  pass  horizontally  forwards  to  be 
distributed  between  the  lower  margin  of  the  orbit  and  the  mouth.  The  superficial 
branches  run  beneath  the  skin  and  above  the  superficial  muscles  of  the  face, 
which  they  supply,  being  distributed  to  the  integument  and  hair  follicles ;  some 
supply  the  lower  eyelid  and  Pyramidalis  nasi,  joining,  at  the  inner  angle  of  the 
orbit,  with  the  infra-trochlear  and  nasal  branches  of  the  ophthalmic.  The  deep 
branches  pass  beneath  the  Levator  labii  superioris,  supply  it  and  the  Levator 
anguli  oris,  and  form  a  plexus  (infra-orbital)  by  joining  with  the  infra-orbital 
branch  of  the  superior  maxillary  nerve. 

The  Cervico-facial  division  of  the  facial  nerve  passes  obliquely  downwards 
and  forwards  through  the  parotid  gland,  where  it  is  joined  by  branches  from  the 
great  auricular  nerve ;  opposite  the  angle  of  the  lower  jaw  it  divides  into 
branches,  which  are  distributed  on  the  lower  half  of  the  face  and  upper  part  of 
the  neck.  These  may  be  divided  into  three  sets :  buccal,  supra-maxillary,  and 
infra-maxillary. 

The  buccal  branches  cross  the  Masseter  muscle,  join  the  infra-orbital  branches 
of  the  temporo-facial  division  of  the  nerve,  and  with  filaments  of  the  buccal 
branch  of  the  inferior  maxillary  nerve.  They  supply  the  Buccinator  and  Orbi- 
cularis oris. 

The  supra-maxillary  branches  pass  forwards  beneath  the  Platysma  and  De- 
pressor anguli  oris,  supplying  the  muscles  and  the  integument  of  the  lip  and  chin, 
anastomosing  with  the  mental  branch  of  the  inferior  dental  nerve. 

The  infra-maxillary  branches  run  forward  beneath  the  Platysma,  and  form  a 
series  of  arches  across  the  side  of  the  neck  over  the  supra-hyoid  region.  One  of 
these  branches  descends  vertically  to  join  with  the  superficial  cervical  nerve  from 
the  cervical  plexus ;  others  supply  the  Platysma  and  Levator  labii  inferioris. 


544 


CRANIAL   NERVES. 


Ninth  or  Hypoglossal  Nerve. 

The  Ninth  or  Hypoglossal  Nerve  is  the  motor  nerve  of  the  tongue.  It 
arises  by  several  filaments,  from  ten  to  fifteen  in  number,  from  the  groove  between 
the  pyramidal  and  olivary  bodies,  in  a  continuous  line  with  the  anterior  roots  of 
the  spinal  nerves.  According  to  Stilling,  these  roots  may  be  traced  to  a  gray 
nucleus  in  the  floor  of  the  medulla  oblongata,  between  the  posterior  median  furrow 
and  the  nuclei  of  the  glossopharyngeal  and  vagus  nerves.  The  filaments  of  this 
nerve  are  collected  into  two  bundles,  which  perforate  the  dura  mater  separately, 
opposite  the  anterior  condyloid  foramen,  and  unite  together  after  their  passage 
through  it.     The  nerve  descends  almost  vertically  to  a  point  corresponding  with 


Fig.  279. — Hypoglossal  Nerve,  Cervical  Plexus,  and  their  Branches. 


the  arTgle  of  the  jaw.  It  is  at  first  deeply  seated  beneath  the  internal  carotid  and 
internal  jugular  vein,  and  intimately  connected  with  the  pneumogastric  nerve ; 
it  then  passes  forwards  between  the  vein  and  artery,  and,  descending  the  neck, 
becomes  superficial  below  the  Digastric  muscle.  The  nerve  then  loops  round  the 
occipital  artery,  and  crosses  the  external  carotid  below  the  tendon  of  the  Digastric 
muscle.  It  passes  beneath  the  Mylo-hyoid  muscle,  lying  between  it  and  the 
Hyoglossus,  and  is  connected  at  the  anterior  border  of  the  latter  muscle  with  the 
gustatory  nerve ;  it  is  then  continued  forwards  into  the  Genio-hyo-glossus  muscle 
as  far  as  the  tip  of  the  tongue,  distributing  branches  to  its  substance. 


NINTH   OR   HYPOGLOSSAL   NERVE.  545 

Branches  of  this  nerve  communicate  with  the 

Pneumogastric.  First  and  second  cervical  nerves. 

Sympathetic.  Gustatory. 

The  communication  with  the  pneumogastric  takes  place  close  to  the  exit  of  the 
nerve  from  the  skull,  numerous  filaments  passing  between  the  hypoglossal  and 
second  ganglion  of  the  pneumogastric,  or  both  being  united  so  as  to  form  one  mass. 

*The  communication  with  the  sympathetic  takes  place  opposite  the  atlas,  by 
branches  derived  from  the  superior  cervical  ganglion,  and  in  the  same  situation 
it  is  joined  by  a  filament  with  the  loop  connecting  the  first  two  cervical  nerves. 

The  communication  with  the  gustatory  takes  place  near  the  anterior  border  of 
the  Hyo-glossus  muscle  by  numerous  filaments,  which  ascend  upon  it. 

The  branches  of  distribution  are  the 

Descendens  noni.  Thyro-hyoid. 

Muscular. 

The  Descendens  noni  is  a  long  slender  branch,  which  quits  the  hypoglossal 
where  it  turns  round  the  occipital  artery.  It  descends  obliquely  across  the  sheath 
of  the  carotid  vessels,  and  joins  just  below  the  middle  of  the  neck,  to  form  a  loop 
with  the  communicating  branches  from  the  second  and  third  cervical  nerves.  From 
the  convexity  of  this  loop,  branches  pass  forwards  to  supply  the  Sterno-hyoid, 
Sterno-thyroid,  and  both  bellies  of  the  Omo-hyoid.  According  to  Arnold,  another 
filament  descends  in  front  of  the  vessels  into  the  chest,  which  joins  the  cardiac 
and  phrenic  nerves.  The  descendens  noni  is  occasionally  contained  in  the  sheath 
of  the  carotid  vessels,  being  sometimes  placed  over  and  sometimes  beneath  the 
internal  jugular  vein. 

The  Thyro-hyoid  is  a  small  branch,  arising  from  the  hypoglossal  near  the  pos- 
terior border  of  the  Hyo-glossus ;  it  passes  obliquely  across  the  great  cornu  of  the 
hyoid  bone,  and  supplies  the  Thyro-hyoid  muscle. 

The  Muscular  branches  are  distributed  to  the  Stylo-glossus,  Hyo-glossus, 
Genio-hyoid,  and  Genio-hyo-glossus  muscles.  At  the  under  surface  of  the  tongue, 
numerous  slender  branches  pass  upwards  into  the  substance  of  the  organ. 

3.  Nerves  of  Common  Sensation. 

Fifth  Nerve. 

The  Fifth  Nerve  [trifacial,  trigeminus)  is  the  largest  cranial  nerve,  and  resem- 
bles a  spinal  nerve,  in  its  origin  by  two  roots,  and  in  the  existence  of  a  ganglion 
on  its  posterior  root.  The  functions  of  this  nerve  are  various.  It  is  a  nerve  of 
special  sense,  of  common  sensation,  and  of  motion.  It  is  the  great  sensitive  nerve 
of  the  head  and  face,  the  motor  nerve  of  the  muscles  of  mastication  (except  the 
Buccinator),  and  its  lingual  branch  is  one  of  the  nerves  of  the  special  sense  of 
taste.  It  arises  by  two  roots,  a  posterior  larger  or  sensory,  and  an  anterior  smaller 
or  motor  root.  Its  superficial  origin  is  from  the  side  of  the  pons  Varolii,  a  little 
nearer  to  its  upper  than  its  lower  border.  The  smaller  root  consists  of  three  or 
four  bundles ;  in  the  larger,  the  bundles  are  more  numerous,  varying  in  number 
from  seventy  to  a  hundred ;  the  two  roots  are  separated  from  one  another  by  a 
few  of  the  transverse  fibres  of  the  pons.  The  deep  origin  of  the  larger  or  sensory 
root  may  be  traced  between  the  transverse  fibres  of  the  pons  Varolii  to  the  lateral 
tract  of  the  medulla  oblongata,  immediately  behind  the  olivary  body.  According 
to  some  anatomists,  it  is  connected  with  the  gray  nucleus  at  the  back  part  of  the 
medulla,  between  the  fasciculi  teretes  and  restiform  columns.  By  others,  it  is 
said  to  be  continuous  with  the  fasciculi  teretes  and  lateral  column  of  the  cord ; 
and,  according  to  Foville,  some  of  its  fibres  are  connected  with  the  transverse 
fibres  of  the  pons ;  whilst  others  enter  the  cerebellum,  spreading  out  on  the  sur- 
face of  its  middle  peduncle.  The  motor  root  has  been  traced  by  Bell  and  Retzius 
to  be  connected  with  the  pyramidal  body.  The  two  roots  of  the  nerve  pass  for- 
wards through  an  oval  opening  in  the  dura  mater,  at  the  apex  of  the  petrous 
35 


54G  CRANIAL   NERVES. 

portion  of  the  temporal  bone ;  here  the  fibres  of  the  larger  root  enter  a  large 
semilunar  ganglion  (Casserian),  while  the  smaller  root  passes  beneath  the  ganglion 
without  having  any  connection  with  it,  and  joins  outside  the  cranium  with  one 
of  the  trunks  derived  from  it. 

The  Casserian  or  Semilunar  Ganglion  is  lodged  in  a  depression  near  the 
apex  of  the  petrous  portion  of  the  temporal  bone.  It  is  of  a  somewhat  crescentic 
form,  with  its  convexity  turned  forwards.  Its  upper  surface  is  intimately  adhe- 
rent to  the  dura  mater. 

Branches.  This  ganglion  receives,  on  its  inner  side,  filaments  from  the  carotid 
plexus  of  the  sympathetic ;  and  from  it  some  minute  branches  are  given  off  to  the  ten- 
torium cerebelli,  and  the  dura  mater,  in  the  middle  fossa  of  the  cranium.  From 
its  anterior  border,  which  is  directed  forwards  and  outwards,  three  large  branches 
proceed ;  the  ophthalmic,  superior  maxillary,  and  inferior  maxillary.  The  two 
first  divisions  of  this  nerve  consist  exclusively  of  fibres  derived  from  the  larger 
root  and  ganglion,  and  are  solely  nerves  of  common  sensation.  The  third  or 
inferior  maxillary  is  composed  of  fibres  from  both  roots.  This,  therefore,  strictly 
speaking,  is  the  only  portion  of  the  fifth  nerve  which  can  be  said  to  resemble  a 
spinal  nerve. 

Branches  of  the  Fifth  Nerve. 
(1.)  Ophthalmic  Nerve. 

The  Ophthalmic,  the  first  division  of  the  fifth,  is  a  sensory  nerve.  It  supplies 
the  eyeball,  the  lachrymal  gland,  the  mucous  lining  of  the  eye  and  nose,  and  the 
integument  and  muscles  of  the  eyebrow  and  forehead  (fig.  275).  It  is  the  smallest 
of  the  three  divisions  of  the  fifth,  arising  from  the  upper  part  of  the  Casserian 
ganglion.  It  is  a  short,  flattened  band,  about  an  inch  in  length,  which  passes  for- 
wards along  the  outer  wall  of  the  cavernous  sinus,  below  the  other  nerves,  and 
just  before  entering  the  orbit,  through  the  sphenoidal  fissure,  divides  into  three 
branches,  frontal,  lachrymal,  and  nasal.  The  ophthalmic  nerve  is  joined  by  fila- 
ments from  the  cavernous  plexus  of  the  sympathetic,  and  gives  off  recurrent 
filaments  which  pass  between  the  layers  of  the  tentorium,  with  a  branch  from  the 
fourth  nerve. 

Its  branches  are  the 

Lachrymal.  Frontal.  Nasal. 

The  Lachrymal  is  the  smallest  of  the  three  branches  of  the  ophthalmic.  Not 
un frequently  it  arises  by  two  filaments,  one  from  the  ophthalmic,  the  other  from 
the  fourth,  and  this,  Swan  considers,  as  the  usual  condition.  It  passes  forwards 
in  a  separate  tube  of  dura  mater,  and  enters  the  orbit  through  the  narrowest  part 
of  the  sphenoidal  fissure.  In  this  cavity,  it  runs  along  the  upper  border  of  the 
External  rectus  muscle,  with  the  lachrymal  artery,  and  is  connected  with  the 
orbital  branch  of  the  superior  maxillary  nerve.  Within  the  lachrymal  gland  it 
gives  off  several  filaments,  which  supply  it  and  the  conjunctiva.  Finally  it  pierces 
the  palpebral  ligament,  and  terminates  in  the  integument  of  the  upper  eyelid, 
joining  with  filaments  of  the  facial  nerve. 

The  Frontal  is  the  largest  division  of  the  ophthalmic,  and  may  be  regarded,  both 
from  its  size  and  direction,  as  the  continuation  of  this  nerve.  It  enters  the  orbit 
above  the  muscles,  through  the  highest  and  broadest  part  of  the  sphenoidal  fissure, 
and  runs  forwards  along  the  middle  line,  between  the  Levator  palpebral  and  the 
periosteum.  Midway  between  the  apex  and  base  of  this  cavity,  it  divides  into 
two  branches,  supra-trochlear  and  supra-orbital. 

The  supra-trochlear  branch,  the  smaller  of  the  two,  passes  inwards,  above  the 
pulley  of  the  Superior  oblique  muscle,  and  gives  off  a  descending  filament,  which 
joins  with  the  infra-trochlear  branch  of  the  nasal  nerve.  It  then  escapes  from 
the  orbit  between  the  pulley  of  the  Superior  oblique  and  the  supra-orbital  foramen, 
curves  up  on  to  the  forehead  close  to  the  bone,  and  ascends  behind  the  Corru gator 
supercilii  and  Occipito-frontalis  muscles,  to  both  of  which  it  is  distributed 
finally,  it  is  lost  in  the  integument  of  the  forehead. 


SUPERIOR   MAXILLARY   NERVE.  547 

The  supra-orbital  branch  passes  forwards  through  the  supra-orbital  foramen, 
and  gives  oftj  in  this  situation,  palpebral  filaments  to  the  upper  eyelid.  It  then 
ascends  upon  the  forehead,  and  terminates  in  muscular,  cutaneous,  and  pericranial 
branches.  The  muscular  branches  supply  the  Corrugator  supercilii,  Occipito- 
frontalis,  and  Orbicularis  palpebrarum,  joining  in  the  substance  of  the  latter 
muscle  with  the  facial  nerve.  The  cutaneous  branches,  two  in  number,  an  inner 
and  an  outer,  supply  the  integument  of  the  cranium  as  far  back  as  the  occiput. 
They  are  at  first  situated  beneath  the  Occipito-frontalis,  the  inner  branch  per- 
forating the  frontal  portion  of  the  muscle,  the  outer  branch  its  tendinous  aponeu- 
rosis. The  pericranial  branches  are  distributed  to  the  pericranium  over  the 
frontal  and  parietal  bones.  They  are  derived  from  the  cutaneous  branches  whilst 
beneath  the  muscle. 

The  Nasal  nerve  is  intermediate  in  size  between  the  frontal  and  lachrymal, 
and  more  deeply  placed  than  the  other  branches  of  the  ophthalmic.  It  enters  the 
orbit  between  the  two  heads  of  the  External  rectus,  passes  obliquely  inwards 
across  the  optic  nerve  beneath  the  Levator  palpebras  and  Superior  rectus  muscles, 
to  the  inner  wall  of  this  cavity,  where  it  enters  the  anterior  ethmoidal  foramen, 
immediately  below  the  Superior  oblique.  It  then  enters  the  cavity  of  the  cranium, 
traverses  a  shallow  groove  on  the  front  of  the  cribriform  plate  of  the  ethmoid 
bone,  and  passes  down,  through  the  slit  by  the  side  of  the  crista  galli,  into  the 
nose,  where  it  divides  into  two  branches,  an  internal  and  an  external.  The 
internal  branch  supplies  the  mucous  membrane  near  the  fore  part  of  the  septum 
of  the  nose.  The  external  branch  descends  in  a  groove  on  the  inner  surface  of 
the  nasal  bone,  and  supplies  a  few  filaments  to  the  mucous  membrane  covering  the 
fore  part  of  the  outer  wall  of  the  nares  as  far  as  the  inferior  spongy  bone ;  it 
then  leaves  the  cavity  of  the  nose,  between  the  lower  border  of  the  nasal  bone  and 
the  upper  lateral  cartilage  of  the  nose,  and,  passing  down  beneath  the  Com- 
pressor naris,  supplies  the  integument  of  the  ala  and  tip  of  the  nose,  joining  with 
the  facial  nerve. 

The  branches  of  the  nasal  nerve  are  the  ganglionic,  ciliary,  and  infra- 
trochlear. 

The  ganglionic  is  a  long,  slender  branch,  about  half  an  inch  in  length,  which 
usually  arises  from  the  nasal,  between  the  two  heads  of  the  External  rectus.  It 
passes  forwards  on  the  outer  side  of  the  optic  nerve,  and  enters  the  superior  and 
posterior  angle  of  the  ciliary  ganglion,  forming  its  superior  or  long  root.  It  is 
sometimes  joined  by  a  filament  from  the  cavernous  plexus  of  the  sympathetic,  or 
from  the  superior  division  of  the  third  nerve. 

The  long  ciliary  nerves,  two  or  three  in  number,  are  given  off  from  the  nasal 
as  it  crosses  the  optic  nerve.  They  join  the  short  ciliary  nerves  from  the  ciliary 
ganglion,  pierce  the  posterior  part  of  the  sclerotic,  and,  running  forwards  between 
it  and  the  choroid,  are  distributed  to  the  Ciliary  muscle  and  iris. 

The  infra- trochlear  branch  is  given  off  just  as  the  nasal  nerve  passes  through 
the  anterior  ethmoidal  foramen.  It  runs  forwards  along  the  upper  border  of  the 
Internal  rectus,  and  is  joined,  beneath  the  pulley  of  the  Superior  oblique,  by  a 
filament  from  the  supra-trochlear  nerve.  It  then  passes  to  the  inner  angle  of  the 
eye,  and  supplies  the  Orbicularis  palpebrarum,  the  integument  of  the  eyelids  and 
side  of  the  nose,  the  conjunctiva,  lachrymal  sac,  and  caruncula  lacrymalis. 

(2.)  Superior  Maxillary  Nerve  (fig.  280). 

The  Superior  Maxillary,  the  second  division  of  the  fifth,  is  a  sensory  nerve. 
It  is  intermediate,  both  in  position  and  size,  between  the  ophthalmic  and  inferior 
maxillary.  It  commences  at  the  middle  of  the  Casserian  ganglion  as  a  flattened 
plexiform  band,  and  passes  forwards  through  the  foramen  rotundum,  where  it  be- 
comes more  cylindrical  in  form,  and  firmer  in  texture.  It  then  crosses  the  spheno- 
maxillary fossa,  traverses  the  infra-orbital  canal  in  the  floor  of  the  orbit,  and  ap- 
pears upon  the  face  at  the  infra-orbital  foramen.     At  its  termination,  the  nerve 


548 


CRANIAL   NERVES. 


lies  beneath  the  Levator  labii  superioris  muscle,  and  divides  into  a  leash  of 
branches,  which  spread  out  upon  the  side  of  the  nose,  the  lower  eyelid,  and  upper 
lip,  joining  with  filaments  of  the  facial  nerve. 

The  branches  of  this  nerve  may  be  divided  into  three  groups :  1.  Those  given 
off  in  the  spheno-maxillary  fossa.  2.  Those  in  the  infra-orbital  canal.  3.  Those 
on  the  face. 

I  Orbital. 
Spheno-maxillary  fossa  •<  Spheno-palatine. 
(  Posterior  dental. 


Infra-orbital  canal 
On  the  face     .     . 


Anterior  dental. 

{Palpebral. 
Nasal. 
,  Labial. 


The  Orbital  branch  arises  in  the  spheno-maxillary  fossa,  enters  the  orbit  by  the 
spheno-maxillary  fissure,  and  divides  at  the  back  of  that  cavity  into  two  branches, 
temporal  and  malar. 

Fig.  280. — Distribution  of  the  Second  and  Third  Divisions  of  the  Fifth  Nerve 
and  Submaxillary  Ganglion. 


The  temporal  branch  runs  in  a  groove  along  the  outer  wall  of  the  orbit  (in  the 
malar  bone),  receives  a  branch  of  communication  from  the  lachrymal,  and,  passing 
through  a  foramen  in  the  malar  bone,  enters  the  temporal  fossa.  It  ascends 
between  the  bone  and  substance  of  the  Temporal  muscle,  pierces  this  muscle  and 
the  temporal  fascia  about  an  inch  above  the  zygoma,  and  is  distributed  to  the 
integument  covering  the  temple  and  side  of  the  forehead,  communicating  with  the 
facial  and  auriculotemporal  branch  of  the  inferior  maxillary  nerve. 

The  malar  branch  passes  along  the  external  inferior  angle  of  the  orbit,  emerges 


INFERIOR   MAXILLARY  NERVE.  549 

upon  the  face  through  a  foramen  in  the  malar  bone,  and,  perforating  the  Orbi- 
cularis palpebrarum  muscle  on  the  prominence  of  the  cheek,  joins  with  the 
facial. 

The  Spheno-palatine  branches,  two  in  number,  descend  to  the  spheno-palatine 
ganglion. 

The  Posterior  dental  branches  arise  from  the  trunk  of  the  nerve  just  as  it  is 
about  to  enter  the  infra-orbital  canal;  they  are  two  in  number,  posterior  and 
anterior. 

The  posterior  branch  passes  from  behind  forwards  in  the  substance  of  the  supe- 
rior maxillary  bone,  and  joins  opposite  the  canine  fossa  with  the  anterior  dental. 
Numerous  filaments  are  given  off  from  the  lower  border  of  this  nerve,  which  form 
a  minute  plexus  in  the  outer  wall  of  the  superior  maxillary  bone,  immediately 
above  the  alveolus.  From  this  plexus,  filaments  are  distributed  to  the  pulps  of 
the  molar  and  bicuspid  teeth,  the  lining  membrane  of  the  antrum,  and  correspond- 
ing portion  of  the  gums. 

The  anterior  branch  is  distributed  to  the  gums  and  Buccinator  muscle. 

The  Anterior  dental,  of  large  size,  is  given  off  from  the  superior  maxillary  nerve 
just  before  its  exit  from  the  infra-orbital  foramen ;  it  enters  a  special  canal  in  the 
anterior  wall  of  the  antrum,  and  anastomoses  with  the  posterior  dental.  From 
this  nerve  some  filaments  are  distributed  to  the  incisor,  canine,  and  first  bicuspid 
teeth ;  others  are  lost  upon  the  lining  membrane  covering  the  fore  part  of  the 
inferior  meatus. 

The  Palpebral  branches  pass  upwards  beneath  the  Orbicularis  palpebrarum. 
They  supply  this  muscle,  the  integument,  and  conjunctiva  of  the  lower  eyelid, 
joining  at  the  outer  angle  of  the  orbit  with  the  facial  nerve  and  malar  branch  of 
the  orbital. 

The  Nasal  branches  pass  inwards ;  they  supply  the  muscles  and  integument  of 
the  side  of  the  nose,  and  join  with  the  nasal  branch  of  the  ophthalmic. 

The  Labial  branches,  the  largest  and  most  numerous,  descend  beneath  the  Leva- 
tor labii  superioris,  and  are  distributed  to  the  integument  and  muscles  of  the  upper 
lip,  the  mucous  membrane  of  the  mouth,  and  labial  glands. 

All  these  branches  are  joined,  immediately  beneath  the  orbit,  by  filaments  from 
the  facial  nerve,  forming  an  intricate  plexus,  the  infra-orbital. 

(3.)  Inferior  Maxillary  Nerve. 

The  Inferior  Maxillary  Nerve  distributes  branches  to  the  teeth  and  gums 
of  the  lower  jaw,  the  integument  of  the  temple  and  external  ear,  the  lower  part 
of  the  face  and  lower  lip,  and  the  muscles  of  mastication :  it  also  supplies  the 
tongue  with  one  of  its  special  nerves  of  the  sense  of  taste.  It  is  the  largest  of 
the  three  divisions  of  the  fifth,  and  consists  of  two  portions,  the  larger  or  sensory 
root,  proceeding  from  the  inferior  angle  of  the  Casserian  ganglion;  and  the  smaller 
or  motor  root,  which  passes  beneath  the  ganglion,  and  unites  with  the  inferior 
maxillary  nerve,  just  after  its  exit  through  the  foramen  ovale.  Immediately 
beneath  the  base  of  the  skull,  this  nerve  divides  into  two  trunks,  anterior  and 
posterior. 

The  Anterior  and  smaller  division,  which  receives  nearly  the  whole  of  the  motor 
root,  divides  into  five  branches,  which  supply  the  muscles  of  mastication.  They 
are  the  masseteric,  deep  temporal,  buccal,  and  pterygoid. 

The  masseteric  branch  passes  outwards,  above  the  External  pterygoid  muscle,  in 
front  of  the  temporo-maxillary  articulation,  and  crosses  the  sigmoid  notch,  with 
the  masseteric  artery,  to  the  Masseter  muscle,  in  which  it  ramifies  nearly  as  far  as 
its  anterior  border.  It  occasionally  gives  a  branch  to  the  Temporal  muscle,  and 
a  filament  to  the  articulation  of  the  jaw. 

The  deep  temporal  branches,  two  in  number,  anterior  and  posterior,  supply  the 
deep  surface  of  the  temporal  muscle.  The  posterior  branch,  of  small  size,  is 
"aced  at  the  back  of  the  temporal  fossa.     It  is  sometimes  joined  with  the 


550  CRANIAL   NERVES. 

masseteric  branch.  The  anterior  branch  is  reflected  upwards,  at  the  pterygoid 
ridge  of  the  sphenoid,  to  the  front  of  the  temporal  fossa.  It  is  occasionally  joined 
with  the  buccal  nerve. 

The  buccal  branch  pierces  the  External  pterygoid,  and  passes  downwards 
beneath  the  inner  surface  of  the  coronoid  process  of  the  lower  jaw  or  through  the 
fibres  of  the  Temporal  muscle,  to  reach  the  surface  of  the  Buccinator,  upon  which 
it  divides  into  a  superior  and  an  inferior  branch.  It  gives  a  branch  to  the  External 
pterygoid  during  its  passage  through  this  muscle,  and  a  few  ascending  filaments 
to  the  Temporal  muscle,  one  of  which  occasionally  joins  with  the  anterior  branch 
of  the  deep  temporal  nerve.  The  upper  branch  supplies  the  integument  and  upper 
part  of  the  Buccinator  muscle,  joining  with  the  facial  nerve  round  the  facial  vein. 
The  lower  branch  passes  forwards  to  the  angle  of  the  mouth ;  supplies  the  integu- 
ment and  Buccinator  muscle,  as  well  as  the  mucous  membrane  lining  its  inner 
surface,  joining  with  the  facial  nerve. 

The  pterygoid  branches  are  two  in  number,  one  for  each  Pterygoid  muscle. 
The  branch  to  the  Internal  pterygoid  is  long  and  slender,  and  passes  inwards  to 
enter  the  deep  surface  of  the  muscle.  This  nerve  is  intimately  connected  at  its 
origin  with  the  otic  ganglion.  The  branch  to  the  External  pterygoid  is  most 
frequently  derived  from  the  buccal,  but  it  may  be  given  off  separately  from  the 
anterior  trunk  of  the  nerve. 

The  Posterior  and  larger  division  of  the  inferior  maxillary  nerve  also  receives 
a  few  filaments  from  the  motor  root.  It  divides  into  three  branches,  auriculo- 
temporal, gustatory,  and  inferior  dental. 

The  Auriculo-tempoeal  Nerve  generally  arises  by  two  roots,  between  which 
passes  the  middle  meningeal  artery.  It  passes  backwards  beneath  the  External 
pterygoid  muscle  to  the  inner  side  of  the  articulation  of  the  lower  jaw.  It  then 
turns  upwards  with  the  temporal  artery,  between  the  external  ear  and  condyle  of 
the  jaw,  under  cover  of  the  parotid  gland,  and,  escaping  from  beneath  this  struc- 
ture, divides  into  two  temporal  branches.  The  posterior  temporal,  the  smaller 
of  the  two,  supplies  the  Attrahens  aurem  muscle,  and  is  distributed  to  the  upper 
part  of  the  pinna  and  the  neighboring  integument.  The  anterior  temporal 
accompanies  the  temporal  artery  to  the  vertex  of  the  skull,  and  supplies  the 
integument  of  the  temporal  region,  communicating  with  the  facial  nerve. 

The  auriculo-temporal  nerve  has  branches  of  communication  with  the  facial 
and  otic  ganglion.  Those  joining  the  facial  nerve,  usually  two  in  number,  pass 
forwards  behind  the  neck  of  the  condyle  of  the  jaw,  and  join  this  nerve  at  the 
posterior  border  of  the  Masseter  muscle.  They  form  one  of  the  principal  branches 
of  communication  between  the  facial  and  the  fifth  nerve.  The  filaments  of  com- 
munication with  the  otic  ganglion  are  derived  from  the  commencement  of  the 
auriculo-temporal  nerve. 

The  auricular  branches  are  two  in  number,  inferior  and  superior.  The  inferior 
auricular  arises  behind  the  articulation  of  the  jaw,  and  is  distributed  to  the  ear 
below  the  external  meatus ;  other  filaments  twine  round  the  internal  maxillary 
artery,  and  communicate  with  the  sympathetic.  The  superior  auricular  arises 
in  front  of  the  internal  ear,  and  supplies  the  integument  covering  the  tragus  and 
pinna. 

Branches  to  the  meatus  auditorius,  two  in  number,  arise  from  the  point  of  com- 
munication between  the  temporo-auricular  and  facial  nerves,  and  are  distributed 
to  the  meatus. 

The  branch  to  the  temporo-maxillary  articulation  is  usually  derived  from  the 
auriculo-temporal  nerve. 

The  parotid  branches  supply  the  parotid  gland. 

The  Gustatory  or  Lingual  Nerve  (fig.  280),  one  of  the  special  nerves  of  the 
sense  of  taste,  supplies  the  papillas  and  mucous  membrane  of  the  tongue.  It  is 
deeply  placed  throughout  the  whole  of  its  course.  It  lies  at  first  beneath  the 
External  pterygoid  muscle,  together  with  the  inferior  dental  nerve,  being  placed 
to  the  inner  side  of  the  latter  nerve,  and  is  occasionally  joined  to  it  by  a  branch 


GAXGLIA    OF   THE   FIFTH   NERVE.  551 

which  crosses  the  internal  maxillary  artery.  The  chorda  tympani  also  Joins  it 
at  an  acute  angle  in  this  situation.  The  nerve  then  passes  between  the  Internal 
pterygoid  muscle  and  the  inner  side  of  the  ramus  of  the  jaw,  and  crosses  obliquely 
to  the  side  of  the  tongue  over  the  Superior  constrictor  muscle  of  the  pharynx,  and 
between  the  Stylo-glossus  muscle  and  deep  part  of  the  submaxillary  gland ;  the 
nerve  lastly  runs  across  Wharton's  duct,  and  along  the  side  of  the  tongue  to  its 
apex,  being  covered  by  the  mucous  membrane  of  the  mouth. 

Its  branches  of  communication  are  with  the  submaxillary  ganglion  and  hypo- 
glossal nerve.  The  branches  to  the  submaxillary  ganglion  are  two  or  three  in 
number ;  those  connected  with  the  hypoglossal  nerve  form  a  plexus  at  the  anterior 
margin  of  the  Hyo-glossus  muscle. 

Its  branches  of  distribution  are  few  in  number.  They  supply  the  mucous  mem- 
brane of  the  mouth,  the  gums,  the  sublingual  gland,  the  conical  and  fungiform 
papillae  and  mucous  membrane  of  the  tongue,  the  terminal  filaments  anastomosing 
at  the  tip  of  this  organ  with  the  hypoglossal  nerve. 

The  Inferior  Dental  is  the  largest  of  the  three  branches  of  the  inferior 
maxillary  nerve.  It  passes  downwards  with  the  inferior  dental  artery,  at  first 
beneath  the  External  pterygoid  muscle,  and  then  between  the  internal  lateral 
ligament  and  the  ramus  of  the  jaw  to  the  dental  foramen.  It  then  passes  forwards 
in  the  dental  canal  in  the  inferior  maxillary  bone,  lying  beneath  the  teeth,  as  far 
as  the  mental  foramen,  where  it  divides  into  two  terminal  branches,  incisor  and 
mental.  The  incisor  branch  is  continued  onwards  within  the  bone  to  the  middle 
line,  and  supplies  the  canine  and  incisor  teeth.  The  mental  branch  emerges  from 
the  bone  at  the  mental  foramen,  and  divides  beneath  the  Depressor  anguli  oris 
into  an  external  branch,  which  supplies  this  muscle,  the  Orbicularis  oris,  and  the 
integument,  communicating  with  the  facial  nerve ;  and  an  inner  branch,  which 
ascends  to  the  lower  lip  beneath  the  Quadratus  menti  and  supplies  this  muscle  and 
the  mucous  membrane  and  integument  of  the  lip,  communicating  with  the  facial 
nerve.  ' 

The  branches  of  the  inferior  dental  are  the  mylo-hyoid  and  dental. 

The  Mylo-hyoid  is  divided  from  the  inferior  dental  just  as  that  nerve  is  about 
to  enter  the  dental  foramen.  It  descends  in  a  groove  on  the  inner  surface  of  the 
ramus  of  the  jaw,  in  which  it  is  retained  by  a  process  of  fibrous  membrane.  It 
supplies  the  cutaneous  surface  of  the  Mylo-hyoid  muscle,  and  the  anterior  belly 
of  the  Digastric,  occasionally  sending  one  or  two  filaments  to  the  submaxillary 
gland. 

The  Dental  branches  supply  the  molar  and  bicuspid  teeth.  They  correspond  in 
number  to  the  fangs  of  those  teeth ;  each  nerve  entering  the  orifice  at  the  point 
of  the  fang,  and  supplying  the  pulp  of  the  tooth. 

Two  small  ganglia  are  connected  with  the  inferior  maxillary  nerve :  the  otic, 
with  the  trunk  of  the  nerve ;  and  the  submaxillary,  with  its  lingual  branch,  the 
gustatory. 

Ganglia  connected  with  the  Fifth  Nerve. 

Connected  with  the  three  divisions  of  the  fifth  nerve  are  four  small  ganglia, 
which  form  the  whole  of  the  cephalic  portion  of  the  sympathetic.  With  the  first 
division  is  connected  the  ophthalmic  ganglion ;  with  the  second  division,  the  spheno- 
palatine or  Meckel's  ganglion ;  and  with  the  third,  the  otic  and  submaxillary 
ganglia.  These  ganglia  receive  sensitive  filaments  from  the  fifth,  and  motor  and 
sympathetic  filaments  from  various  sources ;  these  filaments  are  called  the  roots  of 
the  ganglia.  The  ganglia  are  also  connected  with  each  other,  and  with  the 
cervical  portion  of  the  sympathetic. 

(1.)  Ophthalmic  or  Ciliary  Ganglion. 

The  Ophthalmic,  Lenticular  or  Ciliary  Ganglion  (fig.  276)  is  a  small, 
quadrangular,  flattened  ganglion,  of  a  reddish-gray  color,  and  about  the  size  of  a 


552  CRANIAL   NERVES. 

pin's  head,  situated  at  the  back  part  of  the  orbit  between  the  optic  nerve  and  the 
External  rectus  muscle,  generally  lying  on  the  outer  side  of  the  ophthalmic  artery. 
It  is  inclosed  in  a  quantity  of  loose  fat,  which  makes  its  dissection  somewhat 
difficult. 

Its  branches  of  communication,  or  its  roots,  are  three,  all  of  which  enter  its 
posterior  border.  One,  the  long  root,  is  derived  from  the  nasal  branch  of  the 
ophthalmic,  and  joins  its  superior  angle.  Another  branch,  the  short  root,  is  a  short 
thick  nerve,  occasionally  divided  into  two  parts ;  it  is  derived  from  that  branch 
of  the  third  nerve  which  supplies  the  Inferior  oblique  muscle,  and  is  connected 
with  the  inferior  angle  of  the  ganglion.  A  third  branch,  the  sympathetic  root,  is  a 
slender  filament  from  the  cavernous  plexus  of  the  sympathetic.  This  is  occasion- 
ally blended  with  the  long  root,  and  sometimes  passes  to  the  ganglion  separately. 
According  to  Tiedemann,  this  ganglion  receives  a  filament  of  communication  from 
the  spheno-palatine  ganglion. 

Its  branches  of  distribution  are  the  short  ciliary  nerves.  These  consist  of  from 
ten  to  twelve  delicate  filaments,  which  arise  from  the  fore  part  of  the  ganglion  in 
two  bundles,  connected  with  its  superior  and  inferior  angles ;  the  upper  bundle 
consisting  of  four  filaments,  and  the  lower  of  six  or  seven.  They  run  forwards 
with  the  ciliary  arteries  in  a  wavy  course,  one  set  above  and  the  other  below  the 
optic  nerve,  pierce  the  sclerotic  at  the  back  part  of  the  globe,  pass  forwards  in 
delicate  grooves  on  its  inner  surface,  and  are  distributed  to  the  Ciliary  muscle  and 
iris.  A  small  filament  is  described  by  Tiedemann,  penetrating  the  optic  nerve 
with  the  arteria  centralis  retinas. 

(2.)  Spheno-palatine  Ganglion. 

The  Spheno-palatine  Ganglion  or  Meckel's  Ganglion  (fig.  281),  the  largest 
of  the  cranial  ganglia,  is  deeply  placed  in  the  spheno-maxillary  fossa,  close  to  the 
spheno-palatine  foramen.  It  is  triangular  or  heart-shaped  in  form,  of  a  reddish- 
gray  color,  and  placed  mainly  behind  the  palatine  branches  of  the  superior  maxil- 
lary nerve,  at  the  point  where  the  sympathetic  root  joins  the  ganglion^  It  conse- 
quently does  not  involve  those  nerves  which  pass  to  the  palate  and  nose.  Like 
other  ganglia,  it  possesses  a  motor,  a  sensory,  and  a  sympathetic  root.  Its  motor 
root  is  derived  from  the  facial,  through  the  Vidian ;  its  sensory  root  from  the  fifth  ; 
and  its  sympathetic  root  from  the  carotid  plexus,  through  the  Vidian.  Its  branches 
are  divisible  into  four  groups ;  ascending,  which  pass  to  the  orbit ;  descending,  to 
the  palate ;  internal,  to  the  nose ;  and  posterior  branches  to  the  pharynx. 

The  Ascending  branches  are  two  or  three  delicate  filaments,  which  enter  the  orbit 
by  the  spheno-maxillary  fissure,  and  supply  the  periosteum.  Arnold  describes  and 
delineates  these  branches  as  descending  to  the  optic  nerve ;  one,  to  the  sixth  nerve 
(Bock) ;  and  one,  to  the  ophthalmic  ganglion  (Tiedemann). 

The  Descending  or  Palatine  branches  are  distributed  to  the  roof  of  the  mouth, 
the  soft  palate,  tonsil,  and  lining  membrane  of  the  nose.  They  are  almost  a  direct 
continuation  of  the  spheno-palatine  branches  of  the  superior  maxillary  nerve,  and 
are  three  in  number,  anterior,  middle,  and  posterior. 

The  anterior  or  large  palatine  nerve  descends  through  the  posterior  palatine 
canal,  emerges  upon  the  hard  palate,  at  the  posterior  palatine  foramen,  and  passes 
forwards  through  a  groove  in  the  hard  palate,  nearly  as  far  as  the  incisor  teeth. 
It  supplies  the  gums,  the  mucoUs  membrane  and  glands  of  the  hard  palate,  and  com- 
municates in  front  with  the  termination  of  the  naso-palatine  nerve.  While  in  the 
posterior  palatine  canal,  it  gives  off  inferior  nasal  branches,  which  enter  the  nose 
through  openings  in  the  palate-bone,,  and  ramify  over  the  middle  meatus,  and  the 
middle  and  inferior  spongy  bones;  and,  at  its  exit  from  the  canal,  a  palatine 
branch  is  distributed  to  both  surfaces  of  the  soft  palate. 

The  middle  or  external  palatine  nerve,  descends  in  the  same  canal  as  the  pre- 
ceding, to  the  posterior  palatine  foramen,  distributing  branches  to  the  uvula, 
tonsil,  and  soft  palate.     It  is  occasionally  wanting. 


SPHENO-PALATINE   GANGLION. 


553 


The  posterior  or  small  palatine  nerve  descends  with  a  small  artery  through 
the  small  posterior  palatine  canal,  emerging  by  a  separate  opening  behind  the 
posterior  palatine  foramen.  It  supplies  the  Levator  palati  and  Azygos  uvulae 
muscles,  the  soft  palate,  tonsil,  and  uvula. 

The  Internal  branches  are  distributed  to  the  septum,  and  outer  wall  of  the  nasal 
fossae.     They  are  the  superior  nasal  (anterior),  and  the  naso-palatine. 

The  superior  nasal  branches  (anterior),  four  or  five  in  number,  enter  the  back 
part  of  the  nasal  fossa  by  the  spheno-palatine  foramen.  They  supply  the  mucous 
membrane,  covering  the  superior  and  middle  spongy  bones,  and  that  lining 
the  posterior  ethmoidal  cells,  a  few  being  prolonged  to  the  upper  and  back  part 
of  the  septum. 

The  naso-palatine  nerve  (Cotunnius)  enters  the  nasal  fossa  with  the  other 
nasal  nerves,  and  passes  inwards  across  the  roof  of  the  nose,  below  the  orifice 
of  the  sphenoidal  sinus,  to  reach  the  septum ;  it  then  runs  obliquely  downwards 
and  forwards  along  the  lower  part  of  the  septum,  to  the  anterior  palatine  foramen, 
lying  between  the  periosteum  and  mucous  membrane.  It  descends  to  the  roof  of 
the  mouth  by  a  distinct  canal,  which  opens  below  in  the  anterior  palatine  fossa ; 
the  right  nerve,  also  in  a  separate  canal,  being  posterior  to  the  left  one.  In  the 
mouth,  they  become  united,  and  supply  the  mucous  membrane  behind  the  incisor 
teeth,  joining  with  the  anterior  palatine  nerve.  It  occasionally  furnishes  a  few 
small  filaments  to  the  mucous  membrane  of  the  septum. 


281. — The  Spheno-palatine  Ganglion  and  its  Branches. 


Term*  <f 


The  Posterior  branches  are  the  Vidian  and  pharyngeal  or  pterygopalatine. 

The  Vidian  arises  from  the  back  part  of  the  spheno-palatine  ganglion,  passes 
through  the  Vidian  canal,  enters  the  cartilage  filling  in  the  foramen  lacerum  basis 
cranii,  and  divides  into  two  branches,  the  large  petrosal  and  the  carotid.  In  its 
course  along  the  Vidian  canal,  it  distributes  a  few  filaments  to  the  lining  membrane 
at  the  back  part  of  the  roof  of  the  nose  and  septum,  and  that  covering  the  end 
of  the  Eustachian  tube.     These  are  upper  posterior  nasal  branches. 

The  large  petrosal  branch  (nervus  petrosus  superficialis  major)  enters  the  cranium 
through  the  foramen  lacerum  basis  cranii,  having  pierced  the  cartilaginous  sub- 
stance  filling  in  this  aperture.     It  runs  beneath  the  Casserian  ganglion  and  dura 


554 


CRANIAL   NERVES. 


mater,  contained  in  a  groove  in  the  anterior  surface  of  the  petrous  portion  of  the 
temporal  bone,  enters  the  hiatus  Fallopii,  and,  being  continued  through  it,  into 
the  aquseductus  Fallopii,  joins  the  gangliform  enlargement  on  the  facial  nerve. 
Properly  speaking,  this  nerve  passes  from  the  facial  to  the  spheno-palatine 
ganglion,  forming  its  motor  root. 

The  carotid  branch  is  shorter  but  larger  than  the  petrosal,  of  a  reddish-gray 
color,  and  soft  in  texture.  It  crosses  the  foramen  lacerum,  surrounded  by  .the 
cartilaginous  substance  which  fills  in  that  aperture,  and  enters  the  carotid  canal, 
on  the  outer  side  of  the  carotid  artery,  to  join  the  carotid  plexus. 

The  Pharyngeal  nerve  (ptery go-palatine)  is  a  small  branch  arising  from  the  back 
part  of  the  ganglion,  occasionally  springing  from  the  Vidian  nerve.  It  passes 
through  the  pterygopalatine  canal  with  the  pterygo-palatine  artery,  and  is  dis- 
tributed to  the  lining  membrane  of  the  pharynx,  behind  the  Eustachian  tube. 

(3.)  Otic  or  Arnold's  Ganglion. 

The  Otic  Ganglion  (Arnold's)  is  a  small,  oval-shaped,  flattened  ganglion  of  a 
reddish-gray  color,  situated  immediately  below  the  foramen  ovale,  on  the  inner 
surface  of  the  inferior  maxillary  nerve,  and  round  the  origin  of  the  internal 
pterygoid  nerve  (fig.  282).  It  is  in  relation,  externally,  with  the  trunk  of  the  infe- 
rior maxillary  nerve,  at  the  point  where  the  motor  root  joins  the  sensory  portion ; 
internally,  with  the  cartilaginous  part  of  the  Eustachian  tube,  and  the  origin  of 
the  Tensor  palati  muscle ;  behind  it,  is  the  middle  meningeal  artery. 

Fig.  2S2. — The  Otic  Ganglion  and  its  Branches. 


Branches  of  communication.  This  ganglion  is  connected  with  the  inferior 
maxillary  nerve,  and  its  internal  pterygoid  branch,  by  two  or  three  short,  delicate 
filaments,  and  also  with  the  auriculo-temporal  nerve ;  from  the  former,  it  obtains 
its  motor,  from  the  latter,  its  sensory  root;  its  communication  with  the  sympathetic 
being  effected  by  a  filament  from  the  plexus  surrounding  the  middle  meningeal 
artery.  This  ganglion  also  communicates  with  the  glossopharyngeal  and  facial 
nerves,  through  the  small  petrosal  nerve  continued  from  the  tympanic  plexus. 

Its  branches  of  distribution  are  a  filament  to  the  Tensor  tympani,  and  one  to  the 
Tensor  palati.  The  former  passes  backwards,  on  the  outer  side  of  the  Eustachian 
tube ;  the  latter  arises  from  the  ganglion,  near  the  origin  of  the  internal  pterygoid 
nerve,  and  passes  forwards. 


EIGHTH  PAIR.  555 

(4.)  Submaxillary  Ganglion. 

The  Submaxillary  Ganglion  (fig.  280)  is  of  small  size,  circular  in  form,  and 
situated  above  tie  deep  portion  of  the  submaxillary  gland,  near  the  posterior 
border  of  the  Mylo-hyoid  muscle,  being  connected  by  filaments  with  the  lower 
border  of  the  gustatory  nerve. 

Branches  of  communication.  This  ganglion  is  connected  with  the  gustatory 
nerve  by  a  few  filaments  which  join  it  separately,  at  its  fore  and  back  part.  It 
also  receives  a  branch  from  the  chorda  tympani,  by  which  it  communicates  with 
the  facial ;  and  communicates  with  the  sympathetic  by  filaments  from  the  nervi 
molles,  surrounding  the  facial  artery. 

Branches  of  distribution.  These  are  five  or  six  in  number ;  they  arise  from  the 
lower  part  of  the  ganglion,  and  supply  the  mucous  membrane  of  the  mouth  and 
Wharton's  duct,  some  being  lost  in  the  submaxillary  gland.  According  to  Meckel, 
a  branch  from  this  ganglion  occasionally  descends  in  front  of  the  Hyo-glossus 
muscle,  and,  after  joining  with  one  from  the  hypoglossal,  passes  to  the  Gemo- 
hyo-glossus  muscle. 

Eighth  Pair. 

The  eighth  pair  consists  of  three  nerves,  the  glossopharyngeal,  pneumogastric, 
and  spinal  accessory. 

(1.)  Glosso-pharyngeal  Nerve. 

The  Glosso-pharyngeal  Nerve  is  distributed,  as  its  name  implies,  to  the 
tongue  and  pharynx,  being  the  nerve  of  . 

°    .         ,     Ki       J  t_  e  *t  Fi<r.  283.— Origin  of  the  Eighth  Pair,  their 

sensation  to  the  mucous  membrane  ol  the        °     Gauglia  aud  communications. 

pharynx,  fauces,  and  tonsil ;  of  motion,  to  ^yrf-trt»jt 

the  Pharyngeal   muscles,  and   a   special  *^^        [    ■**—■  a«»s*- 

nerve  of  taste,  in    all  the   parts   of  the 

tongue  to  which  it  is  distributed.     It  is 

the  smallest  of  the  three  divisions  of  the 

eighth  pair,  and  arises  by  three  or  four 

filaments,  closely  connected  together,  from 

the  upper  part  of  the  medulla  oblongata, 

immediately  behind  the  olivary  body. 

Its  deep  origin  may  be  traced  through  p««J^!ki></ 

the   fasciculi   of  the   lateral   tract,   to    a 

nucleus  of  gray  matter  at  the  lower  part  of  the  floor  of  the  fourth  ventricle, 
external  to  the  fasciculi  teretes.  From  its  superficial  origin,  it  passes  outwards 
across  the  flocculus,  and  leaves  the  skull  at  the  central  part  of  the  jugular  foramen, 
in  a  separate  sheath  of  the  dura  mater  and  arachnoid,  in  front  of  the  pneumogastric 
and  spinal  accessory  nerves.  In  its  passage  through  the  jugular  foramen,  it  grooves 
the  lower  border  of  the  petrous  portion  of  the  temporal  bone ;  and,  at  its  exit  from 
the  skull,  passes  forwards  between  the  jugular  vein  and  internal  carotid  artery, 
and  descends  in  front  of  the  latter  vessel,  and  beneath  the  styloid  process  and  the 
muscles  connected  with  it,  to  the  lower  border  of  the  Stylo-pharyngeus.  The  nerve 
now  curves  inwards,  forming  an  arch  on  the  side  of  the  neck,  lying  upon  the 
Stylo-pharyngeus  and  the  Middle  constrictor  of  the  pharynx,  above  the  superior 
laryngeal  nerve.  It*then  passes  beneath  the  Hyo-glossus,  and  is  finally  distributed 
to  the  mucous  membrane  of  the  fauces,  and  base  of  the  tongue,  the  mucous  glands 
of  the  mouth  and  tonsil. 

In  passing  through  the  jugular  foramen,  the  nerve  presents,  in  succession,  two 
gangliform  enlargements.  The  superior  one,  the  smaller,  is  called  the  jugular 
ganglion ;  the  inferior  and  larger  one,  the  petrous  ganglion  or  the  ganglion  of 
Andersch. 

The  superior  or  jugular  ganglion  is  situated  in  the  upper  part  of  the  groove 
in  which  the  nerve  is  lodged  during  its  passage  through  the  jugular  foramen.     It 


556 


CRANIAL   NERVES, 


is  of  very  small  size,  and  involves  only  the  outer  side  of  the  trunk  of  the  nerve, 

a  small   fasciculus   passing 

Fig.  284.— Course  and  Distribution  of  the  Eighth  Pair  of         beyond     it      which     is     not 

connected  directly  with  it. 

The  inferior  or  petrous 
ganglion  is  situated  in  a 
depression  in  the  lower 
border  of  the  petrous  por- 
tion of  the  temporal  bone; 
it  is  larger  than  the  for- 
mer, and  involves  the  whole 
of  the  fibres  of  the  nerve. 
From  this  ganglion  arise 
those  filaments  which  con- 
nect the  glossopharyngeal 
with  other  nerves  at  the 
base  of  the  skull. 

Its  branches  of  communi- 
cation are  with  the  pneu- 
mogastric,  sympathetic, 
and  facial,  and  the  tympanic 
branch. 

The  branches  to  the 
pneumogastric  are  two  fila- 
ments, one  to  its  auricular 
branch,  and  one  to  the  up- 
per ganglion  of  the  pneu- 
mogastric. 

The  branch  to  the  sym- 
pathetic is  connected  with 
the  superior  cervical  gan- 
glion. 

The  branch  of  commu- 
nication with  the  facial 
perforates  the  posterior 
belly  of  the  Digastric.  It 
arises  from  the  trunk  of 
the  nerve  below  the  petrous 
ganglion,  and  joins  the  fa- 
cial just  after  its  exit  from 
the  stylo-mastoid  foramen. 

The  tympanic  branch 
(Jacobson's  nerve)  arises 
from  the  petrous  ganglion, 
and  enters  a  small  bony 
canal  on  the  base  of  the 
petrous  portion  of  the  tem- 
poral bone.  (This  opening 
is  placed  on  the  bony  ridge 
which  separates  the  ca- 
rotid canal  from  the  jugular 
fossa.)     It    ascends    to   the 

tympanum,  enters  this  cavity  by  an  aperture  in  its  floor  close  to  the  inner  wall, 

and  divides  into  three  branches,  which  are  contained  in  grooves  upon  the  surface 

of  the  promontory. 

Its  branches  of  distribution  are,  one  to  the  fenestra  rotunda,  one  to  the  fenestra 

ovalis,  and  one  to  the  lining  membrane  of  the  Eustachian  tube  and  tympanum. 


EIGHTH  PAIR.  55T 

Its  branches  of  communication  are  three,  and  occupy  separate  grooves  on  the 
surface  of  the  promontory.  One  of  these  arches  forwards  and  downwards  to  the 
carotid  canal  to  join  the  carotid  plexus.  A  second  runs  vertically  upwards  to 
join  the  greater  superficial  petrosal  nerve,  as  it  lies  in  the  hiatus  Fallopii.  The 
third  branch  runs  forwards  and  upwards  towards  the  anterior  surface  of  the  petrous 
bone,  and  passes  through  a  small  aperture  in  the  sphenoid  and  temporal  bones,  to 
the  exterior  of  the  skull,  where  it  joins  the  otic  ganglion.  This  nerve,  in  its  course 
through  the  temporal  bone,  passes  by  the  ganglionic  enlargement  of  the  facial,  and 
has  a  connecting  filament  with  it. 

The  branches  of  the  glosso-pharyngeal  nerve  are  the  carotid,  pharyngeal,  mus- 
cular, tonsillitic,  and  lingual. 

The  carotid  branches  descend  along  the  trunk  of  the  internal  carotid  artery  as 
far  as  its  point  of  bifurcation,  communicating  with  the  pharyngeal  branch  of  the 
pneumogastric,  and  with  branches  of  the  sympathetic. 

The  pharyngeal  branches  are  three  or  four  filaments  which  unite  opposite  the 
Middle  constrictor  of  the  pharynx  with  the  pharyngeal  branches  of  the  pneumo- 
gastric, superior  laryngeal,  and  sympathetic  nerves,  to  form  the  pharyngeal  plexus, 
branches  from  which  perforate  the  muscular  coat  of  the  pharynx  to  supply  the 
mucous  membrane. 

The  muscular  branches  are  distributed  to  the  Stylo-pharyngeus. 

The  tonsillitic  branches  supply  the  tonsil,  forming  a  plexus  (circulus  tonsillaris) 
around  this  body,  from  which  branches  are  distributed  to  the  soft  palate  and 
fauces,  where  they  anastomose  with  the  palatine  nerves. 

The  lingual  branches  are  two  in  number;  one  supplies  the  mucous  membrane 
covering  the  surface  of  the  base  of  the  tongue,  the  other  perforates  its  substance, 
and  supplies  the  mucous  membrane  and  papillae  of  the  side  of  the  organ. 

(2.)  Pneumogastric  or  Par  Yagum  Nerve. 

The  Pneumogastric  Nerve  (nervus  vagus  or  par  vagum),  one  of  the  three 
divisions  of  the  eighth  pair,  has  a  more  extensive  distribution  than  any  of  the 
other  cranial  nerves,  passing  through  the  neck  and  cavity  of  the  chest  to  the  upper 
part  of  the  abdomen.  It  is  composed  of  both  motor  and  sensitive  filaments.  It 
supplies  the  organs  of  voice  and  respiration  with  motor  and  sensitive  fibres,  and 
the  pharynx,  oesophagus,  stomach,  and  heart  with  motor  influence.  Its  superficial 
origin  is  by  eight  or  ten  filaments  from  the  lateral  tract  immediately  behind  the 
olivary  body,  and  below  the  glosso-pharyngeal ;  its  fibres  may,  however,  be  traced 
deeply  through  the  fasciculi  of  the  medulla,  to  terminate  in  a  gray  nucleus  near 
the  lower  part  of  the  floor  of  the  fourth  ventricle.  The  filaments  become  united, 
and  form  a  flat  cord,  which  passes  outwards  across  the  flocculus  to  the  jugular 
foramen,  through  which  it  emerges  from  the  cranium.  In  passing  through  this 
opening,  the  pneumogastric  accompanies  the  spinal  accessory,  being  contained  in 
the  same  sheath  of  dura  mater  with  it,  a  membranous  septum  separating  it  from 
the  glosso-pharyngeal,  which  lies  in  front.  The  nerve  in  this  situation  presents  a 
well-marked  ganglionic  enlargement,  which  is  called  ganglion  jugulare  or  the 
ganglion  of  the  root  of  the  pneumogastric ;  to  it  the  accessory  part  of  the  spinal 
accessory  nerve  is  connected.  After  the  exit  of  the  nerve  from  the  jugular 
foramen,  a  second  gangliform  swelling  is  formed  upon  it,  called  the  ganglion  infe- 
rius  or  the  ganglion  of  the  trunk  of  the  nerve;  below  which  it  is  again  joined  by 
filaments  from  the  sjxinal  accessory  nerve.  The  nerve  descends  the  neck  in  a  straight 
direction  within  the  sheath  of  the  carotid  vessels,  lying  between  the  internal  caro- 
tid artery  and  internal  jugular  vein  as  far  as  the  thyroid  cartilage,  and  then  be- 
tween the  same  vein  and  the  common  carotid  to  the  root  of  the  neck.  Here  the 
course  of  the  nerve  becomes  different  on  the  two  sides  of  the  body. 

On  the  right  side,  the  nerve  passes  across  the  subclavian  artery  between  it  and 
the  subclavian  vein,  and  descends  by  the  side  of  the  trachea  to  the  back  part  of  the 
root  of  the  lung,  where  it  spreads  out  in  a  plexiform  network  (posterior  pulmonary), 


558  CRANIAL   NERVES. 

from  the  lower  part  of  which  two  cords  descend  upon  the  oesophagus,  on  which 
they  divide,  forming,  with  branches  from  the  opposite  nerve,  the  oesophageal 
plexus ;  below,  these  branches  are  collected  into  a  single  cord,  which  runs  along 
the  back  part  of  the  oesophagus,  enters  the  abdomen,  and  is  distributed  to  the 
posterior  surface  of  the  stomach,  joining  the  left  side  of  the  coeliac  plexus,  and  the 
splenic  plexus. 

On  the  left  side,  the  pneumogastric  nerve  enters  the  chest,  between  the  left 
carotid  and  subclavian  arteries,  behind  the  left  innominate  vein.  It  crosses  the 
arch  of  the  aorta,  and  descends  behind  the  root  of  the  left  lung,  and  along  the 
anterior  surface  of  the  oesophagus  to  the  stomach,  distributing  branches  over  its 
anterior  surface,  some  extending  over  the  great  cul-de-sac,  and  others  along  the 
lesser  curvature.  Filaments  from  these  latter  branches  enter  the  gastro-hepatic 
omentum,  and  join  the  left  hepatic  plexus. 

The  ganglion  of  the  root  is  of  a  grayish  color,  circular  in  form,  about  two  lines 
in  diameter,  and  resembles  the  ganglion  on  the  large  root  of  the  fiftb  nerve. 

Connecting  branches.  To  this  ganglion  the  accessory  portion  of  the  spinal 
accessory  nerve  is  connected  by  several  delicate  filaments;  it  also  has  an  anasto- 
motic twig  with  the  petrous  ganglion  of  the  glossopharyngeal,  with  the  facial 
nerve  by  means  of  the  auricular  branch,  and  with  the  sympathetic  by  means  of  an 
ascending  filament  from  the  superior  cervical  ganglion. 

The  ganglion  of  the  trunk  (inferior)  is  a  plexiform  cord,  cylindrical  in  form,  of 
a  reddish  color,  and  about  an  inch  in  length ;  it  involves  the  whole  of  the  fibres 
of  the  nerve,  except  the  portion  of  the  accessory  nerve  derived  from  the  spinal 
accessory,  which  blends  with  the  nerve  beyond  the  ganglion. 

Connecting  branches.  This  ganglion  is  connected  with  the  hypoglossal,  the  supe- 
rior cervical  ganglion  of  the  sympathetic,  and  with  the  loop  between  the  first  and 
second  cervical  nerves. 

The  branches  of  the  pneumogastric  are — 

In  the  jugular  fossa    .         .     Auricular. 

["  Pharyngeal. 
In  the  neck.       .  .  J  Superior  laryngeal. 

]  Eecurrent  laryngeal. 
[  Cervical  cardiac, 
f  Thoracic  cardiac. 

In  the  thorax.  .  .  J  Anterior  pulmonary. 

.Posterior  pulmonary. 
[  (Esophageal. 
In  the  abdomen  .        .         .     Gastric. 

The  Auricular  branch  arises  from  the  ganglion  of  the  root,  and  is  joined  soon 
after  its  origin  by  a  filament  from  the  glosso-pharyngeal ;  it  crosses  the  jugular 
fossa  to  an  opening  near  the  root  of  the  styloid  process.  Traversing  the  substance 
of  the  temporal  bone,  it  crosses  the  aquaaductus  Fallopii  about  two  lines  above  its 
termination  at  the  stylo-mastoid  foramen ;  it  here  gives  off  an  ascending  branch, 
which  joins  the  facial,  and  a  descending  branch,  which  anastomoses  with  the  pos- 
terior auricular  branch  of  the  same  nerve ;  the  continuation  of  the  nerve  reaches 
the  surface  between  the  mastoid  process  and  the  external  auditory  meatus,  and 
supplies  the  integument  at  the  back  part  of  the  pinna. 

The  Pharyngeal  branch,  the  principal  motor  nerve  of  the  pharynx  and  soft 
palate,  arises  from  the  upper  part  of  the  inferior  ganglion  of  the  pneumogastric, 
receiving  a  filament  from  the  accessory  portion  of  the  spinal  accessory ;  it  passes 
across  the  internal  carotid  artery  (in  front  or  behind),  to  the  upper  border  of  the 
Middle  constrictor,  where  it  divides  into  numerous  filaments,  which  anastomose 
with  those  from  the  glosso-pharyngeal,  superior  laryngeal,  and  sympathetic,  to 
form  the  pharyngeal  plexus,  from  which  branches  are  distributed  to  the  muscles 
and  mucous  membrane  of  the  pharynx.  As  this  nerve  crosses  the  internal  carotid, 
some  filaments  are  distributed,  together  with  those  from  the  glosso-pharyngeal, 
upon  the  wall  of  this  vessel. 


EIGHTH   PAIR.  559 

The  Sujierior  laryngeal  is  the  nerve  of  sensation  to  the  larynx.  It  is  larger 
than  the  preceding,  and  arises  from  the  middle  of  the  inferior  ganglion  of  the 
pneumogastric.  It  descends,  by  the  side  of  the  pharynx,  behind  the  internal 
carotid,  where  it  divides  into  two  branches,  the  external  and  internal  laryngeal. 

The  external  laryngeal  branch,  the  smaller,  descends  by  the  side  of  the 
larynx,  beneath  the  Sterno-thyroid,  to  supply  the  Crico-thyroid  muscle  and  the 
thyroid  gland.  It  gives  branches  to  the  pharyngeal  plexus,  and  the  Inferior 
constrictor,  and  communicates  with  the  superior  cardiac  nerve,  behind  the  common 
carotid. 

The  internal  laryngeal  branch  descends  to  the  opening  in  the  thyro-hyoid 
membrane,  through  which  it  passes  with  the  superior  laryngeal  artery,  and  is 
distributed  to  the  mucous  membrane  of  the  larynx,  and  the  Arytenoid  muscle, 
anastomosing  with  the  recurrent  laryngeal. 

The  branches  to  the  mucous  membrane  are  distributed,  some  in  front,  to  the 
epiglottis,  the  base  of  the  tongue,  and  epiglottidean  gland ;  and  others  pass  back- 
wards, in  the  aryteno-epiglottidean  fold,  to  supply  the  mucous  membrane  sur- 
rounding the  superior  orifice  of  the  larynx,  as  well  as  the  membrane  which  lines 
the  cavity  of  the  larynx  as  low  down  as  the  vocal  chord. 

The  filament  to  the  Arytenoid  muscle  is  distributed  partly  to  it,  and  partly  to 
the  mucous  lining  of  the  larynx. 

The  filament  which  joins  with  the  recurrent  laryngeal  descends  beneath  the 
mucous  membrane  on  the  posterior  surface  of  the  larynx,  behind  the  lateral  part 
of  the  thyroid  cartilage,  where  the  two  nerves  become  united. 

The  Inferior  or  recurrent  laryngeal,  so  called  from  its  reflected  course,  is  the 
motor  nerve  of  the  larynx.  It  arises  on  the  right  side,  in  front  of  the  subclavian 
artery ;  winds  from  before  backwards  round  this  vessel,  and  ascends  obliquely  to 
the  side  of  the  trachea,  behind  the  common  carotid  and  inferior  thyroid  arteries. 
On  the  left  side,  it  arises  in  front  of  the  arch  of  the  aorta,  and  winds  from  before 
backwards  round  the  vessel  at  the  point  where  the  obliterated  remains  of  the 
ductus  arteriosus  are  connected  with  it,  and  then  ascends  to  the  side  of  the  trachea. 
The  nerves  on  both  sides  ascend  in  the  groove  between  the  trachea  and  oesophagus, 
and,  piercing  the  lower  fibres  of  the  Inferior  constrictor  muscle,  enter  the  larynx 
behind  the  articulation  of  the  inferior  cornu  of  the  thyroid  cartilage  with  the 
cricoid,  being  distributed  to  all  the  muscles  of  the  larynx,  excepting  the  Crico- 
thyroid, and  joining  with  the  superior  laryngeal. 

The  recurrent  laryngeal,  as  it  winds  round  the  subclavian  artery  and  aorta, 
gives  off  several  cardiac  filaments,  which  unite  with  cardiac  branches  from  the 
pneumogastric  and  sympathetic.  As  it  ascends  the  neck,  it  gives  off  oesophageal 
branches,  more  numerous  on  the  left  than  on  the  right  side,  which  supply  the 
mucous  membrane  and  muscular  coat  of  the  oesophagus;  tracheal  branches  to  the 
mucous  membrane  and  muscular  fibres  of  the  trachea;  and  some  pharyngeal 
filaments  to  the  Inferior  constrictor  of  the  pharynx. 

The  Cervical  cardiac  branches,  two  or  three  in  number,  arise  from  the  pneumo- 
gastric, at  the  upper  and  lower  part  of  the  neck. 

The  superior  branches  are  small,  and  communicate  with  the  cardiac  branches 
of  the  sympathetic,  and  with  the  great  cardiac  plexus. 

The  inferior  cardiac  branches,  one  on  each  side,  arise  at  the  lower  part  of  the 
neck,  just  above  the  first  rib.  On  the  right  side,  this  branch  passes  in  front  of 
the  arteria  innominata,  and  anastomoses  with  the  superior  cardiac  nerve.  On  the 
left  side,  it  passes  in  front  of  the  arch  of  the  aorta,  and  anastomoses  either  with 
the  superior  cardiac  nerve  or  with  the  cardiac  plexus. 

The  Thoracic  cardiac  branches,  on  the  right  side,  arise  from  the  trunk  of  the 
pneumogastric,  as  it  lies  by  the  side  of  the  trachea:  passing  inwards,  they  terminate 
in  the  deep  cardiac  plexus.  On  the  left  side,  they  arise  from  the  left  recurrent 
laryngeal  nerve. 

The  Anterior  pulmonary  branches,  two  or  three  in  number,  and  of  small  size, 
are  distributed  on  the  anterior  aspect  of  the  root  of  the  lungs.  They  join  with 
filaments  from  the  sympathetic,  and  form  the  anterior  pulmonary  plexus. 


560  CRANIAL   NERVES. 

The  Posterior  pulmonary  tranches,  more  numerous  and  larger  than  the  anterior, 
are  distributed  on  the  posterior  aspect  of  the  root  of  the  lung ;  they  are  joined  by 
filaments  from  the  third  and  fourth  thoracic  ganglia  of  the  sympathetic,  and  form 
the  posterior  pulmonary  plexus.  Branches  from  both  plexuses  accompany  the 
ramifications  of  the  air-tubes  through  the  substance  of  the  lungs. 

The  (Esophageal  branches  are  given  off  from  the  pneumogastric  both  above 
and  below  the  pulmonary  branches.  The  latter  are  the  more  numerous  and 
largest.  They  form,  together  with  branches  from  the  opposite  nerve,  the  oeso- 
phageal plexus. 

The  Gastric  branches  are  the  terminal  filaments  of  the  pneumogastric  nerve. 
The  nerve  on  the  right  side  is  distributed  to  the  posterior  surface  of  the  stomach, 
and  joins  the  left  side  of  the  cceliac  plexus,  and  the  splenic  plexus.  The  nerve 
on  the  left  side  is  distributed  over  the  anterior  surface  of  the  stomach,  some 
filaments  passing  across  the  great  cul-de-sac,  and  others  along  the  lesser  curvature. 
They  unite  with  branches  of  the  right  nerve  and  sympathetic,  some  filaments 
passing  through  the  lesser  omentum  to  the  left  hepatic  plexus. 

(3.)  Spinal  Accessoey  Nerve. 

The  Spinal  Accessory  Nerve  consists  of  two  parts ;  one,  the  accessory  part 
to  the  vagus,  and  the  other  the  spinal  portion. 

The  accessory  part,  the  smaller  of  the  two,  arises  by  four  or  five  delicate 
filaments  from  the  lateral  tract  of  the  cord  below  the  roots  of  the  vagus ;  these 
filaments  may  be  traced  to  a  nucleus  of  gray  matter  at  the  back  of  the  medulla, 
below  the  origin  of  the  vagus.  It  joins,  in  the  jugular  foramen,  with  the  upper 
ganglion  of  the  vagus  by  one  or  two  filaments,  and  is  continued  into  the  vagus 
below  the  second  ganglion.  It  gives  branches  to  the  pharyngeal  and  superior 
laryngeal  branches  of  the  vagus. 

The  spinal  portion,  firm  in  texture,  arises  by  several  filaments  from  the  lateral 
tract  of  the  cord,  as  low  down  as  the  sixth  cervical  nerve ;  the  fibres  pierce  the 
tract,  and  are  connected  with  the  anterior  horn  of  the  gray  crescent  of  the  cord. 
This  portion  of  the  nerve  ascends  between  the  ligamentum  denticulaturn  and  the 
posterior  roots  of  the  spinal  nerves,  enters  the  skull  through  the  foramen  magnum, 
and  is  then  directed  outwards  to  the  jugular  foramen,  through  which  it  passes, 
lying  in  the  same  sheath  as  the  pneumogastric,  separated  from  it  by  a  fold  of  the 
arachnoid,  and  is  here  connected  with  the  accessory  portion.  At  its  exit  from  the 
jugular  foramen,  it  passes  backwards  behind  the  internal  jugular  vein,  and  descends 
obliquely  behind  the  Digastric  and  Stylo-hyoid  muscles  to  the  upper  part  of  the 
Sterno-mastoid.  It  pierces  this  muscle,  and  passes  obliquely  across  the  sub- 
occipital triangle,  to  terminate  in  the  deep  surface  of  the  Trapezius.  This  nerve 
gives  several  branches  to  the  Sterno-mastoid  during  its  passage  through  it,  and 
joins  in  its  substance  with  branches  from  the  third  cervical.  In  the  sub-occipital 
triangle  it  joins  with  the  second  and  third  cervical  nerves,  assists  in  the  formation 
of  the  cervical  plexus,  and  occasionally  of  the  great  auricular  nerve.  On  the 
front  of  the  Trapezius,  it  is  reinforced  by  branches  from  the  third,  fourth,  and 
fifth  cervical  nerves,  joins  with  the  posterior  branches  of  the  spinal  nerves,  and  is 
distributed  to  the  Trapezius,  some  filaments  ascending  and  others  descending  in 
its  substance  as  far  as  its  inferior  angle. 

4.  Mixed  Nerves. 

The  Pneumogastric  and  Spinal  Accessory  Nerves,  which  constitute  this  sub- 
division, have  already  been  described  in  connection  with  the  Eighth  Pair,  of  which 
they  form  part. 


For  fuller  details  concerning  the  Cranial  Nerves,  the  student  may  refer  to  F.  Arnold's  "Icones 
Nervorum  Capitis." 


The  Spinal  Nerves. 


The  Spinal  Nerves  are  so  called,  from  taking  their  origin  from  the  spinal  cord, 
and  from  being  transmitted  through  the  intervertebral  foramina  on  either  side 
of  the  spinal  column.  There  are  thirty-one  pairs  of  spinal  nerves,  which  are 
arranged  into  the  following  groups,  corresponding  to  the  region  of  the  spine 
through  which  they  pass: — 

Cervical  ...         8  pairs. 

Dorsal  .         .         .12     " 

Lumbar  .         .         .         5     " 

Sacral  .         .         .         5     ■ 

Coccygeal  ...         1  pair. 

It  will  be  observed,  that  each  group  of  nerves  corresponds  in  number  with  the 
vertebrae  in  each  region,  excepting  in  the  cervical  and  coccygeal. 

Each  spinal  nerve  arises  by  two  roots,  an  anterior  or  motor  root,  and  a 
posterior  or  sensitive  root. 

EOOTS  OF  THE  SPINAL  NERVES. 

The  anterior  roots  arise  somewhat  irregularly  from  a  linear  series  of  foramina, 
on  the  antero-lateral  column  of  the  spinal  cord,  gradually  approaching  towards 
the  anterior  median  fissure  as  they  descend. 

The  fibres  of  the  anterior  roots  are,  according  to  the  researches  of  Mr.  Lockhart 
Clarke,  attached  to  the  anterior  part  of  the  antero-lateral  column;  and,  after 
penetrating  horizontally  through  the  longitudinal  fibres  of  this  tract,  enter  the 
gray  substance,  where  their  fibrils  cross  each  other  and  diverge  in  all  directions, 
like  the  expanded  hairs  of  a  brush,  some  of  them  running  more  or  less  longi- 
tudinally upwards  and  downwards,  and  others  decussating  with  those  of  the 
opposite  side  through  the  anterior  commissure  in  front  of  the  central  canal 
(figs.  258  and  259).  Kolliker  states  that  many  fibres  of  the  anterior  root  enter  the 
lateral  column  of  the  same  side,  where,  turning  upwards,  they  pursue  their  course 
as  longitudinal  fibres.  In  other  respects,  the  description  of  the  origin  of  the 
anterior  roots  by  these  observers  is  very  similar. 

The  posterior  roots  are  all  attached  immediately  to  the  posterior  white  columns 
only ;  but  some  of  them  pass  through  the  gray  substance  into  both  the  lateral  and 
anterior  white  columns.  Within  the  gray  substance,  they  run,  longitudinally, 
upwards  and  downwards;  transversely,* through  the  posterior  commissure  to  the 
opposite  side  and  into  the  anterior  column  of  their  own  side  (figs.  258  and  259). 

The  posterior  roots  of  the  nerves  are  larger,  but  the  individual  filaments  are 
finer  and  more  delicate  than  those  of  the  anterior.  As  their  component  fibrils 
pass  outwards,  towards  the  aperture  in  the  dura  mater,  they  coalesce  into  two 
bundles,  receive  a  tubular  sheath  from  this  membrane,  and  enter  the  ganglion 
which  is  developed  upon  each  root. 

The  posterior  root  of  the  first  cervical  nerve  forms  an  exception  to  these 
characters.  It  is  smaller  than  the  anterior,  has  frequently  no  ganglion  developed 
upon  it,  and,  when  the  ganglion  exists,  it  is  often  situated  within  the  dura  mater. 

The  anterior  roots  are  the  smaller  of  the  two  devoid  of  any  ganglionic 
enlargement,  and  their  component  fibrils  are  collected  into  two  bundles,  near  the 
intervertebral  foramina. 

36  561 


5G2  SPINAL   NERVES. 


Ganglia  of  the  Spinal  Nerves. 

A  ganglion  is  developed  upon  each  posterior  root  of  the  spinal  nerves. 
These  ganglia  are  of  an  oval  form,  of  a  reddish  color,  bear  a  proportion  in  size 
to  the  nerves  upon  which  they  are  formed,  and  are  placed  in  the  intervertebral 
foramina,  external  to  the  point  wh^re  the  nerves  perforate  the  dura  mater.  Each 
ganglion  is  bifid  internally,  where  it  is  joined  by  the  two  bundles  of  the  posterior 
root,  the  two  portions  being  united  into  a  single  mass  externally.  The  ganglia 
upon  the  first  and  second  cervical  nerves  form  an  exception  to  these  characters, 
being  placed  on  the  arches  of  the  vertebras  over  which  they  pass.  The  ganglia, 
also,  of  the  sacral  nerves  are  placed  within  the  spinal  canal ;  and  that  on  the 
coccygeal  nerve,  also  in  the  canal  about  the  middle  of  its  posterior  root.  Imme- 
diately beyond  the  ganglion,  the  two  roots  coalesce,  their  fibres  intermingle,  and 
the  trunk  thus  formed  passes  out  of  the  intervertebral  foramen,  and  divides  into  an 
anterior  branch  for  the  supply  of  the  anterior  part  of  the  body,  and  a  posterior 
branch  for  the  posterior  part,  each  branch  containing  fibres  from  both  roots. 

Anterior  Branches  of  the  Spinal  Nerves. 

The  anterior  branches  of  the  spinal  nerves  supply  the  parts  of  the  body  in  front 
of  the  spine,  including  the  limbs.  They  are  for  the  most  part  larger  than  the 
posterior  branches ;  this  increase  of  size  being  proportioned  to  the  larger  extent 
of  structures  they  are  required  to  supply.  Each  branch  is  connected  by  slender 
filaments  with  the  sympathetic.  In  the  dorsal  region,  the  anterior  branches  of 
the  spinal  nerves  are  completely  separate  from  each  other,  and  are  uniform  in 
their  distribution ;  but  in  the  cervical,  lumbar,  and  sacral  regions,  they  form  in- 
tricate plexuses  previous  to  their  distribution. 

Posterior  Branches  of  the  Spinal  Nerves. 

The  posterior  brandies  of  the  spinal  nerves  are  generally  smaller  than  the  anterior, 
they  arise  from  the  trunk  resulting  from  the  union  of  the  nerves  in  the  interverte. 
bral  foramina,  and,  passing  backwards,  divide  into  external  and  internal  branches, 
which  are  distributed  to  the  muscles  and  integument  behind  the  spine.  The  first 
cervical  and  lower  sacral  nerves  are  exceptions  to  these  characters. 

Cervical  Nerves. 

The  roots  of  the  cervical  nerves  increase  in  size  from  the  first  to  the  fifth,  and 
then  maintain  the  same  size  to  the  eighth.  The  posterior  roots  bear  a  proportion 
to  the  anterior  as  3'  to  1,  which  is  much  greater  than  in  any  other  region ;  the 
individual  filaments  being  also  much  larger  than  those  of  the  anterior  roots.  In 
direction,  they  are  less  oblique  than  those  of  the  other  spinal  nerves.  The  first 
is  directed  a  little  upwards  and  outwards ;  the  second  is  horizontal ;  the  others 
are  directed  obliquely  downwards  and  outwards,  the  lowest  being  the  most  oblique, 
and  consequently  longer  than  the  upper,  the  distance  between  their  place  of  origin 
and  their  point  of  exit  from  the  spinal  canal  never  exceeding  the  depth  of  one 
vertebra. 

The  trunk  of  the  first  cervical  nerve  {suboccipital),  leaves  the  spinal  canal,  between 
the  occipital  bone  and  the  posterior  arch  of  the  atlas;  the  second  between  the 
posterior  arch  of  the  atlas  and  the  lamina  of  the  axis ;  and  the  eighth  (the  last), 
between  the  last  cervical  and  first  dorsal  vertebras. 

Each  nerve,  at  its  exit  from  the  intervertebral  foramen,  divides  into  an  anterior 
and  a  posterior  branch.  The  anterior  branches  of  the  four  upper  cervical  nerves 
form  the  cervical  plexus.  The  anterior  branches  of  the  four  lower  cervical  nerves, 
together  with  the  first  dorsal,  form  the  brachial  plexus. 


CERVICAL   PLEXUS. 


563 


Anterior  Branches  of  the  Cervical  Nerves. 

The  anterior  branch  of  the  first  or  suboccipital  nerve  is  of  small  size.  It  escapes 
from  the  spinal  canal,  through  a  groove  upon  the  posterior  arch  of  the  atlas.  In 
this  groove  it  lies  beneath  the  vertebral  artery,  to  the  inner  side  of  the  Rectus 
lateralis.  As  it  crosses  the  foramen  in  the  transverse  process  of  the  atlas,  it 
receives  a  filament  from  the  sympathetic.  It  then  descends,  in  front  of  this  process, 
to  communicate  with  an  ascending  branch  from  the  second  cervical  nerve. 

Communicating  filaments  from  this  nerve  join  the  pneumogastric,  the  hypo- 
glossal and  sympathetic,  and  some  branches  are  distributed  to  the  Rectus  lateralis 
and  the  two  Anterior  recti.  According  to  Valentin,  it  also  distributes  filaments 
to  the  occipito-atloid  articulation,  and  mastoid  process  of  the  temporal  bone. 

The  anterior  branch  of  the  second  cervical  nerve  escapes  from  the  spinal  canal, 
between  the  posterior  arch  of  the  atlas  and  the  lamina  of  the  axis,  and,  passing 
forwards  on  the  outer  side  of  the  vertebral  artery,  divides  in  front  of  the  Inter- 
transverse muscle,  into  an  ascending  branch,  which  joins  the  first  cervical,  and 
two  descending  branches  Avhich  join  the  third. 

The  anterior  branch  of  the  third  cervical  nerve  is  double  the  size  of  the  preceding. 
At  its  exit  from  the  intervertebral  foramen,  it  passes  downwards  and  outwards 
beneath  the  Sterno-mastoid,  and  divides  into  two  branches.  The  ascending  branch 
joins  the  anterior  division  of  the  second  cervical,  communicates  with  the  sympa- 
thetic and  spinal  accessory  nerves,  and  subdivides  into  the  superficial  cervical, 
and  great  auricular  nerves.  The  descending  branch  passes  down  in  front  of  the 
Scalenus  anticus,  anastomoses  with  the  fourth  cervical  nerve,  and  becomes  con- 
tinuous with  the  clavicular  nerves. 

The  anterior  branch  of  the  fourth  cervical  is  of  the  same  size  as  the  preceding. 
It  receives  a  branch  from  the  third,  sends  a  communicating  branch  to  the  fifth 
cervical,  and,  passing  downwards  and  outwards,  divides  into  numerous  filaments, 
which  cross  the  posterior  triangle  of  the  neck,  towards  the  clavicle  and  acromion. 
It  usually  gives  a  branch  to  the  phrenic  nerve  whilst  it  is  contained  in  the  inter- 
transverse space. 

The  anterior  branches  of  the  fifth,  sixth,  seventh,  and  eighth  cervical  nerves  are 
remarkable  for  their  large  size.  They  are  much  larger  than  the  preceding  nerves, 
and  are  all  of  equal  size.     They  assist  in  the  formation  of  the  brachial  plexus. 


Cervical  Plexus. 

The  cervical  plexus  (fig.  279)  is  formed  by  the  anterior  branches  of  the  four 
upper  cervical  nerves.  It  is  situated  in  front  of  the  four  upper  vertebras,  resting 
upon  the  Levator  anguli  scapulae,  and  Scalenus  medius  muscles,  and  covered  in  by 
the  Sterno-mastoid. 

Its  branches  may  be  divided  into  two  groups,  superficial  and  deep,  which  may- 
be thus  arranged : — 


Ascending 


Superficial 


SSuperficialis  colli. 
Auricularis  magnus. 
Occipitalis  minor. 

( 


Descending    -\  Supra-clavicular 


\ 


Sternal. 

Clavicular. 

Acromial. 


Deep 


Internal 


External 


f  Communicating. 

J  Muscular. 

j  Communicans  noni. 

[  Phrenic. 

(  Communicating. 

I  Muscular. 


564 


SPINAL   NERVES.   *V ' -v^/^^^^^ 


Superficial  Branches  of  the  Cervical  Plexus. 

The  Superficialis  Colli  arises  from  the  second  and  third  cervical  nerves,  turns 
round  the  posterior  border  of  the  Sterno-mastoid  about  its  middle,  and,  passing 
obliquely  forwards  behind  the  external  jugular  vein  to  the  anterior  border  of  that 
muscle,  perforates  the  deep  cervical  fascia,  and  divides  beneath  the  Platysma  into 
two  branches,  which  are  distributed  to  the  anterior  and  lateral  parts  of  the  neck. 

The  ascending  branch  gives  a  filament,  which  accompanies  the  external  jugular 
vein;  it  then  passes  upwards  to  the  submaxillary  region,  and  divides  into 
branches,  some  of  which  form  a  plexus  with  the  cervical  branches  of  the  facial 
nerve  beneath  the  Platysma ;  others  pierce  this  muscle,  supply  i*»  an(i  are  distri- 
buted to  the  integument  of  the  upper  half  of  the  neck,  at  its  fore  part,  as  high 
as  the  chin. 

The  descending  branch  pierces  the  Platysma,  and  is  distributed  to  the  integument 
of  the  side  and  front  of  the  neck,  as  low  as  the  sternum. 

This  nerve  is  occasionally  represented  by  two  or  more  filaments. 

The  Auricularis  Magnus  is  the  largest  of  the  ascending  branches.  It  arises 
from  the  second  and  third  cervical  nerves,  winds  Tound  the  posterior  border  of 
the  Sterno-mastoid,  and,  after  perforating  the  deep  fascia,  ascends  upon  that 
muscle  beneath  the  Platysma  to  the  parotid  gland,  where  it  divides  into  numerous 
branches. 

The  facial  branches  pass  across  the  carotid,  and  are  distributed  to  the  integu- 
ment of  the  face ;  others  penetrate  the  substance  of  the  gland,  and  communicate 
with  the  facial  nerve. 

The  posterior  or  auricular  branches  ascend  vertically  to  supply  the  integument 
of  the  back  part  of  the  pinna,  communicating  with  the  auricular  branches  of  the 
facial  and  pneumogastric  nerves. 

The  mastoid  branch  joins  the  posterior  auricular  branch  of  the  facial,  and,  crossing 
the  mastoid  process,  is  distributed  to  the  integument  behind  the  ear. 

The  Occipitalis  Minor  arises  from  the  second  cervical  nerve ;  it  curves  round 
the  posterior  border  of  the  Sterno-mastoid  above  the  preceding,  aud  ascends 
vertically  along  the  posterior  border  of  this  muscle  to  the  back  part  of  the  side 
of  the  head.  Near  the  cranium  it  perforates  the  deep  fascia,  and  is  continued 
upwards  along  the  side  of  the  head  behind  the  ear,  supplying  the  integument  and 
Occipito-frontalis  muscle,  and  communicating  with  the  occipitalis  major,  auricu- 
laris magnus,  and  posterior  auricular  branch  of  the  facial. 

This  nerve  gives  off  an  auricular  branch,  which  supplies  the  Attollens  aurem 
and  the  integument  of  the  upper  and  back  part  of  the  auricle.  This  branch  is 
occasionally  derived  from  the  great  occipital  nerve.  The  occipitalis  minor  varies 
in  size ;  it  is  occasionally  double. 

The  Descending  or  Supra-clavicular  branches  arise  from  the  third  and  fourth 
cervical  nerves;  emerging  beneath  the  posterior  border  of  the  Sterno-mastoid,  they 
descend  in  the  interval  between  this  muscle  and  the  Trapezius,  and  divide  into 
branches,  which  are  arranged,  according  to  their  position,  into  three  groups. 

The  inner  or  sternal  branch  crosses  obliquely  over  the  clavicular  and  sternal 
attachments  of  the  Sterno-mastoid,  and  supplies  the  integument  as  far  as  the 
median  line. 

The  middle  or  clavicular  branch  crosses  the  clavicle,  and  supplies  the  integu- 
ment over  the  Pectoral  and  Deltoid  muscles,  communicating  with  the  cutaneous 
branches  of  the  upper  intercostal  nerves.  Not  unfrequently,  the  clavicular 
branch  passes  through  a  foramen  in  the  clavicle,  at  the  junction  of  the  outer  with 
the  inner  two-thirds  of  the  bone. 

The  external  or  acromial  branch  passes  obliquely  across  the  outer  surface  of  the 
Trapezius  and  the  acromion,  and  supplies  the  integument  of  the  upper  and  back 
part  of  the  shoulder. 


COMMUNICANS   NONI  — PHRENIC.  565 


Deep  Branches  of  the  Cervical  Plexus.    Internal  Series. 

The  communicating  branches  consist  of  several  filaments,  which  pass  from  the 
loop  between  the  first  and  second  cervical  nerves  in  front  of  the  atlas  to  the 
pneumogastric,  hypoglossal,  and  sympathetic. 

Muscular  branches  supply  the  Anterior  recti  and  Rectus  lateralis  muscles; 
they  proceed  from  the  first  cervical  nerve,  and  from  the  loop  formed  between  it 
and  the  second. 

The  Communicans  Noni  (fig.  279)  consists  usually  of  two  filaments,  one  being 
derived  from  the  second,  and  the  other  from  the  third  cervical.  These  filaments 
pass  vertically  downwards  on  the  outer  side  of  the  internal  jugular  vein,  cross  in 
front  of  the  vein  a  little  beiow  the  middle  of  the  neck,  and  form  a  loop  with  the 
descendens  noni  in  front  of  the  sheath  of  the  carotid  vessels.  Occasionally,  the 
junction  of  these  nerves  takes  place  within  the  sheath. 

The  Phrenic  Nerve  {internal  respiratory  of  Bell)  arises  from  the  third  and 
fourth  cervical  nerves,  and  receives  a  communicating  branch  from  the  fifth.  It 
descends  to  the  root  of  the  neck,  lying  obliquely  across  the  front  of  the  Scalenus 
anticus,  passes  over  the  first  part  of  the  subclavian  artery,  between  it  and  the 
subclavian  vein,  and,  as  it  enters  the  chest,  crosses  the  internal  mammary  artery 
near  its  root.  Within  the  chest,  it  descends  nearly  vertically  in  front  of  the  root 
of  the  lung,  and  by  the  side  of  the  pericardium,  between  it  and  the  mediastinal 
portion  of  the  pleura,  to  the  Diaphragm,  where  it  divides  into  branches,  which 
separately  pierce  that  muscle,  and  are  distributed  to  its  under  surface. 

The  two  phrenic  nerves  differ  in  their  length,  and  also  in  their  relations  at  the 
upper  part  of  the  thorax. 

The  right  nerve  is  situated  more  deeply,  and  is  shorter  and  more  vertical  in 
direction  than  the  left ;  it  lies  on  the  outer  side  of  the  right  vena  innominata  and 
superior  vena  cava. 

The  left  nerve  is  rather  longer  than  the  right,  from  the  inclination  of  the  heart 
to  the  left  side,  and  from  the  Diaphragm  being  lower  in  this  than  on  the  opposite 
side.  At  the  upper  part  of  the  thorax,  it  crosses  in  front  of  the  arch  of  the  aorta 
to  the  root  of  the  lung. 

Each  nerve  supplies  filaments  to  the  pericardium  and  pleura,  and  near  the  chest 
is  joined  by  a  filament  from  the  sympathetic,  by  another  derived  from  the  fifth 
and  sixth  cervical  nerves,  and,  occasionally,  by  one  from  the  union  of  the 
descendens  noni  with  the  spinal  nerves,  which,  Swan  states,  occurs  only  on  the 
left  side. 

From  the  right  nerve,  one  or  two  filaments  pass  to  join  in  a  small  ganglion 
with  phrenic  branches  of  the  solar  plexus;  and  branches  from  this  ganglion  are 
distributed  to  the  hepatic  plexus,  the  supra-renal  capsule,  and  inferior  vena  cava. 
From  the  left  nerve,  filaments  pass  to  join  the  phrenic  plexus,  but  without  any 
ganglionic  enlargement. 

Deep  Branches  of  the  Cervical  Plexus.    External  Series. 

Communicating  branches.  The  cervical  plexus  communicates  with  the  spinal 
accessory  nerve,  in  the  substance  of  the  Sterno-mastoid  muscle,  in  the  subocci- 
pital triangle,  and  beneath  the  Trapezius. 

Muscular  brandies  are  distributed  to  the  Sterno-mastoid,  Levator  anguli 
scapulas,  Scalenus  medius  and  Trapezius. 

The  branch  for  the  Sterno-mastoid  is  derived  from  the  second  cervical ;  the 
Levator  anguli  scapulas  receiving  branches  from  the  third ;  and  the  Trapezius 
branches  from  the  third  and  fourth. 

Posterior  Branches  of  the  Cervical  Nerves. 

The  posterior  branches  of  the  cervical  nerves,  with  the  exception  of  the  first 
two,  pass  backwards,  and  divide,  behind  the  posterior  Inter-transverse  muscles,  into 
external  and  internal  branches. 


5G6  SPINAL   NERVES. 

The  external  branches  supply  the  muscles  at  the  side  of  the  neck,  viz.,  the 
Cervicalis  ascendens,  Transversalis  colli,  and  Trachelo-mastoid. 

The  external  branch  of  the  second  cervical  nerve  is  the  largest;  it  is  often 
joined  with  the  third,  and  supplies  the  Complexus,  Splenius,  and  Trachelo- 
mastoid  muscles. 

The  internal  branches,  the  larger,  are  distributed  differently  in  the  upper  and 
lower  part  of  the  neck.  Those  derived  from  the  third,  fourth,  and  fifth  serves 
pass  between  the  Semi-spinalis  and  Complexus  muscles,  and,  having  reached  the 
spinous  processes,  perforate  the  aponeurosis  of  the  Splenius  and  Trapezius,  and 
are  continued  outwards  to  the  integument  over  the  Trapezius ;  whilst  those  derived 
from  the  three  lowest  cervical  nerves  are  the  smallest,  and  are  placed  beneath  the 
Semi-spinalis,  which  they  supply,  and  do  not  furnish  any  cutaneous  filaments. 
These  internal  branches  supply  the  Complexus,  Semi-spinalis  colli,  Inter-spinales, 
and  Multifidus  spinse. 

The  posterior  branches  of  the  three  first  cervical  nerves  require  a  separate 
description. 

The  'posterior  branches  of  the  first  cervical  nerve  {suboccipital)  is  larger  than  the 
anterior,  and  escapes  from  the  spinal  canal  between  the  occipital  bone  and  the 
posterior  arch  of  the  atlas,  lying  behind  the  vertebral  artery,  and  enters  the  tri- 
angular space  formed  by  the  Kectus  posticus  major,  the  Obliquus  superior,  and 
Obliquus  inferior.  It  supplies  the  Kecti  and  Obliqui  muscles,  and  the  Com- 
plexus. From  the  branch  which  supplies  the  Inferior  oblique  a  filament  is  given 
off,  which  joins  the  second  cervical  nerve.  It  also  occasionally  gives  off  a  cuta- 
neous filament,  which  accompanies  the  occipital  artery,  and  communicates  with  the 
occipitalis  major  and  minor  nerves. 

The  posterior  division  of  the  first  cervical  has  no  branch  analogous  to  the 
external  branch  of  the  other  cervical  nerves. 

The  posterior  branch  of  the  second  cervical  nerve  is  three  or  four  times  greater 
than  the  anterior  branch,  and  the  largest  of  all  the  other  posterior  cervical  nerves. 
It  emerges  from  the  spinal  canal  between  the  posterior  arch  of  the  atlas  and 
lamina  of  the  axis,  below  the  Inferior  oblique.  It  supplies  this  muscle,  and 
receives  a  communicating  filament  from  the  first  cervical.  It  then  divides  into 
an  external  and  an  internal  branch. 

The  internal  branch,  called,  from  its  size  and  distribution,  the  occipitalis  major, 
ascends  obliquely  inwards  between  the  Obliquus  inferior  and  Complexus,  and 
pierces  the  latter  muscle  and  the  Trapezius  near  their  attachments  to  the  cranium. 
It  is  now  joined  by  a  filament  from  the  third  cervical  nerve,  and,  ascending  on  the 
back  part  of  the  head  with  the  occipital  artery,  divides  into  two  branches,  which 
supply  the  integument  of  the  scalp  as  far  forwards  as  the  vertex,  communicating 
with  the  occipitalis  minor.  It  gives  off  an  auricular  branch  to  the  back  part  of 
the  ear,  and  muscular  branches  to  the  Complexus. 

The  posterior  branch  of  the  third  cervical  is  smaller  than  the  preceding,  but 
larger  than  the  fourth ;  it  differs  from  the  posterior  branches  of  the  other  cervical 
nerves  in  its  supplying  an  additional  filament  to  the  integument  of  the  occiput. 
This  occipital  branch  arises  from  the  internal  or  cutaneous  branch  beneath  the 
Trapezius ;  it  pierces  that  muscle,  and  supplies  the  skin  on  the  lower  and  back 
part  of  the  head.  It  lies  to  the  inner  side  of  the  occipitalis  major,  with  which  it 
is  connected. 

The  internal  branches  of  the  posterior  divisions  of  the  first  three  cervical 
nerves  are  occasionally  joined  beneath  the  Complexus  by  communicating  branches. 
This  communication  has  been  described  by  Cruveilhier  as  the  posterior  cervical 
plexus. 

The  Beachial  Plexus  (fig.  285). 

The  brachial  plexus  is  formed  by  the  union  of  the  anterior  branches  of  the  four 
lower  cervical  and  first  dorsal  nerves.  It  extends  from  the  lower  part  of  the  side 
of  the  neck  to  tne  axilla,  being  very  broad,  and  presenting  but  little  of  a  plexi- 


BRACHIAL   PLEXUS. 


5G7 


^Fasciculus  f  rem 
if'.1!  Cerv.tf. 


Comnrnnicati-ny  vriOi  Phrenic 


Sup  ra  -Scapular 

"  °f  Clavicle 


form  arrangement  at  its  commencement,  narrow  opposite  the  clavicle,  broad  and 
presenting  a  more  dense  interlacement  in  the  axilla,  and  dividing  opposite  the 
coracoid  process  into  numerous  branches  for  the  supply  of  the  upper  limb.  These 
nerves  are  all  similar  in  size,  and  their  mode  of  union  in  the  formation  of  the 
plexus  is  the  following.  The  fifth  and  sixth  nerves  unite  near  their  exit  from 
the  spine  into  a  common  trunk ;  the  seventh  nerve  joins  this  trunk  near  the  outer 
border  of  the  Middle  scalenus ;  and  the  three  nerves  thus  form  one  large  single 
cord.  The  eighth  cervical  and  first  dorsal  nerves  unite  beneath  the  Anterior 
scalenus  into  a  common  trunk.  Thus  two  large  trunks  are  formed,  the  upper  one 
by  the  union  of  the  fifth,  sixth,  and  seventh  cervical ;  and  the  lower  one  by  the 
eighth  cervical  and  first  dorsal.  These  two  trunks  accompany  the  subclavian 
artery  to  the  axilla,  lying  upon  its  outer  side,  the  trunk  formed  by  the  union  of  the 
last  cervical  and  first  dorsal 

being;  nearest  to  the  vessel.  FiS-  285.— Plan  of  the  Brachial  Plexus. 

Opposite  the  clavicle,  and 
sometimes  in  the  axilla, 
each  of  these  cords  gives 
off  a  fasciculus,  which 
uniting,  a  third  trunk  is 
formed,  so  that  in  the 
centre  of  the  axilla  three 
cords  are  found,  one  lying 
on  the  outer  side  of  the 
axillary  artery,  one  on  its 
inner  side,  and  one  behind. 
The  brachial  plexus  com- 
municates with  the  cer- 
vical plexus  by  a  branch 
from  the  fourth  to  the 
fifth  nerve,  and  with  the 
phrenic  by  a  branch  from 
the  fifth  cervical,  which 
joins  that  nerve  on  the 
Anterior  scalenus  muscle : 
the  cervical  and  first  dor- 
sal nerves  are  also  joined 
by  filaments  from  the  mid- 
dle and  inferior  cervical 
ganglia  of  the  sympathetic, 
close  to  their  exit  from  the 
intervertebral  foramina. 

Relations.  In  the  neck,  the  brachial  plexus  lies  at  first  between  the  Anterior 
and  Middle  scaleni  muscles,  and  then  above  and  to  the  outer  side  of  the  subclavian 
artery ;  it  then  passes  beneath  the  clavicle  and  Subclavius  muscle,  lying  upon  the 
first  serration  of  the  Serratus  magnus  and  Subscapularis  muscles.  In  the  axilla, 
it  is  placed  on  the  outer  side  of  the  first  portion  of  the  axillary  artery ;  it  surrounds 
the  artery  in  the  second  part  of  its  course,  one  cord  lying  upon  the  outer  side  of 
that  vessel,  one  on  the  inner  side,  and  one  behind  it ;  and  at  the  lower  part  of  the 
axillary  space  gives  off  its  terminal  branches  to  the  upper  extremity. 

The  Branches  of  the  Brachial  Plexus  may  be  arranged  into  two  groups,  viz., 
those  given  off  above  the  clavicle,  and  those  below  that  bone. 


(1.)  Branches  above  the  Clavicle. 


Communicating. 
Muscular. 


Posterior  thoracic. 
Suprascapular. 


5G8  SPINAL   NERVES. 

The  Communicating  branch  with,  the  phrenic  is  derived  from  the  fifth  cervical 
nerve ;  it  joins  the  phrenic  on  the  Anterior  scalenus  muscle. 

The  Muscular  branches  supply  the  Longus  colli,  Scaleni,  Rhomboidei,  and 
Subclavius  muscles.  Those  for  the  Scaleni  and  Longus  colli  arise  from  the  lower 
cervical  nerves  at  their  exit  from  the  intervertebral  foramina.  The  rhomboid  branch 
arises  from  the  fifth  cervical,  pierces  the  Scalenus  medius,  and  passes  beneath  the 
Levator  anguli  scapulas,  which  it  occasionally  supplies,  to  the  Rhomboid  muscles. 
The  subclavian  branch  is  a  small  filament,  which  arises  from  the  trunk  formed  by 
the  junction  of  the  fifth  and  sixth  cervical  nerves;  it  descends  in  front  of  the 
subclavian  artery  to  the  Subclavius  muscle,  and  is  usually  connected  by  a  filament 
with  the  phrenic  nerve. 

The  Posterior  thoracic  nerve  (long  thoracic,  external  respiratory  of  Bell) 
supplies  the  Serratus  magnus,  and  is  remarkable  for  the  length  of  its  course.  It 
arises  by  two  roots,  from  the  fifth  and  sixth  cervical  nerves,  immediately 'after 
their  exit  from  the  intervertebral  foramina.  These  unite  in  the  substance  of  the 
Middle  scalenus  muscle,  and,  after  emerging  from  it,  the  nerve  passes  down  behind 
the  brachial  plexus  and  the  axillary  vessels,  resting  on  the  outer  surface  of  the 
Serratus  magnus.  It  extends  along  the  side  of  the  chest  to  the  lower  border  of 
this  muscle,  and  supplies  it  with  numerous  filaments. 

The  Suprascapular  nerve  arises  from  the  cord  formed  by  the  fifth,  sixth,  and 
seventh  cervical  nerves ;  passing  obliquely  outwards  beneath  the  Trapezius,  it  enters 
the  supra-spinous  fossa,  through  the  notch  in  the  upper  border  of  the  scapula ; 
and,  passing  beneath  the  Supra-spinatus  muscle,  curves  in  front  of  the  spine  of  the 
scapula  to  the  infra-spinous  fossa.  In  the  supra-spinous  fossa,  it  gives  off  two 
branches  to  the  Supra-spinatus  muscle,  and  an  articular  filament  to  the  shoulder- 
joint  ;  and  in  the  infra-spinous  fossa,  it  gives  off  two  branches  to  the  Infra- spinatus 
muscle,  besides  some  filaments  to  the  shoulder-joint  and  scapula. 

(2.)  Branches  below  the  Clavicle. 
To  the  chest     ....     Anterior  thoracic. 

To  the  shoulder        .         .  j  Subscapular. 

(  Circumflex. 
'  Musculo-cutaneous. 
Internal  cutaneous. 
Lesser  internal  cutaneous. 
Median. 
Ulnar. 
Musculo-spiral. 

The  branches  given  off  below  the  clavicle  are  derived  from  the  three  cords  of 
the  brachial  plexus,  in  the  following  manner: — 

From  the  outer  cord,  arise  the  external  of  the  two  anterior  thoracic  nerves,  the 
musculo-cutaneous  nerve,  and  the  outer  head  of  the  median. 

From  the  inner  cord,  arise  the  internal  of  the  two  anterior  thoracic  nerves,  the 
internal  cutaneous,  the  lesser  internal  cutaneous  (nerve  of  Wrisberg),  the  ulnar, 
and  inner  head  of  the  median. 

From  the  posterior  cord,  arises  the  subscapular ;  and  it  then  subdivides  into  the 
musculo-spiral  and  circumflex  nerves. 

The  Anterior  Thoracic  Nerves,  two  in  number,  supply  the  Pectoral  muscles. 

The  external  or  superficial  branch,  the  larger  of  the  two,  arises  from  the  outer 
cord  of  the  brachial  plexus,  passes  inwards,  across  the  axillary  artery  and  vein. 
and  is  distributed  to  the  under  surface  of  the  Pectoralis  major.  It  sends  down  a 
communicating  filament  to  join  the  internal  branch. 

The  internal  or  deep  branch  arises  from  the  inner  cord,  and  passes  upwards 
between  the  axillary  artery  and  vein  (sometimes  perforates  the  vein),  and  joins  with 
the  filament  from  the  superficial  branch.  From  the  loop  thus  formed,  branches 
are  distributed  to  the  under  surface  of  the  Pectoralis  minor  and  Pectoralis  major 
muscles. 


To  the  arm,  forearm  and  hand  4 


CUTANEOUS  NERVES  OF  THE  FOREARM. 


569 


The  Subscapular  Nerves,  three  in  number,   supply  the  Subscapular^  Teres 

major,  and  Latissimus  dorsi  muscles. 

The  upper  subscapular  nerve,  the  smallest,  enters  the  upper  part  of  the  Subsca- 

pularis  muscle. 

The     lower     subscap>ular     nerve     enters 

the  axillary  border  of  the  Sub^laris,  «*  «*£££»« »SS& fif*  UpP" 

and  terminates  in  the  Teres  major,     lhe 

latter  muscle  is  sometimes  supplied  by  a 

separate  branch. 

The  long  subscapular,  the  largest  of  the 

three,  descends  along  the  lower  border  of 

the  Subscapularis  to  the  Latissimus  dorsi, 

through  which  it  may  be  traced  as  far  as 

its  lower  border. 

The     Circumflex    Nerve    supplies    some 

of  the  muscles,  and  the  integument  of  the 

shoulder,  and  the  shoulder -joint.     It  arises 

from   the   posterior    cord  of  the   brachial 

plexus,    in    common    with    the    musculo- 

spiral  nerve.     It  passes  down  behind  the 

axillary  artery,  and  in  front  of  the  Subsca- 
pularis; and,  at  the  lower  border  of  this 

muscle,  passes  backwards,  and  divides  into 

two  branches. 

The  upper  branch  winds  round  the  neck 

of  the  humerus,  beneath  the  Deltoid,  with 

the  posterior  circumflex  vessels,  as  far  as 

the  anterior  border  of  the  muscle,  supply- 
ing it,  and  giving  off  cutaneous  branches, 

which  pierce  it  to  ramify  in  the  integument 

covering  its  lower  part. 

The  lower  branch,  at  its  origin,  dis- 
tributes filaments  to  the  .Teres  minor  and 

back  part  of  the  Deltoid  muscles.  Upon  the 
filament  to  the  former  muscle,  a  gangliform 
enlargement    usually  exists.      The    nerve 

then  pierces  the  deep  fascia,  and  supplies 

the  integument  over  the  lower  two-thirds  of 
the  posterior  surface  of  the  Deltoid,  as 
well  as  that  covering  the  long  head  of  the 
Triceps. 

The  circumflex  nerve,  before  its  divi- 
sion, gives  off  an  articular  filament,  which 
enters  the  shoulder-joint  below  the  Subsca- 
pularis. 

The  Musculo-cutaneous  Nerve  {exter- 
nal cutaneous,  perforans  Casserii)  supplies 
some  of  the  muscles  of  the  arm,  and 
the  integument  of  the  forearm.  It  arises 
from  the  outer  cord  of  the  brachial 
plexus,  opposite  the   lower   border  of  the 

Pectoralis  minor.  It  then  perforates  the  Coraco-brachialis  muscle,  and  passes 
obliquely  between  the  Biceps  and  Brachialis  anticus,  to  the  outer  side  of  the  arm, 
a  little  above  the  elbow,  where  it  perforates  the  deep  fascia  and  becomes  cutaneous. 
This  nerve,  in  its  course  through  the  arm,  supplies  the  Coraco-brachialis,  Biceps, 
and  Brachialis  anticus  muscles,  besides  some  filaments  to  the  elbow-joint  and 
humerus. 


570 


SPINAL   NERVES. 


Fit 


287. — Cutaneous  Nerves  of  Right  Upper 
Extremity.     Posterior  View. 


_  The  cutaneous  portion  of  the  nerve  passes  behind  the  median  cephalic  vein,  and 
divides,  opposite  the  elbow -joint,  into  an  anterior  and  a  posterior  branch. 

The  anterior  branch  descends  along  the  radial  border  of  the  forearm  to  the 
wrist.  It  is  here  placed  in  front  of  the  radial  artery,  and,  piercing  the  deep 
fascia,  accompanies  that  vessel  to  the  back  of  the  wrist.     It  communicates  with 

a  branch  from  the  radial  nerve,  and  dis- 
tributes filaments  to  the  integument  of- the 
ball  of  the  thumb. 

The  posterior  branch  is  given  off  about 
the  middle  of  the  forearm,  and  passes 
downwards,  along  the  back  part  of  its 
radial  side,  to  the  wrist.  It  supplies  the 
integument  of  the  lower  third  of  the 
forearm,  communicating  with  the  radial 
nerve,  and  the  external  cutaneous  branch 
of  the  musculo-spiral. 

The  Internal  Cutaneous  Nerve  is  one 
of  the  smallest  branches  of  the  brachial 
plexus.  It  arises  from  the  inner  cord, 
in  common  with  the  ulnar  and  internal 
head  of  the  median,  and,  at  its  commence- 
ment, is  placed  on  the  inner  side  of  the 
brachial  artery.  It  passes  down  the  inner 
side  of  the  arm,  pierces  the  deep  fascia 
with  the  basilic  vein,  about  the  middle  of 
the  limb,  and,  becoming  cutaneous,  di- 
vides into  two  branches. 

This  nerve  gives  off,  near  the  axilla,  a 
cutaneous  filament,  which  pierces  the 
fascia,  and  supplies  the  integument  cover- 
ing the  Biceps  muscle,  nearly  as  far  as 
the  elbow.  This  filament  lies  a  little  ex- 
ternal to  the  common  trunk  from  which 
it  arises. 

The  anterior  branch,  the  larger  of  the 
two,  passes  in  front  of,  occasionally  be- 
hind, the  median  basilic  vein.  It  then 
descends  on  the  anterior  surface  of  the 
ulnar  side  of  the  forearm,  distributing 
filaments  to  the  integument  as  far  as  the 
wrist,  and  communicating  with  a  cuta- 
neous branch  of  the  ulnar  nerve. 

The  posterior  branch  passes  obliquely 
downwards  on  the  inner  side  of  the  basilic 
vein,  winds  over  the  internal  condyle  of 
the  humerus  to  the  back  of  the  forearm, 
and  descends,  on  the  posterior  surface  of 
its  ulnar  side,  to  a  little  below  the  middle, 
distributing  filaments  to  the  integument. 
It  anastomoses  above  the  elbow  with 
the  lesser  internal  cutaneous,  and  above 
the  wrist  with  the  dorsal  branch  of  the 
ulnar  nerve  (Swan). 

The   Lesser   Internal   Cutaneous    Nerve 

(nerve  of  Wrisberg)  is  distributed  to  the 

integument  on  the  inner  side  of  the  arm.     It  is  the  smallest  of  the  branches  of  the 

brachial  plexus,  and  usually  arises  from  the  inner  cord,  with  the  internal  cutaneous 


MEDIAN.  5TI 

and  ulnar  nerves.  It  passes  through  the  axillary  space,  at  first  lying  beneath,  and 
then  on  the  inner  side  of,  the  axillary  vein,  and  communicates  with  the  intercosto- 
humeral  nerve.  It  then  descends  along  the  inner  side  of  the  brachial  artery,  to 
the  middle  of  the  arm,  where  it  pierces  the  deep  fascia,  and  is  distributed  to  the 
integument  of  the  back  part  of  the  lower  third  of  the  arm,  extending  as  far  as  the 
elbow,  where  some  filaments  are  lost  in  the  integument  in  front  of  the  inner  con- 
dyle, and  others  over  the  olecranon.  It  communicates  with  the  inner  branch  of 
the  internal  cutaneous  nerve. 

In  some  cases,  the  nerve  of  Wrisberg  and  intercosto-humeral  are  connected 
by  two  or  three  filaments,  which  form  a  plexus  at  the  back  part  of  the  axilla. 
In  other  cases,  the  intercosto-humeral  is  of  large  size,  and  takes  the  place  of  the 
nerve  of  Wrisberg,  receiving  merely  a  filament  of  communication  from  the 
brachial  plexus,  which  represents  this  nerve.  In  other  cases,  this  filament  is 
wanting,  the  place  of  the  nerve  of  Wrisberg  being  supplied  entirely  from  the 
intercosto-humeral. 

The  Mediax  Nerve  (fig.  288)  has  received  its  name  from  the  course  it  takes 
along  the  middle  line  of  the  arm  and  forearm  to  the  hand,  lying  between  the  ulnar 
and  musculo-spiral  and  radial  nerves.  It  arises  by  two  roots,  one  from  the  outer, 
and  one  from  the  inner  cord  of  the  brachial  plexus ;  these  embrace  the  lower  part 
of  the  axillary  artery,  uniting  either  in  front  or  on  the  outer  side  of  that  vessel. 
As  it  descends  through  the  arm,  it  lies  at  first  on  the  outer  side  of  the  brachial 
artery,  crosses  that  vessel  in  the  middle  of  its  course,  usually  in  front,  but  occa- 
sionally behind  it,  and  lies  on  its  inner  side  to  the  bend  of  the  elbow,  where  it  is 
placed  beneath  the  bicipital  fascia,  and  is  separated  from  the  elbow-joint  by  the 
Brachialis  anticus.  In  the  forearm,  it  passes  between  the  two  heads  of  the 
Pronator  radii  teres,  and  descends  beneath  the  Flexor  sublimis,  to  within  two 
inches  above  the  annular  ligament,  where  it  becomes  more  superficial,  lying  between 
the  Flexor  sublimis  and  Flexor  carpi  radialis,  covered  by  the  integument  and 
fascia.     It  then  passes  beneath  the  annular  ligament  into  the  hand. 

Branches.  No  branches  are  given  off  from  the  median  nerve  in  the  arm. 
In  the  forearm,  its  branches  are  the  muscular,  anterior  interosseous,  and  palmar 
cutaneous. 

The  muscular  branches  supply  all  the  superficial  muscles  on  the  front  of  the 
forearm,  except  the  Flexor  carpi  ulnaris.  These  branches  are  derived  from  the 
nerve  near  the  elbow.  The  branch  furnished  to  the  Pronator  radii  teres  often 
arises  above  the  joint. 

The  anterior  interosseous  supplies  the  deep  muscles  on  the  front  of  the  fore- 
arm. It  accompanies  the  anterior  interosseous  artery  along  the  interosseous 
membrane,  in  the  interval  between  the  Flexor  longus  pollicis  and  Flexor  pro- 
fundus digitorum  rnuscles,  both  of  which  it  supplies,  and  terminates  below  in  the 
Pronator  quadratus. 

The  palmar  cutaneous  branch  arises  from  the  median  nerve  at  the  lower  part 
of  the  forearm.  It  pierces  the  fascia  above  the  annular  ligament,  and  divides 
into  two  branches;  the  outer  one  supplies  the  skin  over  the  ball  of  the  thumb,  and 
communicates  with  the  external  cutaneous  nerve ;  the  inner  one  supplies  the  inte- 
gument of  the  palm  of  the  hand,  anastomosing  with  the  cutaneous  branch  of  the 
ulnar.     Both  nerves  cross  the  annular  ligament  previous  to  their  distribution. 

In  the  palm  of  the  hand,  the  median  nerve  is  covered  by  the  integument  and 
palmar  fascia,  and  rests  upon  the  tendons  of  the  Flexor  muscles.  In  this  situation 
it  becomes  enlarged,  somewhat  flattened,  of  a  reddish  color,  and  divides  into  two 
branches.  Of  these,  the  external  one  supplies  a  muscular  branch  to  some  of  the 
muscles  of  the  thumb,  and  digital  branches  to  the  thumb  and  index-finger;  the 
internal  branch  supplying  digital  branches  to  the  middle  finger  and  part  of  the 
index  and  ring  fingers. 

The  branch  to  the  muscles  of  the  thumb  is  a  short  nerve,  which  subdivides  to 
supply  the  Abductor,  Opponens,  and  outer  head  of  the  Flexor  brevis  pollicis 
muscles ;  the  remaining  muscles  of  this  group  being  supplied  by  the  ulnar  nerve. 


572 


SPINAL   NERVES. 


Pig.  288.— Nerves  of  the  Left  Upper  Extremity.     Front  View. 


External 
'Anterior  T7u>raete 


Tntemat 


ULNAR.  573 

The  digital  branches  are  five  in  number.  The  first  and  second  pass  along  the 
borders  of  the  thumb,  the  most  external  one  communicating  with  branches  of 
the  radial  nerve.  The  third  passes  along  the  radial  side  of  the  index-finger,  and 
supplies  the  first  Lumbrical  muscle.  The  fourth  subdivides  to  supply  the  adjacent 
sides  of  the  index  and  middle  fingers,  and  sends  a  branch  to  the  second  Lumbrical 
muscle.  The  fifth  supplies  the  adjacent  sides  of  the  middle  and  ring  fingers,  and 
communicates  with  a  branch  from  the  ulnar  nerve. 

Each  digital  nerve,  opposite  the  base  of  the  first  phalanx,  gives  off  a  dorsal 
branch,  which  joins  the  dorsal  digital  nerve,  and  runs  along  the  side  of  the 
dorsum  of  the  finger,  ending  in  the  integument  over  the  last  phalanx.  At  the 
end  of  the  finger,  the  digital  nerve  divides  into  a  palmar  and  a  dorsal  branch ; 
the  former  supplies  the  extremity  of  the  finger,  and  the  latter  ramifies  round  and 
beneath  the  nail.  The  digital  nerves,  as  they  run  along  the  fingers,  are  placed 
superficial  to  the  digital  arteries. 

The  Ulnar  Nerve  is  placed  along  the  inner  or  ulnar  side  of  the  upper  limb, 
and  is  distributed  to  the  muscles  and  integument  of  the  forearm  and  hand.  It 
is  smaller  than  the  median,  behind  which  it  is  placed,  diverging  from  it  in  its 
course  down  the  arm.  It  arises  from  the  inner  cord  of  the  brachial  plexus,  in 
common  with  the  inner  head  of  the  median  and  the  internal  cutaneous  nerves. 
At  its  commencement,  it  lies  at  the  inner  side  of  the  axillary  artery,  and  holds 
the  same  relation  with  the  brachial  artery  to  the  middle  of  the  arm.  From  this 
point,  it  runs  obliquely  across  the  internal  head  of  the  Triceps,  pierces  the  internal 
intermuscular  septum,  and  descends  to  the  groove  between  the  internal  condyle 
and  olecranon,  accompanied  by  the  inferior  profunda  artery.  At  the  elbow,  it 
rests  upon  the  back  of  the  inner  condyle,  and  passes  into  the  forearm  between 
the  two  heads  of  the  Flexor  carpi  ulnaris.  In  the  forearm,  it  descends  in  a 
perfectly  straight  course  along  its  ulnar  side,  lying  upon  the  Flexor  profundus 
digitorum,  its  upper  half  being  covered  by  the  Flexor  carpi  ulnaris,  its  lower  half 
lying  on  the  outer  side  of  this  muscle,  covered  by  the  integument  and  fascia.  The 
ulnar  artery,  in  the  upper  part  of  its  course,  is  separated  from  the  ulnar  nerve  by 
a  considerable  interval :  but  in  the  rest  of  its  extent,  the  nerve  lies  to  its  inner 
side.  At  the  wrist,  the  ulnar  nerve  crosses  the  annular  ligament  on  the  outer  side 
of  the  pisiform  bone,  a  little  behind  the  ulnar  artery,  and  immediately  beyond  this 
bone  divides  into  two  branches,  superficial  and  deep  palmar. 

The  branches  of  the  ulnar  nerve  are : — 

'  Articular  (elbow). 
-Musculir 
In  the  forearm   A  Cutaneous.  In  hand    1  Superficial  palmar, 

j  Dorsal  branch.  1  Deep  palmar. 

[  Articular  (wrist). 

The  articular  branches  distributed  to  the  elbow-joint  consist  of  several  small 
filaments.  They  arise  from  the  nerve  as  it  lies  in  the  groove  between  the  inner 
condyle  and  olecranon. 

The  muscular  branches  are  two  in  number;  one  supplying  the  Flexor  carpi 
ulnaris ;  the  other,  the  inner  half  of  the  Flexor  profundus  digitorum.  They  arise 
from  the  trunk  of  the  nerve  near  the  elbow. 

The  cutaneous  branch  arises  from  the  ulnar  nerve  about  the  middle  of  the  fore- 
arm, and  divides  into  a  superficial  and  deep  branch. 

The  superficial  branch  (frequently  absent)  pierces  the  deep  fascia  near  the 
wrist,  and  is  distributed  to  the  integument,  communicating  with  a  branch  of  the 
internal  cutaneous  nerve. 

The  deep  branch  lies  on  the  ulnar  artery,  which  it  accompanies  to  the  hand, 
some  filaments  entwining  round  the  vessel,  which  end  in  the  integument  of  the 
palm,  communicating  with  branches  of  the  median  nerve. 

The  dorsal  cutaneous  branch  arises  about  two  inches  above  the  wrist ;  it  passes 
backwards  beneath  the  Flexor  carpi  ulnaris,  perforates  the  deep  fascia,  and,  running 


574 


SPINAL   NERYES. 


Fig.  289. — The  Suprascapular,  Circumflex,  and  Musculo-spiral 
Nerves. 


Supra-Seetyuli 


Circumflex 


along  the  ulnar  side  of  the  wrist  and  hand,  supplies  the  inner  side  of  the  little 
finger,  and  the  adjoining  sides  of  the  little  and  ring  fingers ;  it  also  sends  a  com- 
municating filament  to  that  branch  of  the  radial  nerve  which  supplies  the  adjoining 
sides  of  the  middle  and  ring  fingers. 

The  articular  filaments  to  the  wrist  are  also  supplied  by  the  ulnar  nerve. 
The  superficial  palmar  branch  supplies  the  Palmaris  brevis,  and  the  integument 
on  the  inner  side  of  the  hand,  and  terminates  in  two  digital  branches,  which  are 
distributed,  one  to  the  ulnar  side  of  the  little  finger,  the  other  to  the  adjoining 

sides  of  the  little  and  ring 
fingers,  the  latter  com- 
municating with  a  branch 
from  the  median. 

The  deep  palmar  branch 
passes  between  the  Abduc- 
tor and  Flexor  brevis 
minimi  digiti  muscles,  and 
follows  the  course  of  the 
deep  palmar  arch  beneath 
the  flexor  tendons.  At 
its  origin,  it  supplies  the 
muscles  of  the  little  finger. 
As  it  crosses  the  deep  part 
of  the  hand  it  sends  two 
branches  to  each  interos- 
seous space,  one  for  the 
Dorsal  and  one  for  the 
Palmar  interosseous  mus- 
cle, the  branches  to  the 
second  and  third  Palmar 
interossei  supplying  fila- 
ments to  the  two  inner 
Lumbrical  muscles.  At  its 
termination  between  the 
thumb  and  index-finger,  it 
supplies  the  Adductor  pol- 
licis  and  the  inner  head  of 
the  Flexor  brevis  pollicis. 
The  Musculo-spikal 
Nerve  (fig.  289),  the  largest 
branch  of  the  brachial 
plexus,  supplies  the  mus- 
cles of  the  back  part  of  the 
arm  and  forearm,  and  the 
integument  of  the  same 
parts,  as  well  as  that  of 
the  hand.  It  arises  from 
the  posterior  cord  of  the 
brachial  plexus  by  a  com- 
mon trunk  with  the  cir- 
cumflex nerve.  At  its 
commencement,  it  is  placed 
behind  the  axillary  and 
upper  part  of  the  brachial 
arteries,  passing  down  in 
front  of  the  tendons  of  the 
Latissimus  dorsi  and  Teres 
major.      It    winds    round 


MUSCULO-SPIRAL.  515 

the  "humerus  in  the  spiral  groove  with  the  superior  profunda  artery  and  vein, 
passing  from  the  inner  to  the  outer  side  of  the  bone,  beneath  the  Triceps  muscle. 
At  the  outer  side  of  the  arm,  it  descends  between  the  Brachialis  anticus  and 
Supinator  longus  to  the  front  of  the  external  condyle,  where  it  divides  into  the 
radial  and  posterior  interosseous  nerves. 

The  branches  of  the  musculo-spiral  nerve  are : — 

Muscular.  Radial. 

Cutaneous.  Posterior  interosseous. 

The  muscular  branches  supply  the  Triceps,  Anconeus,  Supinator  longus, 
Extensor  carpi  radialis  longior,  and  Brachialis  anticus.  These  branches  are 
derived  from  the  nerve,  at  the  inner  side,  back  part,  and  outer  side  of  the 
arm. 

The  internal  muscular  branches  supply  the  inner  and  middle  heads  of  the 
Triceps  muscle.  That  to  the  inner  head  of  the  Triceps  is  a  long,  slender 
filament,  which  lies  close  to  the  ulnar  nerve,  as  far  as  the  lower  third  of  the 
arm. 

The  posterior  muscular  branch,  of  large  size,  arises  from  the  nerve  in  the 
groove  between  the  Triceps  and  the  humerus.  It  divides  into  branches  which 
supply  the  outer  head  of  the  Triceps  and  Anconeus  muscles.  The  branch  for 
the  latter  muscle  is  a  long,  slender  filament,  which  descends  in  the  substance  of 
the  Triceps  to  the  Anconeus. 

The  external  muscular  branches  supply  the  Supinator  longus,  Extensor  carpi 
radialis  longior,  and  Brachialis  anticus. 

The  cutaneous  branches  are  three  in  number,  one  internal  and  two  external. 

The  internal  cutaneous  branch  arises  in  the  axillary  space,  with  the  inner 
muscular  branch.  It  is  of  small  size,  and  passes  across  the  axilla  to  the  inner 
side  of  the  arm,  supplying  the  integument  on  its  posterior  aspect  nearly  as  far  as 
the  olecranon. 

The  two  external  cutaneous  branches  perforate  the  outer  head  of  the  Triceps, 
at  its  attachment  to  the  humerus.  The  upper  and  smaller  one  follows  the  course 
of  the  cephalic  vein  to  the  front  of  the  elbow,  supplying  the  integument  of  the 
lower  half  of  the  upper  arm  on  its  anterior  aspect.  The  lower  branch  pierces  the 
deep  fascia  below  the  insertion  of  the  Deltoid,  and  passes  down  along  the  outer 
side  of  the  arm  and  elbow,  and  along  the  back  part  of  the  radial  side  of  the 
forearm  to  the  wrist,  supplying  the  integument  in  its  course,  and  joining,  near  its 
termination,  with  a  branch  of  the  external  cutaneous  nerve. 

The  radial  nerve  passes  along  the  front  of  the  radial  side  of  the  forearm,  to  the 
commencement  of  its  lower  third.  It  lies  at  first  a  little  to  the  outer  side  of  the 
radial  artery,  concealed  beneath  the  Supinator  longus.  In  the  middle  third  of  the 
forearm,  it  lies  beneath  the  same  muscle,  in  close  relation  with  the  outer  side  of 
the  artery.  It  quits  the  artery  about  three  inches  above  the  wrist,  passes  beneath 
the  tendon  of  the  Supinator  longus,  and,  piercing  the  deep  fascia  at  the  outer 
border  of  the  forearm,  divides  into  two  branches. 

The  external  branch,  the  smaller  of  the  two,  supplies  the  integument  of  the 
radial  side,  and  ball  of  the  thumb,  joining  with  the  posterior  branch  of  the 
external  cutaneous  nerve. 

The  internal  branch  communicates,  above  the  wrist,  with  a  branch  from  the 
external  cutaneous,  and,  on  the  back  of  the  hand,  forms  an  arch  with  the  dorsal 
branch  of  the  ulnar  nerve.  It  then  divides  into  four  digital  nerves,  which  are 
distributed  as  follows : — The  first  supplies  the  ulnar  side  of  the  thumb ;  the  second, 
the  radial  side  of  the  index  finger ;  the  third,  the  adjoining  sides  of  the  index 
and  middle  fingers;  and  the  fourth,  the  adjacent  borders  of  the  middle  and  ring 
fingers.  The  latter  nerve  communicates  with  a  filament  from  the  dorsal  branch 
of  the  ulnar  nerve. 

The  posterior  interosseous  nerve  pierces  the  Supinator  brevis,  winds  to  the  back 
of  the  forearm,  in  the  substance  of  this  muscle,  and,  emerging  from  its  lower  border, 


5?6  SPINAL   NERVES. 

passes  down  between  the  superficial  and  deep  layer  of  muscles,  to  the  middle  of 
the  forearm.  Considerably  diminished  in  size,  it  descends  on  the  interosseous 
membrane,  beneath  the  Extensor  secundi  internodii  pollicis,  to  the  back  of  the 
carpus,  where  it  presents  a  gangliform  enlargement,  from  which  filaments  are 
distributed  to  the  ligaments  and  articulations  of  the  carpus.  It  supplies  all  the 
muscles  of  the  radial  and  posterior  brachial  regions,  excepting  the  Anconeus, 
Supinator  longus,  and  Extensor  carpi  radialis  longior. 

Dorsal  Nerves. 

The  Dorsal  Nerves  are  twelve  in  number  on  each  side.  The  first  appears 
between  the  first  and  second  dorsal  vertebrae,  and  the  last  between  the  last  dorsal 
and  first  lumbar. 

The  roots  of  origin  of  the  dorsal  nerves  are  few  in  number,  of  small  size,  and 
vary  but  slightly  from  the  second  to  the  last.  Both  roots  are  very  slender ;  the 
posterior  ones  exceeding  in  thickness  those  of  the  anterior  only  in  a  slight  degree. 
These  roots  gradually  increase  in  length  from  above  downwards,  and  remain  in 
contact  with  the  spinal  cord  for  a  distance  equal  to  the  height  of,  at  least,  two 
vertebrae,  in  the  lower  part  of  the  dorsal  region.  They  then  join  in  the  inter- 
vertebral foramen,  and,  at  their  exit,  divide  into  two  branches,  a  posterior  or 
dorsal,  and  an  anterior  or  intercostal  branch. 

The  first  and  last  dorsal  nerves  are  exceptions  to  these  characters. 

The  posterior  branches  of  the  dorsal  nerves,  which  are  smaller  than  the  intercostal, 
pass  backwards  between  the  transverse  processes,  and  divide  into  external  and 
internal  branches. 

The  external  branches  increase  in  size  from  above  downwards.  They  pass 
through  the  Longissimus  dorsi,  corresponding  to  the  cellular  interval  between  it 
and  the  Sacro-lumbalis,  supplying  these  muscles,  as  well  as  those  by  which  they 
are  continued  upwards  to  the  head,  and  the  Levatores  costarum ;  the  five  or  six 
lower  ones  giving  off  cutaneous  filaments. 

The  internal  branches  of  the  six  upper  nerves  pass  inwards  to  the  interval 
between  the  Multifidus  spinas  and  Semi-spinalis  dorsi  muscles,  which  they  supply; 
then,  piercing  the  origin  of  the  Khomboidei  and  Trapezius,  become  cutaneous 
by  the  side  of  the  spinous  processes.  The  internal  branches  of  the  six  lower 
nerves  are  distributed  to  the  Multifidus  spinas,  without  giving  off  any  cutaneous 
filaments. 

The  cutaneous  branches  of  the  dorsal  nerves  are  twelve  in  number,  the  six 
upper  being  derived  from  the  internal  branches,  and  the  six  lower  from  the  ex- 
ternal branches.  The  former  pierce  the  Rhomboid  and  Trapezius  muscles,  close 
to  the  spinous  processes,  and  ramify  in  the  integument.  They  are  frequently 
'furnished  with  gangliform  enlargements.  The  six  lower  cutaneous  branches 
pierce  the  Serratus  posticus  inferior,  and  Latissimus  dorsi,  in  a  line  with  the 
angles  of  the  ribs. 

Intercostal  Nerves. 

The  Intercostal  Nerves  (anterior  branches  of  the  dorsal  nerves)  are  twelve  in 
number  on  each  side.  They  are  distributed  to  the  parietes  of  the  thorax  and 
abdomen,  separately  from  c;ich  other,  without  being  joined  in  a  plexus,  in  which 
respect  they  differ  from  all  the  other  spinal  nerves.  Each  nerve  is  connected  with 
the  adjoining  ganglia  of  the  sympathetic  by  one  or  two  filaments.  The  intercostal 
nerves  may  be  divided  into  two  sets,  from  the  difference  they  present  in  their  dis- 
tribution. The  six  upper,  with  the  exception  of  the  first,  are  limited  in  their 
distribution  to  the  parietes  of  the  chest.  The  six  lower  supply  the  parietes  of 
the  chest  and  abdomen. 

The  Upper  Intercostal  Nerves  pass  forwards  in  the  intercostal  spaces  with 
the  intercostal  vessels,  lying  below  the  veins  and  artery.    At  the  back  of  the  chest, 


INTERCOSTAL.  5T7 

they  lie  between  the  pleura  and  the  External  intercostal  muscle,  but  are  soon 
placed  between  the  two  planes  of  Intercostal  muscles  as  far  as  the  costal  car- 
tilages, where  they  lie  between  the  pleura  and  the  Internal  intercostal  muscles. 
Near  the  sternum,  they  cross  the  internal  mammary  artery,  and  Triangularis 
sterni,  pierce  the  Internal  intercostal  and  Pectoralis  major  muscles,  and  supply  the 
integument  of  the  mamma  and  front  of  the  chest,  forming  the  anterior  cutaneous 
nerves  of  the  thorax ;  that  from  the  second  nerve  becoming  joined  with  the  cla- 
vicular nerve. 

Branches,  Numerous  slender  muscular  filaments  supply  the  Intercostal  and 
Triangularis  sterni  muscles.  Some  of  these  branches,  at  the  front  of  the  chest, 
cross  the  costal  cartilages  from  one  to  another  intercostal  space. 

Lateral  cutaneous  nerves.  These  are  derived  from  the  intercostal  nerves,  midway 
between  the  vertebrae  and  sternum,  pierce  the  External  intercostal  and  Serratus 
magnus  muscles,  and  divide  into  two  branches,  anterior  and  posterior. 

The  anterior  branches  are  reflected  forwards  to  the  side  and  forepart  of  the 
chest,  supplying  the  integument  of  the  chest  and  mamma,  and  the  upper  digitations 
of  the  External  oblique. 

The  posterior  branches  are  reflected  backwards,  to  supply  the  integument  over 
the  scapula  and  Latissimus  dorsi. 

The  first  intercostal  nerve  has  no  lateral  cutaneous  branch.  The  lateral  cutaneous 
branch  of  the  second  intercostal  nerve  is  of  large  size,  and  named,  from  its  origin 
and  distribution,  the  intercosto- humeral  nerve.  It  pierces  the  External  intercostal 
muscle,  crosses  the  axilla  to  the  inner  side  of  the  arm,  and  joins  with  a  filament 
from  the  nerve  of  Wrisberg.  It  then  pierces  the  fascia,  and  supplies  the  skin  of 
the  upper  half  of  the  inner  and  back  part  of  the  arm,  communicating  with  the 
internal  cutaneous  branch  of  the  musculo-spiral  nerve.  The  size  of  this  nerve  is 
in  inverse  proportion  to  the  size  of  the  other  cutaneous  nerves,  especially  the 
nerve  of  Wrisberg.  A  second  intercosto-humeral  nerve  is  frequently  given  off 
from  the  third  intercostal.  It  supplies  filaments  to  the  arm-pit  and  inner  side  of 
the  arm. 

The  Lower  Intercostal  Nerves  (excepting  the  last)  have  the  same  arrangement 
as  the  upper  ones  as  far  as  the  anterior  extremities  of  the  intercostal  spaces,  where 
they  pass  behind  the  costal  cartilages,  and  between  the  Internal  oblique  and  Trans- 
versalis  muscles,  to  the  sheath  of  the  Rectus,  which  they  perforate.  They  supply 
the  Rectus  muscle,  and  terminate  in  branches  which  become  subcutaneous  near  the 
linea  alba  (anterior  cutaneous  nerves  of  the  abdomen),  supplying  the  integument 
in  front  of  the  abdomen,  being  directed  outwards  to  the  lateral  cutaneous  nerves. 
The  lower  intercostal  nerves  supply  the  Intercostal  and  abdominal  muscles,  and, 
about  the  middle  of  their  course,  give  off  lateral  cutaneous  branches,  which  pierce 
the  External  intercostal  and  External  oblique  muscles,  and  are  distributed  to  the 
integument  of  the  abdomen,  the  anterior  branches  passing  nearly  as  far  forwards 
as  the  margin  of  the  Rectus ;  the  posterior  branches  passing  to  supply  the  skin 
over  the  Latissimus  dorsi,  where  they  join  the  dorsal  cutaneous  nerves. 

Peculiar  Dorsal  Nerves. 

First  dorsal  nerve.  Its  roots  of  origin  are  similar  to  those  of  a  cervical  nerve. 
Its  posterior  or  dorsal  branch  resembles,  in  its  mode  of  distribution,  the  dorsal 
branches  of  the  cervical  nerves.  Its  anterior  branch  enters  almost  wholly  into  the 
formation  of  the  brachial  plexus,  giving  off,  before  it  leaves  the  thorax,  a  small 
intercostal  branch,  which  runs  along  the  first  intercostal  space,  and  terminates  on 
the  front  of  the  chest,  by  forming  the  first  anterior  cutaneous  nerve  of  the  thorax. 
The  first  intercostal  nerve  gives  off  no  lateral  cutaneous  branch. 

The   last  dorsal  is  larger  than  the  other  dorsal  nerves.     Its  anterior  branch 

runs  along  the  lower  border  of  the  last  rib  in  front  of  the  Quadratus  lumborum, 

perforates  the  aponeurosis  of  the  Transversalis,  and  passes  forwards  between  it 

and  the  Internal  oblique,  to  be  distributed  in  the  same  manner  as  the  preceding 

37 


578  SPINAL   NERYES. 

nerves.  It  communicates  with  the  iliohypogastric  branch  of  the  lumbar  plexus, 
and  is  occasionally  connected  with  the  first  lumbar  nerve  by  a  slender  branch, 
the  dorsi-lumbar  nerve,  which  descends  in  the  substance  of  the  Quadratus  lum- 
borum. 

The  lateral  cutaneous  branch  of  the  last  dorsal  is  remarkable  for  its  large  size ; 
it  perforates  the  Internal  and  External  oblique  muscles,  passes  downwards  over 
the  crest  of  the  ilium,  and  is  distributed  to  the  integument  of  the  front  of  the  hip, 
some  of  its  filaments  extending  as  low  down  as  the  trochanter  major. 

Lumbar  Nerves. 

The  Lumbar  nerves  are  five  in  number  on  each  side ;  the  first  appears  between 
the  first  and  second  lumbar  vertebras,  and  the  last  between  the  last  lumbar  and  the 
base  of  the  sacrum. 

The  roots  of  the  lumbar  nerves  are  the  largest,  and  their  filaments  the  most 
numerous,  of  all  the  spinal  nerves,  and  they  are  closely  aggregated  together  upon 
the  lower  end  of  the  cord.  The  anterior  roots  are  smaller ;  but  there  is  not  the 
same  disproportion  between  them  and  the  posterior  roots  as  in  the  cervical  nerves. 
The  roots  of  these  nerves  have  a  vertical  direction,  and  are  of  considerable  length, 
more  especially  the  lower  ones,  as  the  spinal  cord  does  not  extend  beyond  the  first 
lumbar  vertebra.  The  roots  become  joined  in  the  intervertebral  foramina,  and,  at 
their  exit,  divide  into  two  branches,  anterior  and  posterior. 

The  posterior  branches  of  the  lumbar  nerves  diminish  in  size  from  above  down- 
wards ;  they  pass  backwards  between  the  transverse  processes,  and  divide  into 
external  and  internal  branches. 

The  external  branches  supply  the  Erector  spinas  and  Inter-transverse  muscles. 
From  the  three  upper  branches  cutaneous  nerves  are  derived,  which  pierce  the 
Sacro-lumbalis  and  Latissimus  dorsi  muscles,  and  descend  over  the  back  part  of  the 
crest  of  the  ilium,  to  be  distributed  to  the  integument  of  the  gluteal  region,  some 
of  the  filaments  passing  as  far  as  the  trochanter  major. 

The  internal  branches,  the  smaller,  pass  inwards  close  to  the  articular  processes 
of  the  vertebrae,  and  supply  the  Multifidus  spinas  and  Inter-spinales  muscles. 

The  anterior  branches  of  the  lumbar  nerves  increase  in  size  from  above  down- 
wards. At  their  origin,  they  communicate  with  the  lumbar  ganglia  of  the  sym- 
pathetic by  long  slender  filaments,  which  accompany  the  lumbar  arteries  round  the 
sides  of  the  bodies  of  the  vertebrae,  beneath  the  Psoas  muscle.  The  nerves  pass 
obliquely  outwards  behind  the  Psoas  magnus,  or  between  its  fasciculi,  distributing 
filaments  to  it  and  the  Quadratus  lumborum.  The  anterior  branches  of  the  four 
upper  nerves  are  connected  together  in  this  situation  by  anastomotic  loops,  and 
form  the  lumbar  plexus.  The  anterior  branch  of  the  fifth  lumbar,  joined  with  a 
branch  from  the  fourth,  descends  across  the  base  of  the  sacrum  to  join  the  anterior 
branch  of  the  first  sacral  nerve,  and  assist  in  the  formation  of  the  sacral  plexus. 
The  cord  resulting  from  the  union  of  these  two  nerves  is  called  the  lumbosacral 
nerve. 

Lumbar  Plexus. 

The  Lumbar  plexus  is  formed  by  the  loops  of  communication  between  the  ante- 
rior branches  of  the  four  upper  lumbar  nerves.  The  plexus  is  narrow  above,  and 
occasionally  connected  with  the  last  dorsal  by  a  slender  branch,  the  dorsi-lumbar 
nerve ;  it  is  broad  below,  where  it  is  joined  to  the  sacral  plexus  by  the  lumbo-sacral. 
It  is  situated  in  the  substance  of  the  Psoas  muscle,  near  its  posterior  part,  in  front 
of  the  transverse  processes  of  the  lumbar  vertebrae. 

The  mode  in  which  the  plexus  is  formed  is  the  following : — The  first  lumbar 
nerve  gives  off  the  ilio-hypogastric  and  ilio-inguinal  nerves,  and  a  communicating 
branch  to  the  second.  The  second  gives  off  the  external  cutaneous  and  genito- 
crural,  and  a  communicating  branch  to  the  third  nerve.  The  third  nerve  gives  a 
descending  filament  to  the  fourth,  and  divides  into  two  branches,  which  assist  in 


LUMBAR   PLEXUS. 


579 


forming  the  anterior  crural  and  obturator  nerves.    The  fourth  nerve  completes  the 
formation  of  the  anterior  crural,  and  the  obturator,  furnishes  part  of  the  accessory 
obturator,  and  gives  off  a  communicating  branch  to  the  fifth  lumbar. 
The  branches  of  the  lumbar  plexus  are  the 


Ilio-hypogastric. 
Ilio-inguinal. 
Genito-crural. 
External  cutaneous. 


Obturator. 

Accessory  obturator. 
Anterior  crural. 


These  branches  may  be  divided  into  two  groups,  according  to  their  mode  of 
distribution.  One  group,  including  the  ilio-hypogastric,  ilio-inguinal,  and  part 
of  the  genito-crural  nerves,  supplies  the  lower  part  of  the  parietes  of  the  abdomen ; 
the  other  group,  which  includes  the  remaining  nerves,  supplies  the  forepart  of  the 
thigh  and  inner  side  of  the  leg. 


Fig.  290. — The  Lumbar  Plexus  and  its  Branches. 


The  Ilio-hypogastric  nerve  (superior  muscuh-cutaneous)  arises  from  the  first 
lumbar  nerve.  It  pierces  the  outer  border  of  the  Psoas  muscle  at  its  upper  part, 
and  crosses  obliquely  in  front  of  the  Quadratus  lumborum  to  the  crest  of  the 
ilium.  It  then  perforates  the  Transversalis  muscle  at  its  back  part,  and  divides 
between  it  and  the  Internal  oblique  into  two  branches,  iliac  and  hypogastric. 


580  SPINAL   NERVES. 

The  iliac  hranch  pierces  the  Internal  and  External  oblique  muscles  imme- 
diately above  the  crest  of  the  ilium,  and  is  distributed  to  the  integument  of  the 
gluteal  region,  behind  the  lateral  cutaneous  branch  of  the  last  dorsal  nerve  (fig. 
293).  The  size  of  this  nerve  bears  an  inverse  proportion  to  that  of  the  cutaneous 
branch  of  the  last  dorsal  nerve. 

The  hypogastric  branch  continues  onwards  between  the  Internal  oblique  and 
Transversalis  muscles.  It  first  pierces  the  Internal  oblique,  and  near  the  middle 
line  perforates  the  External  oblique  above  the  external  abdominal  ring,  and  is 
distributed  to  the  integument  covering  the  hypogastric  region. 

The  Ilioinguinal  nerve  (inferior  musculo-cutaneous),  smaller  than  the  pre- 
ceding, arises  with  it  from  the  first  lumbar  nerve.  It  pierces  the  outer  border  of 
the  Psoas  just  below  the  ilio-hypogastric,  and,  passing  obliquely  across  the  Quad- 
ratus  lumborum  and  Iliacus  muscles,  perforates  the  Transversalis,  near  the  fore- 
part of  the  crest  of  the  ilium,  and  communicates  with  the  ilio-hypogastric  nerve 
between  that  muscle  and  the  Internal  oblique.  The  nerve  then  pierces  the  Internal 
oblique,  distributing  filaments  to  it,  and,  accompanying  the  spermatic  cord,  escapes 
at  the  external  abdominal  ring,  and  is  distributed  to  the  integument  of  the 
scrotum  and  upper  and  inner  part  of  the  thigh  in  the  male  and  to  the  labium  in 
the  female.  The  size  of  this  nerve  is  in  inverse  proportion  to  that  of  the  ilio- 
hypogastric. Occasionally  it  is  very  small,  and  ends  by  joining  it ;  in  such  cases, 
a  branch  from  the  ilio-hypogastric  takes  the  place  of  that  nerve,  or  the  nerve  may 
be  altogether  absent. 

The  Genito-crueal  Nerve  arises  from  the  second  lumbar,  and  by  a  few  fibres 
from  the  cord  of  communication  between  it  and  the  first.  It  passes  obliquely 
through  the  substance  of  the  Psoas,  descends  on  its  surface  to  near  Poupart's 
ligament,  and  divides  into  a  genital  and  a  crural  branch. 

The  genital  hranch  descends  on  the  .external  iliac  artery,  sending  a  few  fila- 
ments round  that  vessel;  it  then  pierces  the  fascia  transversalis,  and,  passing 
through  the  internal  abdominal  ring,  descends  along  the  back  part  of  the  sper- 
matic cord  to  the  scrotum,  and  supplies,  in  the  male,  the  Cremaster  muscle.  In 
the  female,  it  accompanies  the  round  ligament,  and  is  lost  upon  it. 

The  crural  hranch  passes  along  the  inner  margin  of  the  Psoas  muscle,  beneath 
Poupart's  ligament,  into  the  thigh,  where  it  pierces  the  fascia  lata,  and  is  distri- 
buted to  the  integument  of  the  upper  and  anterior  aspect  of  the  thigh,  communi- 
cating with  the  middle  cutaneous  nerve. 

A  few  filaments  from  this  nerve  may  be  traced  on  to  the  femoral  artery ;  they 
are  derived  from  the  nerve  as  it  passes  beneath  Poupart's  ligament. 

The  External  Cutaneous  Nerve  arises  from  the  second  lumbar,  or  from  the 
loop  between  it  and  the  third.  It  perforates  the  outer  border  of  the  Psoas  muscle 
about  its  middle,  and  crosses  the  Iliacus  muscle  obliquely,  to  the  notch  imme- 
diately beneath  the  anterior  superior  spine  of  the  ilium,  where  it  passes  beneath 
Poupart's  ligament  into  the  thigh,  and  divides  into  two  branches  of  nearly  equal 
size. 

The  anterior  hranch  descends  in  an  aponeurotic  canal  formed  in  the  fascia  lata, 
becomes  superficial  about  four  inches  below  Poupart's  ligament,  and  divides 
into  branches,  which  are  distributed  to  the  integument  along  the  anterior  and 
outer  part  of  the  thigh,  as  far  down  as  the  knee.  This  nerve  occasionally  com- 
municates with  the  long  saphenous  nerve. 

The  posterior  hranch  pierces  the  fascia  lata,  and  subdivides  into  branches  which 
pass  across  the  outer  and  posterior  surface  of  the  thigh,  supplying  the  integument 
in  this  region  as  far  as  the  middle  of  the  thigh. 

The  Obturator  Nerve  supplies  the  Obturator  externus  and  Adductor  muscles 
of  the  thigh,  the  articulations  of  the  hip  and  knee,  and  occasionally  the  integu- 
ment of  the  thigh  and  leg.  It  arises  by  two  branches ;  one  from  the  third,  the 
other  from  the  fourth  lumbar  nerve.  It  descends  through  the  inner  fibres  of  the 
Psoas  muscle,  and  emerges  from  its  inner  border  near  the  brim  of  the  pelvis ;  it 
then  runs  along  the  lateral  wall  of  the  pelvis,  above  the  obturator  vessels,  to  the 


CUTANEOUS   NERYBS   OF   LOWER   EXTREMITY.         581 


Fig.  291. — Cutaneous  Nerves  of  Lower 
Extremity.     Front  View. 


Fig.  292.— Nerves  of  the  Lower  Extremity. 
Front  View. 


1  •*./?<rfiXtn»ar. 


.Md.  Tibial 


Anterior 
Crural 


A.ntBrierHivision 
of  Obturator 


582  SPINAL   NERVES. 

upper  part  of  the  obturator  foramen,  where  it  enters  the  thigh,  and  divides 
into  an  anterior  and  a  posterior  branch,  separated  by  the  Adductor  brevis 
muscle. 

The  anterior  branch  passes  down  in  front  of  the  Adductor  brevis,  being  covered 
by  the  Pectineus  and  Adductor  longus ;  and,  at  the  lower  border  of  the  latter 
muscle,  communicates  with  the  internal  cutaneous  and  internal  saphenous  nerves, 
forming  a  kind  of  plexus.  It  then  descends  upon  the  femoral  artery,  upon  which 
it  is  finally  distributed. 

This  nerve,  near  the  obturator  foramen,  gives  off  an  articular  branch  to  the 
hip-joint.  Behind  the  Pectineus,  it  distributes  muscular  branches  to  the  Adductor 
longus  and  Gracilis,  and  occasionally  to  the  Adductor  brevis  and  Pectineus,  and 
receives  a  communicating  branch  from  the  accessory  obturator  nerve. 

Occasionally  this  communicating  branch  is  continued  down,  as  a  cutaneous 
branch,  to  the  thigh  and  leg ;  emerging  from  the  lower  border  of  the  Adductor 
longus,  it  descends  along  the  posterior  margin  of  the  Sartorius  to  the  inner  side  of 
the  knee,  where  it  pierces  the  deep  fascia,  communicates  with  the  long  saphenous 
nerve,  and  is  distributed  to  the  integument  of  the  inner  side  of  the  leg,  as  low 
down  as  its  middle.  When  this  branch  is  small,  its  place  is  supplied  by  the 
internal  cutaneous  nerve. 

The  posterior  branch  of  the  obturator  nerve  pierces  the  Obturator  externus, 
and  passes  behind  the  Adductor  brevis  to  the  front  of  the  Adductor  magnus, 
where  it  divides  into  numerous  muscular  branches,  which  supply  the  Obturator 
externus,  the  Adductor  magnus,  and  occasionally  the  Adductor  brevis. 

The  articular  branch  for  the  knee-joint  perforates  the  lower  part  of  the 
Adductor  magnus,  and  enters  the  upper  part  of  the  popliteal  space ;  descending 
upon  the  popliteal  artery,  as  far  as  the  back  part  of  the  knee-joint,  it  perforates 
the  posterior  ligament,  and  is  distributed  to  the  synovial  membrane.  It  gives 
filaments  to  the  artery  in  its  course. 

The  Accessory  Obturator  Nerve  is  of  small  size,  and  arises  either  from  the 
obturator  nerve  near  its  origin,  or  by  separate  filaments  from  the  third  and  fourth 
lumbar  nerves.  It  descends  along  the  inner  border  of  the  Psoas  muscle,  crosses 
the  body  of  the  pubes,  and  passes  beneath  the  Pectineus  muscle,  where  it  divides 
into  numerous  branches.  One  of  these  supplies  the  Pectineus,  penetrating  its 
under  surface;  another  is  distributed  to  the  hip-joint;  while  a  third  communicates 
with  the  anterior  branch  of  the  obturator  nerve.  This  branch,  when  of  large 
size,  is  prolonged  (as  already  mentioned),  as  a  cutaneous  branch,  to  the  leg.  The 
accessory  obturator  nerve  is  not  constantly  found;  when  absent,  the  hip-joint 
receives  branches  from  the  obturator  nerve.  Occasionally  it  is  very  small,  and 
becomes  lost  in  the  capsule  of  the  hip-joint. 

The  Anterior  Crural  Nerve  is  the  largest  branch  of  the  lumbar  plexus.  It 
supplies  muscular  branches  to  the  Iliacus,  Pectineus,  and  all  the  muscles  on  the 
front  of  the  thigh,  excepting  the  Tensor  vaginas  femoris ;  cutaneous  filaments  to 
the  front  and  inner  side  of  the  thigh,  and  to  the  leg  and  foot ;  and  articular  branches 
to  the  knee.  It  arises  from  the  third  and  fourth  lumbar  nerves,  receiving  also  a 
fasciculus  from  the  second.  It  descends  through  the  fibres  of  the  Psoas  muscle, 
emerging  from  it  at  the  lower  part  of  its  outer  border ;  and  passes  down  between 
it  and  the  Iliacus,  and  beneath  Poupart's  ligament,  into  the  thigh,  where  it 
becomes  somewhat  flattened,  and  divides  into  an  anterior  or  cutaneous,  and  a 
posterior  or  muscular  part.  Beneath  Poupart's  ligament,  it  is  separated  from  the 
femoral  artery  by  the  Psoas  muscle,  and  lies  beneath  the  iliac  fascia. 

Within  the  pelvis,  the  anterior  crural  nerve  gives  off  from  its  outer  side  some 
small  branches  to  the  Iliacus,  and  a  branch  to  the  femoral  artery,  which  is 
distributed  upon  the  upper  part  of  that  vessel.  The  origin  of  this  branch 
varies ;  it  occasionally  arises  higher  than  usual,  or  it  may  arise  lower  down  in 
the  thigh. 

External  to  the  pelvis,  the  following  branches  are  given  off: — 


ANTERIOR    CRURAL.  583 

From  the  Anterior  Division.  From  the  Posterior  Division-. 

Middle  cutaneous.  Muscular. 

Internal  cutaneous.  Articular. 

Long  saphenous. 

The  middle  cutaneous  nerve  pierces  the  fascia  lata  (occasionally  the  Sartorius 
also),  about  three  inches  below  Poupart's  ligament,  and  divides  into  two  branches, 
which  descend  in  immediate  proximity  along  the  fore  part  of  the  thigh,  distributing 
numerous  branches  to  the  integument  as  low  as  the  front  of  the  knee,  where  it 
joins  a  branch  of  the  internal  saphenous  nerve.  Its  outer  branch  communicates, 
above,  with  the  crural  branch  of  the  genito-crural  nerve ;  and  the  inner  branch 
with  the  internal  cutaneous  nerve  below.  The  Sartorius  muscle  is  supplied  by 
this  or  the  following  nerve. 

The  internal  cutaneous  nerve  passes  obliquely  across  the  upper  part  of  the  sheath 
of  the  femoral  artery,  and  divides  in  front  of,  or  at  the  inner  side  of,  that  vessel,  into 
two  branches,  anterior  and  internal. 

The  anterior  branch  perforates  the  fascia  lata  at  the  lower  third  of  the  thigh, 
and  divides  into  two  branches,  one  of  which  supplies  the  integument  as  low  down 
as  the  inner  side  of  the  knee ;  the  other  crosses  the  patella  to  the  outer  side  of 
the  joint,  communicating  in  its  course  with  the  long  saphenous  nerve.  A  cuta- 
neous filament  is  occasionally  given  off  from  this  nerve,  which  accompanies  the 
long  saphenous  vein ;  and  it  sometimes  communicates  with  the  internal  branch 
of  the  nerve. 

The  inner  branch  descends  along  the  posterior  border  of  the  Sartorius  muscle 
to  the  knee,  where  it  pierces  the  fascia  lata,  communicates  with  the  long  saphe- 
nous nerve,  and  gives  off  several  cutaneous  branches.  The  nerve  then  passes 
down  the  inner  side  of  the  leg,  to  the  integument  of  which  it  is  distributed.  This 
nerve,  beneath  the  fascia  lata,  joins  in  a  plexiform  network,  by  uniting  with 
branches  of  the  long  saphenous  and  obturator  nerves.  "When  the  communicating 
branch  from  the  latter  nerve  is  large,  and  continued  to  the  integument  of  the  leg, 
the  inner  branch  of  the  internal  cutaneous  is  small,  and  terminates  at  the  plexus, 
occasionally  giving  off  a  few  cutaneous  filaments. 

This  nerve,  before  subdividing,  gives  off  a  few  filaments,  which  pierce  the 
fascia  lata,  to  supply  the  integument  of  the  inner  side  of  the  thigh,  accompanying 
the  long  saphenous  vein.  One  of  these  filaments  passes  through  the  saphenous 
opening;  a  second  becomes  subcutaneous  about  the  middle  of  the  thigh ;  and  a  third 
pierces  the  fascia  at  its  lower  third. 

The  long  or  internal  saphenous  nerve  is  the  largest  of  the  cutaneous  branches 
of  the  anterior  crural  nerve.  It  approaches  the  femoral  artery  where  this  vessel 
passes  beneath  the  Sartorius,  and  lies  on  its  outer  side,  beneath  the  aponeurotic 
covering,  as  far  as  the  opening  in  the  lower  part  of  the  Adductor  magnus. 
It  then  quits  the  artery,  and  descends  vertically  along  the  inner  side  of  the  knee, 
beneath  the  Sartorius,  pierces  the  deep  fascia  between  the  tendons  of  the  Sartorius 
and  Gracilis,  and  becomes  subcutaneous.  The  nerve  then  passes  along  the  inner 
side  of  the  leg,  accompanied  by  the  internal  saphenous  vein,  descends  behind  the 
internal  border  of  the  tibia,  and,  at  the  lower  third  of  the  leg,  divides  into  two 
branches ;  one  continues  its  course  along  the  margin  of  the  tibia,  terminating  at 
the  inner  ankle,  the  other  passes  in  front  of  the  ankle,  and  is  distributed  to  the 
integument  along  the  inner  side  of  the  foot,  as  far  as  the  great  toe. 

Branches.  The  long  saphenous  nerve,  about  the  middle  of  the  thigh,  gives  off 
a  communicating  branch,  which  joins  the  plexus  formed  by  the  obturator  and 
internal  cutaneous  nerves. 

At  the  inner  side  of  the  knee,  it  gives  off  a  large  branch  (n.  cutaneus  patellse), 
which  pierces  the  Sartorius  and  fascia  lata,  and  is  distributed  to  the  integument 
in  front  of  the  patella.  This  nerve  communicates,  above  the  Jcnee,  with  the  anterior 
branch  of  the  internal  cutaneous ;  below  the  Jcnee,  with  other  branches  of  the  long 
saphenous ;  and,  on  the  outer  side  of  the  joint,  with  branches  of  the  middle  ami 


JB4  SPINAL   NERYES. 

external  cutaneous  nerves,  forming  a  plexiform  network,  the  plexus  patellae. 
This  nerve  is  occasionally  small,  and  terminates  by  joining  the  internal  cutaneous, 
which  supplies  its  place  in  front  of  the  knee. 

Below  the  knee,  the  branches  of  the  long  saphenous  nerve  are  distributed  to 
the  integument  of  the  front  and  inner  side  of  the  leg,  communicating  with  the 
cutaneous  branches  from  the  internal  cutaneous,  or  obturator  nerve. 

The  deep  group  of  branches  of  the  anterior  crural  nerve  are  muscular  and 
articular. 

The  muscular  branches  supply  the  Pectineus,  and  all  the  muscles  on  the  front 
of  the  thigh,  except  the  Tensor  vaginas  femoris,  which  is  supplied  from  the 
gluteal  nerve,  and  the  Sartorius,  which  is  supplied  by  filaments  from  the  middle 
or  internal  cutaneous  nerves. 

The  branches  to  the  Pectineus,  usually  two  in  number,  pass  inwards  behind  the 
femoral  vessels,  and  enter  the  muscle  on  its  anterior  surface. 

The  branch  to  the  Rectus  muscle  enters  its  under  surface  high  up. 

The  branch  to  the  Vastus  externus,  of  large  size,  follows  the  course  of  the 
descending  branch  of  the  external  circumflex  artery,  to  the  lower  part  of  the 
muscle.     It  gives  off  an  articular  filament. 

The  branches  to  the  Vastus  internus  and  Crureus  enter  the  middle  of  those 
muscles. 

The  articular  branches,  two  in  number,  supply  the  knee-joint.  One,  a  long, 
slender  filament,  is  derived  from  the  nerve  to  the  Vastus  externus ;  it  penetrates 
the  capsular  ligament  of  the  joint  on  its  anterior  aspect.  The  other  is  derived 
from  the  nerve  to  the  Vastus  internus;  it  descends  along  the  internal  inter- 
muscular septum,  accompanying  the  deep  branch  of  the  anastomotica  magna, 
pierces  the  capsular  ligament  of  the  joint  on  its  inner  side,  and  supplies  the 
synovial  membrane. 

The  Saceal  and  Coccygeal  Nerves. 

The  sacral  nerves  are  five  in  number  on  each  side.  The  four  upper  ones  pass 
from  the  sacral  canal,  through  the  sacral  foramina ;  the  fifth  escaping  through  the 
foramen  between  the  sacrum  and  coccyx. 

The  roots  of  origin  of  the  upper  sacral  (and  lumbar)  nerves  are  the  largest  of  all 
the  spinal  nerves ;  whilst  those  of  the  lowest  sacral  and  coccygeal  nerves  are  the 
smallest. 

The  length  of  the  roots  of  these  nerves  is  very  considerable,  being  longer  than 
those  of  any  of  the  other  spinal  nerves,  on  account  of  the  spinal  cord  not  extending 
beyond  the  first  lumbar  vertebra.  From  their  great  length,  and  the  appearance 
they  present  in  connection  with  the  spinal  cord,  the  roots  of  origin  of  these  nerves 
are  called  collectively  the  cauda  equina.  Each  sacral  and  coccygeal  nerve  divides 
into  two  branches,  anterior  and  posterior. 

The  posterior  sacral  nerves  are  small,  diminish  in  size  from  above  downwards, 
and  emerge,  except  the  last,  from  the  sacral  canal  by  the  posterior  sacral  foramina. 

The  three  upper  ones  are  covered,  at  their  exit  from  the  sacral  canal,  by  the 
Multifidus  spinas,  and  divide  into  external  and  internal  branches. 

The  internal  branches  are  small,  and  supply  the  Multifidus  spinas. 

The  external  branches  communicate  with  one  another,  and  with  the  last  lumbar 
and  fourth  sacral  nerves,  by  means  of  anastomosing  loops.  These  branches  pass 
outwards,  to  the  outer  surface  of  the  great  sacro-sciatic  ligament,  where  they 
form  a  second  series  of  loops  beneath  the  Gluteus  maximus.  Cutaneous  branches 
from  these  second  series  of  loops,  usually  three  in  number,  pierce  this  muscle, 
one  near  the  posterior  inferior  spine  of  the  ilium ;  another  opposite  the  end  of  the 
sacrum ;  and  the  third,  midway  between  these  two.  They  supply  the  integument 
over  the  posterior  part  of  the  gluteal  region. 

The  two  lower  posterior  sacral  nerves  are  situated  below  the  Multifidus  spinas. 
They  are  of  small  size,  and  join  with  each  other,  and  with  the  coccygeal  nerve, 


SACRAL  PLEXUS.  585 

so  as  to  iorm  loops  on  the  back  of  the  sacrum,  filaments  from  which  supply  the 
LTumeut  over  the  coccyx. 

The  posterior  branch  of  the  coccygeal  nerve  is  small.  It  separates  from  the 
anterior  in  the  sacral  canal,  and  receives,  as  already  mentioned,  a  communicating 
branch  from  the  last  sacral.  It  is  lost  in  the  fibrous  structure  on  the  back  of  the 
coccyx. 

The  anterior  sacral  nerves  diminish  in  size  from  above  downwards.  The 
four  upper  ones  emerge  from  the  anterior  sacral  foramina ;  the  anterior  branch  of 
the  fifth,  together  with  the  coccygeal  nerve,  between  the  sacrum  and  the  coccyx. 
All  the  anterior  sacral  nerves  communicate  with  the  sacral  ganglia  of  the  sympa- 
thetic, at  their  exit  from  the  sacral  foramina.  The  first  nerve,  of  large  size,  unites 
with  the  lumbo-sacral  nerve.  The  second  equals  in  size  the  preceding,  with  which 
it  joins.  The  third,  about  one-fourth  the  size  of  the  second,  unites  with  the 
preceding  nerves,  to  form  the  sacral  plexus. 

The  fourth  anterior  sacral  nerve  sends  a  branch  to  join  the  sacral  plexus. 
The  remaining  portion  of  the  nerve  divides  into  visceral  and  muscular  branches ; 
and  a  communicating  filament  descends  to  join  the  fifth  sacral  nerve.  The  visceral 
branches  are  distributed  to  the  viscera  of  the  pelvis,  communicating  with  the 
sympathetic  nerve.  These  branches  ascend  upon  the  rectum  and  bladder ;  in  the 
female,  upon  the  vagina  and  bladder,  communicating  with  branches  of  the  sympa- 
thetic to  form  the  hypogastric  plexus.  The  muscular  branches  are  distributed  to 
the  Levator  ani,  Coccygeus,  and  Sphincter  ani.  Cutaneous  filaments  arise  from 
the  latter  branch,  which  supply  the  integument  between  the  anus  and  coccyx. 

The  fifth  anterior  sacral  nerve,  after  passing  from  the  lower  end  of  the  sacral 
canal,  pierces  the  Coccygeus  muscle,  and  descends  upon  its  anterior  surface  to  the 
tip  of  the  coccyx,  where  it  perforates  that  muscle,  to  be  distributed  to  the  integu- 
ment over  the  back- part  and  side  of  the  coccyx.  This  nerve  communicates  above 
with  the  fourth,  and  below  with  the  coccygeal  nerve,  and  supplies  the  Coccygeus 
muscle. 

The  anterior  branch  of  the  coccygeal  nerve  is  a  delicate  filament  which  escapes 
at  the  termination  of  the  sacral  canal.  It  pierces  the  sacro-sciatic  ligament  and 
Coccygeus  muscle,  is  joined  by  a  branch  from  the  fifth  anterior  sacral,  and 
becomes  lost  in  the  integument  at  the  back  part  and  side  of  the  coccyx. 

Sacral  Plexus. 

The  sacral  plexus  is  formed  by  the  lumbo-sacral,  the  anterior  branches  of  the 
three  upper,  and  part  of  the  fourth  sacral  nerves.  These  nerves  proceed  in 
different  directions ;  the  upper  ones  obliquely  outwards,  the  lower  one  nearly 
horizontally,  and  they  all  unite  into  a  single,  broad,  flat  cord.  The  sacral  plexus 
is  triangular  in  form,  its  base  corresponding  with  the  exit  of  the  nerves  from  the 
sacrum,  its  apex  with  the  lower  part  of  the  great  sacro-sciatie  foramen.  It  rests 
upon  the  anterior  surface  of  the  Pyriformis,  and  is  covered  in  front  by  the  pelvic 
fascia,  which  separates  it  from  the  sciatic  and  pudic  branches  of  the  internal  iliac » 
artery,  and  from  the  viscera  of  the  pelvis. 

The  branches  of  the  sacral  plexus  are : — 

Muscular.  Pudic. 

Superior  gluteal.  Small  sciatic. 

Great  sciatic. 

The  muscular  branches  supply  the  Pyriformis,  Obturator  internus,  the  two 
Gemelli,  and  the  Quadratus  femoris.  The  branch  to  the  Pyriformis  arises  either 
from  the  plexus,  or  from  the  upper  sacral  nerves ;  the  branch  to  the  Obturator  in- 
ternus arises  at  the  junction  of  the  lumbo-sacral  and  first  sacral  nerves ;  it  crosses 
behind  the  spine  of  the  ischium,  and  passes  through  the  lesser  sacro-sciatic  foramen 
to  the  inner  surface  of  the  Obturator  internus ;  the  branch  to  the  Gemellus  superior 
arises  from  the  lower  part  of  the  plexus,  near  the  pudic  nerve ;  the  small  branch 


586  SPINAL   NERVES. 

to  the  Gemellus  inferior  and  Quadratus  femoris  also  arises  from  the  lower  part  of 
the  plexus,  passes  beneath  the  Gemelli  and  tendon  of  the  Obturator  mternws, 
and  supplies  an  articular  branch  to  the  hip-joint.  This  branch  is  occasionally 
derived  from  the  upper  part  of  the  great  sciatic  nerve. 

The  Superior  Gluteal  Nerve  arises  from  the  back  part  of  the  lumbo-sacral ; 
it  passes  from  the  pelvis  through  the  great  sacro-sciatic  foramen  above  the  Piri- 
formis muscle,  accompanied  by  the  gluteal  vessels,  and  divides  into  a  superior  and 
an  inferior  branch. 

The  superior  branch  follows  the  line  of  origin  of  the  Gluteus  minimus,  and 
supplies  it  and  the  Gluteus  medius. 

The  inferior  branch  crosses  obliquely  between  the  Gluteus  minimus  and  Gluteus 
medius,  distributing  filaments  to  both  these  muscles,  and  terminates  in  the  Tensor 
vaginso  femoris,  extending  nearly  to  its  lower  end. 

The  Pudic  Nerve  arises  from  the  lower  part  of  the  sacral  plexus,  and  leaves 
the  pelvis,  through  the  great  sacro-sciatic  foramen,  below  the  Pyriformis.  It  then 
crosses  the  spine  of  the  ischium,  and  re-enters  the  pelvis  through  the  lesser  sacro- 
sciatic  foramen.  It  accompanies  the  pudic  vessels  upwards  and  forwards  along  the 
outer  wall  of  the  ischio-rectal  fossa,  being  covered  by  the  obturator  fascia,  and 
divides  into  two  terminal  branches,  the  perineal  nerve  and  the  dorsal  nerve  of  the 
penis.     Near  its  origin,  it  gives  off  the  inferior  hemorrhoidal  nerve. 

The  inferior  hemorrhoidal  nerve  is  occasionally  derived  from  the  sacral 
plexus.  It  passes  across  the  ischio-rectal  fossa,  with  its  accompanying  vessels, 
towards  the  lower  end  of  the  rectum,  and  is  distributed  to  the  External  sphincter 
and  the  integument  round  the  anus.  Branches  of  this  nerve  communicate  with 
the  inferior  pudendal  and  superficial  perineal  nerves  on  the  inner  margin  of  the 
thigh. 

The  -perineal  nerve,  the  most  inferior  and  largest  of  the  two  terminal  branches 
of  the  pudic,  is  situated  below  the  pudic  artery.  It  accompanies  the  superficial 
perineal  artery  in  the  perineum,  dividing  into  cutaneous  and  muscular  branches. 

The  cutaneous  branches  (superficial  perineal)  are  two  in  number,  posterior  and 
anterior.  The  posterior  branch  passes  to  the  back  part  of  the  ischio-rectal  fossa, 
distributing  filaments  to  the  Sphincter  ani  and  integument  in  front  of  the  anus, 
which  communicate  with  the  inferior  hemorrhoidal  nerve;  it  then  passes  for- 
wards, with  the  anterior  branch,  to  the  back  of  the  scrotum,  communicating  with 
this  nerve  and  the  inferior  pudendal.  The  anterior  branch  passes  to  the  fore 
part  of  the  ischio-rectal  fossa,  in  front  of  the  preceding,  and  accompanies  it  to  the 
scrotum  and  under  part  of  the  penis.  This  branch  gives  one  or  two  filaments  to 
the  Levator  ani. 

The  muscular  branches  are  distributed  to  the  Transversus  perinei,  Accelerator 
urinae,  Erector  penis,  and  Compressor  urethrse.  The  nerve  of  the  bulb  supplies 
the  corpus  spongiosum ;  some  of  its  filaments  run  for  some  distance  on  the  surface, 
before  penetrating  its  interior. 

The  dorsal  nerve  of  the  penis  is  the  superior  division  of  the  pudic  nerve ;  it 
accompanies  the  pudic  artery  along  the  ramus  of  the  ischium,  and  between  the 
two  layers  of  the  deep  perineal  fascia ;  it  then  pierces  the  suspensory  ligament  of 
the  penis,  and  accompanies  the  arteria  dorsalis  penis  to  the  glans,  to  which  it  js 
distributed.  On  the  penis,  this  nerve  gives  off  a  cutaneous  branch,  which  runs 
along  the  side  of  the  organ ;  it  is  joined  with  branches  of  the  sympathetic,  and 
supplies  the  integument  of  the  upper  surface  and  sides  of  the  penis  and  prepuce, 
giving  a  large  branch  to  the  corpus  cavernosum. 

In  the  female,  the  pudic  nerve  is  distributed  to  the  parts  analogous  to  those  in 
the  male;  its  superior  division  terminating  in  the  clitoris,  the  inferior  in  the 
external  labia  and  perineum. 

The  Small  Sciatic  Nerve  supplies  the  integument  of  the  perineum  and  back 
part  of  the  thigh  and  leg,  and  one  muscle,  the  Gluteus  maximus.  It  is  usually 
formed  by  the  union  of  two  branches,  which  arise  from  the  lower  part  of  the 
sacral  plexus.     It  issues  from  the  pelvis  below  the  Pyriformis  muscle,  descends 


SCIATIC. 


587 


Fig.  293. — Cutaneous  Nerves  of  Lower 
Extremity.     Posterior  View. 


Fig.  294. — Nerves  of  the  Lower  Extremity. 
Posterior  View. 


&l 


ft 


7 


\ 


PurHo 

X.tt    OBTURATOR    |||T, 


Small  Sciatic 


Cotnmimicttnt 

I'opUtrC 


External 
Popliteal  ,.r 

I'ero  jitti  t 


Com  muni earn 
I'ero  net 


Plantaf 
C*tem**M* 


538  SPINAL   NERVES. 

beneath  the  Gluteus  maximus  with  the  sciatic  artery,  and  at  the  lower  border  of 
that  muscle  passes  along  the  back  part  of  the  thigh,  beneath  the  fascia  lata,  to  the 
lower  part  of  the  popliteal  region,  where  it  pierces  the  fascia  and  becomes 
cutaneous.  It  then  accompanies  the  external  saphenous  vein  below  the  middle  of 
the  leg,  its  terminal  filaments  communicating  with  the  external  saphenous  nerve. 

The  branches  of  -the  small  sciatic  nerve  are  muscular  (inferior  gluteal)  and 
cutaneous. 

The  inferior  gluteal  consist  of  several  large  branches  given  off  to  the  under 
surface  of  the  Gluteus  maximus,  near  it  lower  part. 

The  cutaneous  branches  consist  of  two  groups,  internal  and  ascending. 

The  internal  cutaneous  branches  are  distributed  to  the  skin  at  the  upper  and  inner 
side  of  the  thigh,  on  its  posterior  aspect.  One  branch,  longer  than  the  rest,  the 
inferior  pudendal,  curves  forward  below  the  tuber  ischii,  pierces  the  fascia  lata  on 
the  outer  side  of  the  ramus  of  that  bone,  and  is  distributed  to  the  integument  of 
the  scrotum,  communicating  with  the  superficial  perineal  nerve. 

The  ascending  cutaneous  branches  consist  of  two  or  three  filaments,  which 
turn  upwards  round  the  lower  border  of  the  Gluteus  maximus,  to  supply  the 
integument  covering  its  surface.  One  or  two  filaments  occasionally  descend 
along  the  outer  side  of  the  thigh,  supplying  the  integument  as  far  as  the  middle 
of  this  region. 

Two  or  three  branches  are  given  off  from  the  lesser  sciatic  nerve  as  it  descends 
beneath  the  fascia  of  the  thigh ;  they  supply  the  integument  of  the  back  part  of 
the  thigh,  popliteal  region,  and  upper  part  of  the  leg. 

The  Geeat  Sciatic  Nerve  supplies  nearly  the  whole  of  the  integument  of  the 
leg,  the  muscles  of  the  back  of  the  thigh,  and  of  the  leg  and  foot.  It  is  the  largest 
nervous  cord  in  the  body,  measuring  three-quarters  of  an  inch  in  breadth,  and  is 
the  continuation  of  the  lower  part  of  the  sacral  plexus.  It  passes  out  of  the  pelvis 
through  the  great  sacro-sciatic  foramen,  below  the  Pyriformis  muscle.  It  descends 
between  the  trochanter  major  and  tuberosity  of  the  ischium,  along  the  back  part 
of  the  thigh  to  about  its  lower  third,  where  it  divides  into  two  large  branches,  the 
internal  and  external  popliteal  nerves. 

This  division  may  take  place  at  any  point  between  the  sacral  plexus  and  the 
lower  third  of  the  thigh.  When  the  division  occurs  at  the  plexus,  the  two  nerves 
descend  together,  side  by  side ;  or  they  may  be  separated,  at  their  commencement, 
by  the  interposition  of  part  or  the  whole  of  the  Pyriformis  muscle.  As  the  nerve 
descends  along  the  back  of  the  thigh,  it  rests  at  first  upon  the  external  rotator 
muscles,  together  with  the  small  sciatic  nerve  and  artery,  being  covered  by  the 
Gluteus  maximus ;  lower  down,  it  lies  upon  the  Adductor  magnus,  being  covered 
by  the  long  head  of  the  Biceps. 

The  branches  of  the  nerve,  before  its  division,  are  articular  and  muscular. 

The  articular  branches  arise  from  the  upper  part  of  the  nerve ;  they  supply  the 
hip-joint,  perforating  its  fibrous  capsule  posteriorly.  These  branches  are  some- 
times derived  from  the  sacral  plexus. 

The  muscular  branches  are  distributed  to  the  Flexors  of  the  leg;  viz.,  the 
Biceps,  Semi-tendinosus,  and  Semi-membranosus,  and  a  branch  to  the  Adductor 
magnus.     These  branches  are  given  off  beneath  the  Biceps  muscle. 

The  Internal  Popliteal  Nerve,  the  larger  of  the  two  terminal  branches  of 
the  great  sciatic  nerve,  descends  along  the  back  part  of  the  thigh  through  the 
middle  of  the  popliteal  space,  to  the  lower  part  of  the  Popliteus  muscle,  where  it 
passes  with  the  artery  beneath  the  arch  of  the  Soleus,  and  becomes  the  posterior 
tibial.  It  lies  at  first  very  superficial,  and  at  the  outer  side  of  the  popliteal  vessels; 
opposite  the  knee-joint,  it  is  in  close  relation  with  these  vessels,  and  crosses  the 
artery  to  its  inner  side. 

The  branches  of  this  nerve  are  articular,  muscular,  and  a  cutaneous  branch,  the 
external  or  short  saphenous  nerve. 

The  articular  branches,  usually  three  in  number,  supply  the  knee-joint ;  two  of 


PLANTAR. 


5S9 


Fig.  295.— The  Plantar  Nerves. 


these  branches  accompany  the  superior  and  inferior  internal  articular  arteries,  and 
a  third  the  azygos. 

The  muscular  branches,  four  or  five  in  number,  arise  from  the  nerve  as  it  lies 
between  the  two  heads  of  the  Gastrocnemius  muscle ;  they  supply  this  muscle, 
the  Plantaris,  Soleus,  and  Popliteus. 

The  external  or  short  saphenous  nerve  descends  between  the  two  heads  of  the 
Gastrocnemius  muscle,  and,  about  the  middle  of  the  back  of  the  leg,  pierces  the 
deep  fascia,  and  receives  a  communicating  branch  (communicans  peronei)  from  the 
external  popliteal  nerve.  The  nerve  then  continues  its  course  down  the  leg  near 
the  outer  margin  of  the  tendo  Achillis,  in  company  with  the  external  saphenous 
vein,  winds  round  the  outer  malleolus,  and  is  distributed  to  the  integument  along 
the  outer  side  of  the  foot  and  little  toe,  communicating  on  the  dorsum  of  the  foot 
with  the  musculo-cutaneous  nerve. 

The  Posterior  Tibial  nerve  commences  at  the  lower  border  of  the  Popliteus 
muscle,  and  passes  along  the  back  part  of  the  leg  with  the  posterior  tibial  vessels 
to  the  interval  between  the  inner  malleolus  and  the  heel,  where  it  divides  into  the 
external  and  internal  plantar  nerves.  It  lies  upon  the  deep  muscles  of  the  leg, 
and  is  covered  by  the  deep  fascia,  the  superficial  muscles,  and  integument.  In 
the  upper  part  of  its  course,'  it  lies  to  the  inner  side  of  the  posterior  tibial  artery ; 
but  it  soon  crosses  that  vessel,  and  lies  to  its  outer  side  as  far  as  the  ankle.  In 
the  lower  third  of  the  leg,  it  is  placed  parallel  with  the  inner  margin  of  the  tendo 
Achillis. 

The  branches  of  the  posterior  tibial 
nerve  are  muscular  and  plantar  cutaneous. 

The  muscular  branches  arise  either 
separately  or  by  a  common  trunk  from 
the  upper  part  of  the  nerve.  They  supply 
the  Tibialis  posticus,  Flexor  longus  digi- 
torum,  and  Flexor  longus  pollicis  muscles ; 
the  branch  to  the  latter  muscle  accompanies 
the  peroneal  artery. 

The  plantar  cutaneous  branch  perforates 
the  internal  annular  ligament,  and  sup- 
plies the  integument  of  the  heel  and  inner 
side  of  the  sole  of  the  foot. 

The  internal  plantar  nerve  (fig.  295), 
the  larger  of  the  two  terminal  branches 
of  the  posterior  tibial,  accompanies  the 
internal,  plantar  artery  along  the  inner 
side  of  the  foot.  From  its  origin  at  the 
inner  ankle  it  passes  forwards  between 
the  Abductor  pollicis  and  Flexor  brevis 
digitorum,  divides  opposite  the  bases  of 
the  metatarsal  bones  into  four  digital 
branches,  and  communicates  with  the 
external  plantar  nerve. 

Branches.  In  its  course,  the  internal 
plantar  nerve  givb3  oft'  cutaneous  branches, 
which  pierce  the  plantar  fascia,  and  supply 
the  integument  of  the  sole  of  the  foot; 
muscular  branches,  which  supply  the 
Abductor  pollicis  and  Flexor  brevis  digi- 
torum ;  articular  branches  to  the  articulations  of  the  tarsus  and  metatarsus ;  and 
four  digital  branches.  These  pierce  the  plantar  fascia  in  the  clefts  between  the 
toes,  and  are  distributed  in  the  following  manner : — The  first  supplies  the  inner 
border  of  the  great  toe,  and  sends  a  filament  to  the  Flexor  brevis  pollicis  muscle; 
the  second  bifurcates,  to  supply  the  adjacent  sides  of  the  great  and  second  toes, 


590  SPINAL   NERVES. 

sending  a  filament  to  the  first  Lumbrical  muscle;  the  third  digital  branch  supplies 
the  adjacent  sides  of  the  second  and  third  toes,  and  the  second  Lumbrical  muscle ; 
the  fourth  supplies  the  corresponding  sides  of  the  third  and  fourth  toes,  and 
receives  a  communicating  branch  from  the  external  plantar  nerve.  It  will  be 
observed,  that  the  distribution  of  these  branches  is  precisely  similar  to  that  of 
the  median.  Each  digital  nerve  gives  off  cutaneous  and  articular  filaments; 
and  opposite  the  last  phalanx  sends  a  dorsal  branch,  which  supplies  the  structures 
round  the  nail,  the  continuation  of  the  nerve  being  distributed  to  the  ball  of 
the  toe. 

The  external  plantar  nerve,  the  smaller  of  the  two,  completes  the  nervous  supply 
to  the  structures  of  the  foot,  being  distributed  to  the  little  toe  and  one  half  of  the 
fourth,  as  well  as  to  some  of  the  deep  muscles.  It  passes  obliquely  forwards 
with  the  external  plantar  artery  to  the  outer  side  of  the  foot,  lying  between  the 
Flexor  brevis  digitorum  and  Flexor  accessorius ;  and,  in  the  interval  between  the 
former  muscle  and  Abductor  minimi  digiti,  divides  into  a  superficial  and  a  deep 
branch.  Before  its  division,  it  supplies  the  Flexor  accessorius  and  Abductor 
minimi  digiti. 

The  superficial  branch  separates  into  two  digital  nerves :  one,  the  smaller  of  the 
two,  supplies  the  outer  side  of  the  little  toe,  the  Flexor  brevis  minimi  digiti,  and 
the  two  interosseous  muscles  of  the  fourth  metatarsal  space ;  the  other,  and  larger 
digital  branch,  supplies  the  adjoining  sides  of  the  fourth  and  fifth  toes,  and  com- 
municates with  the  internal  plantar  nerve. 

The  deep  or  muscular  branch  accompanies  the  external  plantar  artery  into  the 
deep  part  of  the  sole  of  the  foot,  beneath  the  tendons  of  the  Flexor  muscles  and 
Adductor  pollicis,  and  supplies  all  the  Interossei  (except  those  in  the  fourth 
metatarsal  space),  the  two  outer  Lumbricales,  the  Adductor  pollicis,  and  the 
Transversus  pedis. 

The  External  Popliteal  or  Peroneal  Nerve,  about  one-half  the  size  of 
the  internal  popliteal,  descends  obliquely  along  the  outer  side  of  the  popliteal 
space,  close  to  the  margin  of  the  Biceps  muscle,  to  the  fibula;  and,  about  an  inch 
below  the  head  of  this  bone,  pierces  the  origin  of  the  Peroneus  longus,  and 
divides  beneath  this  muscle  into  the  anterior  tibial  and  musculo-cutaneous  nerves. 

The  branches  of  the  peroneal  nerve,  previous  to  its  division,  are  articular  and 
cutaneous. 

The  articular  branches,  two  in  number,  accompany  the  superior  and  inferior 
'  external  articular  arteries  to  the  outer  side  of  the  knee.  The  upper  one  occa- 
sionally arises  from  the  great  sciatic  nerve  before  its  bifurcation.  A  third 
(recurrent)  articular  nerve  is  given  off  at  the  point  of  division  of  the  peroneal 
nerve;  it  ascends  with  the  tibial  recurrent  artery  through  the  Tibialis  antic  us 
muscle  to  the  front  of  the  knee,  which  it  supplies. 

The  cutaneous  branches,  two  or  three  in  number,  supply  the  integument  along 
the  back  part  and  outer  side  of  the  leg,  as  far  as  its  middle  or  lower  part ;  one  of 
these,  larger  than  the  rest,  the  communicans  peronei,  arises  near  the  head  of  the 
fibula,  crosses  the  external  head  of  the  Gastrocnemius  to  the  middle  of  the  leg, 
where  it  joins  with  the  external  saphenous.  This  nerve  occasionally  exists  as  a 
separate  branch,  which  is  continued  down  as  far  as  the  heel. 

The  Anterior  Tibial  Nerve  commences  at  the  bifurcation  of  the  peroneal  nerve, 
between  the  fibula  and  upper  part  of  the  Peroneus  longus,  passes  obliquely  for- 
wards beneath  the  Extensor  longus  digitorum  to  the  fore  part  of  the  interosseous 
membrane,  and  reaches  the  outer  side  of  the  anterior  tibial  artery  above  the 
middle  of  the  leg;  it  then  descends  with  the  artery  to  the  front  of  the  ankle-joint, 
where  it  divides  into  an  external  and  an  internal  branch.  This  nerve  lies  at  first 
on  the  outer  side  of  the  anterior  tibial,  then  in  front  of  it,  and  again  at  its  outer 
side  at  the  ankle-joint. 

The  branches  of  the  anterior  tibial,  in  its  course  through  the  leg,  are  muscular : 
these  supply  the  Tibialis  anticus,  the  Extensor  longus  digitorum,  and  Extensor 
proprius  pollicis  muscles. 


CUTANEOUS  NERVES  OP  FOOT.  591 

The  external  or  tarsal  branch  of  the  anterior  tibial  passes  outwards  across  the 
tarsus,  beneath  the  Extensor  brevis  digitorum,  and,  having  become  ganglionic, 
like  the  posterior  interosseous  nerve  at  the  wrist,  supplies  the  Extensor  brevis 
digitorum  and  the  articulations  of  the  tarsus  and  metatarsus. 

The  internal  branch,  the  continuation  of  the  nerve,  accompanies  the  dorsalis 
pedis  artery  along  the  inner  side  of  the  dorsum  of  the  foot,  and,  at  the  first  inter- 
osseous space,  divides  into  two  branches,  which  supply  the  adjacent  sides  of  the 
great  and  second  toes,  communicating  with  the  internal  division  of  the  musculo- 
cutaneous nerve. 

The  Musculo-cutaneous  branch  supplies  the  muscles  on  the  fibular  side  of  the 
leg,  and  the  integument  of  the  dorsum  of  the  foot.  It  passes  forwards  between 
the  Peronei  muscles  and  the  Extensor  longus  digitorum,  pierces  the  deep  fascia 
at  the  lower  third  of  the  leg,  on  its  front  and  outer  side,  and  divides  into  two 
branches.  This  nerve,  in  its  course  between  the  muscles,  gives  off"  muscular 
branches  to  the  Peroneus  longus  and  Peroneus  brevis,  and  cutaneous  filaments  to 
the  integument  of  the  lower  part  of  the  leg. 

The  internal  branch  of  the  musculo-cutaneous  nerve  passes  in  front  of  the 
ankle-joint,  and  along  the  dorsum  of  the  foot ;  it  supplies  the  inner  side  of  the 
great  toe,  and  the  adjoining  sides  of  the  second  and  third  toes.  It  also  supplies 
the  integument  of  the  inner  ankle  and  inner  side  of  the  foot,  communicating  with 
the  internal  saphenous  nerve,  and  joins  with  the  anterior  tibial  nerve,  between 
the  great  and  second  toes. 

The  external  branch,  the  larger,  passes  along  the  outer  side  of  the  dorsum  of 
the  foot,  to  be  distributed  to  the  adjoining  sides  of  the  third,  fourth,  and  fifth 
toes.  It  also  supplies  the  integument  of  the  outer  ankle  and  outer  side  of  the 
foot,  communicating  with  the  short  saphenous  nerve.  The  distribution  of  these 
nerves  will  be  found  to  vary ;  together,  they  supply  all  the  toes  excepting  the 
outer  side  of  the  little  toe,  and  the  adjoining  sides  of  the  great  and  second  toes. 


The  Sympathetic  Nerve. 

The  Sympathetic  Nerve  is  so  called  from  the  opinion  entertained  that  through 
it  is  produced  a  sympathy  between  the  affections  of  distant  organs.  It  consists 
of  a  series  of  ganglia,  connected  together  by  intervening  cords,  extending  on  each 
side  of  the  vertebral  column  from  the  base  of  the  skull  to  the  coccyx.  It  may, 
moreover,  be  traced  up  into  the  head,  where  the  ganglia  occupy  spaces  between 
the  cranial  and  facial  bones.  These  two  gangliated  cords  lie  parallel  with  one 
another  as  far  as  the  sacrum,  on  which  bone  they  converge,  communicating 
together  through  a  single  ganglion  (ganglion  impar),  placed  in  front  of  the  coccyx. 
Some  anatomists  also  state  that  the  two  cords  are  joined  at  their  cephalic  extremity, 
through  a  small  ganglion  (the  ganglion  of  Ribes),  situated  upon  the  anterior  com- 
municating artery.  Moreover,  the  chains  of  opposite  sides  communicate  between 
these  two  extremities  in  several  parts,  by  means  of  the  nervous  cords  that  arise 
from  them. 

The  ganglia  are  somewhat  less  numerous  than  the  vertebroB ;  thus  there  are 
only  three  in  the  cervical  region,  twelve  in  the  dorsal,  four  in  the  lumbar,  five  in 
the  sacral,  and  one  in  the  coccygeal. 

The  sympathetic  nerve,  for  convenience  of  description,  may  be  divided  into 
several  parts,  according  to  the  position  occupied  by  each ;  and  the  number  of 
ganglia  of  which  each  part  is  composed  may  be  thus  arranged : — 


Cephalic  portion 

4  ganglia. 

Cervical       " 

3       " 

Dorsal          " 

.       12       " 

Lumbar       " 

4       " 

Sacral          " 

5       " 

Coccygeal   " 

1  ganglion 

Each  ganglion  may  be  regarded  as  a  distinct  centre,  from  or  to  which  branches 
pass  in  various  directions.  These  branches  may  be  thus  arranged: — 1.  Branches 
of  communication  between  the  ganglia.  2.  Branches  of  communication  with  the 
cerebral  or  spinal  nerves.  3.  Primary  branches  passing  to  be  distributed  to  the 
arteries  in  the  vicinity  of  the  ganglia,  and  to  the  viscera,  or  proceeding  to  other 
ganglia  placed  in  the  thorax,  abdomen,  or  pelvis. 

1.  The  branches  of  communication  between  the  ganglia  are  composed  of  gray 
and  white  nerve  fibres,  the  latter  being  continuous  with  those  fibres  of  the  spinal 
nerves  which  pass  to  the  ganglia. 

2.  The  branches  of  communication  between  the  ganglia  and  the  cerebral  or 
spinal  nerves  also  consist  of  a  white  and  a  gray  portion ;  the  former  proceeding 
from  the  spinal  nerve  to  the  ganglion,  the  latter  passing  from  the  ganglion  to  the 
spinal  nerve. 

3.  The  primary  branches  of  distribution  also  consist  of  two  kinds  of  nerve 
fibres,  the  sympathetic  and  spinal.  They  have  a  remarkable  tendency  to  form 
intricate  plexuses,  which  encircle  the  bloodvessels,  and  are  conducted  by  them  to 
the  viscera.  The  greater  number,  however,  of  these  branches  pass  to  a  series  of 
ganglia,  or  ganglionic  masses,  of  variable  size,  situated  in  the  large  cavities  of 
the  trunk,  the  thorax,  and  abdomen ;  and  are  connected  with  the  roots  of  the  great 
arteries  of  the  viscera.  These  ganglia  are  single  and  unsymmetrical,  and  are 
called  the  cardiac  and  semilunar.  From  these  visceral  ganglia  numerous  plexuses 
are  derived,  which  entwine  round  the  bloodvessels,  and  are  conducted  by  them  to 
the  viscera. 

592 


SYMPATHETIC   NERVE. 


593 


Fig.  296. — The  Sympathetic  Nervo. 


Suptrinr  Curvirnl  (Jan^lioM. 


^Udells  Cervical  Ganglion 


Inferior  Cervical  Ganijlion 


S.icral  Cauirlia 


Ciinglioti  Impar—-^ 


laryngeal  ZraneJit* 
CarJiae    13  r  4 

tep    Cardiac  Plexus 
Superficial  Cardiac  Plexus 


Solar  Plexum 


—  ^  Aortic  Plexus 


llypogaetrie  FZexu-B 


38 


i>9i  SYMPATHETIC   NERVE. 


Cephalic  Portion  of  the  Sympathetic. 

The  cephalic  portion  of  the  sympathetic  consists  of  four  ganglia.  1.  The  oph- 
thalmic ganglion.  2.  The  spheno-palatine  or  Meckel's  ganglion.  3.  The  otic  or 
Arnold's  ganglion.     4.  The  submaxillary  ganglion. 

These  have  been  already  described  in  connection  with  each  of  the  three  divi- 
sions of  the  fifth  nerve. 

Cervical  Portion  of  the  Sympathetic. 

• 

The  cervical  portion  of  the  sympathetic  consists  of  three  ganglia  on  each  side, 
which  are  distinguished  according  to  their  position,  as  the  superior,  middle,  and 
inferior  cervical. 

The  Superior  Cervical  Ganglion,  the  largest  of  the  three,  is  placed  opposite 
the  second  and  third  cervical  vertebrae,  and  sometimes  as  low  as  the  fourth  or  fifth. 
It  is  of  a  reddish-gray  color,  and  usually  fusiform  in  shape ;  sometimes  broad,  and 
occasionally  constricted  at  intervals,  so  as  to  give  rise  to  the  opinion,  that  it  con- 
sists of  the  coalescence  of  several  smaller  ganglia.  It  is  in  relation,  in  front,  with 
the  sheath  of  the  internal  carotid  artery,  and  internal  jugular  vein ;  behind,  it 
lies  on  the  Eectus  capitis  anticus  major  muscle. 

Its  branches  may  be  divided  into  superior,  inferior,  external,  internal,  and 
anterior. 

The  Superior  branch  appears  to  be  a  direct  continuation  of  the  ganglion.  It  is 
soft  in  texture,  and  of  a  reddish  color.  It  ascends  by  the  side  of  the  internal 
carotid  artery,  and,  entering  the  carotid  canal  in  the  temporal  bone,  divides  into 
two  branches,  which  lie,  one  on  the  outer  side,  and  the  other  on  the  inner  side,  of 
that  vessel. 

The  outer  branch,  the  larger  of  the  two,  distributes  filaments  to  the  internal  caro- 
tid artery,  and  forms  the  Carotid  Plexus  (described  on  page  595). 

The  inner  branch  also  distributes  filaments  to  the  internal  carotid,  and,  continu- 
ing onwards,  forms  the  Cavernous  Plexus  (described  on  page  595). 

The  Inferior  or  Descending  branch  of  the  superior  cervical  ganglion  communi- 
cates with  the  middle  cervical  ganglion. 

The  External  branches  are  numerous,  and  communicate  with  the  cranial  nerves, 
and  with  the  four  upper  spinal  nerves.  Sometimes,  the  branch  of  the  fourth  spinal 
nerve  may  come  from  the  cord  connecting  the  upper  and  middle  cervical  ganglia. 
The  branches  of  communication  with  the  cranial  nerves  consist  of  delicate  filaments, 
which  pass  from  the  superior  cervical  ganglion  to  the  ganglion  of  the  trunk  of  the 
pneumogastric,  and  to  the  ninth  nerve.  A  separate  filament  from  the  cervical 
ganglion  subdivides  and  joins  the  petrosal  ganglion  of  the  glosso-pharyngeal,  and 
the  ganglion  of  the  root  of  the  pneumogastric  in  the  jugular  foramen. 

The  Internal  branches  are  three  in  number:  pharyngeal,  laryngeal,  and  the 
superior  cardiac  nerve.  The  pharyngeal  branches  pass  inwards  to  the  side  of  the 
pharynx,  where  they  join  with  branches  from  the  pneumogastric,  glosso-pharyn- 
geal, and  external  laryngeal  nerves,  and  assist  in  forming  the  pharyngeal  plexus. 
The  laryngeal  branches  unite  with  the  superior  laryngeal  nerve  and  its  branches. 

The  superior  cardiac  nerve  will  be  described  in  connection  with  the  other  cardiac 
nerves. 

The  Anterior  branches  ramify  upon  the  external  carotid  artery  and  its  branches, 
forming  round  each  a  delicate  plexus,  on  the  nerves  composing  which  small 
ganglia  are  occasionally  found.  These  ganglia  have  been  named,  according  to 
their  position,  intercarotid  (one  placed  at  the  angle  of  bifurcation  of  the  common 
carotid),  lingual,  temporal,  and  pharyngeal.  The  plexuses  accompanying  some  of 
these  arteries  have  important  communications  with  other  nerves.  That  sur- 
rounding the  external  carotid  is  connected  with  the  digastric  branch  of  the  facial; 
that  surrounding  the  facial  communicates  with  the  submaxillary  ganglion  by  one 
or  two  filaments ;    and  that  accompanying   the  middle  meningeal  artery  sends 


CERVICAL   GANGLIA.  595 

offsets  which  pass  to  the  otic  ganglion  and  to  the  intumescentia  gangliformis  of 
the  facial  nerve. 

The  Middle  Cervical  Ganglion  (thyroid  ganglion)  is  the  smallest  of  the  three 
cervical  ganglia,  and  is  occasionally  altogether  wanting.  It  is  placed  opposite  the 
fifth  cervical  vertebra,  usually  upon,  or  close  to,  the  inferior  thyroid  artery;  hence 
the  name  "  thyroid  ganglion,"  assigned  to  it  by  Haller. 

Its  superior  branches  ascend  to  communicate  with  the  superior  cervical 
ganglion. 

Its  inferior  branches  descend  to  communicate  with  the  inferior  cervical 
ganglion. 

Its  external  branches  pass  outwards  to  join  the  fifth  and  sixth  spinal  nerve?. 
These  branches  are  not  constantly  found. 

Its  internal  brandies  are  the  thyroid  and  the  middle  cardiac  nerve. 

The  thyroid  branches  are  small  filaments,  which  accompany  the  inferior  thyroid 
artery  to  the  thyroid  gland ;  they  communicate,  on  the  artery,  with  the  superior 
cardiac  nerve,  and,  in  the  gland,  with  branches  from  the  recurrent  and  external 
laryngeal  nerves. 

The  middle  cardiac  nerve  is  described  with  the  other  cardiac  nerves. 

The  Inferior  Cervical  Ganglion  is  situated  between  the  base  of  the  trans- 
verse process  of  the  last  cervical  vertebra  and  the  neck  of  the  first  rib,  on  the 
inner  side  of  the  superior  intercostal  artery.  Its  form  is  irregular ;  it  is  larger  in 
size  than  the  preceding,  and  frequently  joined  with  the  first  thoracic  ganglion. 

Its  superior  branches  communicate  with  the  middle  cervical  ganglion. 

Its  inferior  branches  descend,  some  in  front  of,  others  behind,  the  subclavian 
arterv,  to  join  the  first  thoracic  ganglion.  The  most  important  of  these  branches 
constitutes  the  inferior  cardiac  nerve,  to  be  presently  described. 

The  external  branches  consist  of  several  filaments,  some  of  which  communicate 
with  the  seventh  and  eighth  spinal  nerves;  others  accompany  the  vertebral 
artery  along  the  vertebral  canal,  forming  a  plexus  round  this  vessel,  supplying 
it  with  filaments,  and  communicating  with  the  cervical  spinal  nerves  as  high  as 
the  fourth. 

Carotid  and  Cavernous  Plexuses. 

The  Carotid  Plexus  is  situated  on  the  outer  side  of  the  internal  carotid.  Fila 
ments  from  this  plexus  occasionally  form  a  small  gangliform  swelling  on  the  under 
surface  of  the  artery,  which  is  called  the  carotid  ganglion.  The  carotid  plexus 
communicates  with  the  Casserian  ganglion,  with  the  sixth  nerve,  and  spheno- 
palatine ganglion,  and  distributes  filaments  to  the  wall  of  the  carotid  artery,  and 
to  the  dura  mater  (Valentin). 

The  communicating  branches  with  the  sixth  nerve  consist  of  one  or  two  fila- 
ments, which  join  that  nerve  as  it  lies  upon  the  outer  side  of  the  internal  carotid. 
Other  filaments  are  also  connected  with  the  Casserian  ganglion.  The  communica- 
tion with  the  spheno-palatine  ganglion  is  effected  by  the  carotid  portion  of  the 
Vidian  nerve,  which  passes  forwards,  through  the  cartilaginous  substance  filling 
in  the  foramen  lacerum  medium,  along  the  pterygoid  canal,  to  the  spheno-palatine 
ganglion.     In  this  canal  it  joins  the  petrosal  branch  of  the  Vidian. 

The  Cavernous  Plexus  is  situated  below,  and  to  the  inner  side  of,  that  part  of  the 
internal  carotid,  which  is  placed  by  the  side  of  the  sella  Turcica,  in  the  cavernous 
sinus,  and  is  formed  chiefly  by  the  internal  division  of  the  ascending  branch  from 
the  superior  cervical  ganglion.  It  communicates  with  the  third,  fourth,  fifth,  and 
sixth  nerves,  and  with  the  ophthalmic  ganglion,  and  distributes  filaments  to  the 
wall  of  the  internal  carotid.  The  branch  of  communication  with  the  third  nerve 
joins  it  at  its  point  of  division ;  the  branch  to  the  fourth  nerve  joins  it  as  it  lies 
on  the  outer  wall  of  the  cavernous  sinus ;  other  filaments  are  connected  with  the 
under  surface  of  the  trunk  of  the  ophthalmic  nerve ;  and  a  second  filament  of 
communication  joins  the  sixth  nerve. 

The  filament  of  connection  with  the  ophthalmic  ganglion  arises  from  the  ante- 


596  SYMPATHETIC   NERVE. 

rior  part  of  the  cavernous  plexus ;  it  accompanies  the  nasal  nerve,  or  continues 
forwards  as  a  separate  branch. 

The  terminal  filaments  from  the  carotid  and  cavernous  plexuses  are  prolonged 
along  the  internal  carotid,  forming  plexuses  which  entwine  round  the  cerebral  and 
ophthalmic  arteries ;  along  the  former  vessel  they  may  be  traced  on  to  the  pia  mater ; 
along  the  latter,  into  the  orbit,  where  they  accompany  each  of  the  subdivisions  of 
the  vessel,  a  separate  plexus  passing  with  the  arteria  centralis  retinas  into  the 
interior  of  the  eyeball. 

Cardiac  Nerves. 

The  cardiac  nerves  are  three  in  number  on  each  side ; — superior,  middle,  and 
inferior,  one  being  derived  from  each  of  the  cervical  ganglia. 

The  Superior  Cardiac  nerve  (nervus  superficialis  cordis)  arises  by  two  or  more 
branches  from  the  superior  cervical  ganglion,  and  occasionally  receives  a  filament 
from  the  cord  of  communication  between  the  first  and  second  cervical  ganglia. 
It  runs  down  the  neck  behind  the  common  carotid  artery,  lying  upon  the  Longus 
colli  muscle,  and  crosses  in  front  of  the  inferior  thyroid  artery,  and  the  recurrent 
laryngeal  nerve. 

The  right  superior  cardiac  nerve,  at  the  root  of  the  neck,  passes  either  in  front 
of  or  behind  the  subclavian  artery,  and  along  the  arteria  innominata,  to  the  back 
part  of  the  arch  of  the  aorta,  to  the  deep  cardiac  plexus.  This  nerve,  in  its 
course,  is  connected  with  other  branches  of  the  sympathetic ;  about  the  middle  of 
the  neck  it  receives  filaments  from  the  external  laryngeal  nerve ;  lower  down,  one 
or  two  twigs  from  the  pneumogastric,  and,  as  it  enters  the  thorax,  it  joins  with  the 
recurrent  laryngeal.  Filaments  from  this  nerve  accompany  the  inferior  thyroid 
artery  to  the  thyroid  gland. 

The  left  superior  cardiac  nerve  runs  by  the  side  of  the  left  carotid  artery,  and 
in  front  of  the  arch  of  the  aorta,  to  the  superficial  cardiac  plexus;  it  occasionally 
passes  behind  this  vessel,  and  terminates  in  the  deep  cardiac  ..plexus. 

The  Middle  Cardiac  nerve  (nervus  cardiacus  magnus),  the  largest  of  the  three, 
arises  from  the  middle  cervical  ganglion,  or  from  the  interganglionic  cord  between 
the  middle  and  inferior  ganglia.  On  the  right  side,  it  descends  behind  the  common 
carotid  artery ;  and,  at  the  root  of  the  neck,  passes  either  in  front  of  or  behind  the 
subclavian  artery ;  it  then  descends  on  the  trachea,  receives  a  few  filaments  from 
the  recurrent  laryngeal  nerve,  and  joins  the  deep  cardiac  plexus.  In  the  neck,  it 
communicates  with  the  superior  cardiac  and  recurrent  laryngeal  nerves.  On  the 
left  side,  the  middle  cardiac  nerve  enters  the  chest  between  the  left  carotid  and 
subclavian  arteries,  and  joins  the  left  side  of  the  deep  cardiac  plexus. 

The  Inferior  Cardiac  nerve  (nervus  cardiacus  minor)  arises  from  the  inferior 
cervical  or  first  thoracic  ganglion.  It  passes  down  behind  the  subclavian  artery, 
and  along  the  front  of  the  trachea,  to  join  the  deep  cardiac  plexus.  It  communi- 
cates freely  behind  the  subclavian  artery  with  the  recurrent  laryngeal  and  middle 
cardiac  nerves. 

Cardiac  and  Coronary  Plexuses. 

The  Great  or  Deep  Cardiac  Plexus  {p>lexus  magnus  profundus — Scarpa)  is 
situated  in  front  of  the  trachea  at  its  bifurcation,  above  the  point  of  division  of  the 
pulmonary  artery,  and  behind  the  arch  of  the  aorta.  It  is  formed  by  the  cardiac 
nerves  derived  from  the  cervical  ganglia  of  the  sympathetic,  and  the  cardiac 
branches  of  the  recurrent  laryngeal  and  pneumogastric.  The  only  cardiac  nerves 
which  do  not  enter  into  the  formation  of  this  plexus  are  the  left  superior  cardiac 
nerve,  and  the  left  inferior  cardiac  branch  from  the  pneumogastric.  The  branches 
derived  from  the  great  cardiac  plexus  form  the  posterior  coronary  plexus,  and 
part  of  the  anterior  coronary  plexus ;  whilst  a  few  filaments  proceed  to  the  pul- 
monary plexuses,  and  to  the  auricles  of  the  heart. 

The  branches  from  the  right  side  of  this  plexus  pass  some  in  front  of,  and  othera 


THORACIC    GANGLIA.  597 

behind,  the  right  pulmonary  artery ;  the  former,  the  more  numerous,  transmit  a 
few  filaments  to  the  anterior  pulmonary  plexus,  and  are  continued  along  the  trunk 
of  the  pulmonary  artery,  to  form  part  of  the  anterior  coronary  plexus ;  those 
behind  the  pulmonary  artery  distribute  a  few  filaments  to  the  right  auricle,  and 
form  part  of  the  posterior  coronary  plexus. 

The  branches  from  the  left  side  of  the  cardiac  plexus  distribute  a  few  filaments 
to  the  left  auricle  of  the  heart  and  the  anterior  pulmonary  plexus,  and  then  pass 
on  to  form  the  greater  part  of  the  posterior  coronary  plexus,  a  few  branches 
passing  to  the  superficial  cardiac  plexus. 

The  Superficial  {anterior)  Cardiac  plexus  lies  beneath  the  arch  of  the  aorta, 
in  front  of  the  right  pulmonary  artery.  It  is  formed  by  the  left  superior  cardiac 
nerve,  the  left  (and  occasionally  the  right)  inferior  cardiac  branches  of  the  pneu- 
mogastric,  and  by  filaments  from  the  deep  cardiac  plexus.  A  small  ganglion 
(cardiac  ganglion  of  Wrisberg)  is  occasionally  found  connected  with  these  nerves 
at  their  point  of  junction.  This  ganglion,  when  present,  is  situated  immediately 
beneath  the  arch  of  the  aorta,  on  the  right  side  of  the  ductus  arteriosus.  The 
superficial  cardiac  plexus  forms  the  chief  part  of  the  anterior  coronary  plexus,  and 
several  filaments  pass  along  the  pulmonary  artery  to  the  left  anterior  pulmonary 
plexus. 

The  Posterior  Coronary  plexus  is  formed  chiefly  by  filaments  from  the  left  side 
of  the  deep  cardiac  plexus,  and  by  a  few  from  the  right  side.  It  surrounds  the 
branches  of  the  coronary  artery  at  the  back  of  the  heart,  and  its  filaments  are 
distributed  with  those  vessels  to  the  muscular  substance  of  the  ventricles. 

The  Anterior  Coronary  plexus  is  prolonged  chiefly  from  the  superficial  cardiac 
plexus,  but  receives  filaments  from  the  deep  cardiac  plexus.  Passing  forwards 
between  the  aorta  and  pulmonary  artery,  it  accompanies  the  right  coronary  artery 
on  the  anterior  surface  of  the  heart. 

Valentin  has  described  nervous  filaments  ramifying  under  the  endocardium; 
and  Bemak  has  found,  in  several  mammalia,  numerous  small  ganglia  on  the  cardiac 
nerves,  both  on  the  surface  of  the  heart  and  in  its  muscular  substance.  The 
elaborate  dissections  lately  completed  by  Dr.  Robert  Lee  have  demonstrated  with- 
out any  doubt  the  existence  of  a  dense  mesh  of  nerves  distributed  both  to  the 
surface,  and  in  the  substance  of  the  heart,  having  numerous  ganglia  developed 
upon  them. 

Thoeacic  Part  of  the  Sympathetic. 

The  thoracic  portion  of  the  sympathetic  consists  of  a  series  of  ganglia,  which 
usually  correspond  in  number  to  that  of  the  vertebrae ;  but,  from  the  occasional 
coalescence  of  two,  their  number  is  uncertain.  These  ganglia  are  placed  on 
each  side  of  the  spine,  resting  against  the  heads  of  the  ribs,  and  covered  by  the 
pleura  costalis:  the  last  two  are,  however,  anterior  to  the  rest,  being  placed  on 
the  side  of  the  bodies  of  the  vertebras.  The  ganglia  are  small  in  size,  and  of  a 
grayish  color.  The  first,  larger  than  the  rest,  is  of  an  elongated  form,  and  usually 
blended  with  the  last  cervical.  They  are  connected  together  by  cord-like  pro- 
longations from  their  substance. 

The  external  branches  from  each  ganglion,  usually  two  in  number,  communicate 
with  each  of  the  dorsal  spinal  nerves. 

The  internal  branches  from  the  six  upper  ganglia  are  very  small,  and  distribute 
filaments  to  the  thoracic  aorta  and  its  branches,  besides  small  branches  to  the 
bodies  of  the  vertebras  and  their  ligaments.  Branches  from  the  third  and  fourth 
ganglia  form  part  of  the  posterior  pulmonary  plexus. 

The  internal  branches  from  the  six  lower  ganglia  are  large  and  white  in  color ; 
they  distribute  filaments  to  the  aorta,  and  unite  to  form  the  three  splanchnic 
nerves.     These  are  named,  the  great,  the  lesser,  and  the  smallest  or  renal  splanchnic. 

The  Great  Splanchnic  nerve  is  of  a  white  color,  firm  in  texture,  and  bears  a 
marked  contrast  to  the  ganglionic  nerves.  It  is  formed  by  branches  from  the 
thoracic  ganglia  between  the  sixth  and  tenth,  receiving  filaments  (according  to 


598  SYMPATHETIC   NERYE. 

Mr.  Beck)  from  all  the  thoracic  ganglia  above  the  sixth.  These  roots  unite  to 
form  a  large  round  cord  of  considerable  size.  It  descends  obliquely  inwards  in 
front  of  the  bodies  of  the  vertebras  along  the  posterior  mediastinum,  perforates  the 
crus  of  the  Diaphragm,  and  terminates  in  the  semilunar  ganglion,  distributing 
filaments  to  the  renal  plexus  and  supra-renal  gland. 

The  Lesser  Splanchnic  nerve  is  formed  by  filaments  from  the  tenth  and 
eleventh  ganglia,  and  from  the  cord  between  them.  It  pierces  the  Diaphragm 
with  the  preceding  nerve,  and  joins  the  coeliac  plexus.  It  communicates  in  the 
chest  with  the  great  splanchnic  nerve,  and  occasionally  sends  filaments  to  the 
renal  plexus. 

The  Smallest  or  Renal  Splanchnic  nerve  arises  from  the  last  ganglion,  and,  piercing 
the  Diaphragm,  terminates  in  the  renal  plexus  and  lower  part  of  the  coeliac  plexus. 
It  occasionally  communicates  with  the  preceding  nerve. 

A  striking  analogy  appears  to  exist  between  the  splanchnic  and  the  cardiac 
nerves.  The  cardiac  nerves  are  three  in  number;  they  arise  from  the  three 
cervical  ganglia,  and  are  distributed  to  a  large  and  important  organ  in  the  thoracic 
cavity.  The  splanchnic  nerves,  also  three  in  number,  are  connected  probably 
with  all  the  dorsal  ganglia,  and  are  distributed  to  important  organs  in  the  abdominal 
cavity. 

The  Epigastric  or  Solar  plexus  supplies  all  the  viscera  in  the  abdominal  cavity. 
It  consists  of  a  dense  network  of  nerves  and  ganglia,  situated  behind  the  stomach 
and  in  front  of  the  aorta  and  crura  of  the  Diaphragm.  It  surrounds  the  coeliac 
axis  and  root  of  the  superior  mesenteric  artery,  extending  downwards  as  low  as 
the  pancreas,  and  outwards  to  the  supra-renal  capsules.  This  plexus,  and  the 
ganglia  connected  with  it,  receive  the  great  splanchnic  nerve  of  both  sides,  part 
of  the  lesser  splanchnic  nerves,  and  the  termination  of  the  right  pneumogastric. 
It  distributes  filaments,  which  accompany,  under  the  name  of  plexuses,  all  the 
branches  from  the  front  of  the  abdominal  aorta. 

The  semilunar  ganglia  of  the  solar  plexus,  two  in  number,  one  on  each  side, 
are  the  largest  ganglia  in  the  body.  They  are  large  irregular  gangliform  masses, 
formed  by  the  aggregation  of  smaller  ganglia,  having  interspaces  between  them. 
They  are  situated  by  the  side  of  the  coeliac  axis  and  superior  mesenteric  artery, 
close  to  the  supra-renal  glands,  the  one  on  the  right  side  lying  beneath  the  vena 
cava;  the  upper  part  of  each  ganglion  is  joined  by  the  greater  and  lesser 
splanchnic  nerves,  and  to  the  inner  side  of  each  the  branches  of  the  solar  plexus 
are  connected. 

From  the  solar  plexus  are  derived  the  following : — 

Phrenic  or  diaphragmatic  plexus.  Supra-renal  plexus. 

Coeliac  plexus.  Eenal  plexus. 

Gastric  plexus.  Superior  mesenteric  plexus. 

Hepatic  plexus.  Spermatic  plexus. 

Splenic  plexus.  Inferior  mesenteric  plexus. 

The  phrenic  plexus  accompanies  the  phrenic  artery  to  the  Diaphragm,  which 
it  supplies,  some  filaments  passing  to  the  supra-renal  gland.  It  arises  from  the 
upper  part  of  the  semilunar  ganglion,  and  is  larger  on  the  right  than  on  the  left 
side.  In  connection  with  this  plexus,  on  the  right  side,  at  its  point  of  junction 
with  the  phrenic  nerve,  is  a  small  ganglion  (ganglion  diaphragmaticum).  This 
ganglion  is  placed  on  the  under  surface  of  the  Diaphragm,  near  the  supra-renal 
gland.  Its  branches  are  distributed  to  the  vena  cava,  supra-renal  gland,  and  the 
hepatic  plexus.     The  ganglion  is  absent  on  the  left  side. 

The  supra-renal  plexus  is  formed  by  branches  from  the  solar  plexus,  from  the 
semilunar  ganglion,  and  from  the  splanchnic  and  phrenic  nerves,  a  ganglion  being 
formed  at  the  point  of  junction  of  the  latter  nerve.  It  supplies  the  supra-renal 
gland.  The  branches  of  this  plexus  are  remarkable  for  their  large  size,  in  com- 
parison with  the  size  of  the  organ  they  supply. 

The  renal  plexus  is  formed  by  filaments  from  the  solar  plexus,  the  oiater  part 


SOLAR   PLEXUS— SEMILUNAR    GANGLIA.  599 

of  the  semilunar  ganglion,  and  the  aortic  plexus.  It  is  also  joined  by  filaments 
from  the  lesser  and  smallest  splanchnic  nerves.  The  nerves  from  these  sources, 
fifteen  or  twenty  in  number,  have  numerous  ganglia  developed  upon  them.  They 
accompany  the  branches  of  the  renal  artery  into  the  kidney ;  some  filaments  on 
the  right  side  being  distributed  to  the  vena  cava,  and  others  to  the  spermatic 
plexus,  on  both  sides. 

The  spermatic  plexus  is  derived  from  the  renal  plexus,  receiving  branches  from 
the  aortic  plexus.     It  accompanies  the  spermatic  vessels  to  the  testes. 

In  the  female,  the  ovarian  plexus  is  distributed  to  the  ovaries  and  fundus  of  the 
uterus. 

The  coeliac  plexus,  of  large  size,  is  a  direct  continuation  from  the  solar  plexus : 
it  surrounds  the  coeliac  axis,  and  subdivides  into  the  gastric,  hepatic,  and  splenic 
plexuses.  It  receives  branches  from  one  or  more  of  the  splanchnic  nerves,  and, 
on  the  left  side  a  filament  from  the  pneumogastric. 

The  gastric  plexus  accompanies  the  gastric  artery  along  the  lesser  curvature  of 
the  stomach,  and  joins  with  branches  from  the  left  pneumogastric  nerve.  It  is 
distributed  to  the  stomach. 

The  hepatic  plexus,  the  largest  offset  from  the  cceliac  plexus,  receives  filaments 
from  the  left  pneumogastric  and  right  phrenic  nerves.  It  accompanies  the  hepatic 
artery,  ramifying  in  the  substance  of  the  liver  upon  its  branches  and  upon  those 
of  the  vena  portse. 

Branches  from  this  plexus  accompany  all  the  divisions  of  the  hepatic  artery. 
Thus  there  is  a  pyloric  plexus  accompanying  the  pyloric  branch  of  the  hepatic, 
which  joins  with  the  gastric  plexus,  and  pneumogastric  nerves.  There  is  also  a 
gastro-duodenal  plexus,  which  subdivides  into  the  pancreatico-duodenal  plexus, 
which  accompanies  the  pancreatico-duodenal  artery,  to  supply  the  pancreas  and 
duodenum,  joining  with  branches  from  the  mesenteric  plexus;  and  a  gastro- 
epiploic plexus,  which  accompanies  the  right  gastro-epiploic  arter3r  along  the 
greater  curvature  of  the  stomach,  and  anastomoses  with  branches  from  the  splenic 
plexus.  A  cystic  plexus,  which  supplies  the  gall-bladder,  also  arises  from  the 
hepatic  plexus,  near  the  liver. 

The  splenic  plexus  is  formed  by  branches  from  the  right  and  left  semilunar 
ganglia,  and  from  the  right  pneumogastric  nerve.  It  accompanies  the  splenic 
artery  and  its  branches  to  the  substance  of  the  spleen,  giving  oft)  in  its  course, 
filaments  to  the  pancreas  (pancreatic  plexus),  and  the  left  gastro-  epiploic  plexus, 
which  accompanies  the  gastro-epiploica  sinistra  artery  along  the  convex  border  of 
the  stomach. 

The  superior  mesenteric  plexus  is  a  continuation  of  the  lower  part  of  the  great 
solar  plexus,  receiving  a  branch  from  the  junction  of  the  right  pneumogastric 
nerve  with  the  cceliac  plexus.  It  surrounds  the  superior  mesenteric  artery,  which 
it  accompanies  into  the  mesentery,  and  divides  into  a  number  of  secondary  plex- 
uses, which  are  distributed  to  all  the  parts  supplied  by  the  artery,  viz.,  pan- 
creatic branches  to  the  pancreas ;  intestinal  branches,  which  supply  the  whole  of 
the  small  intestine ;  and  ileo-  colic,  right  colic,  and  middle  colic  branches,  which 
supply  the  corresponding  parts  of  the  great  intestine.  The  nerves  composing 
this  plexus  are  white  in  color,  and  firm  in  texture,  and  have  numerous  ganglia 
developed  upon  them  near  their  origin. 

The  aortic  plexus  is  formed  by  branches  derived,  on  each  side,  from  the  semi- 
lunar ganglia  and  renal  plexuses,  receiving  filaments  from  some  of  the  lumbar 
ganglia.  It  is  situated  upon  the  sides  and  front  of  the  aorta,  between  the  origins 
of  the  superior  and  inferior  mesenteric  arteries.  From  this  plexus  arise  the  in- 
ferior mesenteric,  part  of  the  spermatic,  and  the  hypogastric  plexuses ;  and  it  dis- 
tributes filaments  to  the  inferior  cava. 

The  inferior  mesenteric  plexus  is  derived  chiefly  from  the  left  side  of  the  aortic 
plexus.  It  surrounds  the  inferior  mesenteric  artery,  and  divides  into  a  number  of 
secondary  plexuses,  which  are  distributed  to  all  the  parts  supplied  by  the  artery, 
viz.,  the  left  colic  and  sigmoid  plexuses,  which  supply  the  descending  and  sigmoid 


600  SYMPATHETIC   NERYE. 

flexure  of  the  colon ;  and  the  superior  hemorrhoidal  plexus,  which  supplies  the 
upper  part  of  the  rectum,  and  joins  in  the  pelvis  with  branches  from  the  left 
hypogastric  plexus. 

The  Lumbar  Portion  of  the  Sympathetic. 

The  lumbar  portion  of  the  sympathetic  is  situated  in 'front  of  the  vertebral 
column,  along  the  inner  margin  of  the  Psoas  muscle.  It  consists  usually  of  four 
ganglia,  connected  together  by  interganglionic  cords.  The  ganglia  aie  of  small 
size,  of  a  grayish  color,  hordeiform  in  shape,  and  placed  much  nearer  the  median 
line  than  the  thoracic  ganglia. 

The  superior  and  inferior  branches  of  the  lumbar  ganglia  serve  as  communicat- 
ing branches  between  the  chain  of  ganglia  in  this  region.  They  are  usually  single, 
and  of  a  white  color. 

The  external  branches  communicate  with  the  lumbar  spinal  nerves.  Prom  the 
situation  of  the  lumbar  ganglia,  these  branches  are  longer  than  in  the  other 
regions.  They  are  usually  two  in  number  for  each  ganglion,  and  accompany  the 
lumbar  arteries  around  the  sides  of  the  bodies  of  the  vertebrae,  passing  beneath 
the  fibrous  arches  from  which  the  fibres  of  the  Psoas  muscle  partly  arise. 

The  internal  branches  pass  inwards,  in  front  of  the  aorta,  and  form  the  lumbar 
aortic  plexus  (already  described).  Other  branches  descend  in  front  of  the  com- 
mon iliac  arteries,  and  join,  over  the  promontory  of  the  sacrum,  to  form  the 
hypogastric  plexus.  Numerous  delicate  filaments  are  also  distributed  to  the 
bodies  of  the  vertebras  and  the  ligaments  connecting  them. 

Pelvic  Portion  of  the  Sympathetic. 

The  pelvic  portion  of  the  sympathetic  is  situated  in  front  of  the  sacrum,  along 
the  inner  side  of  the  anterior  sacral  foramina.  It  consists  of  four  or  five  small 
ganglia  on  each  side,  connected  together  by  interganglionic  cords.  Below,  they 
converge  and  unite  on  the  front  of  the  coccyx,  by  means  of  a  small  ganglion 
(ganglion  impar). 

The  superior  and  inferior  branches  are  the  cords  of  communication  between  the 
ganglia  above  and  below. 

The  external  branches,  exceedingly  short,  communicate  with  the  sacral  nerves. 
They  are  two  in  number  to  each  ganglion.  The  coccygeal  nerve  communicates 
either  with  the  last  sacral  or  the  coccygeal  ganglion. 

The  internal  branches  communicate,  on  the  front  of  the  sacrum,  with  the 
corresponding  branches  from  the  opposite  side ;  some,  from  the  first  two  ganglia, 
pass  to  join  the  pelvic  plexus,  and  others  form  a  plexus,  which  accompanies  the 
middle  sacral  artery. 

The  hypogastric  plexus  supplies  the  viscera  of  the  pelvic  cavity.  It  is  situated 
in  front  of  the  promontory  of  the  sacrum,  between  the  two  common  iliac  arteries, 
and  is  formed  by  the  union  of  numerous  filaments,  which  descend  on  each  side 
from  the  aortic  plexus,  from  the  lumbar  ganglia,  and  from  the  first  two  sacral 
ganglia.  This  plexus  contains  no  ganglia,  and  bifurcates,  below,  into  two  lateral 
portions,  which  form  the  inferior  hypogastric  or  pelvic  plexuses. 

Inferior  Hypogastric  or  Pelvic  Plexus. 

The  inferior  hypogastric  or  pelvic  plexus  is  situated  at  the  side  of  the  rectum 
and  bladder  in  the  male,  and  at  the  side  of  the  rectum,  vagina,  and  bladder, 
in  the  female.  It  is  formed  by  a  continuation  of  the  hypogastric  plexus,  by 
branches  from  the  second,  third,  and  fourth  sacral  nerves,  and  by  a  few  filaments 
from  the  sacral  ganglia.  At  the  point  of  junction  of  these  nerves,  small  ganglia 
are  found.  From  this  plexus  numerous  branches  are  distributed  to  all  the  viscera 
of  the  pelvis.     They  accompany  the  branches  of  the  internal  iliac  artery. 


PELVIC   PLEXUS.  601 

The  inferior  hemorrhoidal  plexus  arises  from  the  back  part  of  the  pelvic 
plexus.  It  supplies  the  rectum,  joining  with  branches  of  the  superior  hemorrhoidal 
plexus. 

The  vesical  plexus  arises  from  the  fore  part  of  the  pelvic  plexus.  The  nerves 
composing  it  are  numerous,  and  contain  a  large  proportion  of  spinal  nerve  fibres. 
They  accompany  the  vesical  arteries,  and  are  distributed  to  the  side  and  base  of 
the  bladder.  Numerous  filaments  also  pass  to  the  vesiculas  seminales,  and  vas 
deferens ;  those  accompanying  the  vas  deferens  join,  on  the  spermatic  cord,  with 
branches  from  the  spermatic  plexus. 

The  prostatic  plexus  is  continued  from  the  lower  part  of  the  pelvic  plexus. 
The  nerves  composing  it  are  of  large  size.  They  are  distributed  to  the  prostate 
gland,  vesicula3  seminales,  and  erectile  structure  of  the  penis.  The  nerves  sup- 
plying the  erectile  structure  of  the  penis  consist  of  two  sets,  the  small  and  large 
cavernous  nerves.  They  are  slender  filaments,  which  arise  from  the  fore  part  of 
the  prostatic  plexus;  and,  after  joining  with  branches  from  the  internal  pudic 
nerve,  pass  forwards  beneath  the  pubic  arch. 

The  small  cavernous  nerves  perforate  the  fibrous  covering  of  the  penis  near 
its  root. 

The  large  cavernous  nerve  passes  forwards  along  the  dorsum  of  the  penis,  joins 
with  the  dorsal  branch  of  the  pudic  nerve,  and  is  distributed  to  the  corpus  caver  - 
nosum  and  corpus  spongiosum. 

The  vaginal  plexus  arises  from  the  lower  part  of  the  pelvic  plexus.  It  is  lost 
on  the  walls  of  the  vagina,  being  distributed  to  the  erectile  tissue  at  its  anterior 
part,  and  to  the  mucous  membrane.  The  nerves  composing  this  plexus  contain, 
like  the  vesical,  a  large  proportion  of  spinal  nerve  fibres. 

The  uterine  nerves  arise  from  the  lower  part  of  the  hypogastric  plexus,  above 
the  point  where  the  branches  from  the  sacral  nerves  join  the  pelvic  plexus.  They 
accompany  the  uterine  arteries  to  the  side  of  the  organ  between  the  layers  of  the 
broad  ligament,  and  are  distributed  to  the  cervix  and  lower  part  of  the  body  of 
the  uterus,  penetrating  its  substance. 

Other  filaments  pass  separately  to  the  body  of  the  uterus  and  Fallopian  tube. 

Branches  from  the  hypogastric  plexus  accompany  the  uterine  arteries  into  the 
substance  of  the  uterus.     Upon  these  filaments  ganglionic  enlargements  are  found.1 

1  Much  difference  of  opinion  still  exists  as  to  whether  the  uterine  nerves  enlarge  during  preg- 
nancy. Dr.  Robert  Lee  states,  as  the  result  of  a  series  of  elaborate  investigations,  that  the 
nerves  and  ganglia  supplying  the  uterus  become  greatly  enlarged  during  gestation,  thus  confirm- 
ing the  observations  previously  made  by  William  Hunter,  and  Tiedemann.  Dr.  Snow  Beck,  on 
the  other  hand,  asserts  that  the  nerves  do  not  alter  in  size  during  pregnancy. 

For  a  detailed  account  of  this  subject,  the  reader  should  refer  to  "The  Anatomy  of  the  Nerves 
of  the  Uterus,"  by  Robert  Lee,  M.  D.,  1841;  to  two  papers  by  the  same  author  in  the  Phil. 
Trans.,  for  1842 ;  and  to  Dr.  Snow  Beck's  paper,  "On  the  Nerves  of  the  Uterus,"  in  the  Phil. 
Trans.,  for  1846. 


Organs  of  the  Senses. 


The  Organs  of  the  Senses  are  the  instruments  by  which  the  mind  is  brought 
into  relation  with  external  objects.  These  organs  are  five  in  number,  viz.,  the 
organs  of  touch,  of  smell,  of  taste,  of  hearing,  and  of  sight. 

The  Skin. 

The  skin  is  the  principal  seat  of  the  sense  of  touch,  and  may  be  regarded  as  a 
covering  for  the  protection  of  the  deeper  tissues ;  it  is  also  an  important  excretory 
and  absorbing  organ.  It  consists  of  two  layers,  the  derma  or  cutis  vera,  and  the 
epidermis  or   cuticle.     On  the  surface  of  the  former   layer  are  the  sensitive 


Fig.  297.— A  Sectional  View  of  the  Skin  (magnified). 


1/u.trUat Artery 


papillae  j  and  within,  or  imbedded  beneath  it,  are  the  sweat-glands,  hair-follicles, 
and  sebaceous  glands. 

The  derma  or  true  skin  is  tough,  flexible,  and  highly  elastic,  being  admirably 

adapted  to  defend  the  internal  parts  from  violence.     It  consists  of  fibro-areolar 

tissue,    intermixed  with  numerous  bloodvessels,  lymphatics,    and  nerves.     The 

fibro-areolar  tissue  forms  the  framework  of  the  cutis ;  it  is  composed  of  firm 

602 


THE    SKIN.  603 

interlacing  bundles  of  white  fibrous  tissue,  intermixed  with  a  much  smaller  pro- 
portion of  yellow  elastic  fibres,  the  amount  of  which  varies  in  different  parts. 
The  fibro-areolar  tissue  is  more  abundant  in  the  deeper  layers  of  the  cutis,  where 
it  is  dense  and  firm,  the  meshes  being  large,  and  gradually  becoming  blended  with 
the  subcutaneous  areolar  tissue ;  towards  the  surface,  the  fibres  become  finer  and 
more  closely  interlaced,  the  most  superficial  layer  being  covered  with  numerous 
small,  conical,  vascular  eminences,  the  papilla?.  From  these  differences  in  the 
structure  of  the  cutis  at  different  parts,  it  is  usual  to  describe  it  as  consisting  of 
two  layers ;  the  deep  layer  or  corium,  and  the  superficial  or  papillary  layer. 

The  corium  consists  of  strong  interlacing  fibrous  bands,  composed  chiefly  of 
the  white  variety  of  fibrous  tissue ;  but  containing,  also,  some  fibres  of  the  yellow 
elastic  tissue,  which  vary  in  amount  in  different  parts.  Towards  the  attached 
surface,  the  fasciculi  are  large  and  coarse ;  and  the  areola?  left  by  their  interlacing 
large  and  occupied  by  adipose  tissue  and  the  sweat-glands.  This  element  of 
the  skin  becomes  gradually  blended  with  the  subcutaneous  areolar  tissue.  Towards 
the  free  surface,  the  fasciculi  are  much  finer,  and  they  have  a  closer  interlacing, 
the  most  superficial  layers  consisting  of  a  transparent,  homogeneous  matrix  with 
imbedded  nuclei. 

The  corium  varies  in  thickness,  from  a  quarter  of  a  line  to  a  line  and  a  half,  in 
different  parts  of  the  body.  Thus,  it  is  thicker  in  the  more  exposed  regions,  as 
the  palm  of  the  hand  and  sole  of  the  foot ;  on  the  posterior  aspect  of  the  body, 
than  the  front ;  and  on  the  outer  side  of  the  limbs  than  the  inner.  In  the  eye- 
lids, scrotum,  and  penis,  it  is  exceedingly  thin  and  delicate.  The  skin  generally 
is  thicker  in  the  male  than  in  the  female. 

The  areolae  are  occupied  by  adipose  tissue,  hair  follicles,  and  the  sudatory  and 
sebaceous  glands;  they  are  the  channel  by  which  the  vessels  and  nerves  are 
distributed  to  the  more  superficial  strata  of  the  corium,  and  to  the  papillary 
layer. 

Plain  muscular  fibres  are  found  in  the  superficial  layers  of  the  corium,  where- 
ever  hairs  are  found ;  and  in  the  subcutaneous  areolar  tissue  of  the  scrotum,  penis, 
perineum,  and  areolae  of  the  nipple.  In  the  latter  situations,  the  fibres  are  arranged 
in  bands,  closely  reticulated  and  disposed  in  superimposed  lamina?. 

The  papillary  layer  is  situated  upon  the  free  surface  of  the  corium ;  it  consists 
of  numerous  small,  highly  sensitive,  and  vascular  eminences,  the  papillae,  which' 
rise  perpendicularly  from  its  surface,  and  form  the  essential  element  of  the  organ 
of  touch.  The  papillae  are  conical-shaped  eminences,  having  a  round  or  blunted 
extremity,  occasionally  divided  into  two  or  more  parts,  and  connected  by  their 
base  with  the  free  surface  of  the  corium.  Their  average  length  is  about  T^th 
of  an  inch,  and  they  measure  at  their  base  about  35  ^th  of  an  inch  in  diameter. 
On  the  general  surface  of  the  body,  more  especially  in  those  parts  which  are 
endowed  with  slight  sensibility,  they  are  few  in  number,  short,  exceedingly  minute, 
and  irregularly  scattered  over  the  surface ;  but  in  other  situations,  as  upon  the 
palmar  surface  of  the  hands  and  fingers,  upon  the  plantar  surface  of  the  feet  and 
toes,  and  around  the  nipple,  they  are  long,  of  large  size,  closely  aggregated 
together,  and  arranged  in  parallel  curved  lines,  'forming  the  elevated  ridges  seen 
on  the  free  surface  of  the  epidermis.  In  these  ridges,  the  larger  papillae  are 
arranged  in  a  double  row,  with  smaller  papillae  between  them ;  and  these  rows  are 
subdivided  into  small  square-shaped  masses  by  short  transverse  furrows  regularly 
disposed,  in  the  centre  of  each  of  which  is  the  minute  orifice  of  the  duct  of  a 
sweat-gland.  No  papillae  exist  in  the  grooves  between  the  ridges.  In  structure 
the  papillae  resemble  the  superficial  layer  of  the  cutis;  consisting  of  a  homogeneous 
tissue,  faintly  fibrillated,  and  containing  a  few  fine  elastic  fibres.  The  smaller 
papilla?  contain  a  single  capillary  loop ;  but  in  the  larger  the  vessels  are  convoluted 
to  a  greater  or  less  degree ;  each  papilla  also  contains  one  or  more  nerve  fibres* 
but  the  mode  in  which  these  terminate  is  uncertain.  In  those  parts  in  which  the 
sense  of  touch  is  highly  developed,  as  in  the  lips  and  palm  of  the  hand,  the 
nerve  fibres  appear  to  have  some  intimate  connection  with  an  oval-shaped  body, 


604  ORGANS   OF   THE    SENSES. 

not  unlike  a  Pacinian  corpuscle,  which  occupies  the  principal  part  of  the  interior 
of  each  papilla,  named  "tactile  corpuscle."  The  nature  of  these  bodies  is  obscure. 
Wagner  described  them  as  oval-shaped  bodies,  made  up  of  superimposed  saccular 
laminae,  presenting  some  resemblance  to  a  miniature  fir  cone,  and  regarded  them  as 
directly  concerned  in  the  sense  of  touch.  Kolliker  considers  that  the  central  part 
of  the  papillae  generally  consists  of  a  more  homogeneous  connective  tissue  than 
the  outer  part,  surrounded  by  a  sort  of  sheath  of  elastic  fibres,  and  believes  that 
these  corpuscles  are  merely  a  variety  of  this  structure.  The  nerve  fibres,  accord- 
ing to  this  observer,  run  up  in  a  waving  course  to  the  corpuscle,  not  penetrating 
it,  but  forming  two  or  three  coils  round  it,  and  finally  join  together  in  loops. 
These  bodies  are  not  found  in  all  the  papillae ;  but  from  their  existence  in  those 
parts  in  which  the  skin  is  highly  sensitive,  it  is  probable  that  they  are  specially 
concerned  in  the  sense  of  touch,  but  their  absence  from  the  papillae  of  other 
tactile  parts  shows  that  they  are  not  essential  to  this  sense.  No  lymphatics  have 
as  yet  been  discovered  in  the  papillae. 

The  epidermis,  cuticle,  or  scarf-skin,  is  an  epithelial  structure,  accurately  moulded 
on  the  papillary  layer  of  the  derma.  It  forms  a  defensive  covering  to.  the  surface 
of  the  true  skin,  and  limits  the  evaporation  of  watery  vapor  from  its  free  surface. 
It  varies  in  thickness  in  different  parts.  Where  it  is  exposed  to  pressure  and  the 
influence  of  the  atmosphere,  as  upon  the  palms  of  the  hands  and  soles  of  the  feet, 
it  is  thick,  hard,  and  horny  in  texture ;  whilst  that  which  lies  in  contact  with  the 
rest  of  the  body  is  soft  and  cellular  in  structure.  The  deeper  and  softest  layers 
have  been  called  the  rete  mucosum,  the  term  rete  being  applied,  from  the  deepest 
layers  presenting,  when  isolated,  numerous  depressions,  or  complete  apertures, 
which  have  been  occupied  by  the  projecting  papillae. 

The  free  surface  of  the  epidermis  is  marked  by  a  network  of  linear  furrows  of 
variable  size,  marking  out  the  surface  into  a  number  of  spaces  of  polygonal  or 
lozenge-shaped  form.  Some  of  these  furrows  are  large,  as  opposite  the  flexures 
of  the  joints,  and  correspond  to  the  folds  in  the  derma  produced  by  their  move- 
ments. In  other  situations,  as  upon  the  back  of  the  hand,  they  are  exceedingly 
fine,  and  intersect  one  another  at  various  angles ;  upon  the  palmar  surface  of  the 
hand  and  fingers,  and  upon  the  sole,  these  lines  are  very  distinct,  and  have  a 
curvilinear  arrangement,  and  depend  upon  the  large  size  and  peculiar  arrangement 
of  the  papillae  upon  which  the  epidermis  is  placed.  The  deep  surface  of  the 
epidermis  is  accurately  moulded  upon  the  papillary  layer  of  the  derma,  each 
papilla  being  invested  by  its  epidermic  sheath ;  so  that  when  this  layer  is  removed 
by  maceration,  it  presents  a  number  of  pits  or  depressions  corresponding  to  the 
elevations  of  the  papillae,  as  well  as  the  furrows  left  in  the  intervals  between  them. 
Fine  tubular  prolongations  from  this  layer  are  continued  into  the  ducts  of  the 
sudatory  and  sebaceous  glands.  In  structure,  the  epidermis  consists  of  flattened 
cells,  agglutinated  together,  and  having  a  laminated  arrangement.  In  the  deeper 
layers  the  cells  are  large,  rounded  or  columnar,  and  filled  with  soft  opaque  contents. 

In  the  superficial  layers  the  cells  are  flattened,  transparent,  dry,  and  firm,  and 
their  contents  converted  into  a  kind  of  horny  matter.  The  difference  in  the 
structure  of  these  layers  is  dependent  upon  the  mode  of  growth  of  the  epidermis. 
As  the  external  layers  desquamate,  from  their  being  constantly  subjected  to  attri- 
tion, they  are  reproduced  from  beneath,  successive  layers  gradually  approaching 
towards  the  free  surface,  which,  in  their  turn,  die  and  are  cast  off. 

These  cells  are  developed  in  the  liquor,  sanguinis,  which  is  poured  out  on  the 
free  surface  of  the  derma ;  they  contain  nuclei,  and  form  a  thin  stratum  of  closely- 
aggregated  nucleated  cells,  which  cover  the  entire  extent  of  the  papillary  layer. 
The  deepest  layer  of  cells,  according  to  Kolliker,  are  of  a  columnar  form,  and  are 
arranged  perpendicularly  to  the  free  surface  of  the  derma,  forming  either  a  single 
or  a  double,  or  even  triple,  layer ;  the  laminae  succeeding  these  are  composed  of 
cells  of  a  more  rounded  form,  the  contents  of  which  are  soft,  opaque,  granular,  and 
soluble  in  acetic  acid.  As  these  cells  successively  approach  the  surface  by  the 
development  of  fresh  layers  from  beneath,  they  assume  a  flattened  shape  from  the 


APPENDAGES   OF   THE   SKIN.  605 

evaporation  of  their  fluid  contents,  and  finally  form  a  transparent,  dry,  mem- 
branous scale,  lose  their  nuclei,  and  apparently  become  changed  in  their  chemical 
composition,  as  they  are  unaffected  now  by  acetic  acid. 

The  black  color  of  the  skin  in  the  negro,  and  the  tawny  color  among  some  of 
the  white  races,  is  due  to  the  presence  of  pigment  in  the  cells  of  the  cuticle. 
This  pigment  is  more  especially  distinct  in  the  cells  of  the  deeper  layer  or  rote 
mucosum,  and  is  similar  to  that  found  in  the  choroid.  As  the  cells  approach  the 
surface  and  desiccate,  the  color  becomes  partially  lost. 

The  arteries  which  supply  the  skin  divide  into  numerous  branches  in  the  sub- 
cutaneous tissue ;  they  then  pass  through  the  areola?  of  the  corium,  and  divide 
into  a  dense  capillary  plexus,  which  supplies  the  sudatory  and  sebaceous  glands 
and  the  hair  follicles,  terminating  in  the  superficial  layers  of  the  corium,  by  form- 
ing a  capillary  network,  from  which  numerous  fine  branches  ascend  to  the  papilla?. 

The  lymphatic  vessels  are  arranged  in  a  minute  plexiform  network  in  the 
superficial  layers  of  the  corium,  where  they  become  interwoven  with  the  capillary 
and  nervous  plexuses ;  they  are  especially  abundant  in  the  scrotum  and  round 
the  nipple. 

The  nerves  which  supply  the  skin  ascend  with  the  vessels  through  the  areola? 
of  the  deep  layers  of  the  corium  to  the  more  superficial  layers,  where  they  form 
a  minute  plexiform  mesh.  From  this  plexus,  the  primitive  nerve  fibres  pass  to 
be  distributed  to  the  papilla?.  The  nerves  are  most  numerous  in  those  parts  which 
are  provided  with  the  greatest  sensibility. 

Appendages  of  the  Skin. 

The  appendages  of  the  skin  are,  the  nails,  the  hairs,  the  sudoriferous  and 
sebaceous  glands,  and  their  ducts. 

The  nails  and  hairs  are  peculiar  modifications  of  the  epidermis,  consisting 
essentially  of  the  same  cellular  structure  as  that  membrane. 

The  Nails  are  flattened  elastic  structures  of  a  horny  texture,  placed  upon  the 
dorsal  surface  of  the  terminal  phalanges  of  the  fingers  and  toes.  Each  nail  is 
convex  on  its  outer  surface,  concave  within,  and  is  implanted  by  a  portion  called 
the  root  into  a  groove  of  the  skin;  the  exposed  portion  is  called  the  body,  and  the 
anterior  extremity,  the  free  edge.  The  nail  has  a  very  firm  adhesion  to  the  cutis, 
being  accurately  moulded  upon  its  surface,  as  the  epidermis  is  in  other  parts. 
The  part  of  the  cutis  beneath  the  body  and  root  of  the  nail  is  called  the  matrix, 
from  its  being  the  part  from  which  the  nail  is  produced.  Corresponding  to  the  body 
of  the  nail,  the  matrix  is  thick,  and  covered  with  large  highly  vascular  papilla?, 
arranged  in  longitudinal  rows,  the  color  of  which  is  seen  through  the  transparent 
tissue.  Behind  this,  near  the  root  of  the  nail,  the  papilla?  are  small,  less  vascular, 
and  have  no  regular  arrangement ;  hence  the  portion  of  the  nail  corresponding 
to  this  part  is  of  a  whiter  color,  and  called  lunula  from  its  form. 

The  cuticle,  as  it  passes  forwards  on  the  dorsal  surface  of  the  finger,  is  attached 
to  the  surface  of  the  nail,  a  little  in  advance  of  its  root ;  at  the  extremity  of  the 
finger,  it  is  connected  with  the  under  surface  of  the  nail,  a  little  behind  its  free  edge. 
The  cuticle  and  horny  structure  of  the  nail,  both  epidermic  structures,  are  thus 
seen  to  be  directly  continuous  with  each  other.  The  nails,  in  structure,  consist  of 
cells  having  a  laminated  arrangement,  and  these  are  almost  essentially  similar  to 
those  composing  the  epidermis.  The  deepest  layer  of  cells  which  lie  in  contact 
with  the  papilla?  at  the  root  and  under  surface  of  the  nail,  are  of  elongated  form, 
arranged  perpendicularly  to  the  surface,  and  provided  with  nuclei ;  those  which 
succeed  these  are  of  a  rounded  or  polygonal  form,  the  more  superficial  ones 
becoming  broad,  thin,  and  flattened,  and  so  closely  compacted  together  as  to  make 
the  limits  of  each  cell  very  indistinct. 

It  is  by  the  successive  growth  of  new  cells  at  the  root  and  under  surface  of  the 
body  of  the  nail,  that  it  advances  forwards,  and  maintains  a  due  thickness,  whilst, 
at  the  same  time,  the  growth  of  the  nail  in  the  proper  direction  is  secured.  As 
these  cells  in  their  turn  become  displaced  by  the  growth  of  new  cells,  they  assume 


606        .  ORGANS   OF   THE   SENSES. 

a  flattened  form,  lose  their  nuclei,  and  finally  become  closely  compacted  together 
into  a  firm,  dense,  horny  texture.  In  chemical  composition,  the  nails  resemble  the 
epidermis.  According  to  Mulder,  they  contain  a  somewhat  larger  proportion  of 
carbon  and  sulphur. 

Hairs  are  peculiar  modifications  of  the  epidermis,  and  consist  essentially  of  the 
same  structure  as  that  membrane.  They  are  found  on  nearly  every  part  of  the 
surface  of  the  body,  excepting  the  pa*lms  of  the  hands  and  soles  of  the  feet,  and 
vary  much  in  length,  thickness,  and  color  in  different  parts  of  the  body,  and  in 
the  different  races  of  mankind.  In  some  parts  they  are  so  short  as  not  to  project 
beyond  the  follicle  containing  them ;  in  other  parts,  as  upon  the  scalp,  they  are  of 
considerable  Jength ;  along  the  margin  of  the  eyelids  and  upon  the  face,  they  are 
remarkable  for  their  thickness.  A  hair  consists  of  a  root,  the  part  implanted  in 
the  skin ;  the  shaft,  the  portion  projecting  from  its  surface ;  and  the  point.  They 
generally  present  a  cylindrical  or  more  or  less  flattened  form,  and  a  reniform  out- 
line upon  a  transverse  section. 

The  root  of  the  hair  presents  a  bulbous  enlargement  at  its  extremity ;  it  is 
whiter  in  color,  and  softer  in  texture,  than  the  stem,  and  is  lodged  in  a  follicular 
involution  of  the  epidermis,  called  the  hair-follicle.  When  the  hair  is  of  con- 
siderable length,  the  follicle  extends  into  the  subcutaneous  cellular  tissue.  The 
hair-follicle  is  bulbous  at  its  deep  extremity,  like  the  hair  which  it  contains,  and 
has  opening  into  it,  near  its  free  extremity,  the  orifices  of  the  ducts  of  one  or  more 
sebaceous  glands.  In  structure,  the  hair-follicle  consists  of  two  coats :  an  outer 
or  dermic,  and  an  inner  or  cuticular.  The  outer  coat  is  formed  mainly  of  areolar 
tissue;  it  is  continuous  with  the  corium,  is  highly  vascular,  and  supplied  by 
numerous  minute  nervous  filaments.  The  inner  or  cuticular  lining  is  continuous 
with  the  epidermis,  and,  at  the  bottom  of  the  hair-follicle,  with  the  root  of  the  hair ; 
this  cuticular  lining  resembles  the  epidermis  in  the  peculiar  rounded  form  and  soft 
character  of  those  cells  which  lie  in  contact  with  the  outer  coat  of  the  hair-follicle, 
and  the  thin,  dry,  and  scaly  character  of  those  which  lie  near  the  surface  of  the 
hair,  to  which  they  are  closely  adherent.  "When  the  hair  is  plucked  from  its 
follicle,  this  cuticular  lining  most  commonly  adheres  to  it,  and  forms  what  is  called 
the  root-sheath.  At  the  bottom  of  each  hair-follicle  is  a  small  conical-shaped 
vascular  eminence  or  papilla,  similar  in  every  respect  to  those  found  upon  the 
surface  of  the  skin;  it  is  continuous  with  the  dermic  layer  of  the  follicle,  is  highly 
vascular,  and  probably  supplied  with  nervous  fibrils :  this  is  the  part  through 
which  material  is  supplied  for  the  production  and  constant  growth  of  the  hair. 
The  root  of  the  hair  rests  upon  this  conical-shaped  eminence,  and  is  continuous 
with  the  cuticular  lining  of  the  follicle  at  this  part.  It  consists  of  nucleated  cells, 
similar  in  every  respect  to  those  which  in  other  situations  form  the  epidermis. 
These  cells  gradually  enlarge  as  they  are  pushed  upwards  into  the  soft  bulb,  and 
some  of  them  contain  pigment  granules,  which  exist  either  in  separate  cells,  or 
the  granules  are  separate,  but  aggregated  round  the  nucleus ;  it  is  these  granules 
which  give  rise  to  the  color  of  the  hair.  It  occasionally  happens  that  these 
pigment  granules  completely  fill  the  cells  in  the  centre  of  the  bulb,  which  gives 
rise  to  the  dark  tract  of  pigment  often  found,  of  greater  or  less  length,  in  the  axis 
of  the  hair. 

The  shaft  of  the  hair  consists  of  a  central  part  or  medulla ;  surrounding  this  is 
the  fibrous  part  of  the  hair,  covered  externally  by  the  cortex.  The  medulla 
occupies  the  centre  of  the  shaft,  and  ceases  towards  the  point  of  the  hair.  It  is 
usually  wanting  in  the  fine  hairs  covering  the  surface  of  the  body,  and  commonly 
in  those  of  the  head.  It  is  more  opaque  and  deeper  colored  than  the  fibrous  part, 
and  consists  of  cells  containing  pigment  or  fat-granules.  The  fibrous  portion  of 
the  hair  constitutes  the  chief  part  of  the  stem  ;  its  cells  are  elongated,  and  unite 
to  form  flattened  fusiform  fibres.  These  also  contain  pigment  granules,  which 
assume  a  linear  arrangement.  The  cells  which  form  the  cortex  of  the  hair  consist 
of  a  single  layer  which  surrounds  those  about  to  form  the  fibrous  layer ;  they  arc 
converted  into  thin  flat  scales,  having  an  imbricated  arrangement. 


APPENDAGES   OF   THE    SKIN.  607 

The  Sebaceous  Glands  are  small,  sacculated,  glandular  organs,  lodged  in  the 
substance  of  the  corium  or  sub-dermoid  tissue.  They  are  found  in  most  parts  of 
the  skin,  but  are  most  abundant  in  the  scalp  and  face ;  they  are  also  very  numerous 
around  the  apertures  of  the  anus,  nose,  mouth,  and  external  ear ;  but  are  wanting 
in  the  palms  of  the  hands,  and  the  soles  of  the  feet.  Each  gland  consists  of  a 
single  duct,  more  or  less  capacious,  which  terminates  in  a  lobulated  pouch-like 
extremity.  The  basement  membrane  forming  the  wall  of  the  sac,  as  well  as  the 
duct,  is  lined  by  epithelium,  which  is  filled  with  particles  of  sebaceous  matter ; 
and  this  becoming  detached  into  the  cavity  of  the  sac,  as  its  growth  is  renewed, 
constitutes  the  secretion.  The  number  of  sacculi  connected  with  each  duct  vary 
from  two  to  five,  or  even  twenty,  in  number.  The  orifices  of  the  ducts  open  most 
frequently  into  the  hair-follicles,  but  occasionally  upon  the  general  surface.  On 
the'  nose  and  face,  the  glands  are  of  large  size,  distinctly  lobulated,  and  often 
become  much  enlarged  from  the  accumulation  of  pent-up  secretion.  The  largest 
sebaceous  glands  are  those  found  in  the  eyelid,  the  Meibomian  glands. 

The  Sudoriferous  or  Sweat-glands  are  the  organs  by  which  a  large  portion  of 
the  aqueous  and  gaseous  materials  are  excreted  by  the  skin.  They  are  found  in 
almost  every  part  of  the  skin,  and  are  situated  in  small  pits  in  the  deep  parts  of 
the  corium,  or  in  the  subcutaneous  areolar  tissue,  surrounded  by  a  quantity 
of  adipose  tissue.  They  are  small,  lobular,  reddish  bodies,  consisting  of  one  or 
more  convoluted  tubuli,  from  which  the  efferent  duct  proceeds  upwards  through 
the  corium  and  cuticle,  and  opens  upon  the  surface  by  a  slightly  enlarged  orifice. 
The  efferent  duct,  as  it  passes  through  the  corium,  pursues,  for  a  short  distance,  a 
spiral  course,  becoming  straight  in  the  more  superficial  part  of  this  layer,  and 
opens  on  the  surface  of  the  cuticle  by  an  oblique  valve-like  aperture.  In  the 
parts  where  the  epidermis  is  thin,  the  ducts  are  finer  and  almost  straight  in  their 
course ;  but  where  the  epidermis  is  thicker,  they  assume  again  a  spiral  arrange- 
ment, the  separate  windings  of  the  tube  being  as  close  and  as  regular  as  those  of 
a  common  screw.  The  spiral  course  of  these  ducts  is  especially  distinct  in  the  thick 
cuticle  of  the  palm  of  the  hand  and  sole  of  the  foot.  The  size  of  these  glands 
varies.  They  are  especially  large  in  those  regions  where  the  amount  of  perspira- 
tion is  great,  as  in  the  axillae,  where  they  form  a  thin  mammillated  layer  of  a 
reddish  color,  which  corresponds  exactly  to  the  situation  of  the  hair  in  this 
region ;  they  are  large,  also,  in  the  groin.  Their  number  varies :  they  are  most 
numerous  on  the  palm  of  the  hand,  and  present,  according  to  Krause,  2,800 
orifices  on  a  square  inch  of  the  integument,  and  a  rather  less  number  on  the  sole 
of  the  foot.  In  both  of  these  situations,  the  orifices  of  the  ducts  are  exceedingly 
regular,  and  correspond  to  the  small  transverse  grooves  which  intersect  the  ridges 
of  papillae.  In  other  situations  they  are  more  irregularly  scattered,  but  in  nearly 
equal  numbers  over  parts  including  the  same  extent  of  surface.  In  the  neck  and 
back  they  are  least  numerous,  their  number  amounting  to  417  on  the  square  inch 
(Krause).  Their  total  number  is  estimated  by  the  same  writer  at  2,381,248 ;  and 
supposing  the  aperture  of  each  gland  to  represent  a  surface  of  ?'5  of  a  line  in 
diameter,  he  calculates  that  the  whole  of  these  glands  would  present  an  evaporat- 
ing surface  of  about  eight  square  inches. 

Each  gland  consists  of  a  single  tube  intricately  convoluted,  at  one  end  termi- 
nating by  a  blind  extremity  ;  at  the  other  end  opening  upon  the  surface  of  the 
skin.  In  the  larger  glands,  this  single  duct  usually  divides  and  subdivides 
dichotomously ;  the  smaller  ducts  ultimately  terminating  in  short  caecal  pouches, 
rarely  anastomosing.  The  wall  of  the  duct  is  thick ;  the  width  of  the  canal  rarely 
exceeding  one-third  of  its  diameter.  The  tube,  both  in  the  gland  and  where  it 
forms  the  excretory  duct,  consists  of  two  layers :  an  outer,  formed  by  fine  areolar 
tissue ;  and  an  epithelium  lining  its  interior.  The  external  or  fibro-cellular  coat 
is  thin,  continuous  with  the  superficial  layer  of  the  corium,  and  extends  only  as 
high  as  the  surface  of  the  true  skin.  The  epithelial  lining  is  much  thicker,  con- 
tinuous with  the  epidermis,  and  alone  forms  the  spiral  portion  of  the  tube.  When 
the  cuticle  is  carefully  removed  from  the  surface  of  the  cutis,  these  convoluted 


G08 


ORGANS   OF   THE    SENSES. 


tubes  of  epidermis  may  be  drawn  out,  and  form  nipple-shaped  projections  on  its 
under  surface.  According  to  Kolliker,  a  layer  of  non-striated  muscular  fibres, 
arranged  longitudinally,  is  found  between  the  areolar  and  epithelial  coats  of  the 
ducts  of  the  larger  sweat-glands,  as  in  the  axilla,  root  of  the  penis,  on  the  labia 
majora,  and  around  the  anus. 

The  contents  of  the  smaller  sweat-glands  are  quite  fluid ;  but  in  the  larger 
glands,  the  contents  are  semi-fluid  and  opaque,  and  contain  a  number  of  colored 
granules,  and  cells  which  appear  analogous  to  epithelial  cells. 

The  Tongue. 

The  tongue  is  the  organ  of  the  special  sense  of  taste.  It  is  situated  in  the 
floor  of  the  mouth,  in  the  interval  between  the  two  lateral  portions  of  the  body  of 


Fig.  298. — Upper  Surface  of  the  Tongue. 


Tiliform 


-4  ]i  e  * 
FIC.299.   The  3  hinds    ef    PAPILLA  magnified 


ha  tulle* 


CtrrinnTitFTrtt* 


the  lower  jaw.  Its  base  or  root  is  directed  backwards,  and  connected  with  the 
os  hyoides  by  numerous  muscles,  to  the  epiglottis  by  three  folds  of  mucous  mem- 
brane, which  form  the  glosso-epiglottic  ligaments,  and  to  the  soft  palate  and 
pharynx  by  means  of  the  anterior  and  posterior  pillars  of  the  fauces.     Its  apex 


THE   TONGUE.  609 

or  tip,  thin  and  narrow,  is  directed  forwards  against  the  inner  surface  of  the 
lower  incisor  teeth.  The  under  surface  of  the  tongue  is  connected  with  the 
lower  jaw  by  the  Genio-hyo-glossi  muscles;  from  its  sides,  the  mucous  mem- 
brane is  reflected  to  the  inner  surface  of  the  gums ;  and,  in  front,  a  distinct  fold 
of  that  membrane,  the  fraenum  linguae,  is  formed  beneath  its  under  surface. 

The  tip  of  the  tongue,  part  of  its  under  surface,  its  sides,  and  dorsum,  are  free. 

The  dorsum  of  the  tongue  is  convex,  marked  along  the  middle  line  by  a  raphe, 
which  divides  it  into  two  symmetrical  halves ;  and  this  raphe  terminates  behind, 
about  half  an  inch  from  the  base  of  the  organ,  a  little  in  front  of  a  deep  mucous 
follicle,  the  foramen  csecum.  The  anterior  two-thirds  of  this  surface  are  rough, 
and  covered  with  papillae ;  the  posterior  third  is  more  smooth,  and  covered  by  the 
projecting  orifices  of  numerous  muciparous  glands. 

The  mucous  membrane  invests  the  entire  extent  of  the  free  surface  of  the 
tongue.  On  the  under  surface  of  the  organ  it  is  thin  and  smooth,  and  may  be 
traced  on  either  side  of  the  fraenum,  through  the  ducts  of  the  submaxillary  glands ; 
and  between  the  sides  of  the  tongue  and  the  lower  jaw,  through  the  ducts  of  the 
sublingual  glands.  On  being  traced  over  the  borders  of  the  organ,  it  gradually 
assumes  its  papillary  character. 

The  mucous  membrane  of  the  tongue  consists  of  structures  analogous  to  those 
of  the  skin,  namely,  a  cutis  or  corium,  supporting  numerous  papillse,  and  covered, 
as  well  as  the  papillae,  with  epithelium. 

The  cutis  is  tough,  but  thinner  and  less  dense  than  in  most  parts  of  the  skin, 
and  is  composed  of  similar  tissue.  It  contains  the  ramifications  of  the  numerous 
vessels  and  nerves  from  which  the  papillae  are  supplied,  and  affords  insertion  to 
all  the  intrinsic  muscular  fibres  of  the  organ. 

The  papillae  of  the  tongue  are  thickly  distributed  over  the  whole  of  its  upper 
surface,  giving  to  it  its  characteristic  roughness.  They  are  more  prominent  than 
those  of  the  skin,  which  is  chiefly  due  to  their  not  being  concealed  under  the 
epithelium,  but  from  their  standing  out  prominently  from  the  surface  like  the  villi 
of  the  intestine.  The  principal  varieties  are  the  papillae  maximae  (circumvallatae), 
papillae  mediae  (fungiformes),  and  papillae  minimae  (conicae  and  filiformes). 

The  papillse  maximse  (circumvallatae)  are  of  large  size,  and  vary  from  eight  to 
ten  in  number.  They  are  situated  at  the  back  part  of  the  dorsum  of  the  tongue, 
near  its  base,  forming  a  row  on  each  side,  which,  running  backwards  and  inwards, 
meet  in  the  middle  line,  like  the  two  lines  of  the  letter  A  inverted.  Each  papilla 
consists  of  a  central  flattened  projection  of  mucous  membrane,  circular  in  form, 
from  2'jj  to  ^  of  an  inch  wide,  attached  to  the  bottom  of  a  cup-shaped  depression 
of  the  mucous  membrane ;  the  exposed  part  being  covered  with  numerous  small 
papillae.  The  cup-shaped,  depression  forms  a  kind  of  fossa  round  the  papilla, 
having  a  circular  margin  of  about  the  same  elevation,  covered  with  smaller  papillae. 
The  fissure  corresponding  to  the  papilla,  where  the  two  lines  of  the  circum vallate 
papillae  meet,  is  so  large  and  deep,  that  the  name  foramen  csecum  has  been  applied 
to  it.     In  the  smaller  papillae,  the  fissure  exists  only  on  one  side. 

The  papillse  medise  (fungiformes),  more  numerous  than  the  preceding,  are 
scattered  irregularly  and  sparingly  over  the  dorsum  of  the  tongue,  but  are  found 
chiefly  at  its  sides  and  apex.  They  are  easily  recognized,  among  the  other  papillae, 
by  their  large  size,  rounded  eminences,  and  deep  red  color.  They  are  narrow  at 
their  attachment  to  the  tongue,  but  broad  and  rounded  at  their  free  extremities, 
and  covered  with  secondary  papillae.    Their  epithelium  investment  is  very  thin. 

The  papillse  minimse  (conicae  et  filiformes)  cover  the  anterior  two-thirds  of  the 
dorsum  of  the  tongue.  They  are  very  minute,  more  or  less  conical  or  filiform  in 
shape,  and  arranged  in  lines  corresponding  in  direction  with  the  two  rows  of  the 
papillae  circumvallatae,  excepting  at  the  apex  of  the  organ,  where  their  direction 
is  transverse.  The  filiform  papillae  are  of  a  whitish  tint,  owing  to  the  thickness 
and  density  of  their  epithelium;  they  are  covered  with  numerous  secondary 
papillae,  are  firmer  and  more  elastic  than  the  papillae  of  mucous,  membrane 
generally,  and  often  inclose  minute  hairs. 
39 


610  ORGANS   OF   THE   SENSES. 

Simple  papillse,  similar  to  those  of  the  skin,  are  dispersed  very  unequally 
among  the  compound  forms,  and  exist  sparingly  on  the  surface  of  the  tongue 
behind  the  circumvallate  variety,  buried  under  a  layer  of  epithelium. 

Structure  of  the  papillse.  The  papillae,  in  structure,  apparently  resemble  those 
of  the  cutis,  consisting  of  a  cone-shaped  projection  of  homogeneous  tissue, 
covered  with  a  thick  layer  of  squamous  epithelium,  and  contain  one  or  more 
capillary  loops,  amongst  which  nerves  are  distributed  in  great  abundance.  If  the 
epithelium  is  removed  it  will  be  found  that  they  are  not  simple  processes  like  the 
papillae  of  the  skin,  for,  according  to  Todd  and  Bowman,  the  surface  of  each  is 
studded  with  minute  conical  processes  of  the  mucous  membrane,  which  form 
secondary  papillae.  In  the  papillae  circumvallatae,  the  nerves  are  numerous  and  of 
large  size ;  in  the  papillae  fungiformes  they  are  also  numerous,  and  terminate  in  a 
plexiform  network,  from  which  brush-like  branches  proceed;  in  the  papillae 
flliformes,  their  mode  of  termination  is  uncertain. 

Besides  the  papillae,  the  mucous  membrane  of  the  tongue  is  provided  with 
numerous  follicles  and  glands. 

The  follicles  are  found  scattered  over  its  entire  surface,  but  are  especially 
numerous  between  the  papillae  circumvallatae  and  the  epiglottis. 

The  mucous  glands  (lingual),  similar  in  structure  to  the  labial  and  buccal,  are 
found  chiefly  beneath  the  mucous  membrane  of  the  posterior  third  of  the  dorsum 
of  the  tongue.  There  is  a  small  group  of  these  glands  beneath  the  tip  of  the 
tongue,  a  few  along  the  borders  of  the  organ,  and  some  in  front  of  the  circum- 
vallate papillae  projecting  into  the  muscular  substance.  Their  ducts  open  either 
upon  the  surface,  or  into  the  depressions  round  the  large  papillae. 

The  epithelium  is  of  the  scaly  variety  like  that  of  the  epidermis.  It  covers  the 
free  surface  of  the  tongue,  as  may  be  easily  demonstrated  by  maceration,  or  boiling, 
when  it  can  be  detached  entire,  but  it  is  much  thinner  than  in  the  skin,  the  inter- 
vals between  the  large  papillae  not  being  filled  up  by  it,  but  each  papilla  has  a 
separate  investment  from  root  to  summit.  The  deepest  cells  may  sometimes  be 
detached  as  a  separate  layer,  corresponding  to  the  rete  mucosum,  but  these  never 
contain  coloring  matter. 

The  tongue  consists  of  two  symmetrical  halves,  separated  from  each  other,  in 
the  middle  line,  by  a  fibrous  septum.  Each  half  is  composed  of  muscular  fibres 
arranged  in  various  directions,  containing  much  interposed  fat,  and  supplied 
by  vessels  and  nerves ;  the  entire  organ  is  invested  by  mucous  membrane,  and  a 
submucous  fibrous  stratum.  The  latter  membrane  invests  the  greater  part  of  the 
surface  of  the  tongue,  and  into  it  the  muscular  fibres  are  inserted  that  pass  to  the 
surface.  It  is  thicker  behind  than  in  front,  and  is  continuous  with  the  sheaths  of 
the  muscles  attached  to  it. 

The  fibrous  septum  consists  of  a  vertical  layer  of  fibrous  tissue,  extending 
throughout  the  entire  length  of  the  middle  line  of  the  tongue,  from  the  base  to 
the  apex.  It  is  thicker  behind  than  in  front,  and  occasionally  contains  a  small 
fibro-cartilage,  about  a  quarter  of  an  inch  in  length.  It  is  well  displayed  by 
making  a  vertical  section  through  the  organ.  Another  strong  fibrous  lamina, 
termed  the  hyo-glossal  membrane,  connects  the  under  surface  of  the  base  of  the 
tongue  to  the  body  of  the  hyoid  bone.  This  membrane  receives,  in  front,  some  of 
the  fibres  of  the  Genio-hyo-glossi. 

Each  half  of  the  tongue  consists  of  extrinsic  aud  intrinsic  muscles.  The  former 
have  been  already  described ;  they  are  the  Hyo-glossus,  Genio-hyo-glossus,  Stylo- 
glossus, Palato-glossus,  and  part  of  the  Superior  constrictor.  The  intrinsic  mus- 
cles are  the  Superior  longitudinal,  Inferior  longitudinal,  and  Transverse. 

The  superior  longitudinal  fibres  {lingualis  superficialis)  form  a  superficial 
stratum  of  oblique  and  longitudinal  fibres  on  the  upper  surface  of  the  organ, 
beneath  the  mucous  membrane,  and  extend  from  the  apex  backwards  to  the  hyoid 
bone,  the  individual  fibres  being  attached  in  their  course  to  the  submucous  and 
glandular  structures. 

The  inferior  longitudinal  fibres  are  formed  by  the  Lingualis  muscle,  already 
described  (p.  261). 


THE   NOSE.  611 

The  transverse  fibres  are  placed  between  the  two  preceding  layers ;  they  are 
intermixed  with  a  considerable  quantity  of  adipose  substance,  and  form  the  chief 
part  of  the  substance  of  the  organ.  They  are  attached  internally  to  the  median 
fibrous  septum  ;  and,  passing  outwards,  the  posterior  ones  taking  an  arched  course, 
are  inserted  into  the  dorsum  and  margins  of  the  organ,  intersecting  the  other 
muscular  fibres. 

The  arteries  of  the  tongue  are  supplied  from  the  lingual,  the  facial,  and  ascending 
pharyngeal. 

The  nerves  of  the  tongue  are  three  in  number  in  each  half;  the  gustatory 
branch  of  the  fifth,  which  is  distributed  to  the  papilla?  at  the  fore  part  and  sides 
of  the  tongue ;  the  lingual  branch  of  the  glosso-pharyngeal,  which  is  distributed 
to  the  mucous  membrane  at  the  base  and  side  of  the  tongue,  and  to  the  papilla) 
circumvallatse ;  and  the  hypoglossal  nerve,  which  is  distributed  to  the  muscular 
substance  of  the  tongue.  The  two  former  are  nerves  of  common  sensation  and 
of  taste ;  the  latter  is  the  motor  nerve  of  the  tongue. 

The  Nose. 

The  Nose  is  the  special  organ  of  the  sense  of  smell ;  by  means  of  the  peculiar 
properties  of  its  nerves,  it  protects  the  lungs  from  the  inhalation  of  deleterious 
gases,  and  assists  the  organ  of  taste  in  discriminating  the  properties  of  food. 

The  organ  of  smell  consists  of  two  parts,  one  external,  the  nose ,-  the  other 
internal,  the  nasal  fossae. 

The  nose  is  the  more  anterior  and  prominent  part  of  the  organ  of  smell.  It  is 
of  a  triangular  form,  directed  vertically  downwards,  and  projects  from  the  centre 
of  the  face,  immediately  above  the  upper  lip.  Its  summit  or  root  is  connected 
directly  with  the  forehead.  Its  inferior  part,  the  base  of  the  nose,  presents  two 
elliptical  orifices,  the  nostrils,  separated  from  each  other  by  an  antero-posterior 
septum,  the  columna.     The  margins  of  these  orifices  are  provided  with  a  number 

Figs.  299,  300.— Cartilages  of  the  Nose. 
Seen   from    I  el  our  JfM        St  J*-  Vic  us 


otL-crLalwal  C, 


'esauiola  C 


of  stiff  hairs  or  vibrissse  which  arrest  the  passage  of  foreign  substances  carried 
with  the  current  of  air  intended  for  respiration.  The  lateral  surfaces  of  the  nose 
form,  by  their  union,  the  dorsum,  the  direction  of  which  varies  considerably  in 
different  individuals.  The  dorsum  terminates  below  in  a  rounded  eminence,  the 
lobe  of  the  nose. 


612 


ORGANS   OF   THE    SENSES. 


Fig.  301. 


-Bones  and  Cartilages  of  Septum  of  Nose. 
Right  Side. 


The  nose  is  composed  of  a  framework  of  bones  and  cartilages,  the  latter  being 
slightly  acted  upon  by  certain  muscles.  It  is  covered  externally  by  the  integument^ 
internally  by  mucous  membrane,  and  supplied  with  vessels  and  nerves. 

The  bony  framework  occupies  the  upper  part  of  the  organ ;  it  consists  of  the 
nasal  bones,  and  the  nasal  processes  of  the  superior  maxillary. 

The  cartilaginous  framework  consists  of  five  pieces,  the  two  upper  and  the  two 
lower  lateral  cartilages,  and  the  cartilage  of  the  septum. 

The  upper  lateral  cartilages  are  situated  below  the  free  margin  of  the  nasal 
bones ;  each  cartilage  is  flattened,  and  triangular  in  shape.  Its  anterior  margin  is 
thicker  than  the  posterior,  and  connected  with  the  fibro-cartilage  of  the  septum. 
Its  posterior  margin  is  attached  to  the  nasal  process  of  the  superior  maxillary  and 
nasal  bones.  Its  inferior  margin  is  connected  by  fibrous  tissue  with  the  lower 
lateral  cartilage ;  one  surface  is  turned  outwards,  the  other  inwards  towards  the 
nasal  cavity. 

The  lower  lateral  cartilages  are  two  thin,  flexible  plates,  situated  immediately 

below  the  preceding,  and  curved 
in  such  a  manner  as  to  form  the 
inner  and  outer  walls  of  each 
orifice  of  the  nostril.  The  por- 
tion which  forms  the  inner  wall, 
thicker  than  the  rest,  is  loosely 
connected  with  the  same  part  of 
the  opposite  cartilage,  and  forms 
a  small  part  of  the  columna.  Its 
outer  extremity,  free,  rounded, 
and  projecting,  forms,  with  the 
thickened  integument  and  sub- 
jacent tissue,  the  lobe  of  the 
nose.  The  part  which  forms  the 
outer  wall  is  curved  to  correspond 
with  the  ala  of  the  nose;  it  is 
oval  and  flattened,  narrow  behind, 
where  it  is  connected  with  the 
nasal  process  of  the  superior 
maxilla  by  a  tough  fibrous 
membrane,  in  which  are  found 
three  or  four  small  cartilaginous  plates,  cartilagines  minores  or  sesamoid  cartilages. 
Above,  it  is  connected  to  the  upper  lateral  cartilage  and  front  part  of  the  cartilage 
of  the  septum ;  below,  it  is  separated  from  the  margin  of  the  nostril  by  dense 
cellular  tissue ;  and  in  front,  it  forms,  with  its  fellow,  the  prominence  of  the  tip  of 
the  nose. 

The  cartilage  of  the  septum  is  somewhat  triangular  in  form,  thicker  at  its  mar- 
gins than  at  its  centre,  and  completes  the  separation  between  the  nasal  fossoe  in 
front.  Its  anterior  margin,  thickest  above,  is  connected  from  above  downwards 
with  the  nasal  bones,  the  front  part  of  the  two  upper  lateral  cartilages,  and  the 
inner  portion  of  the  two  lower  lateral  cartilages.  Its  posterior  margin  is  con- 
nected with  the  perpendicular  lamella  of  the  ethmoid ;  its  inferior  margin  with 
the  vomer  and  palate  processes  of  the  superior  maxillary  bones. 

These  various  cartilages  are  connected  to  each  other,  and  to  the  bones,  by  a 
tough  fibrous  membrane,  the  perichondrium,  which  allows  the  utmost  facility  of 
movement  between  them. 

The  muscles  of  the  nose  are  situated  immediately  beneath  the  integument ;  they* 
are  (on  each  side)  the  Pyramidalis  nasi,  the  Levator  labii  superioris  alasque  nasi, 
the  Dilator  naris  anterior,  and  Dilator  naris  posterior,  the  Compressor  naris,  the 
Compressor  narium  minor,  and  the  Depressor  alee  nasi  (see  p.  246). 

The  integument  covering  the  dorsum  and  sides  of  the  nose  is  thin,  and  loosely 
connected  with  the  subjacent  parts;  but  where  it  forms  the  tip  or  lobe  and  the 


NASAL   FOSSAE.  613 

alae  of  the  nose,  it  is  thicker,  and  more  firmly  adherent.  It  is  furnished  with  a 
large  number  of  sebaceous  follicles,  the  orifices  of  which  are  usually  very  distinct. 

The  mucous  membrcme  lining  the  interior  of  the  nose  is  continuous  with  the 
skin  externally,  and  with  that  which  lines  the  nasal  fossa}  within. 

The  arteries  of  the  nose  are  the  lateralis  nasi  from  the  facial,  and  the  nasal 
artery  of  the  septum  from  the  superior  coronary,  which  supplies  the  alae  and 
septum;  the  sides  and  dorsum  being  supplied  from  the  nasal  branch  of  the 
ophthalmic  and  infra-orbital. 

The  veins  of  the  nose  terminate  in  the  facial  and  ophthalmic. 

The  nerves  of  the  nose  are  branches  from  the  facial,  infra-orbital,  and  infra- 
trochlear,  and  a  filament  from  the  nasal  branch  of  the  ophthalmic. 

Nasal  Fossjs. 

The  Nasal  Fossae  are  two  irregular  cavities,  situated  in  the  middle  of  the  face, 
and  extending  from  before  backwards.  They  open  in  front  by  the  two  anterior 
nares,  and  terminate  behind  in  the  pharynx,  by  the  posterior  nares.  The 
boundaries  of  these  cavities,  and  the  openings  which  are  connected  with  them, 
as  they  exist  in  the  skeleton,  have  been  already  described  (p.  109). 

The  mucous  membrane  lining  the  nasal  fossae  is  called  pituitary,  from  the 
nature  of  its  secretion,  or  Schneiderian  from  Schneider,  the  first  anatomist  who 
showed  that  the  secretion  proceeded  from  the  mucous  membrane,  and  not,  as  was 
formerly  imagined,  from  the  brain.  It  is  intimately  adherent  to  the  periosteum 
or  perichondrium  over  which  it  lies.  It  is  continuous  externally  with  the  skin, 
through  the  anterior  nares,  and  with  the  mucous  membrane  of  the  pharynx, 
through  the  posterior  nares.  From  the  nasal  fossae  its  continuity  may  be  traced 
with  the  conjunctiva,  through  the  nasal  duct  and  lachrymal  canals;  with  the 
lining  membrane  of  the  tympanum  and  mastoid  cells,  through  the  Eustachian 
tube;  and  with  the  frontal,  ethmoidal,  and  sphenoidal  sinuses,  and  the  antrum 
maxillare,  through  the  several  openings  in  the  meatuses.  The  mucous  membrane 
is  thickest,  and  most  vascular,  over  the  turbinated  bones.  It  is  also  thick  over 
the  septum ;  but,  in  the  intervals  between  the  spongy  bones,  and  on  the  floor  of  the 
nasal  fossae,  it  is  very  thin.  Where  it  lines  the  various  sinuses  and  the  antrum 
maxillare,  it  is  thin  and  pale. 

The  surface  of  the  membrane  is  covered  with  a  layer  of  tessellated  epithelium, 
at  the  upper  part  of  the  nasal  fossae,  corresponding  with  the  distribution  of  the 
olfactory  nerve,  but  ciliated  throughout  the  rest  of  its  extent,  excepting  near  the 
aperture  of  the  nares. 

This  membrane  is  also  provided  with  a  nearly  continuous  layer  of  branched 
mucous  glands,  the  ducts  of  which  open  upon  its  surface.  They  are  most  nume- 
rous at  the  middle  and  back  parts  of  the  nasal  fossae,  and  largest  at  the  lower  and 
back  part  of  the  septum. 

Owing  to  the  great  thickness  of  this  membrane,  the  nasal  fossae  are  much 
narrower,  and  the  turbinated  bones,  especially  the  lower  ones,  appear  larger,  and 
more  prominent,  than  in  the  skeleton.  From  the  same  circumstance,  also,  the 
various  apertures  communicating  with  the  meatuses  are  either  narrowed  or 
completely  closed. 

In  the  superior  meatus,  the  aperture  of  communication  with  the  posterior 
ethmoidal  cells  is  considerably  diminished  in  size,  and  the  spheno-palatine  foramen 
completely  covered  in. 

In  the  middle  meatus,  the  opening  of  the  infundibulum  is  partially  hidden  by 
a  projecting  fold  of  mucous  membrane,  and  the  orifice  of  the  antrum  is  contracted 
to  a  small  circular  aperture,  much  narrower  than  in  the  skeleton. 

In  the  inferior  meatus,  the  orifice  of  the  nasal  duct  is  partially  hidden  by  either 
a  single  or  double  valvular  mucous  fold,  and  the  anterior  palatine  canal  either 
complete^  closed  in,  or  a  tubular  cul-de-sac  of  mucous  membrane  is  continued  a 
short  distance  into  it. 


614 


ORGANS   OF   THE   SENSES. 


In  the  roof,  the  opening  leading  to  the  sphenoidal  sinus  is  narrowed,  and  the 
apertures  in  the  cribriform  plate  of  the  ethmoid  completely  closed  in. 

The  arteries  of  the  nasal  fossse  are  the  anterior  and  posterior  ethmoidal,  from 
the  ophthalmic,  which  supply  the  ethmoidal  cells,  frontal  sinuses,  and  roof  of  the 
nose  ;  the  spheno-palatine,  from  the  internal  maxillary,  which  supplies  the  mucous 
membrane  covering  the  spongy  bones,  the  meatuses,  and  septum ;  and  the  alveolar 
branch  of  the  internal  maxillary,  which  supplies  the  lining  membrane  of  the 
antrum.  The  ramifications  of  these  vessels  form  a  close,  plexiform  network, 
beneath  and  in  the  substance  of  the  mucous  membrane. 

The  veins  of  the  nasal  fossse  form  a  close  network  beneath  the  mucous  mem- 
brane. They  pass,  some  with  the  veins  accompanying  the  spheno-palatine  artery, 
through  the  spheno-palatine  foramen ;  and  others,  through  the  alveolar  branch, 
join  the  facial  vein;  some  accompany  the  ethmoidal  arteries,  and  terminate  in  the 
ophthalmic  vein ;  and,  lastly,  a  few  communicate  with  the  veins  in  the  interior 
of  the  skull,  through  the  foramina  in  the  cribriform  plate  of  the  ethmoid  bone. 

The  nerves  are  the  olfactory, 
Fig.  303.— Nerves  of  Septum  of  Nose.  Right  Sid,e.  faQ  nasal  branch  of  the  ophthal- 
mic, filaments  from  the  anterior 
dental  branch  of  the  superior 
maxillary,  the  Vidian,  naso-pala- 
tine,  descending  anterior  palatine, 
and  spheno-palatine  branches  of 
Meckel's  ganglion. 

The  olfactory,  the  special  nerve 
of  the  sense  of  smell,  is  distri- 
buted over  the  upper  third  of  the 
septum,  and  over  the  surface  of 
the  superior  and  middle  spongy 
bones. 

The  nasal  branch  of  the  oph- 
thalmic distributes  filaments  to 
the  upper  and  anterior  part  of 
the  septum,  and  outer  wall  of  the 
nasal  fossae. 

Filaments  from  the  anterior  dental  branch  of  the  superior  maxillary  supply  the 
inferior  meatus  and  inferior  turbinated  bone. 

The  Vidian  nerve  supplies  the  upper  and  back  part  of  the  septum,  and  superior 
spongy  bone ;  and  the  upper  anterior  nasal  branches  from  the  spheno-palatine 
ganglion,  have  a  similar  distribution. 

The  nasopalatine  nerve  supplies  the  middle  of  the  septum. 
The  larger   or  anterior  palatine  nerve  supplies  the  middle  and  lower  spongy 
bones. 

The  Eye. 

The  eyeball  is  contained  in  the  cavity  of  the  orbit.  In  this  situation  it  is 
securely  protected  from  injury,  whilst  its  position  is  such  as  to  insure  the  most 
extensive  range  of  sight.  It  is  acted  upon  by  numerous  muscles,  by  which  it  is 
capable  of  being  directed  to  any  part,  is  supplied  by  vessels  and  nerves,  and  is 
additionally  protected  in  front  by  several  appendages,  such  as  the  eyebrow, 
eyelids,  etc. 

The  eyeball  is  spherical  in  form,  having  the  segment  of  a  smaller  and  more 
prominent  sphere  engrafted  upon  its  anterior  part.  It  is  from  this  circumstance, 
that  the  antero-posterior  diameter  of  the  eyeball,  which  measures  about  an  inch, 
exceeds  the  transverse  diameter  by  about  a  line.  The  segment  of  the  larger 
sphere,  which  forms  a"bout  five-sixths  of  the  globe,  is  opaque,  and  formed  by  the 
sclerotic,  the  tunic  of  protection  to  the  eyeball ;  the  smaller  sphere,  which  forms 
the  remaining  sixth,  is  transparent,  and  formed  by  the  cornea.     The  axes  of  the 


THE   EYE, 


615 


eyeballs  are  nearly  parallel,  and  do  not  correspond  to  the  axes  of  the  orbits,  which 
are  directed  outwards.  The  optic  nerves  follow  the  direction  of  the  axes  of  the 
orbits,  and  enter  the  eyeball  a  little  to  their  inner  or  nasal  side.  The  eyeball  is 
composed  of  several  investing  tunics,  and  of  fluid  and  solid  refracting  media, 
called  humors. 

The  tunics  are  three  in  number : — 

1.  Sclerotic  and  Cornea. 

2.  Choroid,  Iris,  and  Ciliary  Processes. 

3.  Eetina. 

The  refracting  media  or  humors  are  also  three : — 

Aqueous.  Crystalline  (lens)  and  Capsule.  Yitreous. 

The  sclerotic  and  cornea  form  the  most  external  tunic  of  the  eyeball ;  they  are 
essentially  fibrous  in  structure,  the  sclerotic  being  opaque,  and  forming  the  pos- 
terior five-sixths  of  the  globe ;  the  cornea,  which  forms  the  remaining  sixth,  being 
transparent. 

Tunics  of  the  Eye. 
scleeotic  and  cornea. 

The  Sclerotic  (axxfaoc,  hard)  has  received  its  name  from  its  extreme  density 
and  hardness ;  it  is  a  firm,  unyielding,  fibrous  membrane,  serving  to  maintain  the 
peculiar  form  of  the  globe  (fig.  303).     It  is  much  thicker  behind  than  in  front. 


Fig.  303.— A  Vertical  Section  of  the  Eyeball.     (Enlarged.) 

Sclerotic  _ 
Choroid  • 
Retina  ■ 


Tendon  of  rectus 


Hyaloid  Mrmbrane 


Ciliary  Muscle 
£=  Ligament 


Circular  Sinua 
anal   of  Petit 


Its  external  surface  is  of  a  white  color,  quite  smooth,  except  at  the  points 
where  the  Recti  and  Obliqui  muscles  are  inserted  into  it,  and  covered,  for  part  of 
its  extent,  by  the  conjunctival  membrane ;  hence  the  whiteness  and  brilliancy  of 
the  front  of  the  eyeball.  Its  inner  surface  is  stained  of  a  brown  color,  marked 
by  grooves,  in  which  are  lodged  the  ciliary  nerves,  and  connected  by  an  exceedingly 
fine  cellular  tissue  {lamina  fused)  with  the  outer  surface  of  the  choroid.  Behind, 
it  is  pierced  by  the  optic  nerve  a  little  to  its  inner  or  nasal  side,  and  is  continuous 
with  its  fibrous  sheath,  which  is  derived  from  the  dura  mater.  At  the  point  where 
the  optic  nerve  passes  through  the  sclerotic,  this  membrane  forms  a  thin  cribriform 


616  ORGANS   OF   THE    SENSES. 

lamina  {lamina  cribrosa);  the  minute  orifices  in  this  part  serve  for  the  trans- 
mission of  the  nervous  filaments,  and  the  fibrous  septa  dividing  them  from  one 
another  are  continuous  with  the  membranous  processes  which  separate  the  bundles 
of  nerve  fibres.  One  of  these  openings,  larger  than  the  rest,  occupies  the  centre 
of  this  lamellae ;  it  is  called  the  porus  opticus,  and  transmits  the  arteria  centralis 
retinas  to  the  interior  of  the  eyeball.  Around  the  cribriform  lamella  are  numerous 
smaller  apertures  for  the  transmission  of  the  ciliary  vessels  and  nerves.  In 
front,  this  membrane  is  continuous  with  the  cornea  by  direct  continuity  of  tissue ; 
but  the  opaque  sclerotic  overlaps  it  rather  more  on  its  outer  than  upon  its  inner 
surface. 

Structure.  The  sclerotic  is  formed  of  white  fibrous  tissue  intermixed  with  the 
elastic  fibres,  and  fusiform  nucleated  cells.  These  are  aggregated  into  bundles, 
which  are  arranged  chiefly  in  a  longitudinal  direction.  It  yields  gelatin  on 
boiling.  Its  vessels  are  not  numerous,  the  capillaries  being  of  small  size,  uniting 
at  long  and  wide  intervals.     The  existence  of  nerves  in  it  is  doubtful. 

The  Cornea  is  the  projecting  transparent  part  of  the  external  tunic  of  the  eye- 
ball, and  forms  the  anterior  sixth  of  the  globe.  Its  form  is  not  quite  circular, 
being  a  little  broader  in  the  transverse  than  in  the  vertical  direction,  in  conse- 
quence of  the  sclerotic  overlapping  the  margin  above  and  below.  It  is  concavo- 
convex,  and  projects  forwards  from  the  sclerotic  in  the.  same  manner  that  a  watch- 
glass  does  from  its  case.  Its  degree  of  curvature  varies  in  different  individuals, 
and  in  the  same  individual  at  different  periods  of  life,  being  more  prominent  in 
youth  than  in  advanced  life,  when  it  becomes  flattened.  This  difference  in  the 
greater  or  smaller  convexity  of  the  cornea  influences  considerably  the  refractive 
power  of  the  eye,  and  is  the  chief  cause  of  the  long  or  short  sight  peculiar  to 
different  individuals.  It  is  dense  and  of  uniform  thickness  throughout,  its  pos- 
terior surface  is  perfectly  circular  in  outline,  and  exceeds  the  anterior  surface 
slightly  in  extent,  from  the  latter  being  overlapped  by  the  sclerotic. 

Structure.  The  cornea  consists  of  five  layers :  a  thick  central  fibrous  structure, 
the  cornea  proper ;  in  front  of  this  the  anterior  elastic  lamina,  covered  by  the  con- 
junctiva ;  behind,  the  posterior  elastic  lamina,  covered  by  the  lining  membrane 
of  the  anterior  chamber  of  the  eyeball. 

The  proper  substance  of  the  cornea  is  fibrous,  tough,  unyielding,  perfectly 
transparent,  and  continuous  with  the  sclerotic,  with  which  it  is  in  structure 
identical.  The  anastomosing  fusiform  cells  of  which  it  is  composed  are  arranged 
in  superimposed  flattened  laminae,  at  least  sixty  in  number,  all  of  which  have  the 
same  direction,  the  contiguous  laminae  becoming  united  at  frequent  intervals. 
If  the  relative  position  of  the  component  parts  of  this  tissue  is  in  any  way  altered, 
either  by  pressure  or  by  an  increase  of  its  natural  tension,  it  immediately  presents 
an  opaque  milky  appearance.  The  interstices  between  the  laminae  are  tubular, 
and  usually  contain  a  small  amount  of  transparent  fluid. 

The  anterior  and  posterior  elastic  laminse,  which  cover  the  proper  structure  of 
the  cornea  behind  and  in  front,  present  an  analogous  structure.  They  consist 
of  a  hard,  elastic,  and  perfectly  transparent  homogeneous  membrane,  of  extreme 
thinness,  which  is  not  rendered  opaque  by  either  water,  alcohol,  or  acids.  This 
membrane  is  intimately  connected  by  means  of  a  fine  cellular  web  to  the  proper 
substance  of  the  cornea  both  in  front  and  behind.  Its  most  remarkable  property 
is  its  extreme  elasticity,  and  the  tendency  which  it  presents  to  curl  up,  or  roll 
upon  itself,  with  the  attached  surface  innermost,  when  separated  from  the  proper 
substance  of  the  cornea.  Its  use  appears  to  be,  as  suggested  by  Dr.  Jacob, 
"to  preserve  the  requisite  permanent  correct  curvature  of  the  flaccid  cornea 
proper." 

The  conjunctival  epithelium,  which  covers  the  front  of  the  anterior  elastic 
lamina,  consists  of  two  or  three  layers  of  transparent  nucleated  cells,  the  deepest 
being  of  an  oblong  form  and  placed  perpendicular  to  the  surface,  the  superficial 
ones  more  flattened. 

The  epithelial  lining  of  the  aqueous  chamber  covers  the  posterior  surface  of  the 


CORNEA— CHOROID.  617 

posterior  elastic  lamina.     It  consists  of  a  single  layer  of  polygonal  transparent 
nucleated  cells,  similar  to  those  found  lining  other  serous  cavities. 

Arteries  and  Nerves.  The  cornea  is  a  non-vascular  structure,  the  capillary 
vessels  terminating  in  loops  at  its  circumference.  Lymphatic  vessels  have  not 
as  yet  been  demonstrated  in  it.  The  nerves  are  numerous,  twenty  or  thirty  in 
number :  they  are  derived  from  the  ciliary  nerves,  and  enter  the  laminated  sub- 
stance of  the  cornea.  They  ramify  throughout  its  substance  in  a  delicate  net- 
work. 

Dissection.  In  order  to  separate  the  sclerotic  and  cornea,  so  as  to  expose  the  second  tunic, 
the  eyeball  should  be  immersed  in  water  contained  in  a  small  vessel.  A  fold  of  the  sclerotic 
near  its  anterior  part  having  been  pinched  up,  an  operation  not  easily  performed  from  the  ex- 
treme tension  of  the  membrane,  it  should  be  divided  with  a  pair  of  blunt-pointed  scissors.  As 
soon  as  the  choroid  is  exposed,  the  end  of  a  blowpipe  should  be  introduced  into  the  orifice,  and 
a  stream  of  air  forced  into  it,  so  as  to  separate  the  slight  cellular  connection  between  the  sclerotic 
and  choroid.  The  sclerotic  should  now  be  divided  around  its  entire  circumference,  and  may  be 
removed  in  separate  portions.  The  front  segment  being  then  drawn  forwards,  the  handle  of  the 
scalpel  should  be  pressed  gently  against  it  at  its  connection  with  the  iris,  and,  these  being  sepa- 
rated, a  quantity  of  perfectly  transparent  fluid  will  escape ;  this  is  the  aqueous  humor.  In  the 
course  of  the  dissection,  the  ciliary  nerves  may  be  seen  lying  in  the  loose  cellular  tissue  between 
the  choroid  and  sclerotic,  or  contained  in  delicate  grooves  on  the  inner  surface  of  the  latter 
membrane. 

Fig.  304.— The  Choroid  and  Iris.   (Enlarged.) 


Choroid,  Iris,  and  Ciliary  Processes. 

The  second  tunic  is  formed  by  the  choroid  behind ;  the  iris  and  ciliary  pro- 
cesses in  front ;  and  by  the  ciliary  ligament,  and  Ciliary  muscle,  at  the  point  of 
junction  of  the  sclerotic  and  cornea. 

The  Choroid  is  the  vascular  and  pigmentary  tunic  of  the  eyeball,  investing  the 
posterior  five-sixths  of  the  globe,  and  extending  as  far  forwards  as  the  cornea ; 
the  Ciliary  Processes  being  appendages  of  the  choroid  developed  from  its  inner 
surface  in  front.  The  Iris  is  the  circular-shaped  muscular  septum,  which  hangs 
vertically  behind  the  cornea,  presenting  in  its  centre  a  large  circular  aperture, 
the  pupil.  The  ciliary  ligament  and  Ciliary  muscle  form  the  white  ring  observed 
at  the  point  where  the  choroid  and  iris  join  with  each  other,  and  with  the  sclerotic 
and  cornea. 


618  ORGANS   OF   THE    SENSES. 

The  Choroid  is  a  thin,  highly  vascular  membrane,  of  a  dark  brown  or  chocolate 
color,  which  invests  the  posterior  five-sixths  of  the  central  part  of  the  globe.  It 
is  pierced  behind  by  the  optic  nerve,  and  terminates  in  front  at  the  ciliary  ligament, 
where  it  bends  inwards,  and  forms  on  its  inner  surface  a  series  of  folds  or  plaitings, 
the  ciliary  processes.  It  is  thicker  behind  than  in  front.  Externally,  it  is  con- 
nected by  a  fine  cellular  web  (membrana  fused)  with  the  inner  surface  of  the 
sclerotic.  Its  inner  surface  is  smooth,  and  lies  in  contact  with  the  retina.  The 
choroid  is  composed  of  three  layers,  external,  middle,  and  internal. 

Fig.  305.— The  Veins  of  the  Choroid.    (Enlarged.) 


The  external  layer  consists  of  the  larger  branches  of  the  short  ciliary  arteries, 
which  run  forwards  between  the  veins  before  they  bend  downwards  to  terminate 
on  the  inner  surface.  This  coat  consists,  however,  principally  of  veins,  which 
are  disposed  in  curves ;  hence  their  name,  vense  vorticosse.  They  converge  to  four 
or  five  equidistant  trunks,  which  pierce  the  sclerotic  midway  between  the  margin 
of  the  cornea  and  the  entrance  of  the  optic  nerve.  Interspersed  between  the 
vessels,  are  lodged  dark  star-shaped  pigment  cells,  the  fibrous  offsets  from  which, 
communicating  with  similar  branches  from  neighboring  cells,  form  a  delicate 
network,  which,  towards  the  inner  surface  of  the  choroid,  loses  its  pigmentary 
character. 

The  middle  layer  consists  of  an  exceedingly  fine  capillary  plexus,  formed  by  the 
short  ciliary  vessels,  and  is  known  as  the  tunica  Ruyschiana.  The  network  is 
close,  and  finer  at  the  hinder  part  of  the  choroid  than  in  front.  About  half  an 
inch  behind  the  cornea,  its  meshes  become  larger,  and  are  continuous  with  those 
of  the  ciliary  processes. 

The  internal  or  pigmentary  layer  is  a  delicate  membrane,  consisting  of  a 
single  layer  of  hexagonal  nucleated  cells,  loaded  with  pigment  granules,  and 
applied  to  each  other,  so  as  to  resemble  a  tessellated  pavement.  Each  cell 
contains  a  nucleus,  and  is  filled  with  grains  of  pigment,  which  are  in  greater 
abundance  at  the  circumference  of  the  cell.  In  perfect  albinos  this  epithelium 
contains  no  pigment,  and  none  is  present  in  the  star-shaped  cells  found  in  the 
other  layers  of  the  choroid. 

The  ciliary  processes  should  be  next  examined ;  they  may  be  exposed,  either  by  detaching  the 
iris  from  its  connection  with  the  ciliary  ligament,  or  by  making  a  transverse  section  of  the  globe, 
and  examining  them  from  behind. 

The  Ciliary  processes  are  formed  by  the  plaiting  or  folding  inwards  of  the 
middle  and  internal  layers  of  the  choroid,  at  its  anterior  margin,  and  are  received 


CHOROID— IRIS. 


619 


between  corresponding  foldings  of  the  suspensory  ligament  of  the  lens,  thus 
establishing  a  communication  between  the  choroid  and  inner  tunic  of  the  eye. 
They  are  arranged  in  a  circle,  behind  the  iris,  round  the  margin  of  the  lens. 
They  vary  in  number  between  sixty  and  eighty,  lie  side  by  side,  and  may  be 
divided  into  large  and  small ;  the  latter,  consisting  of  about  one-third  of  the  entire 
number,  are  situated  in  the  spaces  between  the  former,  but  without  regular  alter- 
nation.    The  larger  processes  are  each  about  one-tenth  of  an  inch  in  length,  and 


Fig.  306. — The  Arteries  of  the  Choroid  and  Iris. 
The  Sclerotic  has  been  mostly  removed.     (Enlarged.) 

Jl  nterior 
Ciliary  At 


Short 
Ciliary  &i 


nterior 
CiliarijA^ 


hemispherical  in  shape,  their  periphery  being  attached  to  the  ciliary  ligament,  and 
continuous  with  the  middle  and  inner  layers  of  the  choroid ;  the  opposite  margin 
is  free,  and  rests  upon  the  circumference  of  the  lens.  Their  anterior  surface  is 
turned  towards  the  back  of  the  iris,  with  the  circumference  of  which  it  is  con- 
tinuous. The  posterior  surface  is  closely  connected  with  the  suspensory  ligament 
of  the  lens. 

Structure.  The  ciliary  processes  are  similar  in  structure  to  the  choroid ;  the 
vessels  are  larger,  having  chiefly  a  longitudinal  direction.  Externally  they  are 
covered  with  several  layers  of  pigment  cells;  the  component  cells  are  small, 
rounded,  and  full  of  pigment  granules. 

The  Iris  {iris,  a  rainbow)  has  received  its  name  from  the  varied  color  it  pre- 
sents in  different  individuals.  It  is  a  thin  circular-shaped,  contractile  curtain, 
suspended  in  the  aqueous  humor  behind  the  cornea,  and  in  front  of  the  lens, 
being  perforated  at  the  nasal  side  of  its  centre  by  a  circular  aperture,  the  pupil, 
for  the  transmission  of  light.  By  its  circumference  it  is  intimately  connected 
with  the  choroid;  externally  to  this  is  the  ciliary  ligament,  by  which  it  is  con- 
nected to  the  sclerotic  and  cornea;  its  inner  edge  forms  the  margin  of  the  pupil; 
its  surfaces  are  flattened,  and  look  forwards  and  backwards,  the  anterior  surface 
towards  the  cornea,  the  posterior  towards  the  ciliary  processes  and  lens.  The 
anterior  surface  is  variously  colored  in  different  individuals,  and  marked  by  lines 
which  converge  towards  the  pupil.  The  posterior  surface  is  of  a  deep  purple 
tint,  from  being  covered  by  dark  pigment;  it  is  hence  named  uvea,  from  its 
resemblance  in  color  to  a  ripe  grape. 

Structure.  The  iris  is  composed  of  a  fibrous  stroma,  muscular  fibres,  and  pig- 
ment cells. 

The  fibrous  stroma  consists  of  fine,  delicate  bundles  of  fibrous  tissue,  which  have 
a  circular  direction  at  the  circumference;  but  the  chief  mass  radiate  towards 
the  pupil.  They  form,  by  their  interlacement,  a  delicate  mesh,  in  which  the  pig- 
ment cells,  vessels,  and  nerves  are  contained. 


G20  ORGANS   OF   THE    SENSES. 

The  muscular  fibre  is  involuntary,  and  consists  of  circular  and  radiating  fibres. 
The  circular  fibres  (sphincter  of  the  pupil)  surround  the  margin  of  the  pupil  on 
the  posterior  surface  of  the  iris,  like  a  sphincter,  forming  a  narrow  band,  about 
one-thirtieth  of  an  inch  in  width ;  those  near  the  free  margin  being  closely  aggre- 
gated ;  those  more  external  are  separated  somewhat,  and  form  less  complete  circles. 
The  radiating  fibres  (dilator  of  the  pupil)  converge  from  the  circumference  towards 
the  centre,  and  blend  with  the  circular  fibres  near  the  margin  of  the  pupil.  The 
circular  fibres  contract  the  pupil,  the  radiating  fibres  dilate  it. 

The  pigment  cells  are  found  in  the  stroma  of  the  iris,  and  also  as  a  distinct  layer 
on  its  anterior  and  posterior  surfaces.  In  the  stroma,  the  cells  are  ramified,  and 
contain  yellow  or  brown  pigment,  according  to  the  color  of  the  eye.  On  the  front 
of  the  iris,  there  is  a  single  layer  of  oval  or  rounded  cells,  with  branching  offsets. 
On  the  back  of  the  iris,  there  are  several  layers  of  small,  round  cells,  filled  with 
dark  pigment.  *This  layer  is  continuous  with  the  pigmentary  covering  of  the 
ciliary  processes. 

The  arteries  of  the  iris  are  derived  from  the  long  and  anterior  ciliary,  and  from 
the  vessels  of  the  ciliary  processes. 

Membrana  pupillaris.  In  the  foetus,  the  pupil  is  closed  by  a  delicate,  transparent 
vascular  membrane,  the  membrana  pupillaris,  which  divides  the  space  in  which  the 
iris  is  suspended  into  two  distinct  chambers.  This  membrane  contains  numerous 
minute  vessels  continued  from  the  margin  of  the  iris  to  those  on  the  front  part  of 
the  capsule  of  the  lens.  These  vessels  have  a  looped  arrangement,  converging 
towards  each  other  without  anastomosing.  Between  the  seventh  and  eighth  month, 
this  membrane  begins  to  disappear,  by  its  gradual  absorption  from  the  centre 
towards  the  circumference,  and  at  birth  only  a  few  fragments  remain.  Sometimes 
it  remains  permanent,  and  produces  blindness. 

The  Ciliary  ligament  is  a  narrow  ring  of  circular  fibres,  about  one-fortieth  of 
an  inch  thick,  and  of  a  whitish  color,  which  serves  to  connect  the  external  and 
middle  tunics  of  the  eye.  It  is  placed  round  the  circumference  of  the  iris,  at  its 
point  of  connection  with  the  external  layer  of  the  choroid,  the  cornea,  and  sclerotic. 
Its  component  fibres  are  delicate,  and  resemble  those  of  elastic  tissue.  At  its  point 
of  connection  with  the  sclerotic  a  minute  canal  is  situated  between  the  two,  called 
the  sinus  circular  is  iridis. 

The  Ciliary  muscle  (Bowman)  consists  of  unstriped  fibres ;  it  forms  a  grayish, 
semi-transparent,  circular  band,  about  one-eighth  of  an  inch  broad,  on  the  outer 
surface  of  the  forepart  of  the  choroid.  It  is  thickest  in  front,  and  gradually 
becomes  thinner  behind.  Its  fibres  are  soft,  of  a  yellowish- white  color,  longitu- 
dinal in  direction,  and  arise  at  the  point  of  junction  of  the  cornea  and  sclerotic. 
Passing  backwards,  they  are  attached  to  the  choroid,  in  front  of  the  retina,  and 
correspond  by  their  inner  surface  to  the  plicated  part  of  the  former  membrane. 
Mr.  Bowman  supposes  that  this  muscle  is  so  placed  as  to  advance  the  lens,  by 
exercising  compression  on  the  vitreous  body,  and  by  drawing  the  ciliary  processes 
towards  the  line  of  junction  of  the  sclerotic  and  cornea,  and  by  this  means  to 
adjust  the  eye  to  the  vision  of  near  objects. 

The  Retina. 

The  Retina  may  be  exposed  by  carefully  removing  the  choroid  from  its  external 
surface.  It  is  a  delicate  nervous  membrane,  upon  the  surface  of  which  the  images 
of  external  objects  are  received.  Its  outer  surface  is  in  contact  with  the  pigmentary 
layer  of  the  choroid ;  its  inner  surface,  with  the  vitreous  body.  Behind,  it  is  con- 
tinuous with  the  optic  nerve ;  it  gradually  diminishes  in  thickness  from  behind 
forwards ;  and,  in  front,  extends  nearly  as  far  forwards  as  the  ciliary  ligament, 
where  it  terminates  by  a  jagged  margin,  the  ora  serrata.  It  is  soft,  and  semi- 
transparent,  in  the  fresh  state ;  but  soon  becomes  clouded,  opaque,  and  of  a  pinkish 
tint.  Exactly  in  the  centre  of  the  posterior  part  of  the  retina,  and  at  a  point 
corresponding  to  the  axis  of  the  eye,  in  which  the  sense  of  vision  is  most  perfect, 
is  a  round,  elevated,  yellowish  spot,  called,  after  its  discoverer,  limbus   luteus, 


RETINA. 


G21 


yellow  spot,  of  SG'mmering  ;  having  a  central  depression  at  its  summit,  the  fovea 
centralis.  The  retina  in  the  situation  of  the  fovea  centralis  is  exceedingly  thin,  so' 
much  so,  that  the  dark  color  of  the  choroid  is  distinctly  seen  through  it ;  so  that 
it  presents  more  the  appearance  of  a  foramen,  and  hence  the  name  "  foramen  of 
Sommering"  at  first  given  to  it.  It  exists  only  in  man,  the  quadrumana,  and  some 
saurian  reptiles.  Its  use  is  unknown.  About  TV  of  an  inch  to  the  inner  side  of 
the  yellow  spot  is  the  point  of  entrance  of  the  optic  nerve ;  the  arteria  centralis 
retinse  piercing  its  centre.  This  is  the  only  part  of  the  surface  of  the  retina  from 
which  the  power  of  vision  is  absent. 


Fig, 


307. — The  Arteria  Centralis  Retinse,  Yellow  Spot,  etc.,  the  Anterior  Half 
of  the  Eyeball  being  removed.     (Enlarged.) 

Sclerotic 
Choroid 
■Retina 


Structure.     The  retina  is  composed  of  three  layers,  together  with  bloodvessels : — 

External  or  columnar  layer  (Jacob's  membrane). 
Middle  or  granular  layer. 
Internal  or  nervous  layer. 

The  bloodvessels  do  not  form  a  distinct  layer ;  they  ramify  in  the  substance  of 
the  internal  layer. 

The  external  or  JacoVs  membrane  is  exceedingly  thin,  and  can  be  detached  from 
the  external  surface  of  the  retina  by  the  handle  of  the  scalpel,  in  the  form  of  a 
flocculent  film.  It  is  thicker  behind  than  in  front,  and  consists  of  rod-like  bodies 
of  two  kinds : — 1.  Columnar  rods,  solid,  nearly  of  uniform  size,  and  arranged  per- 
pendicularly to  the  surface.  2.  Bulbous  particles  or  cones,  which  are  interspersed 
at  regular  intervals  among  the  former ;  these  are  conical  or  flask-shaped,  their 
broad  ends  resting  upon  the  granular  layer,  the  narrow-pointed  extremity  being 
turned  towards  the  choroid  ;  they  are  not  solid,  like  the  columnar  rods,  but  consist 
of  an  external  membrane  with  fluid  contents.  By  their  deep  ends,  both  kinds  are 
joined  to  the  fibres  of  Miiller. 

The  middle  or  granular  layer  forms  about  one-third  of  the  entire  thickness  of 
the  retina.  It  consists  of  two  laminae  of  rounded  or  oval  nuclear  particles,  separated 
from  each  other  by  an  intermediate  layer,  which  is  transparent,  finely  fibrillated, 
and  contains  no  bloodvessels.  The  outermost  layer  is  the  thickest,  and  its  con- 
stituent particles  are  globular.  The  innermost  layer  is  the  thinnest ;  its  component 
particles  are  flattened,  looking  like  pieces  of  money  seen  edgeways ;  hence  it  has 
been  called  by  Bowman,  the  nummular  layer. 

The  internal  or  nervous  layer  is  a  thin  semi-transparent  membrane,  consisting 
of  an  expansion  of  the  terminal  fibres  of  the  optic  nerve  and  nerve  cells.  The 
nerve  fibres  are  collected  into  bundles,  which  radiate  from  the  point  at  which  the 
trunk  of  the  optic  nerve  terminates.     As  they  proceed  in  a  tolerably  straight 


G22  ORGANS   OF   THE   SENSES. 

course  towards  the  anterior  margin  of  the  retina  the  bundles  interlace,  forming  a 
delicate  net,  with  flattened  elongated  meshes.  The  nerve  fibres  which  form  this 
layer  differ  from  the  fibres  of  the  optic  nerve  in  this  respect ;  they  lose  their  dark 
outline,  and  their  tendency  to  become  varicose,  and  consist  only  of  the  central 
part  or  axis  of  the  nerve  tubes.  The  mode  of  termination  of  the  nerve  fibres  is 
unknown.  According  to  some  observers,  they  terminate  in  loops ;  according  to 
others,  in  free  extremities.  Recent  observers  have  stated,  that  some  of  the  nerve 
fibres  are  continuous  with  the  caudate  prolongations  of  the  nerve  cells  external  to 
the  fibrous  layer.  The  nerve  cells  are  placed  on  both  sides  of  the  fibrous  layer, 
but  chiefly  upon  its  inner  surface,  and  imbedded  within  the  meshes  formed  by  the 
interlacing  nerve  fibres ;  they  are  round  or  pear-shaped  transparent  cells,  nucleated, 
with  granular  contents,  furnished  with  caudate  prolongations,  some  of  which  join 
the  fibres  of  the  optic  nerve,  whilst  others  are  directed  externally  towards  the 
granular  layer.  It  is  probable  that  these  cells  are  identical  with  the  ganglion  cor- 
puscles of  vesicular  nervous  substance. 

An  extremely  thin  and  delicate  structureless  membrane  lines  the  inner  surface 
of  the  retina,  and  separates  it  from  the  vitreous  body ;  it  is  called  the  membrane 
limitans. 

The  radiating  fibres  of  the  retina,  described  by  Heinrich  Miiller,  consist  of 
extremely  fine  fibrillated  threads,  which  are  connected  externally  with  each  of  the 
rods  of  the  columnar  layer,  of  which  they  appear  to  be  direct  continuations ;  and, 
passing  through  the  entire  substance  of  the  retina,  are  united  to  the  outer  surface 
of  the  membrana  limitans.  In  their  course  through  the  retina,  they  become  con- 
nected with  the  nuclear  particles  of  the  granular  layer,  and  give  off  branching 
processes  opposite  its  innermost  lamina ;  as  they  approach  the  fibrous  expansion 
of  the  optic  nerve,  they  are  collected  into  bundles,  which  pass  through  the  areolae* 
between  its  fibres,  and  are  finally  attached  to  the  inner  surface  of  the  membrana 
limitans,  where  each  fibre  terminates  in  a  triangular  enlargement. 

The  arteria  centralis  retinse  and  its  accompanying  vein  pierce  the  optic  nerve, 
and  enter  the  globe  of  the  eye  through  the  porus  opticus.  It  immediately  divides 
into  four  or  five  branches,  which  at  first  run  between  the  hyaloid  membrane  and 
the  nervous  layer ;  but  they  soon  enter  the  latter  membrane,  and  form  a  close 
capillary  network  in  its  substance.  At  the  ora  serrata  they  terminate  in  a  single 
vessel,  which  bounds  the  terminal  margin  of  the  retina. 

The  structure  of  the  retina  at  the  yellow  spot  presents  some  modifications. 
Jacob's  membrane  is  thinner,  and  of  its  constituents  only  the  cones  are  present ; 
but  they  are  small,  and  more  closely  aggregated  than  in  any  other  part.  The 
granular  layer  is  absent  over  the  fovea  centralis.  Of  the  two  elements  of  the 
nervous  layer,  the  nerve  fibres  extend  only  to  the  circumference  of  the  spot ;  but 
the  nerve  cells  cover  its  entire  surface.  The  radiating  fibres  are  found  at  the  cir- 
cumference, and  here  only  extend  to  the  inner  strata  of  the  granular  layer.  Of 
the  capillary  vessels,  the  larger  branches  pass  round  the  spot,  but  the  smaller  capil- 
laries meander  through  it.  The  color  of  the  spot  appears  to  imbue  all  the  layers 
except  Jacob's  membrane ;  it  is  of  a  rich  yellow,  deepest  towards  the  centre,  and 
does  not  appear  to  consist  of  pigment  cells,  but  resembles  more  a  straining  of  the 
constituent  parts. 

humoes   of   the  eye. 
Aqueous  Humoe. 

The  Aqueous  Humor  completely  fills  the  anterior  and  posterior  chambers  of 
the  eyeball.  It  is  small  in  quantity,  scarcely  exceeding,  according  to  Petit,  four  or 
five  grains  in  weight,  has  an  alkaline  reaction,  in  composition  is  little  more  than 
water,  less  than  one-fiftieth  of  its  weight  being  solid  matter,  chiefly  chloride  of 
sodium. 

The  anterior  chamber  is  the  space  bounded  in  front  by  the  cornea ;  behind,  by 
the  front  of  the  iris  and  ciliary  ligament. 

The  posterior  chamber,  smaller  than  the  anterior,  is  bounded  in  front  by  the 


VITREOUS   BODY— CRYSTALLINE   LENS.  623 

iris;  behind,  by  the  capsule  of  the  lens  and  its  suspensory  ligament,  and  the  ciliary 
processes. 

In  the  adult,  these  two  chambers  communicate  through  the  pupil ;  but  in  the 
foetus  before  the  seventh  month,  when  the  pupil  is  closed  by  the  membrana  pupil- 
laris,  the  two  chambers  are  quite  separate. 

It  has  been  generally  supposed  that  the  two  chambers  are  lined  by  a  distinct 
membrane,  the  secreting  membrane  of  the  aqueous  humor,  analogous  in  struc- 
ture to  that  of  a  serous  sac.  An  epithelial  covering  can,  however,  only  be  found 
on  the  posterior  surface  of  the  cornea.  That  the  two  chambers  do,  however, 
secrete  this  fluid  separately,  is  shown  from  its  being  found  in  both  spaces  before 
the  removal  of  the  membrana  pupillaris.  It  is  probable  that  the  parts  concerned 
in  the  secretion  of  the  fluid  are  the  posterior  surface  of  the  cornea,  both  surfaces 
of  the  iris,  and  the  ciliary  processes. 

Vitreous  Body. 

The  Vitreous  Body  forms  about  four-fifths  of  the  entire  globe.  It  fills  the 
concavity  of  the  retina,  and  is  hollowed  in  front  for  the  reception  of  the  lens  and 
its  capsule.  It  is  perfectly  transparent,  of  the  consistence  of  thin  jelly,  and 
consists  of  an  albuminous  fluid  inclosed  in  a  delicate,  transparent  membrane,  the 
hyaloid.  This  membrane  invests  the  outer  surface  of  the  vitreous  body ;  it  is 
intimately  connected  in  front  with  the  suspensory  ligament  of  the  lens ;  and  is 
continued  into  the  back  part  of  the  capsule  of  the  lens.  It  has  been  supposed  by 
Hannover,  that  from  its  inner  surface  numerous  thin  lamellae  are  prolonged 
inwards  in  a  radiating  manner,  forming  spaces  in  which  the  fluid  is  contained. 
In  the  adult,  these  lamellae  cannot  be  detected  even  after  careful  microscopic 
examination ;  but  in  the  foetus  a  peculiar  fibrous  texture  pervades  the  mass,  the 
fibres  joining  at  numerous  points,  and  presenting  minute  nuclear  granules  at  their 
point  of  junction.  The  fluid  from  the  vitreous  body  resembles  nearly  pure  water; 
it  contains,  however,  some  salts,  and  a  little  albumen. 

In  the  foetus,  the  centre  of  the  vitreous  humor  presents  a  tubular  canal,  through 
which  a  minute  artery  passes  along  the  vitreous  body  to  the  capsule  of  the  lens.  In 
the  adult,  no  vessels  penetrate  its  substance;  so  that  its  nutrition  must  be  carried 
on  by  the  vessels  of  the  retina  and  ciliary  processes,  situated  upon  its  exterior. 

Crystalline  Lens  and  its  Capsule. 

The  Crystalline  Lens,  inclosed  in  its  capsule,  is  situated  immediately  behind 
the  pupil,  in  front  of  the  vitreous  body,  and  surrounded  by  the  ciliary  processes, 
which  slightly  overlap  its  margin. 

The  capsule  of  the  lens  is  a  transparent,  highly  elastic,  and  brittle  membrane, 
which  closely  surrounds  the  lens.  It  rests,  behind,  in  a  depression  in  front  of 
the  vitreous  body :  in  front,  it  forms  part  of  the  posterior  chamber  of  the  eye ;  and 
it  is  retained  in  its  position  chiefly  by  the  suspensory  ligament  of  the  lens.  The 
capsule  is  much  thicker  in  front  than  behind,  structureless  in  texture ;  and  when 
ruptured,  the  edges  roll  up  with  the  outer  surface  innermost,  like  the  elastic  laminae 
of  the  cornea.  The  lens  is  connected  to  the  inner  surface  of  the  capsule  by  a  single 
layer  of  transparent,  polygonal,  nucleated  cells.  These,  after  death,  absorb  moisture 
from  the  fluids  of  the  eye ;  and,  breaking  down,  form  the  liquor  Morgagni. 

In  the  foetus,  a  small  branch  from  the  arteria  centralis  retinae  runs  forwards,  as 
already  mentioned,  through  the  vitreous  humor  to  the  posterior  part  of  the  cap- 
sule of  the  lens,  where  its  branches  radiate  and  form  a  plexiform  network,  which 
covers  its  surface,  and  are  continuous  round  the  margin  of  the  capsule,  with  the 
vessels  of  the  pupillary  membrane,  and  with  those  of  the  iris.  In  the  adult,  no 
vessels  enter  its  substance. 

The  lens  is  a  transparent,  double  convex  body,  the  convexity  being  greater  on 
the  posterior  than  on  the  anterior  surface.  It  measures  about  a  third  of  an  inch 
in  the   transverse   diameter,  and   about  one-fourth  in  the  antero-posterior.     It 


624  ORGANS   OP   THE    SENSES. 

consists  of  concentric  layers,  of  which  the  external,  in  the  fresh  state,  are  soft  and 
easily  detached ;  those  beneath  are  firmer,  the  central  ones  forming  a  hardened 

nucleus.      These   laminae   are  best   demonstrated   by 

Fig.  308.— The  Crystalline  Lens,  boiling,  or  immersion  in  alcohol.     The  same  reagents 

hardened  ai^d  divided.         demonstrate  that  the  lens  consists  of  three  triangular 

n  arge  .)  segments,  the  sharp  edges  of  which  are  directed  towards 

the  centre,  the  bases  towards  the  circumference.     The 

laminae  consist  of  minute  parallel  fibres,  which  are 

united  to  each  other  by  means  of  wavy  margins,  the 

convexities  upon  one  fibre  fitting  accurately  into  the 

concavities  of  the  adjoining  fibre. 

The  changes  produced  in  the  lens  by  age  are  the  fol- 
lowing : — 

In  the  foetus,  its  form  is  nearly  spherical,  its  color  of 
a  slightly  reddish  tint,  not  perfectly  transparent,  and  so 
soft  as  to  readily  break  down  on  the  slightest  pressure. 
In  the  adult,  the  posterior  surface  is  more  convex  than  the  anterior,  it  is  color- 
less, transparent,  and  firm  in  texture. 

In  old  age,  it  becomes  flattened  on  both  surfaces,  slightly  opaque,  of  an  amber 
tint,  and  increases  in  density. 

The  suspensory  ligament  of  the  lens  is  a  thin,  transparent,  membranous  struc- 
ture, placed  between  the  vitreous  body  and  the  ciliary  processes  of  the  choroid : 
it  connects  the  anterior  margin  of  the  retina  with  the  anterior  surface  of  the  lens, 
near  its  circumference.  It  assists  in  retaining  the  lens  in  its  position.  Its  outer 
surface  presents  a  number  of  folds  or  plaitings,  in  which  the  corresponding  folds 
of  the  ciliary  processes  are  received.  These  plaitings  are  arranged  round  the 
lens  in  a  radiating  form,  and  are  stained  by  the  pigment  of  the  ciliary  processes. 
The  suspensory  ligament  consists  of  two  layers,  which  commence  behind,  at  the 
ora  serrata.  The  external,  a  tough,  milky,  granular  membrane,  covers  the  inner 
surface  of  the  ciliary  processes,  and  extends  as  far  forwards  as  their  anterior 
free  extremities.  The  inner  layer,  an  elastic  transparent,  fibro-membranous 
structure,  extends  as  far  forwards  as  the  anterior  surface  of  the  capsule  of  the 
lens,  near  its  circumference.  That  portion  of  this  membrane  which  intervenes 
between  the  ciliary  processes  and  the  capsule  of  the  lens,  forms  part  of  the  boun- 
dary of  the  posterior  chamber  of  the  eye.  The  posterior  surface  of  this  layer  is 
turned  towards  the  hyaloid  membrane,  being  separated  from  it  at  the  circum- 
ference of  the  lens  by  a  space  called  the  canal  of  Petit. 

The  canal  of  Petit  is  about  one-tenth  of  an  inch  wide.  It  is  bounded  in  front 
by  the  suspensory  ligament ;  behind,  by  the  hyaloid  membrane,  its  base  being 
formed  by  the  capsule  of  the  lens.  When  inflated  with  air,  it  is  sacculated  at 
intervals,  owing  to  the  foldings  on  its  anterior  surface. 

Bloodvessels  and  Nerves  of  the  Eye. 

The  Vessels  of  the  globe  of  the  eye  are  the  short,  long,  and  anterior  ciliary 
arteries,  and  the  arteria  centralis  retinas. 

The  short  ciliary  arteries  pierce  the  back  part  of  the  sclerotic,  round  the  entrance 
of  the  optic  nerve,  and  divide  into  branches  which  run  parallel  with  the  axis  of 
the  eyeball :  they  are  distributed  to  the  middle  layer  of  the  choroid,  and  ciliary 
processes. 

The  long  ciliary  arteries,  two  in  number,  pierce  the  back  part  of  the  sclerotic, 
and  run  forward,  between  this  membrane  and  the  choroid,  to  the  Ciliary  muscle, 
where  they  each  divide  into  an  upper  and  lower  branch;  these  anastomose, 
and  form  a  vascular  circle  round  the  outer  circumference  of  the  iris ;  from  this 
circle  branches  are  given  off  which  unite,  near  the  margin  of  the  pupil,  in  a 
smaller  vascular  circle.  These  branches,  in  their  course,  supj)ly  the  muscular 
structure. 


APPENDAGES   OF   THE   EYE.     .  625 

The  anterior  ciliary  arteries,  five  or  six  in  number,  are  branches  of  the  muscular 
and  lachrymal  branches  of  the  ophthalmic.  They  pierce  the  eyeball,  at  the 
anterior  part  of  the  sclerotic,  immediately  behind  the  margin  of  the  cornea,  and 
are  distributed  to  the  ciliary  processes,  some  branches  joining  the  greater  vascular 
circle  of  the  iris. 

The  arteria  centralis  retinse  has  been  already  described. 

The  veins,  usually  four  in  number,  are  formed  mainly  by  branches  from  the 
surface  of  the  choroid.  They  perforate  the  sclerotic,  midway  between  the  cornea 
and  the  optic  nerve,  and  end  in  the  ophthalmic  vein. 

The  nerves  of  the  eyeball  are  the  optic,  the  long  ciliary  nerves  from  the  nasal 
branch  of  the  ophthalmic,  and  the  short  ciliary  nerves  from  the  ciliary  ganglion. 

Appendages  of  the  Eye. 

The  appendages  of  the  eye  {tutamina  oculi)  include  the  eyebrows,  the  eyelids, 
the  conjunctiva,  and  the  lachrymal  apparatus,  viz.,  the  lachrymal  gland,  the 
lachrymal  sac,  and  the  nasal  duct. 

The  eyebrows  {supercilia)  are  two  arched  eminences  of  integument,  which 
surmount  the  upper  circumference  of  the  orbit  on  each  side,  and  support  numerous 
short,  thick  hairs,  directed  obliquely  on  the  surface.  In  structure,  they  consist 
of  thickened  integument,  connected  beneath  with  the  Orbicularis  palpebrarum, 
Corrugator  supercilii,  and  Occipito-frontalis  muscles.  These  muscles  serve,  by 
their  action  on  this  part,  to  control  to  a  certain  extent  the  amount  of  light  admitted 
into  the  eye. 

The  eyelids  (palpebrse)  are  two  thin,  movable  folds,  placed  in  front  of  the  eye, 
protecting  it  from  injury  by  their  closure.  The  upper  lid  is  the  larger,  the  more 
movable  of  the  two,  and  supplied  by  a  separate  elevator  muscle,  the  Levator 
palpebrse  superioris.  When  the  eyelids  are  opened,  an  elliptical  space  {fissura 
palpebrarun%)  is  left  between  their  margins,  the  angles  of  which  correspond  to  the 
junction  of  the  upper  and  lower  lids,  and  are  called  canthi. 

The  outer  canthus  is  more  acute  than  the  inner,  and  the  lids  here  lie  in  close 
contact  with  the  globe ;  but  the  inner  canthus  is  prolonged  for  a  short  distance 
inwards,  towards  the  nose,  and  the  two  lids  are  separated  by  a  triangular  space, 
the  lacus  lacrymalis.  At  the  commencement  of  the  lacus  lacrymalis,  on  the 
margin  of  each  eyelid,  is  a  small  conical  elevation,  the  lachrymal  papilla,  or 
tubercle,  the  apex  of  which  is  pierced  by  a  small  orifice,  the  vunctum  lacrymale, 
the  commencement  of  the  lachrymal  canal. 

Structure  of  the  eyelids.  The  eyelids  are  composed  of  the  following  structures, 
taken  in  their  order  from  without  inwards : — 

Integument,  areolar  tissue,  fibres  of  the  Orbicularis  muscle,  tarsal  cartilage, 
fibrous  membrane,  Meibomian  glands,  and  conjunctiva.  The  upper  lid  has,  in. 
addition,  the  aponeurosis  of  the  Levator  palpebrse. 

The  integument  is  extremely  thin,  and  continuous  at  the  margin  of  the  lids  with 
the  conjunctiva. 

The  subcutaneous  areolar  tissue  is  very  lax  and  delicate,  seldom  contains  any  fat, 
and  is  extremely  liable  to  serous  infiltration. 

The  fibres  of  the  orbicularis  muscle,  where  they  cover  the  palpebrae,  are  thin, 
pale  in  color,  and  possess  an  involuntary  action. 

The  tarsal  cartilages  are  two  thin  elongated  plates  of  fibro-cartilage,  about  an 
inch  in  length.  They  are  placed  one  in  each  lid,  contributing  to  their  form  and 
support. 

The  superior,  the  larger,  is  of  a  semilunar  form,  about  one-third  of  an  inch 
in  breadth  at  the  centre,  and  becoming  gradually  narrowed  at  each  extremity. 
Into  the  fore  part  of  this  cartilage  the  aponeurosis  of  the  Levator  palpebrse  is 
attached. 

The  inferior  tarsal  cartilage,  the  smaller,  is  thinner,  and  of  an  elliptical 
form. 

40 


626 


ORGANS   OF   THE    SENSES. 


The  free  or  ciliary  margin  of  the  cartilages  is  thick,  and  presents  a  j^erfectlj 
straight  edge.  The  attached  or  orbital  margin  is  connected  to  the  circumference 
of  the  orbit  by  the  fibrous  membrane  of  the  lids.  The  outer  angle  of  each 
cartilage  is  attached  to  the  malar  bone  by  the  external  palpebral  or  tarsal  ligament. 
The  inner  angles  of  the  two  cartilages  terminate  at  the  commencement  of  the  lacus 
lacrymalis,  being  fixed  to  the  margins  of  the  orbit  by  the  tendo  oculi. 

The  fibrous  membrane  of  the  lids,  or  tarsal  ligament  is  a  layer  of  fibrous 
membrane,  beneath  the  Orbicularis,  attached,  externally,  to  the  margin  of  the 
orbit,  and  internally  to  the  orbital  margin  of  the  lids.  It  is  thick  and  dense  at 
the  outer  part  of  the  orbit,  but  becomes  thinner  as  it  approaches  the  cartilages. 
This  membrane  serves  to  support  the  eyelids,  and  retains  the  tarsal  cartilages  in 
their  position. 

The  Meibomian  glands  (fig.  309)  are  situated  upon  the  inner  surface  of  the 
eyelids,  between  the  tarsal  cartilages  and  conjunctiva,  and"  may  be  distinctly  seen 
through  the  mucous  membrane  on  everting  the  eyelids,  presenting  the  appearance 
of  parallel  strings  of  pearls.    They  are  about  thirty  in  number  in  the  upper  cartikge, 


FiL 


309. — The  Meibomian  Glands,  etc.,  seen  from  the  Inner  Surface 
of  the  Eyelids. 


JboNb 
Xar/iri/iiial. 


and  somewhat  fewer  in  the  lower.  They  are  imbedded  in  grooves  in  the  inner 
surface  of  the  cartilages,  and  correspond  in  length  with  the  breadth  of  each 
cartilage ;  they  are,  consequently,  longer  in  the  upper  than  in  the  lower  eyelid. 
Their  ducts  open  on  the  free  margin  of  the  lids  by  minute  foramina,  which 
correspond  in  number  to  the  follicles.  These  glands  are  a  variety  of  the 
cutaneous  sebaceous  glands,  each  consisting  of  a  single  straight  tube  or  follicle, 
having  a  ccecal  termination,  into  which  open  a  number  of  small  secondary  follicles. 
The  tubes  consist  of  basement  membrane,  covered  by  a  layer  of  scaly  epithelium ; 
the  cells  are  charged  with  sebaceous  matter,  which  constitutes  the  secretion.  The 
peculiar  parallel  arrangement  of  these  glands  side  by  side  forms  a  smooth  layer, 
admirably  adapted  to  .the  surface  of  the  globe,  over  which  they  constantly  glide. 
The  use  of  their  secretion  is  to  prevent  adhesion  of  the  lids. 

The  eyelashes  (cilia)  are  attached  to  the  free  edges  of  the  eyelids ;  they  are 
short,  thick,  curved  hairs,  arranged  in  a  double  or  triple  row  at  the  margin  of  the 
lids;  those  of  the  upper  lid,  more  numerous  and  longer  than  the  lower,  curve 
upwards;  those  of  the  lower  lid  curve  downwards,  by  which  means  they  do  not 
interlace  in  closing  the  lids. 

The  conjunctiva  is  the  mucous  membrane  of  the  eye.     It  lines  the  inner  surface 


LACHRYMAL   APPARATUS.  627 

of  the  eyelids,  and  is  reflected  over  the  fore  part  of  the  sclerotic  and  cornea.  In 
each  of  these  situations,  its  structure  presents  some  peculiarities. 

The  palpebral  portion  of  the  conjunctiva  is  thick,  opaque,  highly  vascular,  and 
covered  with  numerous  papilke,  which,  in  the  disease  called  granular  lids,  become 
greatly  hypertrophied.  At  the  margin  of  the  lids,  it  becomes  continuous  with  the 
lining  membrane  of  the  ducts  of  the  Meibomian  glands,  and,  through  the  lachrymal 
canals,  with  the  lining  membrane  of  the  lachrymal  sac  and  nasal  duct.  At  the 
outer  angle  of  the  upper  lid,  it  may  be  traced  along  the  lachrymal  ducts  into 
the  lachrymal  gland ;  and  at  the  inner  angle  of  the  eye,  it  forms  a  semilunar 
fold,  the  plica  semilunaris.  The  folds  formed  by  the  reflection  of  the  conjunctiva 
from  the  lids  on  to  the  eye  are  called  the  superior  and  inferior  palpebral  folds, 
the  former  being  the  deeper  of  the  two.  Upon  the  sclerotic,  the  conjunctiva  is 
loosely  connected  to  the  globe;  it  becomes  thinner,  loses  its  papillary  structure, 
is  transparent,  and  only  slightly  vascular  in  health.  Upon  the  cornea,  the  con- 
junctiva is  extremely  thin  and  closely  adherent,  and  no  vessels  can  be  traced  into 
it  in  the  adult  in  a  healthy  state.  In  the  foetus,  fine  capillary  loops  extend,  for 
some  little  distance  forwards,  into  this  membrane ;  but  in  the  adult  they  pass  only 
to  the  circumference  of  the  cornea. 

The  caruncula  lacrymalis  is  a  small,  reddish,  conical-shaped  body,  situated 
at  the  inner  canthus  of  the  eye,  and  filling  up  the  small  triangular  space  in  this 
situation,  the  lacus  lacrymalis.  It  consists  of  a  cluster  of  follicles  similar  in 
structure  to  the  Meibomian,  covered  with  mucous  membrane,  and  is  the  source  of 
the  whitish  secretion  which  constantly  collects  at  the  inner  angle  of  the  eye.  A 
few  slender  hairs  are  attached  to  its  surface.  On  the  outer  side  of  the  caruncula 
is  a  slight  semilunar  fold  of  mucous  membrane,  the  concavity  of  which  is  directed 
towards  the  cornea;  it  is  called  the  plica  semilunaris.  Between  its  two  layers  is 
found  a  thin  plate  of  cartilage.  This  structure  is  considered  to  be  the  rudiment 
of  the  third  eyelid  in  birds,  the  membrana  nictitans. 

Lachrymal  Apparatus  (fig.  310). 

The  lachrymal  apparatus  consists  of  the  lachrymal  gland,  which  secretes  the 
tears,  and  its  excretory  ducts,  which  convey  the  fluid  to  the  surface  of  the  eye, 

Fig.  310. — The  Lachrymal  Apparatus.     Right  Side. 


This  fluid  is  carried  away  by  the  lachrymal  canals  into  the  lachrymal  sac,  ana 
along  the  nasal  duct  into  the  cavity  of  the  nose. 


G28  ORGANS   OF   THE    SENSES. 

The  lachrymal  gland  is  lodged  in  a  depression  at  the  outer  angle  of  the  orbit, 
on  the  inner  side  of  the  external  angular  process  of  the  frontal  bone.  It  is  of  an 
oval  form,  about  the  size  and  shape  of  an  almond.  Its  upper  convex  surface  is  in 
contact  with  the  periosteum  of  the  orbit,  to  which  it  is  connected  by  a  few  fibrous 
bands.  Its  under  concave  surface  rests  upon  the  convexity  of  the  eyeball,  aud 
upon  the  Superior  and  External  recti  muscles.  Its  vessels  and  nerves  enter  its 
posterior  border,  whilst  its  anterior  margin  is  closely  adherent  to  the  back  part 
of  the  upper  eyelid,  and  is  covered,  on  its  inner  surface,  by  a  reflection  of  the 
conjunctiva.  This  margin  is  separated  from  the  rest  of  the  gland  by  a  slight 
depression,  hence  it  is  sometimes  described  as  a  separate  lobe,  called  the  palpe- 
bral portion  of  the  gland.  In  structure  and  general  appearance,  it  resembles  the 
salivary  glands.  Its  ducts,  about  seven  in  number,  run  obliquely  beneath  the 
mucous  membrane  for  a  short  distance,  and,  separating  from  each  other,  open  by  a 
series  of  minute  orifices  on  the  upper  and  outer  half  of  the  conjunctiva,  near  its 
reflection  on  to  the  globe.  These  orifices  are  arranged  in  a  row,  so  as  to  disperse 
the  secretion  over  the  surface  of  the  membrane. 

The  lachrymal  canals  commence  at  the  minute  orifices,  puncta  lacrymalia, 
seen  on  the  margin  of  the  lids,  at  the  outer  extremity  of  the  lacus  lacrymalis. 
They  commence  on  the  summit  of  a  slightly  elevated  papilla,  the  papilla  lacry- 
malis, and  lead  into  minute  canals,  the  canaliculi,  which  proceed  inwards  to 
terminate  in  the  lachrymal  sac.  The  superior  canal,  the  smaller  and  longer  of 
the  two,  at  first  ascends,  and  then  bends  at  an  acute  angle,  and  passes  inwards  and 
downwards  to  the  lachrymal  sac.  The  inferior  canal  at  first  descends,  and  then, 
abruptly  changing  its  course,  passes  almost  horizontally  inwards.  They  are  dense 
and  elastic  in  structure,  and  somewhat  dilated  at  their  angle. 

The  lachrymal  sac  is  the  upper  dilated  extremity  of  the  nasal  duct,  and  is 
lodged  in  a  deep  groove  formed  by  the  lachrymal  bone  and  nasal  process  of  the 
superior  maxillary.  It  is  oval  in  form,  its  upper  extremity  being  closed  in  and 
rounded,  whilst  below  it  is  continued  into  the  nasal  duct.  It  is  covered  by  the 
Tensor  tarsi  muscle  and  by  a  fibrous  expansion  derived  from  the  tendo  oculi, 
which  is  attached  to  the  ridge  on  the  lachrymal  bone.  In  structure,  it  consists  of 
a  fibrous  elastic  coat,  lined  internally  by  mucous  membrane ;  the  latter  is  continuous, 
through  the  canaliculi,  with  the  mucous  lining  of  the  conjunctiva,  and  through  the 
nasal  duct  with  the  pituitary  membrane  of  the  nose. 

The  nasal  duct  is  a  membranous  canal,  about  three  quarters  of  an  inch  in 
length,  which  extends  from  the  lower  part  of  the  lachrymal  sac  to  the  inferior 
meatus  of  the  nose,  where  it  terminates  by  a  somewhat  expanded  orifice,  provided 
with  an  imperfect  valve  formed  by  the  mucous  membrane.  It  is  contained  in  an 
osseous  canal,  formed  by  the  superior  maxillary,  the  lachrymal,  and  the  inferior 
turbinated  bones,  is  narrower  in  the  middle  than  at  each  extremity,  and  takes  a 
direction  downwards,  backwards,  and  a  little  outwards.  It  is  lined  by  mucous 
membrane,  which  is  continuous  below  with  the  pituitary  lining  of  the  nose.  In 
the  canaliculi,  this  membrane  is  provided  with  scaly  epithelium;  but  in  the 
lachrymal  sac  and  nasal  duct,  the  epithelium  is  ciliated  as  in  the  nose. 

The    Ear. 

The  Organ  of  Hearing  consists  of  three  parts ;  the  external  ear,  the  middle  ear 
or  tympanum,  and  the  internal  ear  or  labyrinth. 

External  Ear. 

The  External  Ear  consists  of  an  expanded  portion  named  the  pinna  or  auricle, 
and  the  auditory  canal  or  meatus.  The  former  serves  to  collect  the  vibrations  of 
the  air  constituting  sound,  and  the  latter  conducts  those  vibrations  to  the  tym- 
panum. 

The  pinna  or  auricle  (fig.  311)  consists  of  a  layer  of  cartilage,  covered  by 
integument,  and  connected  to  the  commencement  of  the  auditory  canal ;  it  is  of  an 


TIIE   EAR. 


G29 


Fig.  311. — The  Pinna  or  Auricle. 
Outer  Surface. 


ovoid  form,  its  surface  uneven,  with  its  larger  end  directed  upwards.  Its  outer 
surface  is  irregularly  concave,  directed  slightly  forwards,  and  presents  numerous 
eminences  and  depressions,  which  result  from  the  foldings  of  its  fibro-cartilaginous 
element.  To  each  of  these  names  have  been  assigned.  Thus,  the  external  pro- 
minent rim  of  the  auricle  is  called  the  helix. 
Another  curved  prominence,  parallel  with, 
and  in  front  of,  the  helix,  is  called  the  anti- 
helix  ;  this  bifurcates  above  into  two  parts, 
so  as  to  inclose  a  triangular  depression,  the 
fossa  of  the  antihelix.  The  narrow  curved 
depression  between  the  helix  and  antihelix 
is  called  the /055a  of  the  helix  {fossa  innomi- 
rtata  seu  scaphoidea).  The  antihelix  de- 
scribes a  circuit  round  a  deep,  capacious 
cavity,  the  concha,  which  is  partially  divided 
into  two  parts  by  the  commencement  of  the 
helix.  In  front  of  the  concha,  and  project- 
ing backwards  over  the  meatus,  is  a  small 
pointed  eminence,  the  tragus;  so  called 
from  its  being  generally  covered,  on  its  under 
surface,  with  a  tuft  of  hair,  resembling  a 
goat's  beard.  Opposite  the  tragus,  and  sepa- 
rated from  it  by  a  deep  notch  (incisura 
intertragica),  is  a  small  tubercle,  the  anti- 
tragus.  Below  this  is  the  lobule,  composed 
of  tough  areolar  and  adipose  tissues,  wanting 
the  firmness  and  elasticity  of  the  rest  of  the 
pinna. 

Structure  of  the  pinna.  The  pinna  is  composed  of  a  thin  plate  of  yellow 
cartilage,  covered  with  integument,  and  connected  to  the  surrounding  parts  by 
ligaments,  and  a  few  muscular  fibres. 

The  integument  is  thin,  closely  adherent  to  the  cartilage,  and  furnished  with 
sebaceous  glands,  which  are  most  numerous  in  the  concha  and  scaphoid  fossa. 

The  cartilage  of  the  pinna  consists  of  one  single  piece ;  it  gives  form  to  this 
part  of  the  ear,  and  upon  its  surface  are  found  all  the  eminences  and  depressions 
above  described.  It  does  not  enter  into  the  construction  of  all  parts  of  the  auricle, 
and  presents  several  intervals  or  fissures  in  its  substance,  which  partially  separate 
the  different  parts.  Thus,  it  does  not  form  a  constituent  part  of  the  lobule ;  it  is 
deficient,  also,  between  the  tragus  and  beginning  of  the  helix,  the  notch  between 
them  being  filled  up  by  dense  fibrous  tissue.  The  fissures  in  the  cartilage  are  the 
fissure  of  the  helix,  a  short,  vertical  slit,  situated  at  the  fore  part  of  the  pinna, 
immediately  behind  a  small  conical  projection  of  cartilage,  opposite  the  first  curve 
of  the  helix  {process  of  the  helix) ;  another  fissure,  the  fissure  of  the  tragus,  is 
seen  upon  the  anterior  surface  of  the  tragus.  The  antihelix  is  divided  below,  by 
a  deep  fissure,  into  two  parts ;  one  part  terminates  by  a  pointed,  tail-like  extremity 
{processus  caudatus) ;  the  other  is  continuous  with  the  antitragus.  The  cartilage 
of  the  pinna  is  very  pliable,  elastic,  of  a  yellowish  color,  and  similar  in  structure  to 
the  cartilages  of  the  ala3  nasi. 

The  ligaments  of  the  pinna  consist  of  two  sets: — 1.  Those  connecting  it  to 
the  side  of  the  head.  2.  Those  connecting  the  various  parts  of  its  cartilage 
together. 

The  former,  the  most  important,  are  two  in  number,  anterior  and  posterior. 
The  anterior  ligament  extends  from  the  process  of  the  helix  to  the  root  of  the 
zygoma.  The  posterior  ligament  passes  from  the  posterior  surface  of  the  concha 
to  the  outer  surface  of  the  mastoid  process  of  the  temporal  bone.  A  few  fibres 
connect  the  tragus  to  the  root  of  the  zygoma. 

Those  connecting  the  various  parts  of  the  cartilage  together  are  also  two  in 


630  ORGANS   OF   THE    SENSES. 

number.  Of  these,  one  is  a  strong  fibrous  band,  stretching  across  from  the  tragus 
to  the  commencement  of  the  helix,  completing  the  meatus  in  front,  and  partly 
encircling  the  boundary  of  the  concha ;  the  other  extends  between  the  concha  and 
the  processus  caudatus. 

The  muscles  of  the  pinna  (fig.  312),  like  the  ligaments,  also  consist  of  two  sets : — 
1.  Those  which  connect  it  with  the  side  of  the  head,  moving  the  pinna  as  a  whole, 

Fig.  312.— The  Muscles  of  the  Pinna. 


viz.,  the  Attollens  aurem,  Attrahens  aurem,  and  Retrahens  aurem  (p.  241).  2. 
The  proper  muscles  of  the  pinna,  which  extend  from  one  part  of  the  auricle  to 
another.     These  are  the 

Helicis  major.  Antitragicus. 

Helicis  minor.  Transversus  auriculae. 

Tragicus.  Obliquus  auris. 

The  Helicis  major  is  a  narrow,  vertical  band  of  muscular  fibres,  situated  upon 
the  anterior  margin  of  the  helix.  It  arises,  below,  from  the  tubercle  of  the  helix, 
and  is  inserted  into  the  anterior  border  of  the  helix,  just  where  it  is  about  to 
curve  backwards.     It  is  pretty  constant  in  its  existence. 

The  Helicis  minor  is  an  oblique  fasciculus,  firmly  attached  to  that  part  of  the 
helix  which  commences  from  the  bottom  of  the  concha. 

The  Tragicus  is  a  short,  flattened  band  of  muscular  fibres,  situated  upon  the 
outer  surface  of  the  tragus,  the  direction  of  its  fibres  being  vertical. 

The  Antitragicus  arises  from  the  outer  part  of  the  antitragus ;  its  fibres  are 
inserted  into  the  processus  caudatus  oftheanti  helix.  This  muscle  is  usually  very 
distinct. 

The  Transversus  auriculae  is  placed  on  the  cranial  surface  of  the  pinna.  It 
consists  of  radiating  fibres,  partly  tendinous  and  partly  muscular,  extending  from 
the  convexity  of  the  concha  to  the  prominence  corresponding  with  the  groove  of 
the  helix. 


AUDITORY   CANAL. 


631 


The  Obliquus  auris  (Todd)  consists  of  a  few  fibres  extending  from  the  upper 
and  back  part  of  the  concha  to  the  convexity  immediately  above  it. 

The  arteries  of  the  pinna  are  the  posterior  auricular,  from  the  external  carotid ; 
the  anterior  auricular,  from  the  temporal ;  and.  an  auricular  branch  from  the  occi- 
pital artery. 

The  veins  accompany  the  corresponding  arteries. 

The  nerves  are  the  auricularis  magnus,  from  the  cervical  plexus ;  the  posterior 
auricular,  from  the  facial ;  the  auricular  branch  of  the  pneumogastric ;  and  the 
auriculo-temporal  branch  of  the  inferior  maxillary  nerve. 

The  Auditory  Canal,  meatus  auditorius  externus  (fig.  313),  extends  from  the 
bottom  of  the  concha  to  the  membrana  tympani.  It  is  about  an  inch  and.  a 
quarter  in  length,  its  direction  obliquely  forwards  and  inwards,  and  it  is  slightly 


Fig.  313. — A  Front  View  of  the  Organ  of  Hearing.     Right  Side. 


Incus 

\   Ma.  1  leas 

\\    S  tap  i3 

^^^tSimi-ehvalar  Ca^ia.1' 

\'t»ft>:,* 

if       .Cochlt^ 

curved  upon  itself,  so  as  to  be  higher  in  the  middle  than  at  either  extremity.  It 
forms  an  oval  cylindrical  canal,  narrowest  at  the  middle,  somewhat  flattened  from 
before  backwards,  the  greatest  diameter  being  in  the  vertical  direction  at  the  ex- 
ternal orifice ;  but,  in  the  transverse  direction,  at  the  tympanic  end.  The  membrana 
tympani,  which  occupies  the  termination  of  the  meatus,  is  obliquely  directed,  in 
consequence  of  the  floor  of  this  canal  being  longer  than  the  roof,  and  the  anterior 
wall  longer  than  the  posterior.  The  auditory  canal  is  formed  partly  by  cartilage 
and  membrane,  and  partly  by  bone. 

The  cartilaginous  portion  is  about  half  an  inch  in  length,  being  rather  less  than 
half  the  canal ;  it  is  formed  by  the  cartilage  of  the  concha  and  tragus,  being  pro- 
longed inwards  to  the  circumference  of  the  auditory  process,  to  which  it  is  firmly 
attached.  This  tube  is  deficient  at  its  upper  and  back  part,  its  place  being  supplied 
by  fibrous  membrane.  This  part  of  the  canal  is  rendered  extremely  movable,  by 
two  or  three  deep  fissures  (incisure  Santorini),  which  extend  through  the  cartilage 
in  a  vertical  direction. 

The  osseous  portion  is  about  three-quarters  of  an  inch  in  length,  and  narrower 
than  the  cartilaginous  portion.  It  is  directed  inwards  and  a  little  forwards,  forming 
a  slight  curve  in  its  course,  the  convexity  of  which  is  upwards  and  backwards. 
Its  inner  end,  which  communicates  with  the  cavity  of  the  tympanum,  is  smaller 
than  the  outer,  and  sloped,  the  anterior  wall  projecting  beyond  the  posterior  about 
two  lines ;  it  is  marked,  excepting  at  its  upper  part,  by  a  narrow  groove  for  the 
insertion  of  the  membrana  tympani.  Its  outer  end  is  dilated,  and  rough  in  the 
greater  part  of  its  circumference  for  the  attachment  of  the  cartilage  of  the  pinna. 
Its  vertical  transverse  section  is  oval,  the  greatest  diameter  being  from  above 


C32  ORGANS   OF   THE    SENSES. 

downwards.  The  front  and  lower  parts  of  this  canal  are  formed  by  a  curved 
plate  of  bone,  which,  in  the  foetus,  exists  as  a  separate  ring  (tympanic  bone), 
incomplete  at  its  upper  part. 

The  skin  lining  the  meatus  is  very  thin,  closely  adherent  to  the  cartilaginous 
and  osseous  portions  of  the  tube,  and  covers  the  surface  of  the  membrana  tympani, 
forming  its  outer  layer.  After  maceration,  the  thin  pouch  of  epidermis,  when 
withdrawn,  preserves  the  form  of  the  meatus.  The  skin  near  the  orifice  is  fur- 
nished with  hairs  and  sebaceous  glands.  In  the  thick  subcutaneous  tissue  of  the 
cartilaginous  part  of  the  meatus  are  numerous  ceruminous  glands,  which  secrete 
the  ear  wax,  the  ducts  of  which  open  on  the  surface  of  the  skin. 

The  arteries  supplying  the  meatus  are  branches  from  the  posterior  auricular, 
internal  maxillary,  and  temporal. 

The  nerves  are  chiefly  derived  from  the  temporo-auricular  branch  of  the  inferior 
maxillary  nerve. 

i  Middle  Ear  or  Tympanum. 

The  middle  ear  or  tympanum  is  an  irregular  cavity,  compressed  from  without 
inwards,  and  situated  within  the  petrous  bone.  It  is  placed  above  the  jugular 
fossa,  the  carotid  canal  lying  in  front,  the  mastoid  cells  behind,  the  meatus  audito- 
rius  externally,  and  the  labyrinth  within.  It  is  filled  with  air,  and  communicates 
with  the  pharynx  by  the  Eustachian  tube.  The  tympanum  is  traversed  by  a 
chain  of  movable  bones,  which  connect  the  membrana  tympani  with  the  laby- 
rinth, and  serve  to  convey  the  vibrations  communicated  to  the  membrana  tympani 
across  the  cavity  of  the  tympanum  to  the  internal  ear. 

The  cavity  of  the  tympanum  measures  about  five  lines  from  before  backwards, 
three  lines  in  the  vertical  direction,  and  between  two  and  three  in  the  transverse, 
being  a  little  broader  behind  and  above  than  below  and  in  front.  It  is  bounded 
externally  by  the  membrana  tympani  and  meatus ;  internally,  by  the  outer  surface 
of  the  internal  ear;  behind,  by  the  mastoid  cells;  and,  in  front,  by  the  Eustachian 
tube  and  canal  for  the  Tensor  tympani.  Its  roof  and  floor  are  formed  by  thin 
osseous  laminae,  which  connect  the  squamous  and  petrous  portions  of  the  temporal 
bone. 

The  roof  is  broad,  flattened,  and  formed  of  a  thin  plate  of  bone,  which  separates 
the  cranial  and  tympanic  cavities. 

The  floor  is  narrow,  and  corresponds  to  the  jugular  fossa,  which  lies  beneath. 

The  outer  wall  is  formed  by  the  membrana  tympani,  a  small  portion  of  bone 
being  seen  above  and  below  this  membrane.  It  presents  three  small  apertures, 
the  iter  chordae  posterius,  the  Glaserian  fissure,  and  the  iter  chordae  anterius. 

The  aperture  of  the  iter  chordee  posterius  is  behind  the  aperture  for  the  membrana 
tympani,  close  to  its  margin,  at  a  level  with  its  centre ;  it  leads  into  a  minute  canal, 
which  descends  in  front  of  the  aquaeductus  Fallopii,  and  terminates  in  this  canal 
near  the  stylo-mastoid  foramen.  Through  it  the  chorda  tympani  nerve  enters  the 
tympanum. 

The  Glaserian  fissure  opens  just  above  and  in  front  of  the  orifice  of  the  mem- 
brana tympani;  in  this  situation  it  is  a  mere  slit,  about  a  line  in  length.  It  gives 
passage  to  the  long  process  of  the  malleus,  the  Laxator  tympani  muscle,  and  some 
tympanic  vessels. 

The  aperture  of  the  iter  chordae  anterius  is  seen  just  above  the  preceding  fissure ; 
it  leads  into  a  canal  (canal  of  Huguier),  which  runs  parallel  with  the  Glaserian 
fissure.     Through  it  the  chorda  tympani  nerve  leaves  the  tympanum. 

The  internal  wall  of  the  tympanum  is  vertical  in  direction,  and  looks  directly 
outwards.     It  presents  for  examination  the  following  parts : — 

Fenestra  ovalis.  Eidge  of  the  Aquaeductus  Fallopii. 

Fenestra  rotunda.  Pyramid. 

Promontory.  .       Opening  for  the  Stapedius. 


THE   TYMPANUM. 


633 


The  fenestra  ovalis  is  a  reniform  opening,  leading  from  the  tympanum  into 
the  vestibule ;  its  long  diameter  is  directed  horizontally,  and  its  convex  border 
upwards.  The  opening  in  the  recent  state  is  closed  by  the  lining  membrane 
common  to  both  cavities,  and  is  occupied  by  the  base  of  the  stapes.  This  mem- 
brane is  placed  opposite  the  membrana  tympani,  and  is  connected  with  it  by  the 
ossicula  auditus. 

The  fenestra  rotunda  is  an  oval  aperture,  placed  at  the  bottom  of  a  funnel- 
shaped  depression,  leading  into  the  cochlea.    It  is  placed  below  and  rather  behind 


Fig.  314. — View  of  Inner  Wall  of  Tympanum.     (Enlarged.) 


Chorda  Tjjn^a 


the  fenestra  ovalis,  from  which  it  is  separated  by  a  rounded  elevation,  the  pro- 
montory ;  it  is  closed  in  the  recent  state  by  a  membrane  {membrana  tympani 
secundaria,  Scarpa).  This  membrane  is  concave  towards  the  tympanum,  convex 
towards  the  cochlea.  It  consists  of  three  layers;  the  external  or  mucous, 
derived  from  the  mucous  lining  of  the  tympanum ;  the  internal  or  serous,  from 
the  lining  membrane  of  the  cochlea ;  and  an  intermediate  or  fibrous  layer. 

The  promontory  is  a  rounded  hollow  prominence,  formed  by  the  projection 
outwards  of  the  first  turn  of  the  cochlea ;  it  is  placed  between  the  fenestras,  and 
furrowed  on  its  surface  by  three  small  grooves,  which  lodge  branches  of  the 
tympanic  plexus. 

The  rounded  eminence  of  the  aquseductm  Fallopii  is  placed  between  the  fenestra 
ovalis  and  roof  of  the  tympanum ;  it  is  the  prominence  of  the  bony  canal  in  which 
the  portio  dura  is  contained.  It  traverses  the  inner  wall  of  the  tympanum  above 
the  fenestra  ovalis,  and,  behind  that  opening,  curves  nearly  vertically  downwards 
along  the  posterior  wall. 

The  pyramid  is  a  conical  eminence,  situated  immediately  behind  the  fenestra 
ovalis,  and  in  front  of  the  vertical  portion  of  the  eminence  above-described ;  it  is 
hollow  in  the  interior,  and  contains  the  Stapedius  muscle;  its  summit  projects 
forwards  towards  the  vestibular  fenestra,  and  presents  a  small  aperture,  which 
transmits  the  tendon  of  the  muscle.  The  cavity  in  the  pyramid  is  prolonged  into 
a  minute  canal,  which  communicates  with  the  aquaeductus  Fallopii. 

The  posterior  wall  of  the  tympanum  is  wider  above  than  below,  and  presents 
for  examination  the 

Openings  of  the  Mastoid  Cells. 

These  consist  of  one  large  irregular  aperture,  and  several  smaller  openings, 
situated  at  the  upper  part  of  the  posterior  wall ;  they  lead  into  canals,  which  com- 
municate with  large  irregular  cavities  contained  in  'the   interior  of  the  mastoid 


634  ORGANS   OF   THE    SENSES. 

process.  These  cavities  vary  considerably  in  number,  size,  and  form ;  they  are 
lined  by  mucous  membrane,  continuous  with  that  covering  the  cavity  of  the 
tympanum. 

The  anterior  wall  of  the  tympanum  is  wider  above  than  below ;  it  corresponds 
with  the  carotid  canal,  from  which  it  is  separated  by  a  thin  plate  of  bone ;  it 
presents  for  examination  the 

Canal  for  the  Tensor  tympani.  Orifice  of  the  Eustachian  Tube. 

Processus  Cochleariformis. 

The  orifice  of  the  canal  for  the  Tensor  tympani,  and  the  orifice  of  the  Eustachian 
tube,  are  situated  at  the  upper  part  of  the  interior  wall,  being  separated  from 
each  other  by  a  thin,  delicate  horizontal  plate  of  bone,  the  processus  cochleari- 
formis. These  canals  run  from  the  tympanum  forward,  inward,  and  a  little 
downward,  to  the  retiring  angle  between  the  squamous  and  petrous  portions  of  the 
temporal  bone. 

The  canal  for  the  Tensor  tympani  is  the  superior  and  the  smaller  of  the  two :  it 
is  rounded  and  lies  beneath  the  upper  surface  of  the  petrous  bone,  close  to  the 
hiatus  Fallopii.  The  tympanic  end  of  this  canal  forms  a  conical  eminence,  which 
is  prolonged  backwards  into  the  cavity  of  the  tympanum,  and  is  perforated  at  its 
summit  by  an  aperture,  which  transmits  the  tendon  of  the  muscle  contained  in  it. 
This  eminence  is  sometimes  called  the  anterior  pyramid.  The  canal  contains  the 
Tensor  tympani  muscle. 

The  Eustachian  tube  is  the  channel  through  which  the  tympanum  communicates 
with  the  pharynx.  Its  length  is  from  an  inch  and  a  half  to  two  inches,  and  its 
direction  downwards,  forwards,  and  inwards.  It  is  formed  partly  of  bone,  partly 
of  cartilage  and  fibrous  tissue. 

The  osseous  portion  is  about  half  an  inch  in  length.  It  commences  in  the  lower 
part  of  the  anterior  wall  of  the  tympanum,  below  the  processus  cochleariformis, 
and,  gradually  narrowing,  terminates  in  an  oval  dilated  opening,  at  the  angle  of 
junction  of  the  petrous  and  squamous  portions,  its  extremity  presenting  a  jagged 
margin,  which  serves  for  the  attachment  of  the  cartilaginous  portion. 

The  cartilaginous  portion,  about  an  inch  in  length,  is  formed  of  a  triangular 
plate  of  cartilage,  curled  upon  itself,  an  interval  being  left  below,  between  the 
non-approximated  margins  of  the  cartilage,  which  is  completed  by  fibrous  tissue. 
Its  canal  is  narrow  behind,  wide,  expanded,  and  somewhat  trumpet-shaped  in 
front,  terminating  by  an  oval  orifice,  placed  at  the  upper  part  and  side  of  the 
pharynx,  behind  the  back  part  of  the  inferior  meatus.  Through  this  canal 
the  mucous  membrane  of  the  pharynx  is  continuous  with,  that  which  lines  the 
tympanum. 

The  membrana  tympani  separates  the  cavity  of  the  tympanum  from  the  bottom 
of  the  external  meatus.  It  is  a  thin  semi-transparent  membrane,  nearly  oval  in 
form,  somewhat  broader  above  than  below,  and  directed  very  obliquely  down- 
wards and  inwards.  Its  circumference  is  contained  in  a  groove  at  the  inner  end 
of  the  meatus,  which  skirts  the  circumference  of  this  part  excepting  above.  The 
handle  of  the  malleus  descends  vertically  between  the  inner  and  middle  layers 
of  this  membrane  as  far  down  as  its  centre,  where  it  is  firmly  attached,  drawing 
the  membrane  inwards,  so  that  its  outer  surface  is  concave,  its  inner  convex. 

Structure.  This  membrane  is  composed  of  three  layers,  an  external  or  cuticular, 
a  middle  or  fibrous,  and  an  internal  or  mucous.  The  cuticular  lining  is  derived 
from  the  integument  lining  the  meatus.  The  fibrous  layer  consists  of  fibrous  and 
elastic  tissues ;  some  of  the  fibres  radiate  from  near  the  centre  to  the  circumfer- 
ence ;  others  are  arranged,  in  the  form  of  a  dense  circular  ring,  round  the  attached 
margin  of  the  membrane.  The  mucous  lining  is  derived  from  the  mucous  lining 
of  the  tympanum.  The  vessels  pass  to  the  membrana  tympani  along  the  handle 
of  the  malleus,  and  are  distributed  between  its  layers. 

Ossicles  of  the  Tympanum.  The  tympanum  is  traversed  by  a  chain  of 
movable  bones,  three  in  number,  the  malleus,  incus,  and  stapes.     The  former  is 


OSSICLES   OF   THE   TYMPANUM.  635 

attached  to  the  membrana  tympani,  the  latter  to  the  fenestra  ovalis,  the  incus 
being  placed  between  the  two,  to  both  of  which  it  is  connected  by  delicate 
articulations. 

The  Malleus,  so  named  from  its  fancied  resemblance  to  a  hammer,  consists  of  a 
head,  neck,  handle  or  manubrium,  and  two  processes,  viz.,  the  processus  gracilis 
and  the  processus  brevis. 

The  head  is  the  large  upper  extremity  of  the  bone ;  it  is  oval  in  shape,  and 
articulates  posteriorly  with  the  incus,  being  free  in  the  rest  of  its  extent. 

The  neck  is  the  narrow  contracted  part  just  beneath  the  head ;  and  below  this 
is  a  prominence,  to  which  the  various  processes  are  attached. 

The  manubrium  is  a  vertical  portion  of  bone,  which  is  connected  by  its  outer 
margin  with  the  membrana  tympani.  It  decreases  in  size  towards  its  extremity, 
where  it  is  curved  slightly  forwards,  and  flattened  from  within  outwards. 

The  processus  gracilis  is  a  long  and  very  delicate  process,  which  passes  from 
the  eminence  below  the  neck  forwards  and  outwards  to  the  Glaserian  fissure,  to 
which  it  is  connected  by  bone  and  ligamentous  fibres.  It  gives  attachment  to  the 
Laxator  tympani. 

The  processus  brevis  is  a  slight  conical  projection,  which  springs  from  the  root 
of  the  manubrium,  and  lies  in  contact  with  the  membrana  tympani.  Its  summit 
gives  attachment  to  the  Tensor  tympani. 

The  Incus  has  received  its  name  from  its  resemblance  to  an  anvil,  but  it  does 
not  look  unlike  a  bicuspid  tooth,  with  two 
roots,  which  differ  in  length,  and  are  widely 

separated  from  each  other.  It  consists  of  a  Fi«-  ™^Z  Sld^l"?ed  T'  "~ 
body  and  two  processes. 

The  body  is  somewhat  quadrilateral,  but 
compressed  laterally.  Its  summit  is  deeply 
concave,  and  articulates  with  the  malleus ;  in 
the  fresh  state,  it  is  covered  with  cartilage 
and  lined  with  synovial  membrane. 

The  two  processes  diverge  from  one 
another  nearly  at  right  angles. 

The  sltort  process,  somewhat  conical  in 
shape,  projects  nearly  horizontally  back- 
wards, and  is  attached  to  the  margin  of  the 
opening  leading  into  the  mastoid  cells  by 
ligamentous  fibres. 

The  long  process,  longer  and  more  slender  than  the  preceding,  descends  nearly 
vertically  behind  the  handle  of  the  malleus,  and,  bending  inwards,  terminates  in  a 
rounded  globular  projection,  the  os  orbiculare,  tipped  with  cartilage,  and  articu- 
lating with  the  head  of  the  stapes.  In  the  foetus  the  os  orbiculare  exists  as  a 
separate  bone,  but  becomes  united  to  the  long  process  of  the  incus  in  the  adult. 

The  Stapes,  so  called  from  its  close  resemblance  to  a  stirrup,  consists  of  a  head, 
neck,  two  branches,  and  a  base. 

The  head  presents  a  depression,  tipped  with  cartilage,  which  articulates  with 
the  os  orbiculare. 

The  neck,  the  constricted  part  of  the  bone  below  the  head,  receives  the  insertion 
of  the  Stapedius  muscle. 

The  two  branches  or  crura  diverge  from  the  neck,  and  are  connected  at  their 
extremities  by  a  flattened,  oval-shaped  plate  (the  base),  which  forms  the  foot  of 
the  stirrup,  and  is  fixed  to  the  margin  of  the  fenestra  ovalis  by  ligamentous  fibres. 

Ligaments  of  the  Ossicula.  These  small  bones  are  connected  with  each  other, 
and  with  the  tympanum,  by  ligaments,  and  moved  by  small  muscles.  The  articular 
surfaces  of  the  malleus  and  incus,  the  orbicular  process  of  the  incus  and  the  head 
of  the  stapes,  are  covered  with  cartilage,  connected  together  by  delicate  capsular 
ligaments,  and  lined  by  synovial  membrane.  The  ligaments  connecting  the  ossicula 
with  the  walls  of  the  tympanum  are  three  in  number,  one  for  each  bone. 


«36  ORGANS   OF   THE    SENSES. 

The  suspensory  ligament  of  the  malleus  is  a  delicate,  round  bundle  of  fibres, 
which,  descends  perpendicularly  from  the  roof  of  the  tympanum  to  the  head  of  the 
malleus. 

The  posterior  ligament  of  the  incus  is  a  short,  thick,  ligamentous  band,  which 
connects  the  extremity  of  the  short  process  of  the  incus  to  the  posterior  wall  of 
the  tympanum,  near  the  margin  of  the  opening  of  the  mastoid  cells. 

The  annular  ligament  of  the  stapes  connects  the  circumference  of  the  base  of 
this  bone  to  the  margin  of  the  fenestra  ovalis. 

A  suspensory  ligament  of  the  incus  has  been  described  by  Arnold,  descending 
from  the  roof  of  the  tympanum  to  the  upper  part  of  the  incus,  near  its  articulation 
with  the  malleus. 

The  Muscles  of  the  tympanum  are  three : — 

Tensor  tympani.  Laxator  tympani.  Stapedius. 

The  Tensor  tympani,  the  largest,  is  contained  in  a  bony  canal,  above  the  osseous 
portion  of  the  Eustachian  tube,  from  which  it  is  separated  by  the  processus 
cochleariformis.  It  arises  from  the  under  surface  of  the  petrous  bone,  from  the 
cartilaginous  portion  of  the  Eustachian  tube,  and  from  the  osseous  canal  in  which 
it  is  contained.  Passing  backwards,  it  terminates  in  a  slender  tendon,  which  is 
reflected  outwards  over  the  processus  cochleariformis,  and  is  inserted  into  the 
handle  of  the  malleus,  near  its  root.  It  is  supplied  by  a  branch  from  the  otic 
ganglion. 

The  Laxator  tympani  major  (Sommering)  arises  from  the  spinous  process  of 
the  sphenoid  bone,  and  from  the  cartilaginous  portion  of  the  Eustachian  tube; 
passing  backwards  through  the  Glaserian  fissure,  it  is  inserted  into  the  neck  of 
the  malleus,  just  above  the  processus  gracilis.  It  is  supplied  by  the  tympanic 
branch  of  the  facial. 

The  Laxator  tympani  minor  (Sommering)  arises  from  the  upper  and  back  part 
of  the  external  meatus,  passing  forwards  and  inwards  between  the  middle  and 
inner  layers  of  the  membrana  tympani;  it  is  inserted  into  the  handle  of  the 
malleus,  and  processus  brevis.  This  is  considered  as  a  ligament  by  some 
anatomists. 

The  Stapedius  arises  from  the  sides  of  a  conical  cavity  hollowed  out  of  the 
interior  of  the  pyramid ;  its  tendon  emerges  from  the  orifice  at  its  apex,  and, 
passing  forwards,  is  inserted  into  the  neck  of  the  stapes.  Its  surface  is  aponeurotic, 
its  interior  fleshy,  and  its  tendon  occasionally  contains  a  slender  bony  spine, 
which  is  constant  in  some  mammalia.  It  is  supplied  by  a  filament  from  the  facial 
nerve. 

Actions.  The  Tensor  tympani  draws  the  membrana  tj^mpani  inwards,  and  thus 
heightens  its  tension.  The  Laxator  tympani  draws  the  malleus  outwards,  and 
thus  the  tympanic  membrane,  especially  at  its  fore  part,  is  relaxed.  The  Stapedius 
depresses  the  back  part  of  the  base  of  the  stapes,  and  raises  its  fore  part.  It 
probably  compresses  the  contents  of  the  vestibule. 

The  Mucous  Membrane  of  the  tympanum  is  thin,  vascular,  and  continuous  with 
the  mucous  membrane  of  the  pharynx,  through  the  Eustachian  tube.  It  invests 
the  ossicula,  and  the  muscles  and  nerves  contained  in  the  tympanic  cavity,  forms 
the  internal  layer  of  the  membrana  tympani,  covers  the  foramen  rotundum,  and 
is  reflected  into  the  mastoid  cells,  which  it  lines  throughout.  In  the  tympanum 
and  mastoid  cells,  this  membrane  is  pale,  thin,  slightly  vascular,  and  covered  with 
ciliated  epithelium.  In  the  osseous  portion  of  the  Eustachian  tube,  the  membrane 
is  thin;  but  in  the  cartilaginous  portion  it  is  very  thick,  highly  vascular, 
covered  with  laminar  ciliated  epithelium,  and  provided  with  numerous  mucous 
glands. 

The  Arteries  supplying  the  tympanum  are  five  in  number,  viz.,  the  tympanic 
branch  of  the  internal  maxillary,  which  supplies  the  membran/i  tympani ;  the 
stylo-mastoid  branch  of  the  posterior  auricular,  which  supplies  the  back  part  of 
the  tympanum  and  mastoid  cells ;  the  smaller  branches  being  the  petrosal  branch 


INTERNAL   EAR.  637 

of  the  middle  meningeal,  and  branches  from  the  ascending  pharyngeal  and  internal 
carotid. 

The  Veins  of  the  tympanum  terminate  in  the  middle  meningeal  and  pharyngeal 
veins,  and,  through  these,  in  the  internal  jugular. 

The  Nerves  of  the  tympanum  may  be  divided  into : — 1.  Those  supplying  the  mus- 
cles. 2.  Those  distributed  to  the  lining  membrane.  3.  Branches  communicating 
with  other  nerves. 

Nerves  to  muscles.  The  Tensor  tympani  is  supplied  by  a  branch  from  the  otic 
ganglion ;  the  Laxator  tympani  and  the  Stapedius,  by  a  filament  from  the  facial 
(Sommering). 

The  nerves  distributed  to  the  lining  membrane  are  derived  from  the  tympanic 
plexus. 

Communications  between  the  following  nerves  take  place  in  the  tympanum ;  the 
tympanic  branch,  from  the  petrous  ganglion  of  the  glossopharyngeal ;  a  filament 
from  the  carotid  plexus ;  a  branch  which  joins  the  great  superficial  petrosal  nerve 
from  the  Vidian ;  and  a  branch  to  the  otic  ganglion  (small  superficial  petrosal 
nerve). 

The  tympanic  branch  of  the  glossopharyngeal  (Jacobson's  nerve)  enters  the  tym- 
panum by  an  aperture  in  its  floor,  close  to  the  inner  wall,  and  ascends  on  to  the 
promontory.  It  distributes  filaments  to  the  lining  membrane  of  the  tympanum, 
and  divides  into  three  branches,  which  are  contained  in  grooves  on  the  promontory, 
and  serve  to  connect  this  with  other  nerves.  One  branch  runs  in  a  groove,  for- 
wards and  downwards,  to  an  aperture  situated  at  the  junction  of  the  anterior  and 
inner  walls,  just  above  the  floor,  and  enters  the  carotid  canal,  to  communicate 
with  the  carotid  plexus  of  the  sympathetic.  The  second  branch  is  contained  in 
a  groove  which  runs  vertically  upwards  to  an  aperture  on  the  inner  wall  of  the 
tympanum,  just  beneath  the  anterior  pyramid,  and  in  front  of  the  fenestra  ovalis. 
The  canal  leading  from  this  opens  into  the  hiatus  Fallopii,  where  the  nerve 
contained  in  it  joins  the  great  petrosal  nerve.  The  third  branch  ascends  towards 
the  anterior  surface  of  the  petrous  bone ;  it  then  passes  through  a  small  aperture 
in  the  sphenoid  and  temporal  bones  to  the  exterior  of  the  skull,  and  joins  the  otic 
ganglion.  As  this  nerve  passes  by  the  gangliform  enlargement  of  the  facial,  it 
has  a  connecting  filament  with  it. 

The  chorda  tympani  quits  the  facial  near  the  stylo-mastoid  foramen,  enters 
the  tympanum  at  the  base  of  the  pyramid,  and  arches  forwards  across  its  cavity, 
between  the  handle  of  the  malleus  and  long  process  of  the  incus,  to  an  opening 
internal  to  the  Glaserian  fissure.  It  is  invested  by  a  reflection  of  the  lining  mem- 
brane of  the  tympanum. 

Internal  Ear  or  Labyrinth. 

The  internal  ear  is  the  essential  part  of  the  acoustic  organ,  receiving  the  ulti- 
mate distribution  of  the  auditory  nerve.  It  is  called  the  labyrinth,  from  the  com- 
plexity of  its  communications,  and  consists  of  three  parts,  the  vestibule,  semi- 
circular canals,  and  cochlea.  It  consists  of  a  series  of  cavities,  channelled  out  of 
the  substance  of  the  petrous  bone,  communicating  externally  with  the  cavity  of 
the  tympanum,  through  the  fenestra  ovalis  and  fenestra  rotunda ;  and  internally, 
with  the  meatus  auditorius  internus,  which  contains  the  auditory  nerve.  Within  the 
osseous  labyrinth  is  contained  the  membranous  labyrinth,  upon  which  the  ramifi- 
cations of  the  auditory  nerve  are  distributed. 

The  Vestibule  is  the  common  central  cavity  of  communication  between  the  parts 
of  the  internal  ear.  It  is  situated  on  the  inner  side  of  the  tympanum,  behind  the 
cochlea,  and  in  front  of  the  semicircular  canals.  It  is  somewhat  ovoidal  in  shape 
from  before  backwards,  flattened  from  side  to  side,  and  measures  about  one-fifth  of 
an  inch  from  before  backwards,  as  well  as  from  above  downwards,  being  narrower 
from  without  inwards.  On  its  outer  or  tympanic  wall  is  the  fenestra  ovalis, 
closed,  in  the  recent  state,  by  the  base  of  the  stapes,  and  its  annular  ligament. 


C38  ORGANS   OF   THE    SENSES. 

On  its  inner  wall,  at  its  fore  part,  is  a  small  circular  depression,  fovea  hemisplie- 
rica;  it  is  perforated,  at  its  anterior  and  inferior  part  (macula  cribrosa),  by  seve- 
ral minute  holes  for  the  passage  of  filaments  of  the  auditory  nerve ;  and  behind 
it  is  a  vertical  ridge,  the  pyramidal  eminence.  At  the  hinder  part  of  the  inner 
wall  is  the  orifice  of  the  aquseductus  vestibuli,  which  extends  to  the  posterior  sur- 
face of  the  petrous  portion  of  the  temporal  bone.     It  transmits  a  small  vein,  and, 

Fig.  316. — The  Osseous  Labyrinth  laid  open.     (Enlarged.) 


Opcrrim, 


Jlm*f/e  passed  t/troit, 

I'am  m .   rotund. 


Opening  of 


according  to  some,  contains  a  tubular  prolongation  of  the  lining  membrane  of  the 
vestibule,  which  ends  in  a  cul-de-sac,  between  the  layers  of  the  dura  mater  within 
the  cranial  cavity.  On  the  upper  wall  or  roof  is  a  transversely-oval  depression, 
fovea  semi-elliptica,  separated  from  the  fovea  hemispherica  by  the  pyramidal 
eminence,  already  mentioned.  Behind,  the  semicircular  canals  open  into  the 
vestibule  by  five  orifices.  In  front  is  a  large  oval  opening  which  communicates 
with  the  scala  vestibuli  of  the  cochlea  by  a  single  orifice,  apertura  scalse  vestibuli 
cochleae. 

The  Semicircular  canals  are  three  bony  canals,  situated  above  and  behind  the 
vestibule.  They  are  of  unequal  length,  compressed  from  side  to  side,  and  describe 
the  greater  part  of  a  circle.  They  measure  about  one-twentieth  of  an  inch  in 
diameter,  and  each  presents  a  dilatation  at  one  end,  called  the  ampulla,  which 
measures  more  than  twice  the  diameter  of  the  tube.  These  canals  open  into  the 
vestibule  by  five  orifices,  one  of  the  apertures  being  common  to  two  of  the 
canals. 

The  superior  semicircular  canal  is  vertical  in  direction,  its  arch  forming  a 
round  projection  on  the  anterior  surface  of  the  petrous  bone.  It  forms  about  two- 
thirds  of  a  circle.  Its  outer  extremity,  which  is  ampullated,  commences  by  a 
distinct  orifice  in  the  upper  part  of  the  vestibule ;  the  opposite  end  of  the  canal, 
which  is  not  dilated,  joins  with  the  corresponding  part  of  the  posterior  canal,  and 
opens  by  a  common  orifice  with  it  in  the  back  part  of  the  vestibule. 

The  posterior  semicircular  canal,  also  vertical  in  direction,  is  directed  back- 
wards to  the  posterior  surface  of  the  petrous  bone ;  it  is  the  longest  of  the  three, 
its  ampullated  end  commencing  at  the  lower  and  back  part  of  the  vestibule,  its 
opposite  end  joining  the  common  canal  already  mentioned. 

The  external  or  horizontal  canal  is  the  shortest  of  the  three,  its  arch  being 


COCHLEA.  G39 

directed  outwards  and  backwards.  Its  ampullated  end  corresponds  to  the  upper 
and  outer  angle  of  the  vestibule,  just  above  the  fenestra  ovalis ;  its  opposite  end 
opens  by  a  distinct  orifice  at  the  upper  and  back  part  of  the  vestibule. 

The  Cochlea  bears  some  resemblance  to  a  common  snail-shell ;  it  forms  the 
anterior  part  of  the  labyrinth,  is  conical  in  form,  and  placed  almost  horizontally 
in  front  of  the  vestibule ;  its  apex  is  directed  forwards  and  outwards  towards  the 
upper  and  front  part  of  the  inner  wall  of  the  tympanum ;  its  base  corresponds 
with  the  anterior  depression  at  the  bottom  of  the  internal  auditory  meatus ;  and 
is  perforated  by  numerous  apertures,  for  the  passage  of  the  cochlear  branch  of  the 
auditory  nerve.  It  measures  about  a  quarter  of  an  inch  in  length,  and  its  breadth 
towards  the  base  is  about  the  same.  It  consists  of  a  conical-shaped  central  axis, 
the  modiolus  or  columella;  of  a  canal  wound  spirally  round  the  axis  for  two 
turns  and  a  half,  from  the  base  to  the  apex ;  and  of  a  delicate  lamina  {lamina- 
spiralis)  contained  within  the  canal,  which  follows  its  windings,  and  subdivides  it 
into  two. 

The  central  axis  or  modiolus  is  conical  in  form,  and  extends  from  the  base  to 
the  apex  of  the  cochlea.  Its  base  is  broad,  corresponds  with  the  first  turn  of  tho 
cochlea,  and  is  perforated  by  numerous  orifices,  which  transmit  filaments  of 
the  cochlear  branch  of  the  auditory  nerve ;  the  axis  diminishes  rapidly  in  size  in 
the  second  coil,  and  terminates  within  the  last  half-coil  or  cupola,  in  an  expanded, 
delicate,  bony  lamella,  which  resembles  the  half  of  a  funnel,  divided  longitudinally, 
and  called  the  infundibulum  •  the  broad  part  of  this  funnel  is  directed  towards 
the  summit  of  the  cochlea,  and  blends  with  the  last  half-turn  of  the  spiral  canal 
of  the  cochlea,  the  cupola.  The  outer  surface  of  the  modiolus  is  formed  of  the 
wall  of  the  spiral  canal,  and  is  dense  in  structure  ;  but  its  centre  is  channelled,  as 
far  as  the  last  half-coil,  by  numerous  branching  canals,  which  transmit  nervous 
filaments  in  regular  succession  into  the  canal  of  the  cochlea,  or  upon  the  surface 
of  the  lamina  spiralis.  One  of  these,  larger  than  the  rest,  occupies  the  centre  of 
the  modiolus,  and  is  named  the  tubulus  centralis  modioli;  it  extends  from  the  base 
to  the  extremity  of  the  modiolus,  and  transmits  a  small  nerve  and  artery  (arteria 
centralis  modioli). 

The  spiral  canal  (fig.  317)  takes  two  turns  and  a  half  round  the  modiolus.  It 
is  about  an  inch  and  a  half  in  length,  measured  along  its  outer  wall ;  and  diminishes 


Fig.  317.— The  Cochlea  laid  open.     (Enlarged.) 


gradually  in  size  from  the  base  to  the  summit,  where  it  terminates  in  a  cul-de- 
sac,  the  cupola,  which  forms  the  apex  of  the  cochlea.  The  commencement  of 
this  canal  is  about  the  tenth  of  an  inch  in  diameter;  it  diverges  from  the  modiolus 
towards  the  tympanum  and  vestibule,  and  presents  three  openings.  One,  the 
fenestra  rotunda,  communicates  with  the  tympanum;  in  the  recent  state,  this 
aperture  is  closed  by  a  membrane,  the  membrana  tympani  secundaria.  Another 
aperture,  of  an  oval  form,  enters  the  vestibule.     The  third  is  the  aperture  of  the 


640  ORGANS   OF   THE    SENSES. 

aquseductus  cochlese,  which  leads  to  a  minute  funnel-shaped  canal,  which  opens  on 
the  basilar  surface  of  the  petrous  bone,  and  transmits  a  small  vein. 

The  interior  of  the  spiral  canal  is  divided  into  two  passages  {scalse)  bj  a  thin, 
osseous,  and  membranous  lamina,  which  winds  spirally  round  the  modiolus.  This 
is  the  lamina  spiralis,  the  essential  part  of  the  cochlea  upon  which  the  nerve 
tubules  are  distributed.  The  osseous  part  of  the  spiral  lamina  -extends  about  half 
way  across  the  diameter  of  the  spiral  canal ;  it  is  called  the  osseous  zone.  It 
commences  in  the  vestibule  between  the  tympanic  and  vestibular  opening  of  the 
cochlea,  and  gradually  becoming  narrower  in  its  course,  terminates  in  a  projecting 
hook,  the  hamular  process,  just  where  the  expansion  of  the  infundibulum  com- 
mences. The  lamina  spiralis  consists  of  two  thin  lamellae  of  bone,  between  which 
are  numerous  canals  for  the  passage  of  nervous  filaments,  which  open  chiefly 
on  the  lower  or  tympanic  surface.  At  the  point  where  the  osseous  lamina  is 
attached  to  the  modiolus,  and  following  its  windings,  is  a  small  canal,  called  by 
Rosenthal,  the  canalis  spiralis  modioli.  In  the  recent  state,  the  osseous  zone  is 
continued  to  the  opposite  wall  of  the  canal  by  a  membranous  and  muscular  layer 
(membranous  zone),  so  as  to  form  a  complete  partition  in  the  tube  of  the  cochlea. 
Two  passages  or  scalce  are  thus  formed,  by  a  division  of  the  canal  of  the  cochlea 
into  two.  One,  the  scala  tympani,  is  closed  below  by  the  membrane  of  the 
fenestra  rotunda;  the  other,  the  scala  vestvbuU,  communicates,  by  an  oval 
aperture,  with  the  vestibule.  Near  the  termination  of  the  scala  vestibuli,  close 
by  the  fenestra  rotunda,  is  the  orifice  of  the  aquosductus  cochleae.  The  scalae 
communicate,  at  the  apex  of  the  cochlea,  by  an  opening  common  to  both,  the 
helicotrema,  which  exists  in  consequence  of  the  deficiency  of  the  lamina  spiralis 
in  the  last  half-coil  of  the  canal. 

In  structure,  the  membranous  zone  is  a  transparent  glassy  lamina,  presenting 
near  its  centre  a  number  of  minute  transverse  lines,  which  radiate  outwards,  ana 
give  it  a  fibrous  appearance;  and  at  its  circumference,  where  it  is  connected  with 
the  outer  wall  of  the  spiral  canal,  it  is  composed  of  a  semi-transparent  structure, 
the  Cochlearis  muscle  (Todd  and  Bowman),  connective  tissue  (Kolliker). 

The  vestibular  surface  of  the  osseous  portion  of  the  lamina  spiralis  is  covered, 
for  about  the  outer  fifth  of  its  surface,  with  a  thin  layer,  resembling  cartilage  in 
texture.  It  is  described  as  the  denticulate  lamina  (Todd  and  Bowman),  from  its 
presenting  a  series  of  wedge-shaped  teeth  which  form  its  free  margin,  and  which 
project  into  the  vestibular  scalar. 

The  inner  surface  of  the  osseous  labyrinth  is  lined  by  an  exceedingly  thin 
fibro-serous  membrane,  analogous  to  a  periosteum,  from  its  close  adhesion  to  the 
inner  surface  of  these  cavities,  and  performing  the  office  of  a  serous  membrane  by 
its  free  surface.  It  lines  the  vestibule,  and  from  this  cavity  is  continued  into  the 
semicircular  canals  and  the  scala  vestibuli  of  the  cochlea,  and  through  the  heli- 
cotrema into  the  scala  tympani.  Two  delicate  tubular  processes  are  prolonged 
along  the  aqueducts  of  the  vestibule  and  cochlea,  to  the  inner  surface  of  the  dura 
mater.  This  membrane  is  continued  across  the  fenestra  ovalis  and  fenestra  rotunda, 
and  consequently  has  no  communication  with  the  lining  membrane  of  the  tympa- 
num. Its  attached  surface  is  rough  and  fibrous,  and  closely  adherent  to  the  bone ; 
its  free  surface  is  smooth  and  pale,  covered  with  a  layer  of  epithelium,  and  secretes 
a  thin,  limpid  fluid,  the  aqua  labyrinthi,  perilymph  (Blainville),  or  liquor  Cotunnii. 
In  the  vestibule  and  semicircular  canals,  it  separates  the  osseous  from  the  mem- 
branous labyrinth;  but  in  the  cochlea  it  lines  the  two  surfaces  of  the  bony  lamina 
spiralis,  and,  being  continued  from  its  free  margin  across  the  canal  to  its  outer 
wall,  forms  the  lamina  spiralis  membranacea,  serving  to  complete  the  separation 
between  the  two  scalce. 

The  Membranous  Labyrinth. 

The  Membranous  Labyrinth  (fig.  318)  is  a  closed  membranous  sac,  containing 
d  aid ;  upon  the  wall  of  the  sac,  the  ramifications  of  the  auditory  nerve  are  distributed. 


MEMBRANOUS   LABYRINTH. 


641 


It  has  the  same  general  form  as  the  vestibule  and  semicircular  canals,  in  which  it 
is  inclosed ;  but  is  considerably  smaller,  and  separated  from  their  lining  membrane 
by  the  perilymph. 

The  vestibular  'portion  consists  of  two  sacs,  the  utricle  and  the  saccule. 

The  utricle  is  the  larger  of  the  two,  of  an  oblong  form,  compressed  laterally, 
and  occupies  the  upper  and  back  part  of  the  vestibule,  lying  in  contact  with  the 


Fig.  318. — The  Membranous  Labyrinth  detached.     (Enlarged.) 


Ofoliths 
ixn  iArcupA.  tht  ira 


JK  to  Cochlea 


fovea  semi-elliptica.  Numerous  filaments  of  the  auditory  nerve  are  distributed  on 
the  wall  of1  this  sac ;  and  its  cavity  communicates,  behind,  with  the  membranous 
semicircular  canals  by  five  orifices. 

The  saccule  is  the  smaller  of  the  two  vestibular  sacs;  it  is  globular  in  form,  lies 
in  the  fovea  hemispherica,  near  the  opening  of  the  vestibular  scala  of  the  cochlea, 
and  receives  numerous  nervous  filaments,  which  enter  from  the  bottom  of  the 
depression  in  which  it  is  contained.  Its  cavity  is  apparently  distinct  from  that 
of  the  utricle. 

The  membranous  semicircular  canals  are  about  one-third  the  diameter  of  the 
osseous  canals,  but  in  number,  shape,  and  general  form  they  are  precisely  similar ; 
they  are  hollow,  and  open  by  five  orifices  into  the  utricle,  one  being  common  to 
two  canals.  Their  ampullae  are  thicker  than  the  rest  of  the  tubes,  and  nearly  fill 
the  cavities  in  which  they  are  contained. 

The  membranous  labyrinth  is  held  in  its  position  by  the  numerous  nervous  fila- 
ments distributed  to  the  utricle,  the  saccule,  and  to  the  ampulla  of  each  canal. 
These  nerves  enter  the  vestibule  through  the  minute  apertures  on  its  inner  wall. 

Structure.  The  wall  of  the  membranous  labyrinth  is  semi-transparent,  and  con- 
sists of  three  layers.  The  outer  layer  is  a  loose  and  flocculent  tissue,  containing 
bloodvessels  and  numerous  pigment-cells,  analogous  to  those  in  the  choroid.  The 
middle  layer,  thicker  and  more  transparent,  bears  some  resemblance  to  the  hyaloid 
membrane,  but  it  presents  in  parts  marks  of  longitudinal  fibrillation  and  elongated 
nuclei  on  the  addition  of  acetic  acid.  The  inner  layer  is  formed  of  polygonal 
nucleated  epithelial  cells,  which  secrete  the  endolymph. 
41 


642  ORGANS   OF   THE    SENSES. 

The  endolyrnph  {liquor  Scarpa)  is  a  limpid  serous  fluid,  which  fills  the  mem- 
branous labyrinth ;  in  composition,  it  closely  resembles  the  perilymph. 

The  otoliths  are  two  small  rounded  bodies,  consisting  of  a  mass  of  minute 
crystalline  grains  of  carbonate  of  lime,  held  together  in  a  mesh  of  delicate  fibrous 
tissue,  and  contained  in  the  wall  of  the  utricle  and  saccule,  opposite  the  distribu- 
tion of  the  nerves.  A  calcareous  material  is  also,  according  to  Bowman,  sparingly 
scattered  in  the  cells  lining  the  ampulla  of  each  semicircular  canal. 

The  Arteries  of  the  labyrinth  are  the  internal  auditory  from  the  basilar  or 
superior  cerebellar,  the  stylo-mastoid  from  the  posterior  auricular,  and,  occasion- 
ally, branches  from  the  occipital.  The  internal  auditory  divides  at  the  bottom  of 
the  internal  meatus  into  two  branches,  cochlear  and  vestibular. 

The  cochlear  branch  subdivides  into  from  twelve  to  fourteen  twigs,  which 
traverse  the  canals  in  the  modiolus,  and  are  distributed,  in  the  form  of  a  capillary 
network,  in  the  substance  of  the  lamina  spiralis. 

The  vestibular  branches  accompany  the  nerves,  and  are  distributed,  in  the  form 
of  a  minute  capillary  network,  in  the  substance  of  the  membranous  labyrinth. 

The  Veins  of  the  vestibule  and  semicircular  canals  accompany  the  arteries,  and, 
receiving  those  of  the  cochlea  at  the  base  of  the  modiolus,  terminate  in  the  superior 
petrosal  sinus. 

The  Auditory  nerve,  the  special  nerve  of  the  sense  of  hearing,  divides,  at  the 
bottom  of  the  internal  auditory  meatus,  into  two  branches,  the  cochlear  and  vesti- 
bular. The  trunk  of  the  nerve,  as  well  as  the  branches,  contains  numerous  ganglion 
cells  with  caudate  prolongations. 

The  Vestibular  nerve,  the  most  posterior  of  the  two,  divides  into  three  branches, 
superior,  middle,  and  inferior. 

The  superior  vestibular  branch,  the  largest,  divides  into  numerous  filaments, 
which  pass  through  minute  openings  at  the  upper  and  back  part  of  the  cul-de-sac 
at  the  bottom  of  the  meatus,  and,  entering  the  vestibule,  are  distributed  to  the 
utricle,  and  to  the  ampulla  of  the  external  and  superior  semicircular  canals. 

The  middle  vestibular  branch  consists  of  numerous  filaments,  which  enter  the 
vestibule  by  a  smaller  cluster  of  foramina,  placed  below  those  above  mentioned, 
and  which  correspond  to  the  bottom  of  the  fovea  hemispherica ;  they  are  dis- 
tributed to  the  saccule. 

The  inferior  and  smallest  branch  passes  backwards  in  a  canal  behind  the 
foramina  for  the  nerves  of  the  saccule,  and  is  distributed  to  the  ampulla  of  the 
posterior  semicircular  canal. 

The  nervous  filaments  enter  the  ampullary  enlargement  at  a  deep  depression  seen 
on  their  external  surface,  and  a  corresponding  elevation  is  seen  within,  the  nerve 
fibres  ending  in  loops,  and  in  free  extremities.  In  the  utricle  and  saccule,  the 
nerve  fibres  spread  out,  some  blending  with  the  calcareous  matter,  others  radiat- 
ing on  the  inner  surface  of  the  wall  of  each  cavity,  becoming  blended  with  a  layer 
of  nucleated  cells,  and  terminating  in  a  thin  fibrous  film. 

The  Cochlear  nerve  divides  into  numerous  filaments  at  the  base  of  the  modiolus, 
which  ascend  along  its  canals,  and  then,  bending  outwards  at  right  angles,  pass 
between  the  plates  of  the  bony  lamina  spiralis,  close  to  its  tympanic  surface. 
Between  the  plates  of  the  spiral  lamina,  the  nerves  form  a  plexus,  which  contains 
ganglion  cells ;  and  from  the  margin  of  the  osseous  zone,  branches  from  this  plexus 
are  distributed  to  the  membranous  part  of  the  septum,  where  they  are  arranged  in 
small,  conical-shaped  bundles,  parallel  with  one  another.  The  filaments  which 
supply  the  apical  portion  of  the  lamina  spiralis  are  conducted  to  this  part  through 
the  tubulus  centralis  modioli. 


Organs  of  Digestion. 


The  Apparatus  for  the  digestion  of  the  food  consists  of  the  alimentary  canal, 
and  of  certain  accessory  organs. 

The  alimentary  canal  is  a  musculo-membranous  tube,  about  thirty  feet  in  length, 
extending  from  the  mouth  to  the  anus,  and  lined  throughout  its  entire  extent  by 
mucous  membrane.  It  has  received  different  names  in  the  various  parts  of  its 
course :  at  its  commencement,  which  comprises  the  mouth,  we  find  every  provision 
for  the  mechanical  division  of  the  Food  (mastication),  and  for  its  admixture  with 
a  peculiar  fluid  secreted  by  the  salivary  glands  (insalivation) ;  beyond  this  are  the 
pharynx  and  the  oesophagus  (the  organs  of  deglutition),  which  convey  the  food 
into  the  stomach,  that  part  of  the  alimentary  canal  in  which  the  principal  chemi- 
cal changes  occur ;  in  that  organ  the  reduction  and  solution  of  the  food  take  place ; 
by  its  admixture  with  the  bile  and  pancreatic  fluid,  in  the  small  intestines,  the 
nutritive  principles  of  the  food  (the  chyle)  are  separated  from  that  portion  which 
passes  into  the  large  intestine,  and  which  is  expelled  from  the  system. 


Mouth. 
Pharynx. 
(Esophagus. 
Stomach. 


Teeth. 


Alimentary  Canal. 
Small  intestine 

Large  intestine 
Accessory  Organs. 


{Parotid. 
Submaxillary. 
Sublingual. 


Duodenum. 

Jejunum. 

Ileum. 

Caecum. 

Colon. 

Eectum. 


Liver. 

Pancreas. 

Spleen. 


The  Mouth  (fig.  319)  is  placed  at  the  commencement  of  the  alimentary  canal; 
it  is  a  nearly  oval-shaped  cavity,  in  which  the  mastication  of  the  food  takes  place. 
It  is  bounded,  in  front,  by  the  lips ;  laterally,  by  the  cheeks  and  alveolar  process 
of  the  upper  and  lower  jaw ;  above,  by  the  hard  palate  and  teeth  of  the  upper 
jaw ;  below,  by  the  tongue,  the  mucous  membrane  stretched  between  the  under 
surface  of  this  organ  and  the  inner  surface  of  the  jaws,  and  by  the  teeth  of  the 
lower  jaw;  behind,  by  the  soft  palate  and  fauces. 

The  mucous  membrane  lining  the  mouth  is  continuous  with  the  integument  at 
the  free  margin  of  the  lips,  and  with  the  mucous  lining  of  the  fauces  behind ;  it 
is  of  a  pink  rose  tinge  during  life,  and  very  thick  where  it  covers  the  hard  parts 
bounding  this  cavity. 

The  Lips  are  two  fleshy  folds,  which  surround  the  orifice  of  the  mouth,  formed 
externally  of  integument,  internally  of  mucous  membrane,  between  which  are  found 
the  Orbicularis  oris  muscle,  the  coronary  vessels,  some  nerves,  areolar  tissue,  fat, 
and  numerous  small  labial  glands.  The  inner  surface  of  each  lip  is  connected  in 
the  middle  line  to  the  gum  of  the  corresponding  jaw  by  a  fold  of  mucous  mem- 
brane, the  frsenum  labii  superioris  and  frsenum  ktbii  inferioris,  the  former  being 
the  larger  of  the  two. 

The  labial  glands  are  situated  between  the  mucous  membrane  and  the  Orbicularis 

646 


644 


ORGANS   OF   DIGESTION. 


oris,  round  the  orifice  of  the  mouth.  They  are  rounded  in  form,  about  the  size 
of  a  small  pea,  their  ducts  opening  by  small  orifices  upon  the  mucous  membrane. 
In  structure,  they  resemble  the  other  salivary  glands. 

The  Cheeks  form  the  sides  of  the  face,  and  are  continuous  in  front  with  the 
lips.  They  are  composed,  externally,  of  integument ;  internally,  of  mucous  mem- 
brane ;  and,  between  the  two,  of  a  muscular  stratum,  besides  a  large  quantity  of 
fat,  areolar  tissue,  vessels,  nerves,  and  buccal  glands. 

The  mucous  membrane  lining  the  cheek  is  reflected  above  and  below  upon  the 
gums,  and  is  continuous  behind  with  the  lining  membrane  of  the  soft  palate. 
Opposite  the  second  molar  tooth  of  the  upper  jaw  is  a  papilla,  the  summit  of 


Fig.  319. — Sectional  View  of  the  Nose,  Mouth,  Pharynx,  etc. 


K) fie  nitty  of 
A'atai  duct 


Bristle 
pa**ed  through 
i's  duct 


which  presents  the  minute  aperture  of  the  duct  of  the  parotid  gland.  The  prin- 
cipal muscle  of  the  cheek  is  the  Buccinator;  but  numerous  others  enter  into  its 
formation,  viz.,  the  Zygomatic!,  Masseter,  and  the  Platysma  myoides. 

The  buccal  glands  are  placed  between  the  mucous  membrane  and  Buccinator 
muscle :  they  are  similar  in  structure  to,  but  smaller  than,  the  labial  glands.  Two 
or  three,  of  larger  size  than  the  rest,  are  placed  between  the  Masseter  and 
Buccinator  muscles;  their  ducts  open  into  the  mouth,  opposite  the  last  molar 
tooth.     They  are  called  molar  glands. 

The  Gums  are  composed  of  a  dense  fibrous  tissue,  closely  connected  to  the 
periosteum  of  the  alveolar  processes,  and  surrounding  the  necks  of  the  teeth. 


THE   TEETH. 


645 


They  are  covered  by  smooth  and  vascular  mucous  membrane,  which  is  remarkable 
for  its  limited  sensibility.  Around  the  necks  of  the  teeth,  this  membrane 
presents  numerous  fine  papillae;  and  from  this  point  it  is  reflected  into  the 
alveolus,  where  it  is  continuous  with  the  periosteal  membrane  lining  that 
cavity. 

The  Teeth. 

The  human  subject  is  provided  with  two  sets  of  teeth,  which  make  their  ap- 
pearance at  different  periods  of  life.  The  first  set  appear  in  childhood,  and  are 
called  the  temporary,  deciduous,  or  milk  teeth.  The  second  set,  which  also  appear 
at  an  early  period,  continue  until  old  age,  and  are  named  permanent. 

The  temporary  teeth  are  twenty  in  number ;  four  incisors,  two  canine,  and  four 
molars,  in  each  jaw. 

The  permanent  teeth  are  thirty- two  in  number ;  four  incisors  (two  central  and 
two  lateral),  two  canine,  four  bicuspids,  and  six  molars,  in  each  jaw. 

General  characters.     Each  tooth  consists  of  three  portions;  the  crown  or  body, 


Fig.  320.— The  Permanent  Teeth.     External  View. 


Jfolarf 


Wiiclom  t„nh. 


Uj>2>er    Juw 

Bicuspid*  Canine  TiusitoT* 


FU71J 


Keck 


JLotver  Jaw 


which  projects  above  the  gum ;  the  root  or  fang,  entirely  concealed  within  the 
alveolus ;  and  the  neck,  the  constricted  portion  between  the  other  two. 

The  roots  of  the  teeth  are  firmly  implanted  within  the  alveoli :  these  depressions 
are  lined  with  periosteum,  which  is  reflected  on  to  the  tooth  at  the  point  of  the 
fang,  and  covers  it  as  far  as  the  neck.  At  the  margin  of  the  alveolus,  the  peri- 
osteum becomes  continuous  with  the  fibrous  structure  of  the  gums. 


G46  ORGANS   OF   DIGESTION. 


Permanent  Teeth. 


The  Incisors  or  cutting  teeth  are  so  named  from  their  presenting  a  sharp,  cut- 
ting edge,  adapted  for  cutting  the  food.  They  are  eight  in  number,  and  form  the 
four  front  teeth  in  each  jaw. 

The  crown  is  directed  vertically,  is  wedge-like  in  form,  being  bevelled  at  the 
expense  of  its  posterior  surface,  so  as  to  terminate  in  a  sharp,  horizontal  cutting 
edge,  which,  before  being  subject  to  attrition,  presents  three  small  prominent 
points.  It  is  convex,  smooth,  and  highly  polished  in  front ;  slightly  concave  be- 
hind, where  it  is  frequently  marked  by  slight  longitudinal  furrows. 

The  neck  is  constricted. 

The  fang  is  long,  single,  conical,  transversely  flattened,  thicker  before  than 
behind,  and  slightly  grooved  on  each  side  in  the  longitudinal  direction. 

The  incisors  of  the  upper  jaw  are  altogether  larger  and  stronger  than  those 
of  the  lower  jaw.  They  are  directed  obliquely  downwards  and  forwards.  The 
two  central  ones  are  larger  than  the  two  lateral,  and  their  free  edges  sharp  and 
chisel-like,  being  bevelled  at  the  expense  of  their  posterior  edge ;  the  root  is  more 
rounded. 

The  incisors  of  the  lower  jaw  are  smaller  than  the  upper;  the  two  central 
ones  are  smaller  than  the  two  lateral,  and  are  the  smallest  of  all  the  incisor 
teeth. 

The  Canine  Teeth  (cuspidati)  are  four  in  number,  two  in  the  upper,  and  two 
in  the  lower  jaw;  one  being  placed  behind  each  lateral  incisor.  They  are  larger 
and  stronger  than  the  incisors,  especially  the  root,  which  sinks  deeply  into  the  jaw, 
and  causes  a  well-marked  prominence  upon  its  surface. 

The  crown  is  large  and  conical,  very  convex  in  front,  a  little  hollowed  and  un- 
even posteriorly,  and  tapering  to  a  blunted  point  or  cusp  which  rises  above  the 
level  fcf  the  other  teeth. 

The  root  is  single,  but  longer  and  thicker  than  that  of  the  incisors,  conical  in 
form,  compressed  laterally,  and  marked  by  a  slight  groove  on  each  side. 

The  upper  canine  teeth  (vulgarly  called  eye-teeth)  are  larger  and  longer  than  the 
two  lower,  and  situated  a  little  behind  them. 

The  lower  canine  teeth  are  placed  in  front  of  the  upper,  so  that  their  summits 
correspond  to  the  interval  between  the  upper  canine  teeth  and  the  neighboring 
incisor. 

The  Bicuspid  Teeth  (small  or  false  molars)  are  eight  in  number,  four  in  each 
jaw,  two  being  placed  immediately  behind  each  of  the  canine  teeth.  They  are 
smaller  and  shorter  than  the  canine. 

The  crown  is  compressed  from  without  inwards,  and  surmounted  by  two  pyra- 
midal eminences  or  cusps  separated  by  a  groove ;  hence  their  name,  bicuspidate. 
The  outer  of  these  cusps  is  larger  and  more  prominent  than  the  inner. 

The  neck  is  oval. 

The  root  is  generally  single,  compressed,  and  presents  a  tendency  to  become 
double,  as  seen  from  the  deep  groove  on  each  side.     The  apex  is  generally  bifid. 

The  upper  bicusjnds  are  larger,  and  present  a  greater  tendency  to  the  division 
of  their  roots  than  the  lower;  this  is  especially  marked  in  the  second  upper 
bicuspid. 

The  Molar  Teeth  {multicuspidati,  true  or  large  molars)  are  the  largest  of  the 
permanent  set,  and  are  adapted,  from  the  great  breadth  of  their  crowns,  for  grind- 
ing and  pounding  the  food.  They  are  twelve  in  number,  six  in  each  jaw,  three 
being  placed  behind  each  of  the  posterior  bicuspids. 

The  crown  is  nearly  cubical  in  form,  rounded  on  each  of  its  lateral  surfaces, 
flattened  in  front  and  behind ;  the  upper  surface  being  surmounted  by  four  or  five 
tubercles  or  cusps  (four  in  the  upper,  five  in  the  lower  molars)  separated  from 
each  other  by  a  crucial  depression;  hence  their  name,  multicuspidati. 


THE    TEETH.  G4V 

The  neck  is  distinct,  large,  and  rounded. 

The  root  is  subdivided  into  from  two  to  five  fangs,  each  of  which  presents  an 
aperture  at  its  summit. 

The  first  molar  tooth  is  the  largest  and  broadest  of  all;  its  crown  has  usually 
five  cusps,  three  outer  and  two  inner.  In  the  upper  jaw,  the  root  consists  of 
three  fangs,  widely  separated  from  one  another,  two  being  external,  the  other 
internal.  The  latter  is  the  largest  and  the  longest,  slightly  grooved,  and  some- 
times bifid.  In  the  lower  jaw,  the  root  consists  of  two  fangs,  one  being  placed  in 
front,  the  other  behind ;  they  are  both  compressed  from  before  backwards,  and 
grooved  on  their  contiguous  faces,  indicating  a  tendency  to  division. 

The  second  molar  is  a  little  smaller  than  the  first. 

The  crown  has  four  cusps  in  the  upper,  and  five  in  the  lower  jaw. 

The  root  has  three  fangs  in  the  upper  jaw,  and  two  in  the  lower,  the  characters 
of  which  are  similar  to  the  preceding  tooth. 

The  third  molar  tooth  is  called  the  wisdom  tooth  (dens  sapientise),  from  its  late 
appearance  through  the  gum.  It  is  smaller  than  the  others,  and  its  axis  is  directed 
inwards. 

The  crown  is  small  and  rounded,  and  furnished  with  three  tubercles. 

The  root  is  generally  single,  short,  conical,  slightly  curved,  and  grooved  so  as 
to  present  traces  of  a  subdivision  into  three  fangs  in  the  upper,  and  two  in  the 
lower  jaw. 

Temporary  Teeth. 

The  temporary  or  milk  teeth  are  smaller,  but  resemble  in  form  those  of  the 
permanent  set.     The  hinder  of  the  two  temporary  molars  is  the  largest  of  all  the 


Fig.  321.— The  Temporary  or  Milk  Teeth.     External  View. 


Zjoiver    J u  w 


Canine  Inciters 


milk  teeth,  and  is  succeeded  by  the  second  permanent  bicuspid.  The  first  upper 
molar  has  only  three  cusps,  two  external,  one  internal ;  the  second  upper  molar 
has  four  cusps.  The  first  lower  molar  has  four  cusps ;  the  second  lower  molar 
has  five.  The  fangs  of  the  temporary  molar  teeth  are  smaller,  and  more  diverging 
than  those  of  the  permanent  set ;  but,  in  other  respects,  bear  a  strong  resemblance 
to  them. 


648 


ORGANS   OF   DIGESTION". 


Fig.  322.— Vertical 
Section  of  a  Molar 
Tooth. 


T-Cr 


Neck 


-J^a 


Fig.  323.— Vertical  Section 
of  a  Bicuspid  Tooth. 
Magnified. 


Structure  of  the  Teeth. 

Structure.  On  making  a  vertical  section  of  a  tooth  (fig.  322),  a  hollow  cavity 
will  be  found  in  the  interior.  This  cavity  is  situated  at  the  base  of  the  crown,  and 
is  continuous  with  a  canal  which  traverses  the  centre  of 
each  fang,  and  opens  by  a  minute  orifice  at  its  extremity. 
The  shape  of  the  cavity  corresponds  somewhat  with  that  of 
the  tooth :  it  forms  what  is  called  the  pulp  cavity,  and  con- 
tains a  soft,  highly  vascular,  and  sensitive  substance,  the 
dental  pulp.  The  pulp  is  richly  supplied  with  vessels  and 
nerves,  which  enter  the  cavity  through  the  small  aperture  at 
the  point  of  each  fang. 

The  solid  portion  of  the  tooth  consists  of  three  distinct 
structures,  viz.,  ivory  (tooth-bone  or  dentine),  which  forms 
the  larger  portion  of  the  tooth ;    enamel,  which  covers  the 
exposed  part  or  crown ;  and  the  cortical  substance  or  cement 
(crusta  petrosa),  which  is  disposed  as  a  thin  layer  on  the  surface  of  the  fang. 

The  Ivory  or  dentine  (fig.  323)  forms  the  principal  mass  of  a  tooth ;  in  its 
central  part  is  the  cavity  inclosing  the  pulp.  It  is  a  modification  of  the  osseous 
tisue,  from  which  it  differs,  however,  in  structure  and  chemical  composition.    On 

examination  with  the  microscope,  it  is  seen  to  consist 
of  a  number  of  minute  wavy  and  branching  tubes, 
having  distinct  parietes.  They  are  called  the  dental 
tubuli,  and  are  imbedded  in  a  dense  homogeneous  sub- 
stance, the  intertubular  tissue. 

The  dental  tubuli  are  placed  parallel  with  one  ano- 
ther, and  open  at  their  inner  ends  into  the  pulp  cavity. 
They  pursue  a  wavy  and  undulating  course  towards 
the  periphery.  The  direction  of  these  tubes  varies; 
they  are  vertical  in  the  upper  portion  of  the  crown, 
oblique  in  the  neck  and  upper  part  of  the  root,  and 
towards  the  lower  part  of  the  root  they  are  inclined 
downwards.  The  tubuli,  at  their  commencement, 
are  about  75^71  °f  an  mcn  in  diameter;  in  their 
course  they  divide  and  subdivide  dichotomously, 
so  as  to  give  to  the  cut  surface  of  the  dentine  a  striated 
appearance.  From  the  sides  of  the  tubes,  especially 
in  the  fang,  ramifications  of  extreme  minuteness  are 
given  off,  which  join  together  in  loops  in  the  inter- 
tubular substance,  or  terminate  in  small  dilatations,  from 
which  branches  are  given  off.  Near  the  periphery  of 
the  dentine,  the  finer  ramifications  of  the  tubuli  ter- 
minate in  a  somewhat  similar  manner.  In  the  fang, 
these  ramifications  occasionally  pass  into  the  crusta 
petrosa.  The  dental  tubuli  have  comparatively  thick 
walls,  and  contain,  according  to  Mr.  Tomes,  slender  cylindrical  prolongations  of 
the  pulp-tissue. 

The  intertubular  substance  is  translucent,  finely  granular,  and  contains  the  chief 
part  of  the  earthy  matter  of  the  dentine.  After  the  earthy  matter  has  been 
removed,  by  steeping  a  tooth  in  weak  acid,  the  animal  basis  remaining  is  described 
by  Henle  as  consisting  of  bundles  of  pale,  granular,  flattened  fibres,  running 
parallel  with  the  tubes ;  but  by  Mr.  Nasmyth  as  consisting  of  a  mass  of  brick- 
shaped  cells  surrounding  the  tubules.  By  Czermak  and  Mr.  Salter  it  is  supposed 
to  consist  of  laminae  which  run  parallel  with  the  pulp  cavity,  across  the  direction 
of  the  tubes. 

Chemical  Composition.  According  to  Berzelius  and  Bibra,  dentine  consists  of 
28  parts  of  animal,  and  72  of  earthy  matter.     The  animal  matter  is  resolvable  by 


Fang 


DEVELOPMENT   OF   THE   TEETH.  049 

boiling  into  gelatin.  The  earthy  matter  consists  of  phosphate  of  lime,  carbonate 
of  lime,  a  trace  of  fluoride  of  calcium,  and  phosphate  of  magnesia,  and  other  salts. 

The  Enamel  is  the  hardest  and  most  compact  part  of  a  tooth,  and  forms  a  thin 
crust  over  the  exposed  part  of  the  crown,  as  far  as  the  commencement  of  the  fang. 
It  is  thickest  on  the  grinding  surface  of  the  crown,  until  worn  away  by  attrition, 
and  becomes  thinner  towards  the  neck.  It  consists  of  a  congeries  of  minute  hexa- 
gonal rods.  They  lie  parallel  with  one  another,  resting  by  one  extremity  upon 
the  dentine,  which  presents  a  number  of  minute  depressions  for  their  reception ; 
the  outer  extremity  forming  the  free  surface  of  the  crown.  These  fibres  are 
directed  vertically  on  the  summit  of  the  crown,  horizontally  at  the  sides ;  they  are 
about  the  -gs^-ir  of  an  inch  in  diameter,  and  pursue  a  more  or  less  wravy  course, 
which  gives  to  the  cut  surface  of  the  enamel  a  series  of  concentric  lines. 

Numerous  minute  interstices  intervene  between  the  enamel-fibres  near  their 
dentinal  surface,  a  provision  calculated  to  allow  of  the  permeation  of  fluids  from 
the  dentinal  tubuli  into  the  substance  of  the  enamel.  The  enamel-rods  consist  of 
solid  hexagonal  or  four-sided  prisms,  connected  by  their  surfaces  and  ends,  and  filled 
with  calcareous  matter.  If  the  latter  is  removed,  by  weak  acid,  from  newly-formed 
or  growing  enamel,  it  will  be  found  to  present  a  network  of  delicate  prismatic  cells 
of  animal  matter. 

Chemical  Composition.  According  to  Bibra,  enamel  consists  of  96.5  per  cent. 
of  earthy  matter,  and  3.5  per  cent,  of  animal  matter.  The  earthy  matter  consists 
of  phosphate  of  lime,  with  traces  of  fluoride  of  calcium,  carbonate  of  lime,  phos- 
phate of  magnesia  and  other  salts. 

The  Cortical  Substance  or  cement  (crusta  petrosa)  is  disposed  as  a  thin 
layer  on  the  roots  of  the  teeth,  from  the  termination  of  the  enamel,  as  far  as  the 
apex  of  the  fang,  where  it  is  usually  very  thick.  In  structure  and  chemical  com- 
position, it  resembles  bone.  It  contains,  sparingly,  the  lacunae  and  canaliculi  which 
characterize  true  bone ;  those  lacunas  placed  near  the  surface  have  the  canaliculi 
radiating  from  the  side  of  the  lacunae  towards  the  periodontal  membrane ;  and 
those  more  deeply  placed,  join  with  the  adjacent  dental  tubuli.  In  the  thicker 
portions  of  the  crusta  petrosa,  the  lamellae  and  Haversian  canals  peculiar  to  bone 
are  also  found.  As  age  advances,  the  cementum  increases  in  thickness,  and  gives 
rise  to  those  bony  growths  or  exostoses,  so  common  in  the  teeth  of  the  aged ;  the 
pulp  cavity  becomes  also  partially  filled  up  by  a  hard  substance,  intermediate  in 
structure  between  dentine  and  bone  (osieo-dcntine,  Owen ;  secondary  dentine, 
Tomes).  It  appears  to  be  formed  by  a  slow  conversion  of  the  dental  pulp,  which 
shrinks,  or  even  disappears. 

Development  of  the  Teeth  (figs.  324  to  329). 

According  to  the  observations  of  Arnold  and  Groodsir,  the  teeth  are  developed 
from  the  mucous  membrane  covering  the  edges  of  the  maxillary  arches.  About 
the  sixth  week  of  foetal  life  (fig.  324),  the  mucous  membrane  covering  the  edge  of 
the  upper  jaw,  presents  a  semicircular  depression  or  groove ;  this  is  the  primitive 
dental  groove  (Goodsir),  from  the  floor  of  which  the  germs  of  the  ten  deciduous 
or  milk-teeth  are  developed.  The  germ  of  each  tooth  is  formed  by  a  conical 
elevation  or  papilla  of  mucous  membrane  (fig.  325),  which  constitutes  the  rudimen- 
tary pulp  of  a  milk-tooth.  The  germs  of  the  milk-teeth  make  their  appearance  in 
the  following  order :  at  the  seventh  week,  the  germ  of  the  first  deciduous  molar 
of  the  upper  jaw  appears ;  at  the  eighth  week,  that  for  the  canine  tooth  is  deve- 
loped ;  the  two  incisor  papillae  appear  about  the  ninth  week  (the  central  preceding 
the  lateral) ;  lastly,  the  second  molar  papilla  is  seen  at  the  tenth  week,  behind  the 
anterior  molar.  The  teeth  of  the  lower  jaw  appear  rather  later,  the  first  molar 
papilla  being  only  just  visible  at  the  seventh  week;  and  the  tenth  papilla  not 
being  developed  before  the  eleventh  week.  This  completes  the  first  or  papillary 
stage  of  their  development. 


650 


ORGANS   OF   DIGESTION. 


Development  of  Teeth. 
Flo.  224. 

Frimifive  .Dental  Groove*         * 


r  I  c .  325. 
TaJiilla.in-Gtr-m.  ofMXf^tootb 


He.  327. 


fie.  328. 


r  I  C .   329. 
Srlc/dian  ofMM.'totrth 


£*finusitnt   IcuUt 


The  dental  groove  now  becomes  contracted, 
its  margins  thickened  and  prominent,  and  the 
groove  is  converted  into  follicles  for  the  re- 
ception of  the  papillae,  by  the  growth  of  mem- 
branous septa,  which  pass  across  the  groove 
between  its  borders  (fig.  326).  The  follicles 
by  this  means  become  the  alveoli,  lined  by 
periosteum,  from  the  bottom  of  which  a  process 
of  the  mucous  membrane  of  the  gum  rises, 
which  is  the  germ  of  the  future  tooth.  The 
follicle  for  the  first  molar  is  complete  about  the 
tenth  week ;  the  canine  follows  next,  succeeded 
by  the  follicles  for  the  incisors,  which  are  com- 
pleted about  the  eleventh  or  twelfth  week ;  and, 
lastly,  the  follicle  of  the  posterior  deciduous 
molar  is  completed  about  the  fourteenth  week. 
These  changes  constitute  the  second  or  follicu- 
lar stage. 

About  the  thirteenth  week,  the  papilla?  begin 
to  grow  rapidly,  project  from  the  follicles,  and 
assume  a  form  corresponding  with  that  of  the 
future  teeth ;  the  follicles  soon  become  deeper, 
and  from  their  margins  small  membranous 
processes  or  opercula  are  developed,  which, 
meeting,  unite  and  form  a  lid  to  the  now  closed 
cavity  (fig.  327).  These  processes  correspond 
in  shape  to  the  form  of  the  crown  of  the 
tooth,  and  in  number  to  the  tubercles  on  its 
surface.  The  follicles  of  the  incisor  teeth  have 
two  opercula,  the  canine  three,  and  the  molars 
four  or  five  each.  The  follicles  are  thus  con- 
verted into  dental  sacs,  and  the  contained 
papillae  become  pulps.  The  lips  of  the  dental 
groove  gradually  advance  over  the  follicles  from 
behind  forwards,  and,  uniting,  gradually  ob- 
literate it.  This  completes  the  third  or  saccular 
stage,  which  takes  place  about  the  end  of  the 
fifteenth  week. 

The  deep  portion  of  the  primitive  dental 
groove  is  now  closed-in;  but  the  more  super- 
ficial portion,  near  the  surface  of  the  gum, 
still  remains  open ;  it  is  called,  by  Mr.  Goodsir, 
the  secondary  dental  groove;  from  it  are 
developed  the  ten  anterior  permanent  teeth. 
About  the  fourteenth  week,  certain  lunated 
depressions  are  formed,  one  behind  each  of 
the  sacs  of  the  rudimentary  milk-teeth.  They 
are  ten  in  number  in  each  jaw,  and  are 
formed  successively  from  before  backwards; 
they  are  the  rudimentary  follicles  of  the  four 
permanent  incisors,  the  two  canine,  and  the 
four  bicuspids.  As  the  secondary  dental  groove 
closes  in,  these  follicles  become  closed  cavities  of 
reserve  (fig.  327).  The  cavities  soon  elongate, 
and  recede  from  the  surface  into  the  substance 
of  the  gum,  behind  the  sacs  of  the  deciduous 
teeth,  and  a  papilla  projects  from  the  bottom  of 


DEVELOPMENT   OF   THE   TEETH.  651 

each,  which  is  the  germ  of  the  permanent  tooth ;  at  the  same  time,  one  or  more 
operculse  are  developed  from  the  sides  of  the  cavity ;  and  these,  uniting,  divide  it 
into  two  portions ;  the  lower  portion  containing  the  papilla  of  the  permanent 
tooth,  the  upper  narrower  portion  becoming  gradually  contracted  in  the  same  way 
that  the  primitive  dental  groove  was  obliterated  over  the  sacs  of  the  deciduous 
teeth  (fig.  328). 

The  six  posterior  permanent  teeth  in  each  jaw,  three  on  each  side,  arise  from 
successive  extensions  backwards  of  the  back  part  of  the  primitive  dental 
groove.  During  the  fourth  month,  that  portion  of  the  dental  groove  which  lies 
behind  the  last  temporary  molar  follicle  remains  open,  and  from  it  is  developed 
the  papilla,  the  rudiment  of  the  first  permanent  molar.  The  follicle  in  which  it 
is  contained  becomes  closed  by  its  operculum,  and  the  upper  part  of  the  now- 
formed  sac  elongates  backwards  to  form  a  cavity  of  reserve,  in  which  the  papilla 
of  the  second  permanent  molar  appears  at  the  seventh  month  after  birth.  After 
a  considerable  interval,  during  which  the  sacs  of  the  first  and  second  permanent 
molars  have  considerably  increased  in  size,  the  remainder  of  the  cavity  of  reserve 
presents  for  the  last  time  a  series  of  changes  similar  to  the  preceding,  and  gives 
rise  to  the  sac  and  papilla  of  the  wisdom-tooth,  which  appears  at  the  sixth 
year. 

Growth  of  the  Teeth.  As  soon  as  the  dental  sacs  are  formed  by  the  closing-in 
of  the  follicles,  they  gradually  enlarge,  as  well  as  their  contained  papillae.  Each 
sac  consists  of  two  layers ;  an  internal,  highly  vascular  layer,  lined  by  epithelium ; 
and  an  external  or  areolo-fibrous  membrane,  analogous  to  the  corium  of  the  mucous 
membrane. 

The  dental  pulps  soon  become  moulded  to  the  form  of  the  future  teeth,  and  are 
adherent  by  their  bases  to  the  bottom  of  the  dental  sacs ;  in  the  case  of  the  molars, 
the  base  of  the  pulp  is  divided  into  two  or  more  portions,  which  form  the  future 
fangs.  During  the  fourth  or  fifth  month  of  fcetal  life,  a  thin  lamina  or  cap  of  dentine 
is  formed  on  the  most  prominent  point  of  the  pulp  of  all  the  milk-teeth.  In  the 
incisor  and  canine  teeth,  this  newly-formed  lamina  has  the  form  of  a  hollow  cone ; 
in  the  molar  teeth,  as  many  separate  laminas  are  found  as  there  are  eminences  upon 
its  crown.  These  lamina)  grow  at  the  expense  of  the  pulp-substance,  increasing 
in  breadth  by  a  growth  round  their  margins,  and  in  thickness  by  a  similar  forma- 
tion in  its  substance ;  the  separate  cones  (if  a  molar  tooth)  ultimately  coalesce,  and 
the  crown  is  completely  formed.  The  pulp  now  becomes  constricted,  so  as  to  form 
the  cervix ;  and  the  remaining  portion  becomes  narrow  and  elongated,  to  form  the 
fang.  The  growth  of  dentine  takes  place  from  the  surface  towards  the  interior, 
until  nothing  but  the  small  cavitas  pulpse  remains  in  the  centre  of  the  tooth,  com- 
municating by  the  aperture  left  at  the  point  of  each  fang,  with  the  dental  vessels 
and  nerves. 

As  soon  as  the  formation  of  the  dentine  has  commenced,  there  is  developed 
from  the  inner  wall  of  the  dental  sac,  a  soft  pulpy  mass,  the  enamel  organ,  which 
is  intimately  united  to  the  surface  of  the  dental  pulp,  or  its  cap  of  dentine.  It 
consists  of  a  mesh  of  fibres,  elastic  and  spongy,  containing  within  its  reticulations 
fluid  albumen;  and  at  the  point  of  junction  of  each  fibre,  a  transparent  nucleus  is 
visible.  The  surface  towards  the  dentinal  pulp  is  covered  by  a  layer  of  elongated 
nucleated  cells,  the  enamel  membrane.  The  deposition  of  the  enamel  takes  place 
on  the  outer  surface  of  the  cap  of  dentine. 

The  cementum  appears  to  be  formed,  at  a  later  period  of  life,  by  the  periodontal 
membrane,  extending  from  the  margin  of  the  enamel  downwards. 

Eruption.  When  the  calcification  of  the  different  tissues  of  the  tooth  is  suffi- 
ciently advanced  to  enable  it  to  bear  the  pressure  to  which  it  will  be  afterwards 
subjected,  its  eruption  takes  place,  the  tooth  making  its  way  through  the  gum. 
The  gum  is  absorbed  by  the  pressure  of  the  crown  of  the  tooth  against  it,  which 
is  itself  pressed  up  by  the  increasing  size  of  the  fang  (fig.  329).  Concurrent  with 
this,  the  septa  between  the  dental  sacs,  at  first  fibrous  in  structure,  soon  ossify,  and 


G52     *  ORGANS   OF   DIGESTION. 

constitute  the  alveoli ;  these  firmly  embrace  the  necks  of  the  teeth,  and  afford  them 
a  solid  basis  of  support. 

The  eruption  of  the  temporary  teeth  commences  at  the  seventh  month,  and  is 
complete  about  the  end  of  the  second  year,  those  of  the  lower  jaw  preceding  the 
upper. 

The  periods  for  the  eruption  of  the  temporary  set  are : — 

7th  month,  central  incisors.  14th  to  20th  month,  canine. 

7th  to  10th  month,  lateral  incisors.         18th  to  36th  month,  posterior  molars. 

12th  to  14th  month,  anterior  molars. 

Calcification  of  the  permanent  teeth  commences  a  little  before  birth,  and  pro- 
ceeds in  the  following  order  in  the  upper  jaw,  in  the  lower  jaw  appearing  a  little 
earlier : — First  molar,  five  or  six  months ;  the  central  incisor  a  little  later ;  lateral 
incisors  and  canine,  about  the  eighth  or  ninth  month ;  the  bicuspids  at  the  second 
year ;  second  molar,-  five  or  six  years ;  wisdom-tooth,  about  twelve  years. 

Previous  to  the  permanent  teeth  penetrating  the  gum,  the  bony  partitions 
separating  their  sacs  from  the  deciduous  teeth  are  absorbed,  the  fangs  of  the 
temporary  teeth  disappear,  and  the  permanent  teeth  become  placed  under  the 
loose  crowns  of  the  deciduous  teeth ;  the  latter  finally  become  detached,  when  the 
permanent  teeth  take  their  place  in  the  mouth. 

The  eruption  of  the  permanent  teeth  takes  place  at  the  following  periods,  the 
teeth  of  the  lower  jaw  preceding  those  of  the  upper  by  a  short  interval : — 

6|  years,  first  molars.  10th  year,  second  bicuspid. 

7th  year,  two  middle  incisors.  11th  to  12th  year,  canine. 

8th  year,  two  lateral  incisors.  12th  to  13th  year,  second  molars. 

9th  year,  first  bicuspid.  17th  to  21st  year,  wisdom-teeth. 

The  Palate. 

The  Palate  forms  the  roof  of  the  mouth ;  it  consists  of  two  portions,  the  hard 
palate  in  front,  the  soft  palate  behind. 

The  hard  palate  is  bounded  in  front  and  at  the  sides  by  the  alveolar  arches 
and  gums ;  behind,  it  is  continuous  with  the  soft  palate.  It  is  covered  by  a  dense 
structure,  formed  by  the  periosteum  and  mucous  membrane  of  the  mouth,  which 
are  intimately  adherent.  Along  the  middle  line  is  a  linear  ridge  or  raphe,  which 
terminates  anteriorly  in  a  small  papilla,  corresponding  with  the  inferior  opening 
of  the  anterior  palatine  fossa.  This  papilla  receives  filaments  from  the  naso- 
palatine and  anterior  palatine  nerves.  On  either  side  and  in  front  of  the  raphe, 
the  mucous  membrane  is  thick,  pale  in  color,  and  corrugated ;  behind,  it  is  thin, 
smooth,  and  of  a  deeper  color ;  it  is  covered  with  squamous  epithelium,  and  fur- 
nished with  numerous  glands  (palatal  glands),  which  lie  between  the  mucous 
membrane  and  the  surface  of  the  bone. 

The  soft  palate  or  Velum  pendulum  palati  is  a  movable  fold,  suspended  from  the 
posterior  border  of  the  hard  palate,  forming  an  incomplete  septum  between  the 
mouth  and  pharynx.  It  consists  of  a  fold  of  mucous  membrane,  inclosing  mus- 
cular fibres,  an  aponeurosis,  vessels,  nerves,  and  mucous  glands.  "When  occupy- 
ing its  usual  position  (a  relaxed  pendent  state),  its  anterior  surface  is  concave, 
continuous  with  the  roof  of  the  mouth,  and  marked  by  a  median  ridge  or  raphe, 
which  indicates  its  original  separation  into  two  lateral  halves.  Its  posterior 
surface  is  convex,  and  continuous  with  the  mucous  membrane  covering  the  floor 
of  the  posterior  nares.  Its  upper  border  is  attached  to  the  posterior  margin  of 
the  hard  palate,  and  its  sides  are  blended  with  the  pharynx.  Its  lower  border  is 
free. 

Hanging  from  the  middle  of  its  lower  border  is  a  small  conical-shaped  pendu- 
lous process,  the  uvula;  and  arching  outwards  and  downwards  from  the  base  of 


PALATE  — SALIVARY   GLANDS.  653 

the  uvula  on  each  side,  are  two  curved  folds  of  mucous  membrane,  containing 
muscular  fibres,  called  the  arches  or  pillars  of  the  soft  palate. 

The  anterior  pillar  runs  downwards  and  forwards  to  the  side  of  the  base  of  the 
tongue,  and  is  formed  by  the  projection  of  the  Palato-glossus  muscle,  covered  by 
mucous  membrane. 

The  posterior  filter*  are  more  closely  approximated  and  larger  than  the  anterior; 
they  run  downwards  and  backwards  to  the  sides  of  the  pharynx,  and  are  formed 
by  the  projection  of  the  Palato-pharyngei  muscles,  covered  by  mucous  membrane. 
The  anterior  and  posterior  pillars  are  separated  below  by  a  triangular  interval,  in 
which  the  tonsil  is  lodged. 

The  space  left  between  the  arches  of  the  palate  on  the  two  sides  is  called  the 
isthmus  of  the  fauces.  It  is  bounded  above  by  the  free  margin  of  the  palate ; 
below,  by  the  tongue ;  and  on  each  side,  by  the  pillars  of  the  soft  palate  and 
tonsils. 

The  mucous  membrane  of  the  soft  palate  is  thin,  and  covered  with  squamous 
epithelium  on  both  surfaces,  excepting  near  the  orifice  of  the  Eustachian  tube, 
where  it  is  columnar  and  ciliated.  The  palatine  glands  form  a  continuous  layer 
on  its  posterior  surface  and  round  the  uvula. 

The  aponeurosis  of  the  soft  palate  is  a  thin  but  firm  fibrous  layer,  attached  above 
to  the  hard  palate,  and  becoming  thinner  towards  the  free  margin  of  the  velum. 
It  is  blended  with  the  aponeurotic  tendon  of  the  Tensor  palati  muscle. 

The  muscles  of  the  soft  palate  are  five  on  each  side ;  the  Levator  palati,  Tensor 
palati,  Palato-glossus,  Palato-pharyngeus,  and  the  Azygos  uvulae. 

The  tonsils  {amygdalse)  are  two  glandular  organs,  situated  one  on  each  side 
of  the  fauces,  between  the  anterior  and  posterior  pillars  of  the  soft  palate.  They 
are  of  a  rounded  form,  and  vary  considerably  in  size  in  different  individuals. 
Externally,  the  tonsil  is  in  relation  with  the  inner  surface  of  the  Superior  con- 
strictor, and  with  the  internal  carotid  and  ascending  pharyngeal  arteries,  and 
corresponds  to  the  angle  of  the  lower  jaw.  Its  inner  surface  presents  from 
twelve  to  fifteen  orifices,  leading  into  small  recesses,  from  which  numerous  follicles 
branch  out  into  the  substance  of  the  gland.  These  follicles  are  lined  by  a  con- 
tinuation of  the  mucous  membrane  of  the  pharynx,  covered  with  epithelium,  their 
walls  being  formed  by  a  layer  of  closed  capsules  imbedded  in  the  submucous 
tissue.  These  capsules  are  analogous  to  those  of  Peyer's  glands ;  they  contain  a 
thick  grayish  secretion. 

The  arteries  supplying  the  tonsil  are  the  dorsalis  linguae  from  the  lingual, 
the  ascending  palatine  and  tonsillar  from  the  facial,  the  ascending  pharyngeal 
from  the  external  carotid,  and  the  descending  palatine  branch  of  the  internal 
maxillary. 

The  veins  terminate  in  the  tonsillar  plexus,  on  the  outer  side  of  the  tonsil. 

The  nerves  are  derived  from  the  fifth,  and  from  the  glossopharyngeal. 

The  Salivaey  Glands. 

The  principal  salivary  glands  communicating  with  the  mouth,  and  pouring  their 
secretion  into  its  cavity,  are  the  parotid,  submaxillary,  and  sublingual. 

The  Parotid  gland  (fig.  330),  so  called  from  being  placed  near  the  ear  (*apa, 
near ;  ovj,  wro{,  the  ear),  is  the  largest  of  the  three  salivary  glands,  varying  in 
weight  from  half  an  ounce  to  an  ounce.  It  lies  upon  the  side  of  the  face,  imme- 
diately below  and  in  front  of  the  external  ear.  It  is  limited  above  by  the  zygoma; 
below,  by  the  angle  of  the  jaw,  and  by  an  imaginary  line  drawn  between  it  and 
the  Sterno-mastoid  muscle ;  anteriorly,  it  extends  to  a  variable  extent  over  the 
Masseter  muscle ;  posteriorly,  it  is  bounded  by  the  external  meatus,  the  mastoid 
process,  and  the  Sterno-mastoid  and  Digastric  muscles,  slightly  overlapping  the 
former. 

Its  anterior  surface  is  grooved  to  embrace  the  posterior  margin  of  the  ramus  of 
the  lower  jaw,  and  advances  forwards  beneath  the  ramus,  between  the  two  ptery- 


654 


ORGANS   OF   DIGESTION. 


goid  muscles.  Its  outer  surface,  slightly  lobulated,  is  covered  by  the  integument 
and  fascia,  and  lias  one  or  two  lymphatic  glands  resting  on  it.  Its  inner  surface 
extends  deeply  into  the  neck,  by  means  of  two  large  processes,  one  of  which  dips 
behind  the  styloid  process,  and  projects  beneath  the  mastoid  process  and  the 
Sterno-mastoid  muscle ;  the  other  is  situated  in  front  of  the  styloid  process,  and 
passes  into  the  back  part  of  the  glenoid  fossa,  behind  the  articulation  of  the  lower 
jaw.  Imbedded  in  its  substance  is  the  external  carotid,  which  ascends  behind 
the  ramus  of  the  jaw ;  the  posterior  auricular  artery  emerges  from  it  behind ;  the 
temporal  artery  above;  the  transverse  facial  in  front;  and  the  internal  maxillary 
winds  through  it  inwards,  behind  the  neck  of  the  jaw.  Superficial  to  the  external 
carotid  is  the  trunk  formed  by  the  union  of  the  temporal  and  internal  maxillary 
veins ;  a  branch,  connecting  it  with  the  internal  jugular,  also  traversing  the 
gland.  It  is  traversed,  from  before  backwards,  by  the  facial  nerve  and  its 
branches,  which  emerge  at  its  anterior  border ;  the  great  auricular  nerve  pierces 
the  gland  to  join  the  facial,  and  the  temporal  branch  of  the  inferior  maxillary 
nerve  lies  above  the  upper  part  of  the  gland.  The  internal  carotid  artery  and 
internal  jugular  vein  lie  close  to  its  deep  surface. 

Steno's  duct,  the  duct  of  the  parotid  gland,  is  about  two  inches  and  a  half  in 
length.     It  commences  upon  the  inner  surface  of  the  cheek  by  a  small  orifice, 

Fig.  330.— The  Salivary  Gland. 


opposite  the  second  molar  tooth  of  the  upper  jaw ;  running  obliquely  for  a  short 
distance  beneath  the  mucous  membrane,  it  pierces  the  Buccinator  muscle,  and 
crosses  the  Masseter  to  the  anterior  border  of  the  gland,  in  the  substance  of 
which  it  subdivides  into  numerous  branches.  The  direction  of  the  duct  corre- 
sponds to  a  line  drawn  across  the  face  about  a  finger's  breadth  below  the  zygoma, 
from  the  lower  part  of  the  concha  to  midway  between  the  free  margin  of  the 
upper  lip  and  the  ala  of  the  nose.  While  crossing  the  Masseter,  it  receives  the 
duct  of  a  small  detached  portion  of  the  gland,  socia  parotidis,  which  occasionally 
exists  as  a  separate  lobe,  just  beneath  the  zygomatic  arch.     The  parotid  duct  is 


SALIVARY   GLANDS.  Wfl 

dense,  of  considerable  thickness,  and  its  canal  is  about  tlie  size  of  a  crow-quill ;  it 
consists  of  an  external  or  fibrous  coat,  of  considerable  density,  containing  con- . 
tractile  fibres,  and  of  an  internal  or  mucous  coat,  lined  with  columnar  epithelium. 

Vessels  and  Nerves.  The  arteries  supplying  the  parotid  gland  are  derived  from 
the  external  carotid,  and  from  the  branches  of  that  vessel  in  or  near  its  substance. 
The  veins  follow  a  similar  course.  The  lymphatics  terminate  in  the  superficial 
and  deep  cervical  glands,  passing  in  their  course  through  two  or  three  lymphatic 
glands,  placed  on  its  surface  and  in  its  substance.  The  nerves  are  derived  from 
the  carotid  plexus  of  the  sympathetic,  the  facial,  superficial,  temporal,  and  great 
auricular  nerves. 

The  Submaxillary  gland  is  situated  below  the  jaw,  in  the  anterior  part  of  the 
submaxillary  triangle  of  the  neck.  It  is  irregular  in  form,  and  weighs  about  two 
drachms.  It  is  covered  by  the  integument,  Platysma,  deep  cervical  fascia,  and 
the  body  of  the  lower  jaw,  corresponding  to  a  depression  on  its  inner  surface, 
and  lies  upon  the  Mylo-hyoid,  Hyo-glossus,  and  Stylo-glossus  muscles,  a  portion 
of  the  gland  passing  beneath  the  posterior  border  of  the  Mylo-hyoid.  In  front  of 
it  is  the  anterior  belly  of  the  Digastric ;  behind,  it  is  separated  from  the  parotid 
gland  by  the  stylo-maxillary  ligament,  and  from  the  sublingual  gland  in  front  by 
the  Mylo-hyoid  muscle.  The  facial  artery  lies  in  a  groove  in  its  posterior  and 
upper  border. 

Wharton's  duct,  the  duct  of  the  submaxillary  gland,  is  about  two  inches  in 
length,  and  its  walls  much  thinner  than  those  of  the  parotid  duct.  It  commences 
by  a  narrow  orifice  on  the  summit  of  a  small  papilla,  at  the  side  of  the  fraenum 
linguae.  Passing  between  the  sublingual  gland  and  the  Genio-hyo-glossus  mus- 
cle, it  runs  backwards  and  outwards  between  the  Mylo-hyoid,  and  the  Hyo-glossus 
and  Genio-hyo-glossus  muscles,  and  beneath  the  gustatory  nerve,  to  the  deep  por- 
tion of  the  gland,  where  it  divides  into  numerous  branches. 

Vessels  and  Nerves.  The  arteries  supplying  the  submaxillary  gland  are  branches 
of  the  facial  and  lingual.  Its  veins  follow  the  course  of  the  arteries.  The  nerves 
are  derived  from  the  submaxillary  ganglion,  from  the  mylo-hyoid  branch  of  the 
inferior  dental,  and  from  the  sympathetic. 

The  Sublingual  gland  is  the  smallest  of  the  salivary  glands.  It  is  situated 
beneath  the  mucous  membrane  of  the  floor  of  the  mouth,  on  either  side  of  the 
fraenum  linguae,  in  contact  with  the  inner  surface  of  the  lower  jaw,  close  to  the 
symphysis.  It  is  narrow,  flattened,  in  shape  somewhat  like  an  almond,  and 
weighs  about  a  drachm.  It  is  in  relation,  above,  with  the  mucous  membrane ; 
below,  with  the  Mylo-rryoid  muscle ;  in  front,  with  the  depression  on  the  side  of 
the  symphysis  of  the  lower  jaw,  and  with  its  fellow  of  the  opposite  side ;  behind, 
with  the  deep  part  of  the  submaxillary  gland;  and  internally,  with  the  Genio- 
hyo-glossus,  from  which  it  is  separated  by  the  lingual  nerve  and  Wharton's  duct. 
Its  excretory  ducts  (ductus  Biviniani),  from  eight  to  twenty  in  number,  open  sepa- 
rately into  the  mouth,  on  the  elevated  crest  of  mucous  membrane,  caused  by  the 
projection  of  the  gland,  on  either  side  of  the  fraenum  linguae.  One  or  more  join 
to  form  a  tube  which  opens  into  the  Whartonian  duct ;  it  is  called  the  duct  of 
Bartholin^. 

Vessels  and  Nerves.  The  sublingual  gland  is  supplied  with  blood  from  the  sub- 
lingual and  submental  arteries.     Its  nerves  are  derived  from  the  gustatory. 

Structure.  The  salivary  are  conglomerate  glands,  consisting  of  numerous  lobes, 
which  are  made  up  of  smaller  lobules,  connected  together  by  dense  areolar  tissue, 
vessels,  and  ducts.  Each  lobule  consists  of  numerous  closed  vesicles,  which  open 
into  a  common  duct ;  the  wall  of  each  vesicle  is  formed  of  a  delicate  basement 
membrane,  lined  by  epithelium,  and  covered  on  its  outer  surface  with  a  dense  capil- 
lary network.  In  the  submaxillary  and  sublingual  glands,  the  lobes  are  larger 
and  more  loosely  united  than  in  the  parotid. 


656  ORGANS   OF   DIGESTION. 


The  Pharynx 

The  Pharynx  is  that  part  of  the  alimentary  canal  which  is  placed  behind  the 
nose,  mouth,  and  larynx.  It  is  a  musculo-membranous  sac,  somewhat  conical  in 
form,  with  the  base  upwards,  and  the  apex  downwards,  extending  from  the  under 
surface  of  the  skull  to  the  cricoid  cartilage  in  front,  and  the  fifth  cervical  vertebra 
behind. 

The  pharynx  is  about  four  inches  and  a  half  in  length,  and  broader  in  the 
transverse  than  in  the  antero-posterior  diameter.  Its  greatest  breadth  is  opposite 
the  cornua  of  the  hyoid  bone;  its  narrowest  point  at  its  termination  in  the 
oesophagus.  It  is  limited,  above,  by  the  basilar  process  of  the  occipital  bone; 
below,  it  is  continuous  with  the  oesophagus ;  posteriorly,  it  is  connected  by  loose 
areolar  tissue  with  the  cervical  portion  of  the  vertebral  column,  and  the  Longi 
colli  and  Eecti  capitis  antici  muscles ;  anteriorly,  it  is  incomplete,  and  is  attached 
in  succession  to  the  internal  pterygoid  plate,  the  pterygo-maxillary  ligament,  the 
lower  jaw,  the  tongue,  hyoid  bone,  and  larynx ;  laterally,  it  is  connected  to  the 
styloid  processes  and  their  muscles,  and  is  in  contact  with  the  common  and 
internal  carotid  arteries,  the  internal  jugular  veins,  and  the  eighth,  ninth,  and 
sympathetic  nerves,  and,  above,  with  a  small  part  of  the  Internal  pterygoid 
muscles. 

It  has  seven  openings  communicating  with  it;  'the  two  posterior  nares,  the  two 
Eustachian  tubes,  the  mouth,  larynx,  and  oesophagus. 

The  posterior  nares  are  the  two  large  apertures  situated  at  the  upper  part  of 
the  anterior  wall  of  the  pharynx. 

The  two  Eustachian  tubes  open  one  at  each  side  of  the  upper  part  of  the  pharynx, 
at  the  back  part  of  the  inferior  meatus.  Below  the  nasal  fossae  are  the  posterior 
surface  of  the  soft  palate  and  uvula,  the  large  aperture  of  the  mouth,  the  base  of 
the  tongue,  the  epiglottis,  and  the  cordiform  opening  of  the  larynx. 

The  oesophageal  opening  is  the  lower  contracted  portion  of  the  pharynx. 

Structure.  The  pharynx  is  composed  of  three  coats ;  a  mucous  coat,  a  muscular 
layer,  and  a  fibrous  coat. 

The  fibrous  coat  is  situated  between  the  mucous  and  muscular  layers,  and  is 
called  the  pharyngeal  aponeurosis.  It  is  thick  above,  where  the  muscular  fibres 
are  wanting,  and  firmly  connected  to  the  basilar  process  of  the  occipital  and  petrous 
portion  of  the  temporal  bones.  As  it  descends,  it  diminishes  in  thickness,  and  is 
gradually  lost. 

The  mucous  coat  is  continuous  with  that  lining  the  Eustachian  tubes,  the  nares, 
the  mouth,  and  the  larynx.  It  is  covered  by  columnar  ciliated  epithelium,  as  low 
down  as  a  level  with  the  floor  of  the  nares ;  below  that  point,  it  is  of  the  squamous 
variety. 

The  muscular  coat  has  been  already  described  (p.  262). 

The  pharyngeal  glands  are  of  two  kinds,  the  simple  or  compound  follicular, 
which  are  found  in  considerable  numbers  beneath  the  mucous  membrane,  through- 
out the  entire  pharynx ;  and  the  racemose,  which  are  especially  numerous  at  the 
upper  part  of  the  pharynx,  and  form  a  thick  layer,  across  the  back  of  the  fauces, 
between  the  two  Eustachian  tubes. 

The  (Esophagus. 

The  (Esophagus  is  a  membranous  canal,  about  nine  inches  in  length,  extending 
from  the  pharynx  to  the  stomach.  It  commences  at  the  lower  border  of  the 
cricoid  cartilage,  opposite  the  fifth  cervical  vertebra,  descends  along  the  front  of 
the  spine,  through  the  posterior  mediastinum,  passes  through  the  Diaphragm,  and, 
entering  the  abdomen,  terminates  at  the  cardiac  orifice  of  the  stomach,  opposite  the 
ninth  dorsal  vertebra.  The  general  direction  of  the  oesophagus  is  vertical ;  but  it 
presents  two  or  three  slight  curvatures  in  its  course.     At  its  commencement,  it  is 


(ESOPHAGUS.  65T 

placed  in  the  median  line ;  but  it  inclines  to  the  left  side  at  the  root  of  the  neck, 
gradually  passes  to  the  middle  line  again,  and,  finally,  again  deviates  to  the  left,  as 
it  passes  forwards  to  the  oesophageal  opening  of  the  Diaphragm.  The  oesophagus 
also  presents  an  antero-posterior  flexure,  corresponding  to  the  curvature  of  the 
cervical  and  thoracic  portions  of  the  spine.  It  is  the  narrowest  part  of  the  ali- 
mentary canal,  being  most  contracted  at  its  commencement,  and  at  the  point  where 
it  passes  through  the  Diaphragm. 

Relations.  In  the  neck,  the  oesophagus  is  in  relation,  in  front,  with  the  trachea ; 
and,  at  the  lower  part  of  the  neck,  where  it  projects  to  the  left  side,  with  the 
thyroid  gland  and  thoracic  duct ;  behind,  it  rests  upon  the  vertebral  column 
and  Longus  colli  muscle ;  on  each  side,  it  is  in  relation  with  the  common  carotid 
artery  (especially  the  left,  as  it  inclines  to  that  side),  and  part  of  the  lateral  lobes  of 
the  thyroid  gland ;  the  recurrent  laryngeal  nerves  ascend  between  it  and  the  trachea. 

In  the  thorax,  it  is  at  first  situated  a  little  to  the  left  of  the  median  line :  it 
passes  across  the  left  side  of  the  transverse  part  of  the  aortic  arch,  descends  in 
the  posterior  mediastinum,  along  the  right  side  of  the  aorta,  until  near  the 
Diaphragm,  where  it  passes  in  front  and  a  little  to  the  left  of  this  vessel,  previous 
to  entering  the  abdomen.  It  is  in  relation,  in  front,  with  the  trachea,  the  arch 
of  the  aorta,  the  left  bronchus,  and  the  posterior  surface  of  the  pericardium; 
behind,  it  rests  upon  the  vertebral  column,  the  Longus  colli,  and  +,he  intercostal 
vessels ;  below,  near  the  Diaphragm,  upon  the  front  of  the  aorta ;  laterally, 
it  is  covered  by  the  pleurae ;  the  vena  azygos  major  lies  on  the  right,  and  the 
descending  aorta  on  the  left  side.  The  pneumogastric  nerves  descend  in  close 
contact  with  it,  the  right  nerve  passing  down  behind,  and  the  left  nerve  in  front 
of  it. 

Surgical  Anatomy.  The  relations  of  the  oesophagus  are  of  considerable  practical  interest  to 
the  surgeon,  as  he  is  frequently  required,  in  cases  of  stricture  of  this  tube,  to  dilate  the  canal  by 
a  bougie,  when  it  becomes  of  importance  that  its  direction  and  relations  to  surrounding  parts 
should  be  remembered.  In  cases  of  malignant  disease  of  the  oesophagus,  where  its  tissues  have 
become  softened  from  infiltration  of  the  morbid  deposit,  the  greatest  care  is  requisite  in  directing 
the  bougie  through  the  strictured  part,  as  a  false  passage  may  easily  be  made,  and  the  instrument 
may  pass  into  the  mediastinum,  or  into  one  or  the  other  pleural  cavity,  or  even  into  the  peri- 
cardium. 

The  student  should  also  remember  that  contraction  of  the  oesophagus,  and  consequent  symp- 
toms of  stricture,  are  occasionally  produced  by  an  aneurism  of  some  part  of  the  aorta  pressing 
upon  this  tube.     In  such  a  case,  the  passage  of  a  bougie  could  only  hasten  the  fatal  issue. 

It  occasionally  happens  that  a  foreign  body  becomes  impacted  in  the  oesophagus,  which  can 
neither  be  brought  upwards  nor  moved  downwards.  When  all  ordinary  means  for  its  removal 
have  failed,  excision  is  the  only  resource.  This,  of  course,  can  only  be  performed  when  it  is  not 
very  low  down.  If  the  foreign  body  is  allowed  to  remain,  extensive  inflammation  and  ulceration 
of  the  oesophagus  may  ensue.  In  one  case  with  which  I  am  acquainted,  the  foreign  body  ulti- 
mately penetrated  the  intervertebral  substance,  and  destroyed  life  by  inflammation  of  the  mem- 
branes and  substance  of  the  cord. 

The  operation  of  cesophagotomy  is  thus  performed  : — The  patient  being  placed  upon  his  back, 
with  the  head  and  shoulders  slightly  elevated,  an  incision,  about  four  inches  in  length,  should  be 
made  on  the  left  side  of  the  trachea,  from  the  thyroid  cartilage  downwards,  dividing  the  skin  and 
Platysma.  The  edges  of  the  wound  being  separated,  the  Omo-hyoid  muscle  and  the  fibres  of  the 
Sterno-hyoid  and  Sterno-thyroid  muscles  must  be  drawn  inwards ;  the  sheath  of  the  carotid 
vessels  being  exposed  should  be  drawn  outwards,  and  retained  in  that  position  by  retractors;  the 
oesophagus  will  then  be  exposed,  and  should  be  divided  over  the  foreign  body,  which  should  then 
be  removed.  Great  care  is  necessary  to  avoid  wounding  the  thyroid  vessels,  the  thyroid  gland, 
and  the  laryngeal  nerves. 

Structure.  The  oesophagus  has  three  coats ;  an  external  or  muscular,  a  middle 
or  cellular,  and  an  internal  or  mucous  coat. 

The  muscular  coat  is  composed  of  two  planes  of  fibres  of  considerable  thick- 
ness, an  external  longitudinal  and  an  internal  circular. 

The  longitudinal  fibres  are  arranged,  at  the  commencement  of  the  tube,  in 
three  fasciculi ;  one  in  front,  which  is  attached  to  the  vertical  ridge  on  the  posterior 
surface  of  the  cricoid  cartilage,  and  one  at  each  side,  continuous  with  the  fibres 
of  the  Inferior  constrictor;  as  they  descend  they  blend  together,  and  form  a 
uniform  layer,  which  covers  the  outer  surface  of  the  tube. 
42 


658 


ORGANS   OF   DIGESTION. 


The  circular  fibres  are  continuous  above  with  the  Inferior  constrictor :  thei  r 
direction  is  transverse  at  the  upper  and  lower  parts  of  the  tube,  but  oblique  in 
the  central  part. 

The  muscular  fibres  in  the  upper  part  of  the  oesophagus  are  of  a  red  color, 
and  consist  chiefly  of  the  striped  variety ;  but  below,  they  consist  entirely  of  the 
involuntary  muscular  fibre. 

The  cellular  coat  connects  loosely  the  mucous  and  muscular  coats. 

The  mucous  coat  is  thick,  of  a  reddish  color  above,  and  pale  below.  It  is 
loosely  connected  with  the  muscular  coat,  and  disposed  in  longitudinal  plicas, 
which  disappear  on  distension  of  the  tube.  Its  surface  is  studded  with  minute 
papillae,  and  it  is  covered  throughout  with  a  thick  layer  of  squamous  epithelium. 

The  oesophageal  glands  are  numerous  small  compound  glands,  scattered  through- 
out the  tube ;  they  are  lodged  in  the  submucous  tissue,  and  open  upon  the  surface 
by  a  long  excretory  duct.  They  are  most  numerous  at  the  lower  part  of  the  tube, 
where  they  form  a  ring  round  the  cardiac  orifice. 

The  Abdomen". 

The  Abdomen  is  the  largest  cavity  of  the  trunk  of  the  body,  and  is  separated, 
below,  from  the  pelvic  cavity  by  the  brim  of  the  pelvis.  It  is  of  an  oval  form,  the 
extremities  of  the  oval  being  directed  upwards  and  downwards ;  it  is  wider  above 
than  below,  and  measures  more  in  the  vertical  than  in  the  transverse  diameter. 


Fig. 


331. — The  Regions  of  the  Abdomen  and  their  Contents. 
(Edge  of  Costal  Cartilages  in  dotted  outline.) 


Boundaries.  It  is  bounded,  in  front  and  at  the  sides,  by  the  lower  ribs,  the 
Transversales  muscles,  and  venter  ilii ;  behind,  by  the  vertebral  column,  and  the 
Psoae  and  Quadrati  lumborum  muscles ;  above,  by  the  Diaphragm  ;  below,  by  the 


ABDOMEN. 


659 


brim  of  the  pelvis.  The  muscles  forming  the  boundaries  of  this  cavity  are  lined 
upon  their  inner  surface  by  a  layer  of  fascia,  differently  named  according  to  the 
part  to  which  it  is  attached. 

This  cavity  contains  the  greater  part  of  the  alimentary  canal,  some  of  the 
accessory  organs4  to  digestion,  the  liver,  pancreas,  and  spleen,  and  the  kidneys 
and  supra-renal  capsules.  Most  of  these  structures,  as  well  as  the  wall  of  the 
cavity  in  which  they  are  contained,  are  covered  by  an  extensive  and  complicated 
serous  membrane,  the  peritoneum. 

The  apertures  found  in  the  walls  of  the  abdomen,  for  the  transmission  of 
structures  to  or  from  it,  are  the  umbilicus,  for  the  transmission  (in  the  foetus)  of 
the  umbilical  vessels ;  the  caval  opening  iu  the  Diaphragm,  for  the  transmission 
of  the  inferior  vena  cava ;  the  aortic  opening,  for  the  passage  of  the  aorta,  vena 
azygos,  and  thoracic  duct ;  and  the  oesophageal  opening,  for  the  oesophagus  and 
pneumogastric  nerves.  Below,  there  are  two  apertures  on  each  side ;  one  for  the 
passage  of  the  femoral  vessels,  and  the  other  for  the  transmission  of  the  spermatic 
cord  in  the  male,  and  the  round  ligament  in  the  female. 

Regions.  For  convenience  of  description  of  the  viscera,  as  well  as  of  reference 
to  the  morbid  condition  of  the  contained  parts,  the  abdomen  is  artificially  divided 
into  certain  regions.  Thus,  if  two  circular  lines  are  drawn  round  the  body,  the 
one  parallel  with  the  cartilages  of  the  ninth  ribs,  and  the  other  with  the  highest 
point  of  the  crests  of  the  ilia,  the  abdominal  cavity  is  divided  into  three  zones,  an 
upper,  a  middle,  and  a  lower.  If  two  parallel  lines  are  drawn  from  the  cartilage 
of  the  eighth  rib  on  each  side,  down  to  the  centre  of  Poupart's  ligament,  each  of 
these  zones  is  subdivided  into  three  parts,  a  middle  and  two  lateral. 

The  middle  region  of  the  upper  zone  is  called  the  epigastric  (Im,  over,  and 
yacrr^p,  the  stomach);  and  the  two  lateral  regions,  the  right  and  left  hypochondriac 
(irto,  under,  and  xovSpot,  the  cartilages).  The  central  region  of  the  middle  zone 
is  the  umbilical;  and  the  two  lateral  regions,  the  right  and  left  lumbar.  The 
middle  region  of  the  lower  zone  is  the  hypogastric  or  pubic  region  ;  and  the  lateral 
regions  are  the  right  and  left  inguinal.  The  parts  contained  in  these  different 
regions  are  the  following  (fig.  331): — 


Right  Hypochondriac. 

The  right  lobe  of  the 
liver  and  the  gall-bladder, 
the  duodenum,  hepatic 
flexure  of  the  colon,  upper 
part  of  the  right  kidney, 
and  right  supra-renal  cap- 
sule. 


Right  Lumbar. 
Ascending  colon,  lower 
part  of  the  right  kidney, 
and  some  convolutions  of 
the  small  intestines. 


Right  Inguinal. 
The  caecum,  appendix 
caeci,  ureter,  and  spermatic 

vessels. 


Epigastric  Region. 
The  middle  and  pylo- 
ric end  of  the  stomach, 
left  lobe  of  the  liver  and 
lobus  Spigelii,  the  hepa- 
tic vessels,  cceliac  axis, 
semilunar  ganglia,  pan- 
creas, parts  of  the  aorta, 
vena  cava,  vena  azygos, 
and  thoracic  duct. 

Umbilical  Region. 
The  transverse  colon, 
part  of  the  great  omen- 
tum and  mesentery,  trans- 
verse part  of  the  duode- 
num, and  some  convolu- 
tions of  the  jejunum  and 
ileum. 

Hypogastric  Region. 

Convolutions  of  the 
small  intestines,  the  blad- 
der in  children,  and  in 
adults  if  distended,  and 
the  uterus  during  preg- 
nancy. 


Left  Hypochondriac. 
The  splenic  end  of  the 
stomach,  the  spleen  and 
extremity  of  the  pancreas, 
the  splenic  flexure  of  the 
colon,  upper  half  of  the 
left  kidney,  and  left  su- 
pra-renal capsule. 


Left  Lumbar. 
Descending  colon,  lower 
part  of  left  kidney,  and 
some  convolutions  of  the 
small  intestines. 


Left  Inguinal. 
Sigmoid  flexure  of  the 
colon,    ureter,    and    sper- 
matic vessels. 


660 


ORGANS   OF   DIGESTION. 


The  Peritoneum. 

The  Peritoneum  (rtspitttvfiv,  to  extend  around)  is  a  serous  membrane,  and,  like 
all  membranes  of  this  class,  a  shut  sac.  In  the  female,  hoVever,  it  is  not 
completely  closed,  the  Fallopian  tubes  communicating  with  it  by  their  free 
extremities;  and  thus  the  serous  membrane  is  continuous  with  their  mucous 
lining. 

The  peritoneum  partially  invests  all  the  viscera  contained  in  the  abdominal  and 
pelvic  cavities,  forming  the  visceral  layer  of  the  membrane  ;  it  is  then  reflected 
upon  the  internal  surface  of  the  parietes  of  these  cavities,  forming  the  parietal 
layer.  (Fig.  332.)  The  free  surface  of  the  peritoneum  is  smooth,  moist,  and 
covered  by  a  thin,  squamous  epithelium;  its  attached  surface  is  rough,  being 
connected  to  the  viscera  and  inner  surface  of  the  parietes  by  means  of  areolar 
tissue,  called  the  sub-peritoneal  areolar  tissue.  The  parietal  portion  is  loosely 
connected  with  the  fascia  lining  the  abdomen  and  pelvis ;  but  more  closely  to 
the  under  surface  of  the  Diaphragm,  and  in  the  middle  line  of  the  abdomen. 

In  order  to  trace  the  reflections  of  this  membrane  (the  abdomen  having  been 


Fig.  332.- 


-The  Reflections  of  the  Peritoneum,  as  seen  in  a  vertical 
Section  of  the  Abdomen. 


opened),  the  liver  should  be  raised  and  supported  in  that  position,  and  the  stomach 
should  be  depressed,  when  a  thin  membranous  layer  is  seen  passing  from  the 
transverse  fissure  of  the  liver,  to  the  upper  border  of  the  stomach ;  this  is  the 
lesser  or  gastro-hepatic  omentum.  It  consists  of  two  thin,  delicate  layers  of  peri- 
toneum, an  anterior  and  a  posterior,  between  which  are  contained  the  hepatic 


PERITONEUM.  6«1 

vessels  and  nerves.  Of  these  two  layers,  the  anterior  should  first  be  traced,  and 
then  the  posterior1. 

The  anterior  layer  descends  to  the  lesser  curvature  of  the  stomach,  and  covers 
its  anterior  surface  as  far  as  the  great  curvature ;  it  descends  for  some  distance  in 
front  of  the  small  intestines,  and,  returning  upon  itself  to  the  transverse  colon, 
forms  the  external  layer  of  the  great  omentum;  it  then  covers  the  under  surface 
of  the  transverse  colon,  and,  passing  to  the  back  part  of  the  abdominal  cavity, 
forms  the  inferior  layer  of  the  transverse  mesocolon.  It  then  descends  in  front  of 
the  duodenum,  the  aorta,  and  vena  cava,  as  far  as  the  superior  mesenteric  artery, 
along  which  it  passes  to  invest  the  small  intestines,  and,  returning  to  the  vertebral 
column,  forms  the  mesentery;  whilst,  on  either  side,  it  covers  the  ascending  and 
descending  colon,  and  is  thus  continuous  with  the  peritoneum  lining  the  walls  of 
the  abdomen.  From  the  root  of  the  mesentery,  it  descends  along  the  front  of  the 
spine  into  the  pelvis,  and  surrounds  the  upper  part  of  the  rectum,  which  it  holds 
in  its  position  by  means  of  a  distinct  fold,  the  mesorectum.  Its  course  in  the  male 
and  female  now  differs. 

In  the  male,  it  forms  a  fold  between  the  rectum  and  bladder,  the  recto-vesical 
fold,  and  ascends  over  the  posterior  surface  of  the  latter  organ  as  far  as  its  summit. 

In  the  female,  it  descends  into  the  pelvis  in  front  of  the  rectum,  covers  a  small 
part  of  the  posterior  wall  of  the  vagina,  and  is  then  reflected  on  to  the  uterus,  the 
fundus  and  body  of  which  it  covers.  From  the  sides  of  the  uterus,  it  is  reflected 
on  each  side  to  the  wall  of  the  pelvis,  forming  the  broad  ligaments ;  and  from  its 
anterior  surface  it  ascends  upon  the  posterior  wall  of  the  bladder,  as  far  as  its 
summit.  From  this  point  it  may  be  traced,  as  in  the  male,  ascending  upon  the 
anterior  parietes  of  the  abdomen,  to  the  under  surface  of  the  Diaphragm ;  from 
which  it  is  reflected  upon  the  liver,  forming  the  upper  layer  of  the  coronary,  and 
the  lateral  and  longitudinal  ligaments.  It  then  covers  the  upper  and  under  sur- 
faces of  the  liver,  and  at  the  transverse  fissure  becomes  continuous  with  the 
anterior  layer  of  the  lesser  omentum,  the  point  from  whence  its  reflection  was  ori- 
ginally traced. 

The  posterior  layer  of  the  lesser  omentum  descends  to  the  lesser  curvature  of 
the  stomach,  and  covers  its  posterior  surface  as  far  as  the  great  curvature;  it 
then  descends  for  some  distance  in  front  of  the  small  intestines,  and,  returning 
upon  itself  to  the  transverse  colon,  forms  the  internal  layer  of  the  great  omentum ; 
it  covers  the  upper  surface  of  the  transverse  colon,  and,  passing  backwards  to  the 
spine,  forms  the  upper  layer  of  the  transverse  mesocolon.  Ascending  in  front  of 
the  pancreas  and  crura  of  the  Diaphragm,  it  lines  the  back  part  of  the  under  sur- 
face of  this  muscle,  from  which  it  is  reflected  on  to  the  posterior  border  of  the  liver, 
forming  the  inferior  layer  of  the  coronary  ligament.  From  the  under  surface  of 
the  liver,  it  may  be  traced  to  the  transverse  fissure,  where  it  is  continuous  with 
the  posterior  layer  of  the  lesser  omentum,  the  point  from  whence  its  reflection  was 
originally  traced. 

The  space  included  in  the  reflections  of  this  layer  of  the  peritoneum  is  called 
the  lesser  cavity  of  the  peritoneum  or  cavity  of  the  great  omentum.  It  is  bounded,  in 
front,  by  the  lesser  omentum,  the  stomach,  and  the  descending  part  of  the  great 
omentum ;  behind,  by  the  ascending  part  of  the  great  omentum,  the  transverse 
colon,  transverse  mesocolon,  and  its  ascending  layer ;  above,  by  the  liver ;  and 
below,  by  the  folding  of  the  great  omentum.  This  space  communicates  with  the 
general  peritoneal  cavity  through  the  foramen  of  Winslow,  which  is  situated  be- 
hind the  right  free  border  of  the  lesser  omentum. 

The  foramen  of  Winslow  is  bounded  in  front  by  the  lesser  omentum,  inclosing 
the  vena  portas  and  the  hepatic  artery  and  duct ;  behinft,  by  the  inferior  vena  cava ; 
above,  by  the  lobus  Spigelii ;  below,  by  the  hepatic  artery  curving  forwards  from 
the  cceliac  axis. 

This  foramen  is  nothing  more  than  a  constriction  of  the  general  peritoneal 
cavity  at  this  point,  caused  by  the  hepatic  and  gastric  arteries  passing  forwards  from 
the  coeliac  axis  to  reach  their  respective  viscera. 


662  ORGANS   OF   DIGESTION 


The  viscera  thus  shown  to  be  almost  entirely  invested  by  peritoneum  are  the 
liver,  stomach,  spleen,  first  portion  of  duodenum,  jejunum,  and  ileum,  transverse 
colon,  sigmoid  flexure,  upper  end  of  rectum,  uterus,  and  ovaries. 

Those  viscera  partially  covered  by  it  are  the  descending  and  transverse  portions 
of  the  duodenum,  the  caecum,  the  ascending  and  descending  colon,  the  middle  por- 
tion of  the  rectum,  and  the  upper  part  of  the  vagina  and  posterior  wall  of  the  blad- 
der. The  kidneys,  supra-renal  capsules,  and  pancreas,  are  covered  by  this  mem- 
brane without  receiving  any  special  investment  from  it. 

The  lower  end  of  the  rectum,  the  neck,  base,  and  anterior  surface  of  the  bladder, 
and  the  lower  part  of  the  vagina,  have  no  peritoneal  investment. 

Numerous  folds  are  formed  by  the  peritoneum,  extending  between  the  various 
organs.  These  serve  to  hold  them  in  position,  and,  at  the  same  time  inclose  the 
-  -Is  and  nerves  proceeding  to  each  part.  Some  of  the  folds  are  called  liga- 
ments, from  their  serving  to  support  the  organs  in  position.  Others,  which 
connect  certain  parts  of  the  intestine  with  the  abdominal  wall,  constitute  the 
mesenteries;  and,  lastly,  those  are  called  omenta,  which  proceed  from  one  viscus  to 
another. 

The  Ligaments,  formed  by  folds  of  the  peritoneum,  include  those  of  the  -iver, 
spleen,  bladder,  and  uterus.     They  are  described  with  their  respective  organs. 

The  Omenta  are  the  lesser  or  gastro-hepatic  omentum,  the  great  or  gastro-colic 
omentum,  and  the  gastro-  splenic  omentum. 

The  lesser  omentum  (gastro-hepatic)  is  the  duplicature  which  extends  between 
the  transverse  fissure  of  the  liver,  and  the  lesser  curvature  of  the  stomach.  It  is 
extremely  thin,  and  consists,  as  before  said,  of  two  layers  of  peritoneum.  At  the 
left  border,  its  two  layers  pass  on  to  the  end  of  the  oesophagus ;  but,  at  the  right 
border,  where  it  is  free,  they  are  continuous,  and  form  a  free  rounded  margin, 
which  contains  between  its  layers  the  hepatic  artery,  the  ductus  communis  chole- 
dochus,  the  portal  vein,  lymphatics,  and  hepatic  plexus  of  nerves ;  all  these  struc- 
tures being  inclosed  in  loose  areolar  tissue,  called  Glisson's  capsule. 

The  great  omentum  {gastro-colic)  is  the  largest  peritoneal  fold.  It  consists  of 
four  layers  of  peritoneum,  two  of  which  descend  from  the  stomach,  one  from  its 
anterior,  the  other  from  its  posterior  surface ;  these,  uniting  at  its  lower  border, 
descend  in  front  of  the  small  intestines,  as  low  down  as  the  pelvis ;  and  the  same 
two  ascend  again  as  far  as  the  transverse  colon,  where  they  separate  and  inclose 
that  part  of  the  intestine.  These  separate  layers  may  be  easily  demonstrated  in 
the  young  subject ;  but  in  the  adult,  they  are  more  or  less  inseparably  blended. 
The  left  border  of  the  great  omentum  is  continuous  with  the  gastro-splenic  omen- 
tum ;  its  right  border  extends  as  far  only  as  the  duodenum.  The  great  omentum 
is  usually  thin,  presents  a  cribriform  appearance,  and  always  contains  some  adipose 
tissue,  which,  in  fat  subjects,  accumulates  in  considerable  quantity.  Its  use  ap- 
pears to  be  to  protect  the  intestines  from  cold,  and  to  facilitate  their  movement 
upon  each  other  during  their  vermicular  action. 

The  gastro-splenic  omentum  is  the  fold  which  connects  the  concave  surface  of 
the  spleen  to  the  cul-de-sac  of  the  stomach,  being  continuous  by  its  lower  border 
with  the  great  omentum.     It  contains  the  splenic  vessels  and  the  vasa  brevia. 

The  Mesenteries  are  the  mesentery  proper,  the  mesocsecum,  the  ascending, 
transverse,  and  descending  mesocolon,  the  sigmoid  mesocolon,  and  the  meso- 
rectum. 

The  mesentery  (utaov,  fttpov),  so  called  from  being  connected  to  the  middle 
of  the  cylinder  of  the  small  intestine,  is  the  broad  fold  of  peritoneum  which 
connects  the  convolutions  of  the  jejunum  and  ileum  with  the  posterior  wall  of  the 
abdomen.  Its  root,  the  part  connected  with  the  vertebral  column,  is  narrow, 
about  six  inches  in  length,  and  directed  obliquely  from  the  left  side  of  the  second 
lumbar  vertebra,  to  the  right  sacro-iliac  symphysis.  Its  intestinal  border  is  much 
longer ;  and  here  its  two  layers  separate,  so  as  to  inclose  the  intestine,  and  form 
its  peritoneal  coat.  Its  breadth,  between  its  vertebral  and  intestinal  border,  is 
about  four  inches.    Its  upp>er  border  is  continuous  with  the  under  surface  of  the 


STOMACH.  663 

transverse  mesocolon ;  its  lower  border,  with  the  peritoneum  covering  the  caecum 
and  ascending  colon.  It  serves  to  retain  the  small  intestines  in  their  position, 
and  contains  between  its  layers  the  mesenteric  vessels  and  nerves,  the  lacteal 
vessels,  and  mesenteric  glands. 

The  mesocsecum,  when  it  exists,  serves  to  connect  the  back  part  of  the  caecum 
with  the  right  iliac  fossa ;  more  frequently,  the  peritoneum  passes  merely  in  front 
of  this  portion  of  the  large  intestine. 

The  ascending  mesocolon  is  the  fold  which  connects  the  back  part  of  the  ascend- 
ing colon  with  the  posterior  wall  of  the  abdomen. 

The  descending  mesocolon  retains  the  descending  colon  in  connection  with  the 
posterior  abdominal  wall;  more  frequently,  the  peritoneum  merely  covers  the 
anterior  surface  and  sides  of  these  two  portions  of  the  intestine. 

The  transverse  mesocolon  is  a  broad  fold,  which  connects  the  transverse  colon 
with  the  posterior  wall  of  the  abdomen.  It  is  formed  of  the  two  ascending  layers 
of  the  great  omentum,  which,  after  separating  to  surround  the  transverse  colon, 
join  behind  it,  and  are  continued  backwards  to  the  spine,  where  they  diverge  in 
front  of  the  duodenum,  as  already  mentioned.  This  fold  contains  between  its 
layers  the  vessels  which  supply  the  transverse  colon. 

The  sigmoid  mesocolon  is  the  fold  of  peritoneum  which  retains  the  sigmoid 
flexure  in  connection  with  the  left  iliac  fossa. 

The  mesorectum  is  the  narrow  fold  which  connects  the  upper  part  of  the  rectum 
with  the  front  of  the  sacrum.     It  contains  the  hemorrhoidal  vessels. 

The  appendices  epiploicas  are  small  pouches  of  the  peritoneum  filled  with  fat, 
and  situated  along  the  colon  and  upper  part  of  the  rectum.  They  are  chiefly 
appended  to  the  transverse  colon. 


The  Stomach. 

The  Stomach  is  the  principal  organ  of  digestion.  It  is  the  most  dilated  part 
of  the  alimentary  canal,  serving  for  the  solution  and  reduction  of  the  food,  which 
constitutes  the  process  of  chymification.  It  is  situated  in  the  left  hypochondriac, 
the  epigastric,  and  part  of  the  right  hypochondriac  regions.  Its  form  is  irregularly 
conical,  curved  upon  itself,  and  presenting  a  rounded  base,  turned  to  the  left  side. 
It  is  placed  immediately  behind  the  anterior  wall  of  the  abdomen,  above  the 
transverse  colon,  below  the  liver  and  Diaphragm.  Its  size  varies  considerably  in 
different  subjects,  and  also  according  to  its  state  of  distension.  When  moderately 
full,  its  transverse  diameter  is  about  twelve  inches,  its  vertical  diameter  about 
four.  Its  weight,  according  to  Clendenning,  is  about  four  ounces  and  a  half.  It 
presents  for  examination  two  extremities,  two  orifices,  two  borders,  and  two 
surfaces. 

Its  left  extremity  is  called  the  greater  or  splenic  end.  It  is  the  largest  part  of  the 
stomach,  and  expands  for  two  or  three  inches  to  the  left  of  the  point  of  entrance 
of  the  oesophagus.  This  expansion  is  called  the  great  cul-de-sac  or  fundus.  It 
lies  beneath  the  ribs,  in  contact  with  the  spleen,  to  which  it  is  connected  by  the 
gastro-splenic  omentum. 

The  lesser  or  pyloric  end  is  much  smaller  than  the  preceding,  and  situated  on  a 
plane  anterior  and  inferior  to  it.  It  lies  in  contact  with  the  wall  of  the  abdomen, 
the  under  surface  of  the  liver,  and  the  neck  of  the  gall-bladder. 

^  The  oesophageal  or  cardiac  orifice  communicates  with  the  oesophagus ;  it  is  the 
highest  part  of  the  stomach,  and  somewhat  funnel-shaped  in  form. 

The  pyloric  orifice  communicates  with  the  duodenum,  the  aperture  being  guarded 
by  a  valve. 

The  lesser  curvature  extends  between  the  oesophageal  and  cardiac  orifices,  along 
the  upper  border  of  the  organ,  and  is  connected  to  the  under  surface  of  the  liver 
by  the  lesser  omentum. 

The  greater  curvature  extends  between  the  same  points,  along  the  lower  border, 


6G4 


ORGANS   OF   DIGESTION. 


and  gives   attachment  to   the  great   omentum.     The  surfaces  of  the  organ  are 
limited  by  these  two  curvatures. 

The  anterior  surface  is  directed  upwards  and  forwards,  and  is  in  relation  with 
the  Diaphragm,  the  under  surface  of  the  left  lobe  of  the  liver,  and,  in  the  epigas- 
tric region,  with  the  abdominal  parietes. 


Fig.  333. — The  Mucous  Membrane  of  the  Stomach  and  Duodenum,  with  the  Bile  Ducts. 


Cyttie 


The  posterior  surface  is  directed  downwards  and  backwards,  and  is  in  relation 
with  the  pancreas  and  great  vessels  of  the  abdomen,  the  crura  of  the  Diaphragm, 
and  the  solar  plexus. 

The  stomach  is  held  in  position  by  the  lesser  omentum,  which  extends  from 
the  transverse  fissure  of  the  liver  to  its  lesser  curvature,  and  by  a  fold  of  peri- 
toneum, which  passes  from  the  Diaphragm  on  to  the  oesophageal  end  of  the 
stomach,  the  gastro-phrenic  ligament ;  this  constitutes  the  most  fixed  point  of  the 
stomach,  whilst  the  pyloric  end  and  greater  curvature  are  the  most  movable 
parts :  hence,  when  this  organ  becomes  greatly  distended,  the  greater  curvature 
is  directed  forwards,  whilst  the  anterior  and  posterior  surfaces  are  directed,  the 
former  upwards,  and  the  latter  downwards. 

Alterations  in  Position.  There  is  no  organ  in  the  body  the  position  and  connections  of  which 
present  such  frequent  alterations  as  the  stomach.  During  inspiration  it  is  displaced  downwards 
by  the  descent  of  the  Diaphragm,  and  elevated  by  the  pressure  of  the  abdominal  muscles  during 
expiration.  Its  position  to  the  surrounding  viscera  is  also  changed,  according  to  the  empty  or 
distended  state  of  the  organ,  When  empty,  it  occupies  only  a  small  part  of  the  left  hypochon- 
driac region,  the  spleen  lying  behind  it ;  the  left  lobe  of  the  liver  covers  it  in  front,  and  the  under 
surface  of  the  heart  rests  upon  it  above,  and  in  front,  being  separated  from  it  by  the  left  lobe  of 
the  liver  and  pericardium.  Hence  it  is,  that,  in  gastralgia.  the  pain  is  generally  referred  to  the 
heart,  and  is  often  accompanied  by  palpitation  and  intermission  of  the   pulse.      When  the 


STOMACH. 


G65 


stomach  is  distended  the  Diaphragm  is  forced  upwards,  contracting  the  cavity  of  the  chest ; 
hence  the  dyspnoea  complained  of,  from  inspiration  being  impeded.  The  heart  is  also  displaced 
upwards  ;  hence  the  oppression  in  this  region,  and  the  palpitation  experienced  in  extreme  disten- 
sion of  the  stomach.  Pressure  from  without,  as  in  the  pernicious  practice  of  tight  lacing,  pushes 
the  stomach  down  towards  the  pelvis.  In  disease,  also,  the  position  and  connections  of  the 
organ  may  be  greatly  changed,  from  the  accumulation  of  fluid  in  the  chest  or  abdomen,  or  when 
the  size  of  any  of  the  surrounding  viscera  undergoes  alteration. 

On  looking  into  the  pyloric  end  of  the  stomach,  the  mucous  membrane  is  found 
projecting  inwards  in  the  form  of  a  circular  fold,  the  pylorus,  leaving  a  narrow 
circular  aperture,  about  half  an  inch  in  diameter,  by  which  the  stomach  commu- 
nicates with  the  duodenum. 

The  pylorus  is  formed  by  a  reduplication  of  the  mucous  membrane  of  the 
stomach,  containing  numerous  muscular  fibres,  which  are  aggregated  into  a 
thick  circular  ring,  the  longitudinal  fibres  and  serous  membrane  being  continued 
over  the  fold  without  assisting  in  its  formation.  The  aperture  is  occasionally  oval. 
Sometimes,  the  circular  fold  is  replaced  by  two  crescentic  folds,  placed,  one  above, 
and  the  other  below,  the  pyloric  orifice ;  and,  more  rarely,  there  is  only  one. 

Structure.  The  stomach  consists  of  four  coats ;  a  serous,  a  muscular,  a  cellular, 
and  a  mucous  coat,  together  with  vessels  and  nerves. 

The  serous  coat  is  derived  from  the  peritoneum,  and  covers  the  entire  surface 
of  the  organ,  excepting  along  the  greater  and  lesser  curvature,  at  the  points  of 
attachment  of  the  greater  and  lesser  omenta ;  here  the  two  layers  of  peritoneum 
leave  a  small  triangular  space,  along  which  the  nutrient  vessels  and  nerves  pass. 

The  muscular  coat  is  situated  immediately  beneath  the  serous  covering.  It  con 
sists  of  three  sets  of  fibres,  the  longitudinal,  circular,  and  oblique  (fig.  334). 


Fig.  334. — The  Muscular  Coat  of  the  Stomach. 


The  longitudinal  fibres  are  most  superficial ;  they  are  continuous  with  the  longi- 
tudinal fibres  of  the  oesophagus,  radiating  in  a  stellate  manner  from  the  cardiac 
orifice.  They  are  most  distinct  along  the  curvatures,  especially  the  lesser ;  but  are 
very  thinly  distributed  over  the  surfaces.  At  the  pyloric  end,  they  are  more 
thickly  distributed,  and  continuous  with  the  longitudinal  fibres  of  the  small 
intestine. 


G66 


ORGANS   OF   DIGESTION 


The  circular  fibres  form  a  "uniform  layer  over  the  whole  extent  of  the  stomach, 
"beneath  the  longitudinal  fibres.  At  the  pylorus,  they  are  most  abundant,  and 
are  aggregated  into  a  circular  ring,  which  projects  into  the  cavity,  and  forms,  with 
the  fold  of  mucous  membrane  covering  its  surface,  the  pyloric  valve. 

The  oblique  fibres  are  limited  chiefly  to  the  cardiac  end  of  the  stomach,  where 
they  are  disposed  as  a  thick  uniform  layer  covering  both  surfaces,  some  passing 
obliquely  from  left  to  right,  others  from  right  to  left,  round  the  cardiac  orifice. 

The  cellular  coat  consists  of  a  loose,  filamentous,  areolar  tissue,  connecting  the 
mucous  and  muscular  layers.  It  is  sometimes  called  the  submucous  coat.  It 
supports  the  bloodvessels  previous  to  their  distribution  to  the  mucous  membrane ; 
hence  it  is  sometimes  called  the  vascular  coat. 

The  mucous  membrane  of  the  stomach  is  thick;  its  surface  smooth,  soft,  and 
velvety.  During  infancy,  and  immediately  after  death,  it  is  of  a  pinkish  tinge ; 
but  in  adult  life,  and  in  old  age,  it  becomes  of  a  pale  straw  or  ash-gray  color. 
It  is  thin  at  the  cardiac  extremity,  but  thicker  towards  the  pylorus.  During  the 
contracted  state  of  the  organ,  it  is  thrown  into  numerous  plaits  or  rugoe,  which,  for 
the  most  part,  have  a  longitudinal  direction,  and  are  most  marked  towards  the  lesser 
end  of  the  stomach,  and  along  the  greater  curvature.  These  folds  are  entirely 
obliterated  when  the  organ  becomes  distended. 

Structure  of  the  mucous  membrane  (fig.  835).  When  examined  with  a  lens,  the 
inner  surface  of  the  mucous  membrane  presents  a  peculiar  honey-comb  appearance, 


Fig.  335. — Minute  Anatomy  of  Mucous  Membrane  of  Stomach. 


Mouths  of  Tuliuli 


Orifice  of  Tuts 


EpitheJi'cUjoarticlrS 


from  being  covered  with  small  shallow  depressions  or  alveoli,  of  a  polygonal  or 
hexagonal  form,  which  vary  from  l-100th  to  l-350th  of  an  inch  in  diameter,  and 
are  separated  by  slightly  elevated  ridges.  In  the  bottom  of  the  alveoli  are  seen 
the  orifices  of  minute  tubes,  the  gastric  follicles,  which  are  situated  perpendicu- 
larly side  by  side,  in  the  entire  substance  of  the  mucous  membrane.  They  are 
short,  and  simply  tubular  in  character  towards  the  cardiac  end  ;  but  at  the  pyloric 
end,  they  are  longer,  more  thickly  set,  convoluted,  and  terminate  in  dilated  saccular 
extremities,  or  subdivide  into  from  two  to  six  tubular  branches.  The  gastric 
follicles  are  composed  of  a  homogeneous  basement  membrane,  lined  upon  its  free 
surface  by  a  layer  of  cells,  which  differ  in  their  character  in  different  parts  of  the 
stomach.  Towards  the  pylorus,  these  tubes  are  lined  throughout  with  columnar 
epithelium ;  they  are  termed  the  mucous  glands,  and  are  supposed  to  secrete  the 
gastric  mucus.  In  other  parts  of  the  organ,  the  deep  part  of  each  tube  is  filled 
with  nuclei,  and  a  mass  of  granules ;  above  these  is  a  mass  of  nucleated  cells,  the 
upper  fourth  of  the  tube  being  lined  by  columnar  epithelium.  These  are  called 
the  peptic  glands,  the  supposed  agents  in  the  secretion  of  the  gastric  juice. 

Simple  follicles  are  found  in  greater  or  less  number  over  the  entire  surface  of 
the  mucous  membrane ;  they  are  most  numerous  near  the  pyloric  end  of  the 
stomach,  and  especially  distinct  in  early  life.  The  epithelium  lining  the  mucous 
membrane  of  the  stomach  and  its  alveoli  is  of  the  columnar  variety. 


SMALL   INTESTINE.  6G7 

Vessels  and  Nerves.  The  arteries  supplying  the  stomach  are,  the  gastric,  pyloric 
and  right  gastro-epiploic  branches  of  the  hepatic,  the  left  gastro-epiploic  and  vasa 
brevia  from  the  splenic.  They  supply  the  muscular  coat,  ramify  in  the  submucous 
coat,  and  are  finally  distributed  to  the  mucous  membrane.  The  veins  accompany 
the  arteries,  and  terminate  in  the  splenic  and  portal  veins.  The  lymphatics  are 
numerous ;  they  consist  of  a  superficial  and  deep  set,  which  pass  through  the  lym- 
phatic glands  found  along  the  two  curvatures  of  the  organ.  The  nerves  are,  the 
terminal  branches  of  the  right  and  left  pneumogastric,  the  former  being  distributed 
upon  the  back,  and  the  latter  upon  the  front  part  of  the  organ.  Branches  from 
the  sympathetic  also  supply  the  organ. 

The  Small  Intestine. 

The  Small  Intestine  is  that  part  of  the  alimentary  canal  in  which  the  chyme  is 
mixed  with  the  bile,  the  pancreatic  juice,  and  the  secretions  of  the  various  glands 
imbedded  in  the  mucous  membrane  of  the  intestines,  and  where  the  separation  of 
the  nutritive  principles  of  the  food,  the  chyle,  is  effected:  this  constitutes  chyli- 
fication. 

The  small  intestine  is  a  convoluted  tube,  about  twenty  feet  in  length,  which 
gradually  diminishes  in  size  from  its  commencement  to  its  termination.  It  is 
contained  in  the  central  and  lower  parts  of  the  abdominal  and  pelvic  cavities, 
surrounded  above  and  at  the  sides  by  the  large  intestine ;  in  relation,  in  front, 
with  the  great  omentum  and  abdominal  parietes ;  and  connected  to  the  spine  by 
a  fold  of  peritoneum,  the  mesentery.  The  small  intestine  is  divisible  into  three 
portions ;  the  duodenum,  jejunum,  and  ileum. 

The  duodenum  has  received  its  name  from  being  about  equal  in  length  to  the 
breadth  of  twelve  fingers  (eight  or  ten  inches.)  It  is  the  shortest,  the  widest,  and 
the  most  fixed  part  of  the  small  intestine;  it  has  no  mesentery,  and  is  only  partially 
covered  by  the  peritoneum.  Its  course  presents  a  remarkable  curve,  somewhat 
like  a  horseshoe  in  form ;  the  convexity  being  directed  towards  the  right,  and 
the  concavity  to  the  left,  embracing  the  head  of  the  pancreas.  Commencing  at 
the  pylorus,  it  ascends  obliquely  upwards  and  backwards  to  the  under  surface  of 
the  liver ;  it  then  descends  in  front  of  the  right  kidney,  and  passes  nearly  trans- 
versely across  the  front  of  the  spine,  terminating  in  the  jejunum  on  the  left  side 
of  the  second  lumbar  vertebra.  Hence  the  duodenum  has  been  divided  into  three 
portions :  ascending,  descending,  and  transverse. 

The  first  or  ascending  portion,  about  two  inches  in  length,  is  free,  movable, 
and  nearly  completely  invested  by  the  peritoneum.  It  is  in  relation,  above  and  in 
front,  with  the  liver  and  neck  of  the  gall-bladder ;  behind,  with  the  right  border 
of  the  lesser  omentum,  the  hepatic  artery  and  duct,  and  vena  porta).  This  por- 
tion of  the  intestine  is  usually  found  stained  with  bile,  especially  on  its  anterior 
surface. 

The  second  or  descending  portion,  about  three  inches  in  length,  is  firmly  fixed 
by  the  peritoneum  and  pancreas.  It  passes  from  the  neck  of  the  gall-bladder 
vertically  downwards,  in  front  of  the  right  kidney,  as  far  as  the  third  lumbar 
vertebra.  It  is  covered  by  peritoneum  only  on  its  anterior  surface.  It  is  in 
relation,  in  front,  with  the  right  arch  of  the  colon  and  mesocolon ;  behind,  with 
the  front  of  the  right  kidney ;  at  its  inner  side  is  the  head  of  the  pancreas,  and  the 
common  choledoch  duct.  The  common  bile  and  pancreatic  ducts  perforate  the 
inner  side  of  this  portion  of  the  intestine  obliquely,  a  little  below  its  middle. 

The  third  or  transverse  portion,  the  longest  and  narrowest  part  of  the  duodenum, 
passes  across  the  front  of  the  spine,  ascending  from  the  third  to  the  second  lumbar 
vertebra,  and  terminating  in  the  jejunum  on  the  left  side  of  this  bone.  In  front, 
it  is  covered  by  the  descending  layer  of  the  transverse  mesocolon,  and  crossed  by 
the  superior  mesenteric  vessels ;  behind,  it  rests  upon  the  aorta,  the  vena  cava,  and 
the  crura  of  the  Diaphragm ;  above  it  is  the  lower  border  of  the  pancreas,  the 
superior  mesenteric  vessels  passing  forwards  between  the  two. 


668  ORGANS   OF   DIGESTION. 

Vessels  and  Nerves.  The  arteries  supplying  the  duodenum  are  the  pyloric 
and  pancreatico-duodenal  branches  of  the  hepatic,  and  the  inferior  pancreatico- 
duodenal branch  of  the  superior  mesenteric.  The  veins  terminate  in  the  gastro- 
duodenal  and  superior  mesenteric.  Its  nerves  are  derived  from  the  solar 
plexus. 

The  jejunum  (jejunus,  empty),  so  called  from  being  usually  found  empty  after 
death,  includes  the  upper  two-fifths  of  the  rest  of  the  small  intestine.  It  com- 
mences at  the  duodenum  on  the  left  side  of  the  second  lumbar  vertebra,  and 
terminates  in  the  ileum;  its  convolutions  being  chiefly  confined  to  the  umbilical 
and  left  iliac  regions.  The  jejunum  is  wider,  its  coats  thicker,  more  vascular, 
and  of  a  deeper  color  than  those  of  the  ileum ;  but  there  is  no  characteristic 
mark  to  distinguish  the  termination  of  the  one,  or  the  commencement  of  the 
other. 

The  ileum  (ei-ktiv,  to  twist),  so  called  from  its  numerous  coils  or  convolutions, 
includes  the  remaining  three-fifths  of  the  small  intestine.  It  occupies  chiefly  the 
umbilical,  hypogastric,  right  iliac,  and  occasionally  the  pelvic,  regions,  and  ter- 
minates in  the  right  iliac  fossa  by  opening  into  the  inner  side  of  the  commence- 
ment of  the  large  intestine.  The  ileum  is  narrower,  its  coats  thinner  and  less 
vascular  than  those  of  the  jejunum;  a  given  length  of  it  weighing  less  than  the 
same  length  of  jejunum. 

Structure  of  the  small  intestine.  The  wall  of  the  small  intestine  is  composed  of 
four  coats ;  serous,  muscular,  cellular,  and  mucous. 

The  serous  coat  is  derived  from  the  peritoneum.  The  first  or  ascending  por- 
tion of  the  duodenum  is  almost  completely  surrounded  by  this  membrane ;  the 
second  or  descending  portion  is  covered  by  it  only  in  front ;  and  the  third  or 
transverse  portion  lies  behind  the  descending  layer  of  the  transverse  mesocolon, 
by  which  it  is  covered  in  front.  The  remaining  portion  of  the  small  intestine  is 
surrounded  by  the  peritoneum,  excepting  along  its  attached  or  mesenteric  border ; 
here  a  space  is  left  for  the  vessels  and  nerves  to  pass  to  the  gut. 

The  muscular  coat  consists  of  two  layers  of  fibres,  an  external  or  longitudinal, 
and  an  internal  or  circular  layer.  The  longitudinal  fibres  are  thinly  scattered 
over  the  surface  of  the  intestine,  and  are  most  distinct  along  its  free  border. 
The  circular  fibres  form  a  thick,  uniform  layer ;  they  surround  the  cylinder  of 
the  intestine  in  the  greater  part  of  its  circumference,  but  do  not  form  complete 
rings.  The  muscular  coat  is  thicker  at  the  upper,  than  at  the  lower  part  of  the 
small  intestine. 

The  cellular  or  submucous  coat  connects  together  the  mucous  and  muscular 
layers.  It  consists  of  a  loose,  filamentous,  areolar  tissue,  which  forms  a  nidus  for 
the  subdivision  of  the  nutrient  vessels,  previous  to  their  distribution  to  the  mucous 
surface. 

The  mucous  membrane  is  thick  and  highly  vascular  at  the  upper  part  of  the 
small  intestine,  but  somewhat  paler  and  thinner  below.  It  presents  for  examina- 
tion the  following  constituents : — 

-rp   vi    r  Simple  follicles. 

Epithelium.  ,f>    s       ,    ,      i 

-v/%      i  •        ,  (  Duodenal  glands. 

Valvuke  conniventes.  r>,      -,       )  0  v,  -,&    •, 

Y']V  (jrlands.    <  Solitary  glands. 

(  Agminate  or  Peyer's  glands. 

The  epithelium.,  covering  the  mucous  membrane  of  the  small  intestine,  is  of 
the  columnar  variety. 

The  valvulse  conniventes  (valves  of  Kerkring)  are  reduplications  or  foldings 
of  the  mucous  membrane  and  submucous  tissue,  containing  no  muscular  fibres. 
They  extend  transversely  across  the  cylinder  of  the  intestine  for  about  three- 
fourths  or  five-sixths  of  its  circumference.  The  larger  folds  are  about  two  inches 
in  length,  and  two-thirds  of  an  inch  in  depth  at  their  broadest  part ;  but  the 
greater  number  are  of  smaller  size.  The  larger  and  smaller  folds  alternate  with 
each  other.    They  are  not  found  at  the  commencement  of  the  duodenum,  but  begin 


SMALL   INTESTINE. 


669 


Fig.  336.— Two  Villi  magnified. 


Artery 


to  appear  about  one  or  two  inches  beyond  the  pylorus.  In  the  lower  part  of  the 
descending  portion,  below  the  point  where  the  common  choledoch  and  pancreatic 
ducts  enter  the  intestine,  they  are  very  large  and  closely  approximated.  In  the 
transverse  portion  of  the  duodenum  and  upper  half  pf  the  jejunum,  they  are  large 
and  numerous ;  and  from  this  point,  as  far  as  the  middle  of  the  ileum,  they 
diminish  considerably  in  size.  In  the  lower  part  of  the  ileum,  they  almost 
entirely  disappear ;  hence  the  comparative  thinness  of  this  portion  of  the  intes- 
tine, as  compared  with  the  duodenum  and  jejunum.  The  valvulae  conniventes 
retard  the  passage  of  the  food  along  the  intestines,  and  afford  a  more  extensive 
surface  for  absorption. 

The  villi  are  minute,  highly  vascular 
processes,  projecting  from  the  mucous  mem- 
brane of  the  small  intestine  throughout  its 
whole  extent,  and  giving  to  its  surface  a 
beautiful  velvety  appearance.  In  shape, 
some  are  triangular  and  laminated,  others 
conical  or  cylindrical,  with  clubbed  or  fili- 
form extremities.  They  are  largest  and 
most  numerous  in  the  duodenum  and  jeju- 
num, and  become  fewer  and  smaller  in  the 
ileum.  Krause  estimates  their  number  in 
the  upper  part  of  the  small  intestine,  at  from 
fifty  to  ninety  in  a  square  line ;  and  in  the 
lower  part,  from  forty  to  seventy ;  the  total 
number  for  the  whole  length  of  the  intestine 
being  four  millions. 

In  structure  each  villus  consists  of  a  network  of  capillary  and  lacteal  vessels, 
with  nuclear  corpuscles  and  fat  globules  in  their  interstices,  inclosed  in  a  thin 
prolongation  of  basement  membrane  covered  by  a  single  layer  of  columnar 
epithelium,  the  particles  of  which  are  arranged  perpendicularly  to  the  surface.  A 
layer  of  organic  muscular  fibre  has  been  described  forming  a  thin  hollow  cone 
round  the  central  lacteal.  It  is  possible  that  this  assists  in  the  propulsion  of  the 
chyle  along  the  vessel.  The  mode  of  origin  of  the  lacteals  within  the  villi  is  un- 
known. 

The  simple  follicles  or  crypts  of  Lieberkuhn  are  found  in  considerable  numbers 
over  every  part  of  the  mucous  membrane  of  the  small  intestine.  They  consist 
of  minute  tubular  depressions  of  the  mucous  membrane,  arranged  perpendicularly 
to  the  surface,  upon  which  they  open  by  small  circular  apertures.  They  may  be 
seen  with  the  aid  of  a  lens,  their  orifices  appearing  as  minute  dots,  scattered 
between  the  villi.  Their  walls  are  thin,  consisting  of  a  layer  of  basement 
membrane,  lined  by  cylindrical  epithelium,  and  covered  on  their  exterior  by 
capillary  vessels.  Their  contents  vary,  even  in  health,  and  the  purpose  served 
by  their  secretion  is  still  very  doubtful. 

The  duodenal  or  Brunner's  glands  are  limited  to  the  duodenum  and  com- 
mencement  of  the  jejunum.  They  are  small,  flattened,  granular  bodies,  imbedded 
in  the  submucous  areolar  tissue,  and  open  upon  the  surface  of  the  mucous  mem. 
brane  by  minute  excretory  ducts.  They  are  most  numerous  and  largest  near  the 
pylorus.  They  may  be  compared  to  the  elementary  lobules  of  a  salivary  gland, 
spread  out  over  a  broad  surface,  instead  of  being  collected  in  a  mass.  In  structure 
they  resemble  the  pancreas. 

The  solitary  glands  (glandulse  solitarise)  are  found  scattered  throughout  the 
mucous  membrane  of  the  small  intestine,  but  are  most  numerous  in  the  lower 
part  of  the  ileum.  They  are  small,  round,  whitish  bodies,  from  half  a  line  to  a 
line  in  diameter,  consisting  of  a  closed  saccular  cavity,  having  no  excretory  duct, 
and  containing  an  opaque  white  secretion.  Their  free  surface  is  covered  with 
villi,  and  each  gland  is  surrounded  by  openings  like  those  of  the  follicles  of 
Lieberkuhn.     Their  use  is  not  known. 


CTO 


ORGANS   OF   DIGESTION. 


Fig.  337— Patch  of  Peyer's  Glands. 
From  the  lower  part  of  the  Ileum. 


i  Peyer's  glands  may  be  regarded  as  aggregations  of  solitary  glands,  forming 
"ircular  or  oval  patches  from  twenty  to  thirty  in  number,  and  varying  in  length 
from  half  an  inch  to  four  inches.  They  are  largest  and  most  numerous  in  the 
ileum.  In  the  lower  part  of  the  jejunum  they  are  small,  of  a  circular  form,  and  few 
in  number ;  they  are  occasionally  seen  in  the  duodenum.  They  are  placed  lengthwise 
in  the  intestine,  covering  the  portion  of  the  tube  most  distant  from  the  attachment 

of  the  mesentery.  Each  patch  is  formed 
of  a  group  of  small,  round,  whitish  vesicles, 
covered  with  mucous  membrane.  Each 
vesicle  consists  of  a  moderately  thick  ex- 
ternal capsule,  having  no  excretory  duct, 
and  containing  an  opaque  white  secretion. 
Each  is  surrounded  by  a  zone  or  wreath  of 
simple  follicles,  and  the  interspaces  between 
them  are  covered  with  villi.  These  vesicles 
are  usually  closed ;  but  it  has  been  supposed 
that  they  open  at  intervals  to  discharge  the 
secretion  contained  within  them.  The  mu- 
cous and  submucous  coats  of  the  intestine 
are  intimately  adherent,  and  highly  vascular, 
opposite  the  Peyerian  glands.  Their  use  is 
not  known  [but  they  are  now  generally  sup- 
posed to  belong  to  the  lymphatic  system]. 
They  are  largest  and  most  developed  during 
the  digestive  process. 

The  Large  Intestine. 

Fig.  338.— A  portion  of  the  above  magnified.      The   Large  Intestine  extends  from  the 

termination  of  the  ileum  to  the  anus.     It 
is  about  five  feet  in  length ;  being  one-fifth 
of  the  whole  extent  of  the  intestinal  canal. 
It  is  largest  at  its  commencement  at  the 
ceecum,  and  gradually  diminishes  as  far  as 
the  rectum,  where  there  is  a  dilatation  of 
considerable  size,  just  above  the  anus.     It 
differs  from  the  small  intestine  in  its  greater 
size,  its  more  fixed  position,  and  its  saccu- 
lated  form.      The   large    intestine,   in   its 
course,  describes  an  arch,  which  surrounds 
the  convolutions  of  the  small  intestine.     It 
commences   in    the  right   iliac  fossa,  in  a 
dilatation  of  considerable  size,  the  caecum. 
It  ascends  through  the  right  lumbar  and 
hypochondriac  regions,  to  the  under  surface 
of  the  liver ;  passes  transversely  across  the 
abdomen,  on  the  confines  of  the  epigastric 
and  umbilical  regions,  to  the  left  hypochondriac  region ;  descends  through  the 
left  lumbar  region  to  the  left  iliac  fossa,  where  it  becomes  convoluted,  and  forms 
the  sigmoid  flexure ;  finally,  it  enters  the  pelvis,  and  descends  along  its  posterior 
wall  to  the  anus.     The  large  intestine  is  divided  into  the  caecum,  colon,  and  rectum. 
The   Caecum  (csecus,  blind)  is  the  large  blind  pouch  or  cul-de-sac  extending 
downwards  from  the  commencement  of  the  large  intestine.     It  is  the  most  dilated 
part  of  this  tube,  measuring  about  two  and  a  half  inches,  both  in  its  vertical  and 
transverse  diameters.     It  is  situated  in  the  right  iliac  fossa,  immediately  behind 
the  anterior  abdominal  wall,  being  retained  in  its  place  by  the  peritoneum,  which 
passes  over  its  anterior  surface  and  sides ;  its  posterior  surface  being  connected  by 


'&rXW-; 


M*m;m 


jf*:/!.-."^- .CviO 


•LARGE   INTESTINE.  6U 

loose  areolar  tissue  with  the  iliac  fascia.  Occasionally,  it  is  almost  completely 
surrounded  by  peritoneum,  which  forms  a  distinct  fold,  the  mesocaecum,  connecting 
its  back  part  with  the  iliac  fossa.  This  fold  allows  the  caecum  considerable 
freedom  of  movement.  Attached  to  its  lower  and  back  part,  is  the  appendix 
vermiformis,  a  long,  narrow,  worm-shaped  tube,  the  rudiment  of  the  lengthened 
caecum  found  in  all  the  mammalia,  except  the  ourang-outang  and  wombat.  The 
appendix  varies  from  three  to  six  inches  in  length,  its  average  diameter  being 
about  equal  to  that  of  a  goose-quill.  It  is  usually  directed  upwards  and  inwards 
behind  the  caecum,  coiled  upon  itself,  and  terminates  in  a  blunt  point,  being  retained 

Fig.  339. — The  Cfficnm  and  Colon  laid  open  to  show  the 
ileo-caecal  Valve. 


in  its  position  by  a  fold  of  peritoneum,  which  sometimes  forms  a  mesentery  for  it. 
Its  canal  is  small,  and  communicates  with  the  caecum  by  an  orifice  which  is  some- 
times guarded  with  an  incomplete  valve.  Its  coats  are  thick,  and  its  mucous  lining 
furnished  with  a  large  number  of  solitary  glands. 

Ileo-csecal  Valve.  The  lower  end  of  the  ileum  terminates  at  the  inner  and 
back  part  of  the  large  intestine,  opposite  the  junction  of  the  caecum  with  the 
colon.  At  this  point,  the  mucous  membrane  forms  two  valvular  folds,  which  pro- 
ject into  the  large  intestine,  and  are  separated  from  each  other  by  a  narrow 
elongate  aperture.  This  is  the  ileo-caecal  valve  (valvula  Bauhini).  Each  fold  is 
semilunar  in  form.  The  upper  one,  nearly  horizontal  in  direction,  is  attached  by 
its  convex  border  to  the  point  of  junction  of  the  ileum  with  the  colon;  the  lower 
segment  being  connected  at  the  point  of  junction  of  the  ileum  with  the  caecum. 
Their  concave  margins  are  free,  project  into  the  intestine,  separated  from  one  an- 
other by  a  narrow  slit-like  aperture,  transversely  directed.  At  each  end  of  this 
aperture,  the  two  segments  of  the  valve  coalesce,  and  are  continued,  as  a  narrow 
membranous  ridge,  around  the  canal  of  the  intestine  for  a  short  distance,  forming 
the  fraena  or  retinacula  of  the  valve.  The  left  end  of  this  aperture  is  rounded ; 
the  right  end  is  narrow  and  pointed. 

Each  segment  of  the  valve  is  formed  of  a  reduplication  of  the  mucous  mem- 
brane, and  of  the  circular  muscular  fibres  of  the  intestine,  the  longitudinal  fibres 
and  peritoneum  being  continued  uninterruptedly  across  from  one  intestine  to  the 


6T2  ORGANS   OF   DIGESTION. 

other.  When  these  are  divided  or  removed,  the  ileum  may  be  drawn  outwards, 
and  all  traces  of  the  valve  will  be  lost,  the  ileum  appearing  to  open  into  the  large 
intestine  by  a  funnel-shaped  orifice  of  large  size. 

The  surface  of  each  segment  of  the  valve  directed  towards  the  ileum  is  covered 
with  villi,  and  presents  the  characteristic  structure  of  the  mucous  membrane  of 
the  small  intestine ;  whilst  that  turned  towards  the  large  intestine  is  destitute  of 
villi,  and  marked  with  the  orifices  of  the  numerous  tubuli  peculiar  to  this  mem- 
brane. These  differences  in  structure  continue  as  far  as  the  free  margin  of  the 
valve. 

When  the  caecum  is  distended,  the  margins  of  the  opening  are  approximated,  so 
as  to  prevent  any  reflux  into  the  ileum. 

The  colon  is  divided  into  four  parts,  the  ascending,  transverse,  descending,  and 
the  sigmoid  flexure. 

The  ascending  colon  is  smaller  than  the  caecum.  It  passes  upwards  from  the 
right  iliac  fossa,  to  the  under  surface  of  the  liver,  on  the  right  of  the  gall-bladder, 
where  it  bends  abruptly  inwards  to  the  left,  forming  the  hepatic  flexure.  It  is 
retained  in  position  with  the  posterior  wall  of  the  abdomen  by  the  peritoneum, 
which  covers  its  anterior  surface  and  sides,  its  posterior  surface  being  connected  by 
loose  areolar  tissue  with  the  Quadratus  lumborum  and  right  kidney ;  sometimes  the 
peritoneum  almost  completely  invests  it,  and  forms  a  distinct  but  narrow  meso- 
colon. It  is  in  relation,  in  front,  with  the  convolutions  of  the  ileum  and  the 
abdominal  parietes;  behind,  it  lies  on  the  Quadratus  lumborum  muscle,  and  right 
kidney. 

The  transverse  colon,  the  longest  part  of  the  large  intestine,  passes  transversely 
from  right  to  left  across  the  abdomen,  opposite  the  confines  of  the  epigastric  and 
umbilical  zones,  into  the  left  hypochondriac  region,  where  it  curves  downwards 
beneath  the  lower  end  of  the  spleen,  forming  its  splenic  flexure.  In  its  course  it 
describes  an  arch,  the  concavity  of  which  is  directed  backwards  towards  the  ver- 
tebral column ;  hence  the  name,  transverse  arch  of  the  colon.  This  is  the  most 
movable  part  of  the  colon,  being  almost  completely  invested  by  peritoneum  and 
connected  to  the  spine  behind  by  a  large  and  wide  duplicature  of  this  membrane, 
the  transverse  mesocolon.  It  is  in  relation,  by  its  upper  surface,  with  the  liver  and 
gall-bladder,  the  great  curvature  of  the  stomach,  and  the  lower  end  of  the  spleen ; 
by  its  under  surface,  with  the  small  intestines;  by  its  anterior  surface,  with  the 
anterior  layers  of  the  great  omentum  and  the  abdominal  parietes ;  by  its  posterior 
surface,  with  the  transverse  mesocolon. 

The  descending  colon  passes  almost  vertically  downwards  through  the  left  hypo- 
chondriac and  lumbar  regions  to  the  upper  part  of  the  left  iliac  fossa,  where  it 
terminates  in  the  sigmoid  flexure.  It  is  retained  in  position  by  the  peritoneum, 
which  covers  its  anterior  surface  and  sides,  its  posterior  surface  being  connected 
by  areolar  tissue  with  the  left  crus  of  the  Diaphragm,  the  left  kidney,  and  the  Quad- 
ratus lumborum.  It  is  smaller  in  calibre,  and  more  deeply  placed  than  the  ascend- 
ing colon. 

The  sigmoid  flexure  is  the  narrowest  part  of  the  colon ;  it  is  situated  in  the  left 
iliac  fossa,  commencing  at  the  termination  of  the  descending  colon,  at  the  margin 
of  the  crest  of  the  ilium,  and  ending  in  the  rectum,  opposite  the  left  sacro-iliac 
symphysis.  It  curves  in  the  first  place  upwards,  and  then  descends  vertically, 
and  to  one  or  the  other  side  like  the  letter/,  hence  its  name;  and  is  retained  in 
its  place  by  a  loose  fold  of  peritoneum,  the  sigmoid  mesocolon.  It  is  in  relation, 
in  front,  with  the  small  intestines  and  abdominal  parietes;  behind,  with  the  iliac 
fossa. 

The  Rectum  is  the  terminal  part  of  the  large  intestine,  and  extends  from  the 
sigmoid  flexure  to  the  anus ;  it  varies  in  length  from  six  to  eight  inches,  and  has 
received  its  name  from  being  somewhat  less  flexuous  than  any  other  part  of  the 
intestinal  canal.  It  commences  opposite  the  left  sacro-iliac  symphysis,  passes 
obliquely  downwards  from  left  to  right  to  the  middle  of  the  sacrum,  forming  a 
gentle  curve  to  the  right  side.     Regaining  the  middle  line,  it  descends  in  front  of 


LARGE   INTESTINE.  673 

tlie  lower  part  of  the  sacrum  and  coccyx ;  and,  near  the  extremity  of  the  latter 
bone,  inclines  backwards  to  terminate  at  the  anus,  being  curved  both  in  the  lateral 
and  anteroposterior  directions.  The  rectum  is,  therefore,  not  straight,  the  upper 
part  being  directed  obliquely  from  the  left  side  to  the  median  line,  the  middle 
portion  being  curved  in  the  direction  of  the  hollow  of  the  sacrum  and  coccyx,  the 
lower  portion  presenting  a  short  curve  in  the  opposite  direction.  The  rectum  is 
cylindrical,  not  sacculated  like  the  rest  of  the  large  intestine ;  it  is  narrower  at  its 
upper  part  than  the  sigmoid  flexure,  gradually  increases  in  size  as  it  descends, 
and  immediately  above  the  anus  presents  a  considerable  dilatation,  capable  of 
acquiring  an  enormous  size.  The  rectum  is  divided  into  three  portions,  upper, 
middle,  and  lower. 

The  upper  portion,  which  includes  about  half  the  length  of  the  tube,  extends 
obliquely  from  the  left  sacro-iliac  symphysis  to  the  centre  of  the  third  piece  of  the 
sacrum.  It  is  almost  completely  surrounded  by  peritoneum,  and  connected  to  the 
sacrum  behind  by  a.  duplicature  of  this  membrane,  the  mesorectum.  It  is  in 
relation  behind  with  }t]ie  Pyriformis  muscle,  the  sacral  plexus  of  nerves,  and  the 
branches  of  the  internal  iliac  artery  of  the  left  side,  which  separate  it  from  the 
sacrum  and  sacro-iliac  symphysis ;  in  front,  it  is  separated,  in  the  male,  from  the 
posterior  surface  of  the  bladder,  in  the  female,  from  the  posterior  surface  of  the 
uterus  and  its  appendages,  by  some  convolutions  of  the  small  intestine. 

The  middle  portion  of  the  rectum  is  about  three  inches  in  length,  and  extends 
as  far  as  the  tip  of  the  coccyx.  It  is  closely  connected  to  the  concavity  of  the 
sacrum,  and  covered  by  peritoneum  only  on  the  upper  part  of  its  anterior  surface. 
It  is  in  relation,  in  front,  with  the  triangular  portion  of  the  base  of  the  bladder, 
the  vesiculae  seminales,  and  vasa  deferentia ;  more  anteriorly,  with  the  under  sur- 
face of  the  prostate.  In  the  female,  it  is  adherent  to  the  posterior  wall  of  the 
vagina. 

The  lower  portion  is  about  an  inch  in  length ;  it  curves  backwards  at  the  fore 
part  of  the  prostate  gland,  and  terminates  at  the  anus.  This  portion  of  the  intestine 
receives  no  peritoneal  covering.  It  is  invested  by  the  Internal  sphincter,  supported 
by  the  Levatores  ani  muscles,  and  surrounded  at  its  termination  by  the  External 
sphincter.  In  the  male,  it  is  separated  from  the  membranous  portion  and  bulb  of 
the  urethra  by  a  triangular  space  ;  and,  in  the  female,  a  similar  space  intervener 
between  it  and  the  vagina.     This  space  forms  by  its  base  the  perineum. 

Structure  of  the  large  intestine.  The  large  intestine  has  four  coats ;  serous,  mus 
cular,  cellular,  and  mucous. 

The  serous  coat  is  derived  from  the  peritoneum,  and  invests  the  different  portions 
of  the  large  intestine  to  a  variable  extent.  The  caecum  is  covered  only  on  its 
anterior  surface  and  sides ;  more  rarely,  it  is  almost  completely  invested,  being 
held  in  its  position  by  a  duplicature,  the  mesocaecum.  The  ascending  and 
descending  colon  are  usually  covered  only  in  front.  The  transverse  colon  is 
almost  completely  invested,  excepting  at  the  points  corresponding  to  the  attach- 
ment of  the  great  omentum  and  transverse  mesocolon.  The  sigmoid  flexure  is 
nearly  completely  surrounded,  excepting  at  the  point  corresponding  to  the  attach- 
ment of  the  iliac  mesocolon.  The  upper  part  of  the  rectum  is  almost  completely 
invested  by  the  peritoneum ;  the  middle  portion  is  covered  only  on  its  anterior 
surface ;  and  the  lower  portion  is  entirely  devoid  of  any  serous  covering.  In  the 
course  of  the  colon,  and  upper  part  of  the  rectum,  the  peritoneal  coat  is  thrown 
into  a  number  of  small  pouches  filled  with  fat,  called  appendices  epiploicse.  They 
are  chiefly  appended  to  the  transverse  colon. 

The  muscular  coat  consists  of  an  external  longitudinal  and  an  internal  circular 
layer  of  muscular  fibres. 

The  longitudinal  fibres  are  found  as  a  uniform  layer  over  the  whole  surface  of 
the  large  intestine.  In  the  caecum  and  colon,  they  are  especially  collected  into 
three  flat  longitudinal  bands,  each  being  about  half  an  inch  in  width.  These  bands 
commence  at  the  attachment  of  the  appendix  vermiformis  to  the  caecum :  one,  the 
posterior,  is  placed  along  the  attached  border  of  the  intestine ;  the  anterior  band, 
43 


674 


ORGANS   OF   DIGESTION. 


the  largest,  becomes  inferior  along  the  arch  of  the  colon,  where  it  corresponds  to 
the  attachment  of  the  great  omentum,  but  is  in  front  in  the  ascending  and 
descending  colon  and  sigmoid  flexure ;  the  third  or  lateral  band  is  found  on  the 
inner  side  of  the  ascending  and  descending  colon,  and  on  the  under  border  of  the 
transverse  colon.  These  bands  are  nearly  one-half  shorter  than  the  other  parts 
of  the  intestine,  and  serve  to  produce  those  sacculi  characteristic  of  the  csecum 
and  colon ;  accordingly,  when  they  are  dissected  offj  the  tube  can  be  lengthened, 
and  its  sacculated  character  becomes  lost.  In  the  sigmoid  flexure,  the  longitudinal 
fibres  become  more  scattered,  and  upon  its  lower  part,  as  well  as  round  the  rectum, 
they  spread  out,  and  form  a  thick  uniform  layer. 

The  circular  fibres  form  a  thin  layer  over  the  caecum  and  colon,  being  especially 
accumulated  in  the  intervals  between  the  sacculi ;  in  the  rectum,  they  form  a  thick 
layer,  especially  at  its  lower  end,  where  they  become  numerous,  and  form  the 
Internal  sphincter. 

The  cellular  coat  connects  closely  together  the  muscular  and  mucous  layers. 

The  mucous  membrane,  in  the  caecum  and  colon,  is  pale,  and  of  a  grayish  or  pale 
yellow  color.  It  is  quite  smooth,  destitute  of  villi,  and  raised  into  numerous 
crescentic  folds,  which  correspond  to  the  intervals  between  the  sacculi.  In  the 
rectum,  it  is  thicker,  of  a  darker  color,  more  vascular,  and  connected  loosely  to 
the  muscular  coat,  as  in  the  oesophagus.  When  the  lower  part  of  the  rectum  is 
contracted,  its  mucous  membrane  is  thrown  into  a  number  of  folds,  some  of  which, 
near  the  anus,  are  longitudinal  in  direction,  and  are  effaced  by  the  distension  of 
the  gut.  Besides  these,  there  are  three  or  four  permanent  folds,  of  a  semilunar 
shape,  described  by  Mr.  Houston.1  They  are  usually  three  in  number ;  sometimes 
a  fourth  is  found,  and,  occasionally,  only  two  are  present.  One  is  situated  near 
the  commencement  of  the  rectum,  on  the  right  side ;  another  extends  inwards  from 
the  left  side  of  the  tube  opposite  the  middle  of  the  sacrum ;  the  largest  and  most 
constant  one  projects  backwards  from  the  fore  part  of  the  rectum,  opposite  the 
base  of  the  bladder.  When  a  fourth  is  present,  it  is  situated  about  an  inch  above 
the  anus,  on  the  back  of  the  rectum.  These  folds  are  about  half  an  inch  in  width, 
and  contain  some  of  the  circular  fibres  of  the  gut.  In  the  empty  state  of  the 
intestine  they  overlap  each  other,  as  Mr.  Houston  remarks,  so  effectually  as  to 
require  considerable  manoeuvring  to  conduct  a  bougie  or  the  finger  along  the  canal 
of  the  intestine.  Their  use  seems  to  be,  "  to  support  the  weight  of  fecal  matter, 
and  prevent  its  urging  towards  the  anus,  where  its  presence  always  excites  a 
sensation  demanding  its  discharge."  The  mucous  membrane  of  the  large  intestine 
presents  for  examination,  epithelium,  simple  follicles,  and  solitary  glands. 

Fig.  340. — Minute  Structure  of  Large  Intestine. 


Ti.Su/i 


Solitary  Fo/hW. 


Section    of  Mtootur  Mtoibrun* 


Tuhuli  TriUmj 
Su-imucotu  Cell.  tits. 


Free    Surf  a 


The  epithelium  is  of  the  columnar  kind.  . 

The  simple  follicles  are  minute  tubular  prolongations  of  the  mucous  membrane, 
arranged  perpendicularly,  side  by  side,  over  its  entire  surface ;  they  are  longer, 


Dub.  Hosp.  Repoi-ts,  vol.  v.  p.  163. 


J 


THE   LIVER.  6T5 

more  numerous,  and  placed  in  much  closer  apposition  than  those  of  the  small 
intestine ;  and  they  open  by  minute  rounded  orifices  upon  the  surface,  giving  it  a 
cribriform  appearance. 

The  solitary  glands  in  the  large  intestine  are  most  abundant  in  the  caecum  and 
appendix  vermiformis,  being  irregularly  scattered  over  the  rest  of  the  intestine ; 
they  are  small,  prominent,  flask-shaped  bodies,  of  a  whitish  color,  perforated  upon 
the  central  part  of  their  free  surface  by  a  minute  orifice,  which,  in  the  majority, 
is  permanent. 

The  Liver. 

The  Liver  is  a  glandular  organ  of  large  size,  intended  mainly  for  the  secretion 
of  the  bile,  but  effecting  also  important  changes  in  certain  constituents  of  the  blood 
in  their  passage  through  the  gland.  It  is  situated  in  the  right  hypochondriac 
region,  and  extends  across  the  epigastrium  into  the  left  hypochondrium.  It  is  the 
largest  gland  in  the  body,  weighing  from  three  to  four  pounds  (from  fifty  to  sixty 
ounces  avoirdupois).  It  measures,  in  its  transverse  diameter,  from  ten  to  twelve 
inches;  from  six  to  seven  in  its  antero-posterior ;  and  is  about  three  inches  thick 
at  the  back  part  of  the  right  lobe,  which  is  the  thickest  part. 

Its  upper  surface  is  convex,  directed  upwards  and  forwards,  smooth,  covered 
by  peritoneum,  and  is  in  relation  with  the  under  surface  of  the  Diaphragm ;  and 
below,  to  a  small  extent,  with  the  abdominal  parietes.  This  surface  is  divided 
into  two  unequal  lobes,  the  right  and  left,  by  a  fold  of  peritoneum,  the  suspensory 
or  broad  ligament. 

Its  under  surface  is  concave,  directed  downwards  and  backwards,  and  in  rela* 
tion  with  the  stomach  and  duodenum,  the  hepatic  flexure  of  the  colon,  and  the 
right  kidney  and  supra-renal  capsule.  This  surface  is  divided  by  a  longitudinal 
fissure,  into  a  right  and  left  lobe. 

The  posterior  border  is  rounded  and  broad,  and  connected  to  the  Diaphragm  by 
the  coronary  ligament;  it  is  in  relation  with  the  aorta,  the  vena  cava,  and  the 
crura  of  the  Diaphragm. 

The  anterior  border  is  thin  and  sharp,  and  marked,  opposite  the  attachment  of 
the  broad  ligament,  by  a  deep  notch.  In  adult  males,  this  border  usually  corre- 
sponds with  the  margin  of.'the  ribs ;  but  in  women  and  children,  it  projects  usually 
below  this  point. 

The  right  extremity  of  the  liver  is  thick  and  rounded ;  whilst  the  left  is  thin  and 
flattened. 

Changes  of  Position.  The  student  should  make  himself  acquainted  with  the  different  circum- 
stances under  which  the  liver  changes  its  position,  as  they  are  of  importance  as  a  guide  in  deter- 
mining the  existence  of  enlargement,  or  other  disease  of  that  organ. 

Its  position  varies  according  to  the  posture  of  the  body;  in  the  upright  and  sitting  postures, 
its  lower  border  may  be  felt  beneath  the  edges  of  the  ribs  ;  in  the  recumbent  posture,  it  usually 
recedes  beneath  the  ribs. 

Its  position  varies  with  the  ascent  or  descent  of  the  Diaphragm.  In  a  deep  inspiration,  the 
liver  descends  below  the  ribs  ;  in  expiration,  it  is  raised  to  its  ordinary  level.  Again,  in  emphy- 
sema, where  the  lungs  are  distended,  and  the  Diaphragm  descends  very  low,  the  liver  is  pushed 
down ;  but  in  some  other  diseases,  as  phthisis,  where  the  Diaphragm  is  much  arched,  the  liver 
rises  very  high  up. 

Pressure  from  without,  as  in  tight  lacing,  by  compressing  the  lower  part  of  the  chest,  dis- 
places the  liver  considerably,  its  anterior  edge  often  extending  as  low  as  the  crest  of  the  ilium ; 
and  its  convex  surface  is  often,  at  the  same  time,  deeply  indented  from  pressure  of  the  ribs. 

Its  position  varies  greatly,  according  to  the  greater  or  less  distension  of  the  stomach  and 
intestines.  When  the  intestines  are  empty,  the  liver  descends  in  the  abdomen  ;  but  when  they 
are  distended,  it  is  pushed  upwards.  Its  relations  with  surrounding  organs  may  also  be  changed 
by  the  growth  of  tumors,  or  from  collections  of  fluid  in  the  thoracic  or  abdominal  cavities. 

Ligamexts.  The  ligaments  of  the  liver  (fig.  341)  are  five  in  number :  four 
are  formed  of  folds  of  peritoneum ;  the  fifth,  the  ligamentum  teres,  is  a  round, 
fibrous  cord,  resulting  from  the  obliteration  of  the  umbilical  vein.  The  ligaments 
are  the  longitudinal,  two  lateral,  coronary,  and  round. 


676  ORGANS   OF   DIGESTION. 

The  longitudinal  ligament  (broad,  falciform,  or  suspensory  ligament)  is  a  broad 
and  thin  antcro-posterior  peritoneal  fold,  falciform  in  shape,  its  base  being  directed 
forwards,  its  apex  backwards.  It  is  attached  by  one  margin  to  the  under  surface 
of  the  Diaphragm,  and  the  posterior  surface  of  the  sheath  of  the  right  Rectus 
muscle  as  low  down  as  the  umbilicus ;  by  its  hepatic  margin,  it  extends  from  the 
notch  on  the  anterior  margin  of  the  liver,  as  far  back  as  its  posterior  border.  It 
consists  of  two  layers  of  peritoneum  closely  united  together.  Its  anterior  free 
edge  contains  between  its  layers  the  round  ligament. 

The  lateral  ligaments,  two  in  number,  right  and  left,  are  triangular  in  shape. 
They  are  formed  of  two  layers  of  peritoneum  united,  and  extend  from  the  sides 
of  the  Diaphragm  to  the  adjacent  margins  of  the  posterior  border  of  the  liver. 
The  left  is  the  longer  of  the  two,  and  lies  in  front  of  the  oesophageal  opening  in 
the  Diaphragm ;  the  right  lies  in  front  of  the  inferior  vena  cava. 

The  coronary  ligament  connects  the  posterior  border  of  the  liver  to  the  Diaphragm. 

It  is  formed  by  the  reflection  of  the  peritoneum  from  the  Diaphragm  on  to  the 
upper  and  lower  margins  of  the  posterior  border  of  the  organ.     The  coronary 

Fig.  341. — The  Liver.     Upper  Surface. 


ligament  consists  of  two  layers,  which  are  continuous  on  each  side  with  the  lateral 
ligaments,  and,  in  front,  with  the  longitudinal  ligament.  Between  the  layers,  a 
large  oval  interspace  is  left  uncovered  by  peritoneum,  and  connected  to  the 
Diaphragm  by  firm  areolar  tissue.  This  space  is  subdivided,  near  its  left  extremity, 
into  two  parts  by  a  deep  notch  (sometimes  a  canal),  which  lodges  the  inferior 
vena  cava,  and  into  which  open  the  hepatic  veins. 

The  round  ligament  is  a  fibrous  cord,  resulting  from  the  obliteration  of  the 
umbilical  vein.  It  ascends  from  the  umbilicus  in  the  anterior  free  margin  of  the 
longitudinal  ligament,  to  the  notch  in  the  anterior  border  of  the  liver,  from  which 
it  may  be  traced  along  the  longitudinal  fissure  on  the  under  surface  of  the  liver, 
as  far  back  as  the  inferior  vena  cava. 

Fissures.  Five  fissures  are  seen  upon  the  under  surface  of  the  liver,  which 
serve  to  divide  it  into  five  lobes.  They  are  the  longitudinal  fissure,  the  fissure  of 
the  ductus  venosus,  the  transverse  fissure,  the  fissure  for  the  gall-bladder,  and  the 
fissure  for  the  vena  cava. 

The  longitudinal  fissure  is  a  deep  groove,  which  extends  from  the  notch  on  the 
anterior  margin  of  the  liver,  to  the  posterior  border  of  the  organ.  It  separates 
the  right  and  left  lobes ;  the  transverse  fissure  joins  it,  at  right  angles,  about 


THE   LIVER. 


677 


one-third  from  its  posterior  extremity,  and  divides  it  into  two  parts.  The  anterior 
half  is  called  the  umbilical  fissure;  it  is  deeper  than  the  posterior  part,  and  lodges 
the  umbilical  vein  in  the  foetus,  or  its  fibrous  cord  (the  round  ligament)  in  the 
adult.  This  fissure  is  often  partially  bridged  over  by  a  prolongation  of  the  hepatic 
substance,  the  p>ons  hepatis. 

The  fissure  of  the  ductus  venosus  is  the  back  part  of  the  longitudinal  fissure ; 
it  is  shorter  and  shallower  than  the  anterior  portion.  It  lodges  in  the  foetus  the 
ductus  venosus,  and  in  the  adult  a  slender  fibrous  cord,  the  obliterated  remains  of 
that  vessel. 

Via.  342.— The  Liver.     Under  Surface. 


The  transverse  or  portal  fissure  is  a  short  but  deep  fissure,  about  two  inches 
in  length,  extending  transversely  across  the  under  surface  of  the  right  lobe,  nearer 
to  its  posterior  than  its  anterior  border.  It  joins,  nearly  at  right  angles,  with  the 
longitudinal  fissure.  By  the  older  anatomists,  this  fissure  was  considered  the 
gateway  (porta)  of  the  liver ;  hence  the  large  vein  which  enters  at  this  point  was 
called  the  portal  vein.  Besides  this  vein,  the  fissure  transmits  the  hepatic  artery 
and  nerves,  and  the  hepatic  duct  and  lymphatics.  At  their  entrance  into  the 
fissure,  the  hepatic  duct  lies  in  front  to  the  right,  the  portal  vein  behind,  and  the 
hepatic  artery  between  the  other  two  to  the  left. 

The  fissure  for  the  gall-bladder  (fossa  cystidis  fellese)  is  a  shallow,  oblong 
fossa,  placed  on  the  under  surface  of  the  right  lobe,  parallel  with  the  longitudinal 
fissure.  It  extends  from  the  anterior  free  margin  of  the  liver,  which  is  occa- 
sionally notched  for  its  reception,  to  near  the  right  extremity  of  the  transverse 
fissure. 

The  fissure  for  the  vena  cava  is  a  short  deep  fissure,  occasionally  a  complete 
canal,  which  extends  obliquely  upwards  from  a  little  behind  the  right  extremity 
of  the  transverse  fissure,  to  the  posterior  border  of  the  organ,  where  it  joins  the 
fissure  for  the  ductus  venosus.  On  slitting  open  the  inferior  vena  cava  which 
is  contained  in  it,  a  deep  fossa  is  seen,  at  the  bottom  of  which  the  hepatic  veins 
communicate  with  this  vessel.  This  fissure  is  separated  from  the  transverse 
fissure  by  the  lobus  caudatus ;  and  from  the  longitudinal  fissure  by  the  lobus  Spi- 
gelii. 

Lobes.  The  lobes  of  the  liver,  like  the  ligaments  and  fissures,  are  also  five  in 
number ;  the  right  lobe,  the  left  lobe,  the  lobus  quadratus,  the  lobus  Spigelii,  and 
the  lobus  caudatus. 

The  right  lobe  is  much  larger  than  the  left ;  the  proportion  between  them  being 


678  ORGANS   OF   DIGESTION. 

.is  six  to  one.  It  occupies  the  right  hypochondrium,  and  is  separated  from  the  left 
lobe,  on  its  upper  surface,  by  the  longitudinal  ligament;  on  its  under  surface,  by 
the  longitudinal  fissure ;  and  in  front,  by  a  deep  notch.  It  is  of  a  quadrilateral 
form,  its  under  surface  being  marked  by  three  fissures,  the  transverse  fissure, 
the  fissure  for  the  gall-bladder,  and  the  fissure  for  the  inferior  vena  cava ;  and  by 
two  shallow  impressions,  one  in  front  (impressio  colica),  for  the  hepatic  flexure  of 
the  colon,  and  one  behind  {impressio  renalis),  for  the  right  kidney  and  supra-renal 
capsule. 

The  left  lobe  is  smaller  and  more  flattened  than  the  right.  It  is  situated  in  the 
epigastric  and  left  hypochondriac  regions,  sometimes  extending  as  far  as  the  upper 
border  of  the  spleen.  Its  upper  surface  is  convex ;  its  under  concave  surface  rests 
upon  the  front  of  the  stomach ;  and  its  posterior  border  is  in  relation  with  the  car- 
diac orifice  of  the  stomach. 

The  lobus  quadratus  or  square  lobe  is  situated  on  the  under  surface  of  the  right 
lobe,  bounded  in  front  by  the  free  margin  of  the  liver ;  behind,  by  the  transverse 
fissure ;  on  the  right,  by  the  fissure  for  the  gall-bladder ;  and,  on  the  left,  by  the 
umbilical  fissure. 

The  lobus  Sjrigelii  projects  from  the  back  part  of  the  under  surface  of  the 
right  lobe.  It  is  bounded,  in  front,  by  the  transverse  fissure ;  on  the  right,  by 
the  fissure  for  the  vena  cava ;  and  on  the  left,  by  the  fissure  for  the  ductus 
venosus. 

The  lobus  caudatus  or  tailed  lobe  is  a  small  elevation  of  the  hepatic  substance, 
extending  obliquely  outwards,  from  the  base  of  the  lobus  Spigelii,  to  the  under 
surface  of  the  right  lobe.  It  separates  the  right  extremity  of  the  transverse  fissure 
from  the  commencement  of  the  fissure  for  the  inferior  vena  cava. 

Vessels.  The  vessels  connected  with  the  liver  are  also  five  in  number ;  they 
are  the  hepatic  artery,  the  portal  vein,  the  hepatic  vein,  the  hepatic  duct,  and  lym- 
phatics. 

The  hepatic  artery,  portal  vein,  and  hepatic  duct,  accompanied  by  numerous 
lymphatic  vessels  and  nerves,  ascend  to  the  transverse  fissure,  between  the  layers 
of  the  gastro-hepatic  omentum ;  the  hepatic  duct  lying  to  the  right,  the  hepatic 
artery  to  the  left,  and  the  portal  vein  behind  the  other  two.  They  are  enveloped 
in  a  loose  areolar  tissue,  the  capsule  of  Glisson,  which  accompanies  the  vessels 
in  their  course  through  the  portal  canals,  which  are  hollowed  out  of  the  interior 
of  the  organ. 

The  hepatic  veins  convey  the  blood  from  the  liver.  They  commence  at  the  cir- 
cumference of  the  organ,  and  proceed  towards  the  deep  fossa  in  its  posterior  border, 
where  they  terminate  by  two  large,  and  several  smaller  branches,  in  the  inferior 
vena  cava. 

The  hepatic  veins  have  no  cellular  investment,  consequently  their  parietes  are 
adherent  to  the  walls  of  the  canals  through  which  they  run ;  so  that,  on  a  section 
of  the  organ,  these  veins  remain  widely  open  and  solitary,  and  may  be  easily  dis- 
tinguished from  the  branches  of  the  portal  vein,  which  are  more  or  less  collapsed, 
and  always  accompanied  by  an  artery  and  duct. 

The  lymphatics  are  large  and  numerous,  consisting  of  a  deep  and  superficial  set. 
They  have  been  already  described. 

Nerves.  The  nerves  of  the  liver  are  derived  from  the  hepatic  plexus  of  the 
sympathetic,  from  the  pneumogastric  nerves,  especially  the  left,  and  from  the 
right  phrenic. 

Structure.  The  substance  of  the  liver  is  composed  of  lobules,  held  together  by 
an  extremely  fine  areolar  tissue,  of  the  ramifications  of  the  portal  vein,  hepatic 
duct,  hepatic  artery^  hepatic  veins,  lymphatics,  and  nerves;  the  whole  being 
invested  by  a  fibrous  and  a  serous  coat. 

The  serous  coat  is  derived  from  the  peritoneum,  and  invests  the  entire  surface  of 
the  organ,  excepting  at  the  point  corresponding  to  the  attachment  of  its  various 
ligaments,  and  at  the  bottom  of  the  different  fissures,  where  it  is  deficient.  It  is 
intimately  adherent  to  the  fibrous  coat. 


STRUCTURE   OF   THE   LIVER. 


679 


The  fibrous  coat  lies  beneath  the  serous  investment,  and  covers  the  entire 
surface  of  the  organ.  It  is  difficult  of  demonstration,  excepting  where  the  serous 
coat  is  deficient.  At  the  transverse  fissure,  it  is  continuous  with  the  capsule  of 
Glisson ;  and,  on  the  surface  of  the  organ,  with  the  areolar  tissue  separating  the 
lobules. 

The  lobules  form  the  chief  mass  of  the  hepatic  substance ;  they  may  be  seen 
either  on  the  surface  of  the  organ,  or  by  making  a  section  through  the  gland. 
They  are  small  granular  bodies,  about 
the  size  of  a  millet-seed,  measuring  from 
one-twentieth  to  one-tenth  of  an  inch  in 
diameter.  When  divided  longitudinally, 
they  have  a  foliated  margin,  and,  if  trans- 
versely, a  polygonal  outline.  The  bases 
of  the  lobules  are  clustered  round  the 
smallest  branches  (sublobular)  of  the 
hepatic  veins,  to  which  each  is  connected 
by  means  of  a  small  branch,  which  issues 
from  the  centre  of  the  lobule  (intra- 
lobular). The  remaining  part  of  the  sur- 
face of  each  lob  ale  is  imperfectly  isolated 
from  the  surrounding  lobules,  by  a  thin 
stratum  of  areolar  tissue,  and  by  the 
smaller  vessels  and  ducts. 

If  one  of  the  hepatic  veins  be  laid 
open,  the  bases  of  the  lobules  may  be 
seen  through  the  thin  wall  of  the  vein, 
on  which  they  rest,  arranged  in  the  form 
of  a  tessellated  pavement,  the  centre  of 
each  polygonal  space  presenting  a  mi- 
nute aperture,  the  mouth  of  a  sublobular 
vein. 

Each  lobule  is  composed  of  a  mass  of 
cells ;  of  a  plexus  of  biliary  ducts ;  of  a 
venous  plexus,  formed  by  branches  of 
the  portal  vein ;  of  a  branch  of  an  he- 
patic vein  (intralobular);  of  minute 
arteries ;  and  probably,  of  nerves  and 
lymphatics. 

The  hepatic  cells  form  the  chief  mass 
of  the  substance  of  a  lobule,  and  lie  in 
the  interspaces  of  the  capillary  plexus, 
being  probably  contained  in  a  tubular 
network,  which  forms  the  origin  of  the 
biliary  ducts.  The  smallest  branches  of 
the  vena  portaa  pass  between  the  lobules, 
around  which  they  form  a  plexus,  the 
interlobular.  Branches  from  this  plexus 
enter  the  lobules,  and  form  a  network  in 
their  circumference.  The  radicles  of  the 
portal  vein  communicate  with  those  of 
the  hepatic  vein,  which  occupy  the  centre 
of  the  lobule ;  and  the  latter  converge  to 
form  the  intralobular  vein,  which  issues 
from  the  base  of  the  lobule,  and  joins  the 
hepatic  vein.  The  portal  vein  carries 
the  blood  to  the  liver,  from  which  the 
bile  is  secreted;  the  hepatic  vein  carries 


H.  Longitudinal  section  of  an  hepatic  vein  ;  a,  por- 
tion of  the  canal,  from  which  the  vein  has  been 
removed  ;  b,  orifices  of  nltimate  twigs  of  the  vein 
(sub-lobular),  situated  in  the  centre  of  the  lobules. 
After  Kieruan. 


Longitudinal  section  of  a  small  portal  vein  and 
canal,  after  Kiernan.  a.  Portions  of  the  caual 
from  which  the  vein  has  been  removed  ;•  b,  side 
of  the  portal  vein  in  contact  with  the  canal-, 
e,  the  side  of  the  vein  which  is  separated  from 
the  canal  by  the  hepatic  artery  and  d'uct,  with 
areolar  tissue  (Glisson's  capsule);  d,  lateral  sur- 
face of  the  portal  vein,  through  which  are  seen 
the  outlines  of  the  lobules  and  the  openings  of 
the  interlobular  veins  ;  /,  vaginal  voins  of  Kie* 
nan  ;  g,  hepatic  artery  ;  A,,  hepatic. duct 


680 


ORGANS   OF   DIGESTION. 


from  the  liver  the  superfluous  blood ;  and  the  bile  duct  carries  from  the  liver  the 
bile  secreted  by  the  hepatic  cells. 

The  hepatic  cells  form  the  chief  mass  of  each  lobule :  they  are  of  a  more  or 
less  spheroidal  form  ;  but  may  be  rounded,  flattened,  or  many-sided,  from  mutual 
compression.  They  vary  in  size  from  the  TTsW^h  to  the  ^'^th  of  an  inch  in 
diameter,  and  contain  a  distinct  nucleus  in  the  interior,  or  even  sometimes  two. 
In  the  nucleus  is  a  highly  refracting  nucleolus,  with  granules.  The  cell-contents 
are  viscid,  and  contain  yellow  particles,  the  coloring  matter  of  the  bile,  *ind  oil 
globules.  The  cells  adhere  together  by  their  surfaces,  so  as  to  form  rows,  which 
radiate  from  the  centre  towards  the  circumference  of  the  lobule.  These  cells  are 
probably  the  chief  agents  in  the  secretion  of  the  bile. 

Biliary  dwts.  The  precise  mode  of  origin  of  the  biliary  ducts  is  uncertain. 
Mr.  Kiernan's  original  view,  confirmed  as  it  is  by  the  researches  of  Dr.  Beale, 
shows  that  the  ducts  commence  within  the  lobules,  in  a  plexiform  network 
(lobular  biliary  plexus),  in  which  the  hepatic  cells  lie.  According  to  Henle, 
Handheld  Jones,  and  Kolliker,  the  cells  are  packed  in  the  interspaces  of  the 
capillary  plexus,  and,  by  means  of  temporary  communications,  transmit  their 
contents  into  the  minute  bile  ducts  which  originate  in  the  spaces  behveen  the 
lobules,  never  entering  within  them.  The  ducts  form  a  plexus  (interlobular) 
between  the  lobules ;  and  the  interlobular  branches  unite  into  vaginal  branches, 
which  lie  in  the  portal  canals,  with  branches  of  the  portal  vein  and  hepatic  duct. 
The  ducts  finally  join  into  two  large  trunks  which  leave  the  liver  at  the  trans- 
verse fissure,  and  these  joining  form  the  hepatic  duct. 

The  Portal  vein,  on  entering  the  liver  at  the  transverse  fissure,  divides  into 
primary  branches,  which  are  contained  in  the  portal  canals,  together  with  branches 
of  the  hepatic  artery  and  duct,  and  the  nerves  and  lymphatics.  In  the  larger 
portal  canals,  the  vessels  are  separated  from  the  parietes,  and  joined  to  each  other 
by  a  loose  cellular  web,  the  capsule  of  Glisson.  The  veins,  as  they  lie  in  the  portal 
canals,  give  off  vaginal  branches,  which  form  a  plexus  (vaginal  plexus)  in 
Glisson's  capsule.  From  this  plexus,  and  from  the  portal  vein  itself,  small 
branches  are  given  off,  which  pass  between  the  lobules  (interlobular  veins) ;  these 
cover  the  entire  surface  of  the  lobules,  excepting  their  bases.  The  lobular 
branches  are  derived  from  the  interlobular  veins  ;  they  penetrate  into  the  lobule, 
and  form  a  capillary  plexus  within  them.  From  this  plexus  the  intralobular  vein 
arises. 

The  Hepatic  artery  appears  destined  chiefly  for  the  nutrition  of  the  coats  of  the 
large  vessels,  the  ducts,  and  the  investing  membranes  of  the  liver.     It  enters 

the  liver  at  the  transverse  fissure,  with 
the  portal  vein  and  hepatic  duct,  and 
ramifies  with  these  vessels  through  the 
portal  canals.  It  gives  off  vaginal  branches, 
which  ramify  in  the  capsule  of  Glisson ; 
and  other  branches,  which  are  distributed 
to  the  coats  of  the  vena  portse  and  hepatic 
duct.  From  the  vaginal  plexus,  inter- 
lobular branches  are  given  off,  which 
ramify  through  the  interlobular  fissures, 
a  few  branches  being  distributed  to  the 
lobules.  Kiernan  supposes,  that  the 
branches  of  the  hepatic  artery  terminate 
in  a  capillary  plexus,  which  communicates 
with  the  branches  of  the  vena  portse. 

The  Hepatic  veins  commence  in  the 
interior  of  each  lobule  by  a  plexus,  the 
branches  of  which  converge  to  form  the 
intralobular  vein. 

The  intralobular  vein  passes  through  the  centre  of  the  lobule,  and  leaves  it  at 
its  base  to  terminate  in  a  sublobular  vein. 


Fig.  345 


7-y 

A  transverse  section  of  a  small  portal  canal  and  its 
vessels,  after  Kiernan.  1.  Portal  vein;  2,  intrr- 
lobular  branches  ;  3,  branches  of  the  vein,  termed, 
by  Mr.  Kiernan,  vaginal,  also  giving  off  inter- 
lobular branches  ;  4,  hepatic  duct ;  6,  hepatic 
artery. 


GALL-BLADDER.  681 

The  sublobular  veins  unite  with  neighboring  branches  to  form  larger  veins ;  and 
these  join  to  form  the  large  hepatic  trunks,  which  terminate  in  the  vena  cava. 

Gall-bladder. 

The  Gall-bladder  is  the  reservoir  for  the  bile ;  it  is  a  conical  or  pear-shaped 
membranous  sac,  lodged  in  a  fossa  on  the  under  surface  of  the  right  lobe  of  the 
liver,  and  extending  from  near  the  right  extremity  of  the  transverse  fissure  to  the 
anterior  free  margin  of  the  organ.  It  is  about  four  inches  in  length,  one  inch  in 
breadth  at  its  widest  part,  and  holds  from  eight  to  ten  drachms.  It  is  divided  into 
a  fundus,  body,  and  neck.  The  fundus,  the  broad  extremity,  is  directed  down- 
wards, forwards,  and  to  the  right,  and  occasionally  projects  from  the  anterior  border 
of  the  liver :  the  body  and  neck  are  directed  upwards  and  backwards  to  the  left. 
The  gall-bladder  is  held  in  its  position  by  the  peritoneum,  which,  in  the  majority 
of  cases,  passes  over  its  under  surface,  but  it  occasionally  invests  it,  and  is  con- 
nected to  the  liver  by  a  kind  of  mesentery. 

Relations.  The  body  of  the  gall-bladder  is  in  relation,  by  its  upper  surface, 
with  the  liver,  to  which  it  is  connected  by  areolar  tissue  and  vessels ;  by  its  under 
surface,  with  the  first  portion  of  the  duodenum,  occasionally  the  pyloric  end  of  the 
stomach,  and  the  hepatic  flexure  of  the  colon.  The  fundus  is  completely  invested 
by  peritoneum;  it  is  in  relation,  in  front,  with  the  abdominal  parietes,  immediately 
below  the  tenth  costal  cartilage ;  behind,  with  the  transverse  arch  of  the  colon. 
The  neck  is  narrow,  and  curves  upon  itself  like  the  Italic  letter/;  at  its  point  of 
connection  with  the  body  and  with  the  cystic  duct,  it  presents  a  well-marked 
constriction. 

When  the  gall-bladder  is  distended  with  bile  or  calculi,  the  fundus  may  be  felt  through  the 
abdominal  parietes,  especially  in  an  emaciated  subject ;  the  relations  of  this  sac  will  also  serve 
to  explain  the  occasional  occurrence  of  abdominal  biliary  fistulse,  through  which  biliary  calculi 
may  pass  out,  and  of  the  passage  of  calculi  from  the  gall-bladder  into  the  stomach,  duodenum, 
or  colon,  which  occasionally  happens. 

Structure.  The  gall-bladder  consists  of  three  coats ;  serous,  fibrous  and  muscular, 
and  mucous. 

The  external  or  serous  coat  is  derived  from  the  peritoneum;  it  completely  invests 
the  fundus,  but  covers  the  body  and  neck  only  on  their  under  surface. 

The  middle  or  fibrous  coat  is  a  thin  but  strong  fibrous  layer,  which  forms  the 
framework  of  the  sac,  consisting  of  dense  fibres  which  interlace  in  all  directions. 
Plain  muscular  fibres  are  also  found  in  this  coat,  disposed  chiefly  in  a  longitudinal 
direction,  a  few  running  transversely. 

The  internal  or  mucous  coat  is  loosely  connected  with  the  fibrous  layer.  It  is 
generally  tinged  with  a  yellowish-brown  color,  and  is  everywhere  elevated  into 
minute  rugee,  by  the  union  of  which  numerous  meshes  are  formed ;  the  depressed 
intervening  spaces  having  a  polygonal  outline.  The  meshes  are  smaller  at  the 
fundus  and  neck,  being  most  developed  about  the  centre  of  the  sac.  Opposite  the 
neck  of  the  gall-bladder,  the  mucous  membrane  projects  inwards  so  as  to  form  a 
large  valvular  fold. 

The  mucous  membrane  is  covered  with  columnar  epithelium,  and  secretes  an 
abundance  of  thick  viscid  mucus;  it  is  continuous  through  the  hepatic  duct 
with  the  mucous  membrane  lining  the  ducts  of  the  liver,  and  through  the  ductus 
communis  choledochus  with  the  mucous  membrane  of  the  alimentary  canal. 

The  Biliary  Ducts  are  the  hepatic,  the  cystic,  and  the  ductus  communis 
choledochus.  ^ 

The  hepatic  duct  is  formed  of  two  trunks  of  nearly  equal  size,  which  issue 
from  the  liver  at  the  transverse  fissure,  one  from  the  right  and  one  from  the  left 
lobe ;  these  unite,  and  pass  downwards  and  to  the  right  for  about  an  inch  and  a 
half  to  join  at  an  acute  angle  with  the  cystic  duct,  to  form  the  common  choledoch 
duct. 


• 


682  ORGANS   OF   DIGESTION. 

The  cystic  duct,  the  smallest  of  the  three  biliary  ducts,  is  about  an  inch  in  length. 
It  passes  obliquely  downwards  and  to  the  left  from  the  neck  of  the  gall-bladder, 
and  joins  the  hepatic  duct  to  form  the  common  duct.  It  lies  in  the  gastro-hepatic 
omentum  in  front  of  the  vena  cava,  the  cystic  artery  lying  to  its  left  side.  The 
mucous  membrane  lining  its  interior  is  thrown  into  a  series  of  crescentic  folds, 
from  five  to  twelve  in  number,  which  project  into  the  duct  in  regular  succession, 
and  are  directed  obliquely  round  the  tube,  presenting  much  the  appearance  of  a 
continuous  spiral  valve.  They  exist  only  in  the  human  subject.  When  the  duct 
has  been  distended,  the  interspaces  between  the  folds  are  dilated,  so  as  to  give  to 
its  exterior  a  sacculated  appearance. 

The  ductus  communis  'choledochus,  the  largest  of  the  three,  is  the  common  excre- 
tory duct  of  the  liver  and  gall-bladder.  It  is  about  three  inches  in  length,  of  the 
diameter  of  a  goose-quill,  and  formed  by  the  junction  of  the  cystic  and  hepatic 
ducts.  It  descends  along  the  right  border  of  the  lesser  omentum,  behind  the 
first  portion  of  the  duodenum,  in  front  of  the  vena  portae,  and  to  the  right  of  the 
hepatic  artery;  it  then  passes  between  the  pancreas  and  descending  portion  of  the 
duodenum,  and  running  for  a  short  distance  along  the  right  side  of  the  pancreatic 
duct,  near  its  termination,  passes  with  it  obliquely  between  the  mucous  and 
muscular  coats,  the  two  opening  by  a  common  orifice  upon  the  summit  of  a 
papilla,  situated  at  the  inner  side  of  the  descending  portion  of  the  duodenum,  a 
little  below  its  middle. 

Structure.  The  coats  of  the  biliary  ducts  are  composed  of  an  external  or  fibrous, 
and  an  internal  or  mucous  layer.  The  fibrous  coat  is  composed  of  a  strong  areolar 
fibrous  tissue.  The  mucous  coat  is  continuous  with  the  lining  membrane  of  the 
hepatic  ducts  and  gall-bladder,  and  also  with  that  of  the  duodenum.  It  is  provided 
with  numerous  glands,  the  orifices  of  which  are  scattered  irregularly  in  the  larger 
ducts,  but  in  the  smaller  hepatic  ducts  are  disposed  in  two  longitudinal  rows,  one 
on  each  side  of  the  vessel.  These  glands  are  of  two  kinds.  Some  are  ramified 
tubes,  which  occasionally  anastomose,  and  from  the  sides  of  which  saccular  dila- 
tations are  given  off;  others  are  small  clustered  cellular  glands,  which  open  either 
separately  into  the  hepatic  duct,  or  into  the  ducts  of  the  tubular  glands. 

The  Pancreas. 

Dissection.  The  pancreas  may  be  exposed  for  dissection  in  three  different  ways :  1.  By  raising 
the  liver,  drawing  down  the  stomach,  and  tearing  through  the  gastro-hepatic  omentum.  2.  By 
raising  the  stomach,  the  arch  of  the  colon,  and  great  omentum  upwards,  and  then  dividing  the 
inferior  layer  of  the  transverse  mesocolon.  3.  By  dividing  the  two  layers  of  peritoneum,  which 
descend  from  the  great  curvature  of  the  stomach  to  form  the  great  omentum  ;  turning  this  organ 
upwards,  and  then  cutting  through  the  ascending  layer  of  the  transverse  mesocolon. 

The  Pancreas  (*w-«pia$,  all  flesh)  is  a  conglomerate  gland,  analogous  in  its 
structure  to  the  salivary  glands.  In  shape,  it  is  transversely  oblong,  flattened 
from  before  backwards,  and  bears  some  slight  resemblance  to  a  hammer,  its  right 
extremity  being  broad,  and  presenting  a  sort  of  angular  bend  from  above  down- 
wards, called  the  head;  its  left  extremity  gradually  tapers  to  form  the  tail,  the 
intermediate  portion  being  called  the  body.  It  is  situated  transversely  across  the 
posterior  wall  of  the  abdomen,  at  the  back  of  the  epigastric  and  both  hypochon- 
driac regions.  Its  length  varies  from  six  to  eight  inches,  its  breadth  is  an  inch 
and  a  half,  and  its  thickness  from  half  an  inch  to  an  inch,  being  thicker  at  its 
right  extremity  and  along  its  upper  border.  Its  weight  varies  from  two  to  three 
and  a  half  ounces,  but  it  may  reach  six  ounces. 

The  right  extremity  or  head  of  the  pancreas  (fig.  346)  is  curved  upon  itself 
from  above  downwards,  and  is  embraced  by  the  concavity  of  the  duodenum.  The 
common  bile  duct  descends  behind,  between  the  duodenum  and  pancreas ;  and  the 
pancreatico-duodenal  artery  descends  in  front  between  the  same  parts.  Upon  its 
posterior  part  is  a  lobular  fold  of  the  gland,  which  passes  transversely  to  the  left, 
behind  the  superior  mesenteric  vessels,  forming  the  back  part  of  the  canal,  in 


PANCREAS.  683 

which  they  are  contained.  It  is  sometimes  detached  from  the  rest  of  the  gland, 
and  is  called  the  lesser  pancreas. 

The  lesser  end  or  tail  of  the  pancreas  is  narrow;  it  extends  to  the  left  as  far 
as  the  spleen,  and  is  placed  over  the  left  kidney  and  supra-renal  capsule. 

The  body  of  the  pancreas  is  convex  in  front,  and  covered  by  the  ascending 
layer  of  the  transverse  mesocolon  and  the  posterior  surface  of  the  stomach. 

The  posterior  surface  is  concave,  and  has  the  following  structures  interposed 
between  it  and  the  first  lumbar  vertebra: — the  superior  mesenteric  artery  and  vein, 
and  commencement  of  the  vena  portee,  the  vena  cava,  the  aorta,  the  left  kidney, 
supra-renal  capsule,  and  corresponding  renal  vessels. 

The  upper  border  is  thick,  and  has  resting  upon  it,  near  its  centre,  the  cceliac 
axis;  the  splenic  artery  and  vein  are  lodged  in  a  deep  groove  or  canal  in  this 

Fig.  346. — The  Pancreas  and  its  Relations. 


border,  and,  to  the  right,  the  first  part  of  the  duodenum  and  the  hepatic  artery  are 
in  relation  with  it. 

The  lower  border,  thinner  than  the  upper,  is  separated  from  the  transverse 
portion  of  the  duodenum  by  the  superior  mesenteric  artery  and  vein ;  to  the  left 
of  these  the  inferior  mesenteric  vein  ascends  behind  the  pancreas  to  join  the  splenic 
vein. 

The  pancreatic  duct,  called  also  the  canal  of  Wirsung  from  its  discoverer,  extends 
transversely  from  left  to  right  through  the  substance  of  the  pancreas,  nearer  to  its 
lower  than  its  upper  border,  and  lying  nearer  its  anterior  than  its  posterior  sur- 
face. In  order  to  expose  it,  the  superficial  portion  of  the  gland  must  be  removed. 
It  commences  by  an  orifice  common  to  it  and  the  ductus  communis  choledochus 
upon  the  summit  of  an  elevated  papilla,  situated  at  the  inner  side  of  the  descending 
portion  of  the  duodenum,  a  little  below  its  middle.  Passing  very  obliquely 
through  the  mucous  and  muscular  coats,  it  separates  itself  from  the  common 
choledoch  duct,  and,  ascending  slightly,  runs  from  right  to  left  through  the  middle 
of  the  gland,  giving  off  numerous  branches,  which  pass  to  be  distributed  to  its 
lobules. 

Sometimes  the  pancreatic  and  common  choledoch  ducts  open  separately  into  the 


684  ORGANS   OF   DIGESTION. 

duodenum.  The  excretory  duct  of  the  lesser  pancreas  is  called  the  ductus  pan- 
creaticus  minor ;  it  opens  into  the  main  duct  near  the  duodenum,  and  sometimes 
separately  into  that  intestine,  at  a  distance  of  an  inch  or  more  from  the  termination 
of  the  principal  duct. 

The  pancreatic  duct,  near  the  duodenum,  is  about  the  size  of  an  ordinary  quill ; 
its  walls  are  thin,  consisting  of  two  coats,  an  external  fibrous  and  an  internal 
mucous ;  the  latter  is  thin,  smooth,  and  furnished,  near  its  termination,  with  a  few 
scattered  follicles. 

Sometimes  the  pancreatic  duct  is  double,  up  to  its  point  of  entrance  into  the 
duodenum. 

The  Structure  of  the  pancreas  closely  resembles  that  of  the  salivary  glands ;  but  it 
is  looser  and  softer  in  its  texture.  The  fluid  secreted  by  it  is  almost  identical  with 
saliva. 

Vessels  and  Nerves.  The  arteries  of  the  pancreas  are  derived  from  the  splenic, 
the  pancreatico-duodenal  branch  of  the  hepatic,  and  the  superior  mesenteric. 
Its  veins  open  into  the  splenic  and  superior  mesenteric  veins.  Its  lymphatics 
terminate  in  the  lumbar  glands.  The  nerves  are  filaments  from  the  splenic 
plexus. 

The  Spleen. 

The  Spleen  is  usually  classified  together  with  the  thyroid,  supra-renal  and 
thymus  glands,  as  one  of  the  ductless  glands,  from  its  possessing  no  excretory  duct. 
It  is  of  an  oblong  flattened  form,  soft,  of  very  brittle  consistence,  highly  vascular, 
of  a  dark  bluish-red  color,  and  situated  in  the  left  hypochondriac  region,  em- 
bracing the  cardiac  end  of  the  stomach.  It  is  invested  by  peritoneum,  and 
connected  with  the  stomach  by  the  gastro-splenic  omentum. 

Relations.  Its  external  surface  is  convex,  smooth,  and  in  relation  with  the 
under  surface  of  the  Diaphragm,  which  separates  it  from  the  ninth,  tenth,  and 
eleventh  ribs  of  the  left  side. 

The  internal  surface  is  slightly  concave,  and  divided  by  a  vertical  fissure,  the 
hilus,  into  an  anterior  or  larger,  and  a  posterior  or  smaller  portion.  The  hilus  is 
pierced  by  several  large,  irregular  apertures,  for  the  entrance  and  exit  of  vessels 
and  nerves.  At  the  margins  of  the  hilus,  the  two  layers  of  peritoneum  are 
reflected  from  the  surface  of  the  spleen  on  to  the  cardiac  end  of  the  stomach, 
forming  the  gastro-splenic  omentum,  which  contains  between  its  layers  the  splenic 
vessels  and  nerves,  and  the  vasa  brevia.  The  internal  surface  is  in  relation,  in 
front,  with  the  great  end  of  the  stomach ;  below,  with  the  tail  of  the  pancreas ; 
and  behind,  with  the  left  crus  of  the  Diaphragm  and  corresponding  supra-renal 
capsule.  ' 

Its  upper  end,  thick  and  rounded,  is  in  relation  with  the  Diaphragm,  to  which 
it  is  connected  by  a  fold  of  peritoneum,  the  suspensory  ligament. 

Its  lower  end  is  pointed ;  it  is  in  relation  with  the  left  extremity  of  the  trans- 
verse arch  of  the  colon. 

Its  anterior  margin  is  free,  rounded,  and  often  notched,  especially  below. 

Its  posterior  margin  is  rounded,  and  lies  in  relation  with  the  left  kidney,  to 
which  it  is  connected  by  loose  areolar  tissue. 

The  spleen  is  held  in  its  position  by  two  folds  of  peritoneum ;  one,  the  gastro- 
splenic  omentum,  connects  it  with  the  stomach,  and  the  other,  the  susjiensory 
ligament,  with  the  under  surface  of  the  Diaphragm. 

The  size  and  weight  of  the  spleen  are  liable  to  very  extreme  variations  at 
different  periods  of  life,  in  different  individuals,  and  in  the  same  individual  under 
different  conditions.  In  the  adult,  in  whom  it  attains  its  greatest  size,  it  is  usually 
about  five  inches  in  length,  three  or  four  inches  in  breadth,  and  an  inch  or  an  inch 
and  a  half  in  thickness,  and  weighs  about  seven  ounces.  At  birth,  its  weight,  in 
proportion  to  the  entire  body,  is  almost  equal  to  what  is  observed  in  the  adult, 
being  as  1  to  350 ;  whilst  in  the  adult  it  varies  from  1  to  320  to  1  to  400.  In  old 
age,  the  organ  not  only  decreases  in  weight,  but  decreases  considerably  in  pro- 


SPLEEN.      '  6S5 


portion  to  the  entire  body,  being  as  1  to  700.  The  size  of  the  spleen  is  increased 
during  and  after  digestion,  and  varies  considerably,  according  to  the  state  of 
nutrition  of  the  body,  being  large  in  highly  fed,  and  small  in  starved  animals. 
In  intermittent  and  other  fevers,  it  becomes  much  enlarged,  weighing  occasionally 
from  18  to  20  pounds. 

Structure.  The  spleen  is  invested  by  two  coats ;  an  external  serous,  and  an 
internal  fibrous  elastic  coat. 

The  external  or  serous  coat  is  derived  from  the  peritoneum;  it  is  thin,  smooth, 
and  in  the  human  subject  intimately  adherent  to  the  fibrous  elastic  coat.  It 
invests  almost  the  entire  organ,  being  reflected  from  it  at  the  hilus,  on  to  the 
great  end  of  the  stomach,  and  at  the  upper  end  of  the  organ  on  to  the  Dia- 
phragm. 

The  fibrous  elastic  coat  forms  the  framework  of  the  spleen.  It  invests  the 
exterior  of  the  organ,  and  at  the  hilus  is  reflected  inwards  upon  the  vessels  in  the 
form  of  vaginae  or  sheaths.  From  these  sheaths,  as  well  as  from  the  inner  surface 
of  the  fibro-elastic  coat,  numerous  small  fibrous  trabeculve  or  bands  (fig.  347)  are 
given  off  in  all  directions ;  these,  uniting,  constitute  the  areolar  framework  of  the 
spleen.     The  proper  coat,  the  sheaths  of  the  vessels,  and  the  trabecule,  consist  of 

Fig.  347. — Transverse  Section  of  the  Spleen,  showing  the  Trabecular  Tissue 
and  the  Splenic  Vein  and  its  Branches. 


a  dense  mesh  of  white  and  yellow  elastic  fibrous  tissues,  the  latter  considerably 
predominating.  It  is  owing  to  the  presence  of  this  tissue,  that  the  spleen  pos- 
sesses a  considerable  amount  of  elasticity,  admirably  adapted  for  the  very  con- 
siderable variations  in  size  that  it  presents  under  certain  circumstances.  In  some 
of  the  mammalia,  in  addition  to  the  usual  constituents  of  this  tunic,  there  are  found 
numerous  pale,  flattened,  spindle-shaped,  nucleated  fibres,  like  unstriped  muscular 
fibres.  It  is  probably  owing  to  this  structure,  that  the  spleen  possesses,  when  acted 
upon  by  the  galvanic  current,  faint  traces  of  contractility. 

The  proper  substance  of  the  spleen  occupies  the  interspaces  of  the  areolar  frame- 
work of  the  organ ;  it  is  a  soft,  pulpy  mass,  of  a  dark  reddish-brown  color,  consist- 
ing of  colorless  and  colored  elements. 

The  colorless  elements  consist  of  granular  matter;  nuclei,  about  the  size  of 
the  red  blood-disks,  homogeneous  or  granular  in  structure,  and  nucleated  vesicles 
in  small  numbers.     These  elements  form,  probably,  one-half  or  two-thirds  of  the 


686  ORGANS   OF   DIGESTION. 

whole  substance  of  the  pulp,  filling  up  the  interspaces  formed  by  the  partitions  of 
the  spleen,  and  lying  in  close  contact  with  the  walls  of  the  capillary  vessels,  so  as 
to  be  readily  acted  upon  by  the  nutrient  fluid  which  permeates  them.  These 
elements  form  a  large  part  of  the  entire  bulk  of  the  spleen  in  well-nourished  ani- 
mals ;  whilst  they  diminish  in  number,  and  occasionally  are  wanting,  in  starved 
animals.  The  application  of  chemical  tests  shows  that  they  are  essentially  a  pro- 
tein compound. 

The  colored  elements  of  the  pulp  consist  of  red  blood-globules  and  of  colored 
corpuscles,  either  free,  or  included  in  cells.  Sometimes,  unchanged  blood-disks 
are  seen  included  in  a  cell ;  but  more  frequently  the  included  blood-disks  are 
altered  both  in  form  and  color.  Besides  these,  numerous  deep-red,  or  reddish- 
yellow,  or  black  corpuscles  and  crystals,  either  single  or  aggregated  in  masses,  are 
seen  diffused  throughout  the  pulp-substance ;  these,  in  chemical  composition,  are 
closely  allied  to  the  hasmatin  of  the  blood. 

Malpighian  Corpuscles. — On  examining  the  cut  surface  of  a  healthy  spleen,  a 
number  of  small  semi-opaque  bodies,  of  gelatinous  consistence,  are  seen  dissemi- 
nated throughout  its  substance ;  these  are  the  splenic  or  Malpighian  corpuscles 

Fig.  348. — The  Malpighian  Corpuscles,  and  their  Relation  with  the  Splenic  Artery 

and  its  Branches. 


(fig.  348).  They  may  be  seen  at  all  periods  of  life ;  but  they  are  more  distinct 
inearly  life,  than  in  adult  life  or  old  age ;  and  they  are  much  smaller  in  man,  than 
in  most  mammalia.  They  are  of  a  spherical  or  ovoid  form,  vary  considerably 
in  size  and  number,  and  are  of  a  semi-opaque  whitish  color.  They  are  appended 
to  the  sheaths  of  the  smaller  arteries  and  their  branches,  presenting  a  resemblance 
to  the  buds  of  the  moss  rose.  Each  consists  of  a  membranous  capsule,  composed 
of  fine  pale  fibres,  which  interlace  in  all  directions.  In  man,  the  capsule  is  homo- 
geneous in  structure,  and  formed  by  a  prolongation  from  the  sheaths  of  the  small 
arteries  to  which  the  corpuscles  are  attached.  The  bloodvessels  ramifying  on 
the  surface  of  the  corpuscles  consist  of  the  larger  ramifications  of  the  arteries  to 
which  the  sacculus  is  connected ;  and  also  of  a  delicate  capillary  plexus,  similar 
to  that  surrounding  the  vesicles  of  other  glands.  These  vesicles  have  also  a 
close  relation  with  the  veins  (fig.  349).     These  vessels,  which  are  of  considerable 


STRUCTURE   OF   THE   SPLEEN. 


G87 


size  even  at  their  origin,  commence  on  the  surface  of  each  vesicle  throughout  the 
whole  of  its  circumference,  forming  a  dense  mesh  of  veins,  in  which  each  of  these 


Fig.  349.— One  of  the  Splenic  Corpuscles,  showing  its  Relations 
with  the  Bloodvessels. 


bodies  is  inclosed.  It  is  probable,  that  from  the  blood  contained  in  the  capillary 
network,  the  material  is  separated  which  is  occasionally  stored  up  in  their  cavity ; 
the  veins  being  so  placed  as  to  carry  off)  under  certain  conditions,  those  contents 


Fig.  350. — Transverse  Section  of  the  Human  Spleen,  showing  the  Distribution 
of  the  Splenic  Artery  and  its  Branches. 


that  are  again  to  be  discharged  into  the  circulation.  Each  capsule  contains  a  soft, 
white,  semi-fluid  substance,  consisting  of  granular  matter,  nuclei  similar  to  those 
found  in  the  pulp,  and  a  few  nucleated  cells,  the  composition  of  which  is  apparently 


638  ORGANS   OF   DIGESTION. 

albuminous.  These  bodies  are  very  large  after  digestion  is  completed,  in  well-fed 
animals,  and  especially  in  those  fed  upon  albuminous  diet.  In  starved  animals, 
they  disappear  altogether. 

The  splenic  artery  is  remarkable  for  its  large  size,  in  proportion  to  the  size 
of  the  organ ;  and  also  for  its  tortuous  course.  It  divides  into  from  four  to  six 
branches,  which  enter  the  hilus  of  the  organ,  and  ramify  throughout  its  substance 
(fig.  350),  receiving  sheaths  from  an  involution  of  the  external  fibrous  tunic, 
the  same  sheaths  also  investing  the  nerves  and  veins.  Each  branch  runs  in  the 
transverse  axis  of  the  organ,  from  within  outwards,  diminishing  in  size  during  its 
transit,  and  giving  off,  in  its  passage,  smaller  branches,  some  of  which  pass  to  the 
anterior,  others  to  the  posterior  part ;  these  ultimately  terminate  in  the  proper 
substance  of  the  spleen,  in  small  tufts  or  pencils  of  capillary  vessels,  which  lie  in 
direct  contact  with  the  pulp.  Each  of  the  larger  branches  of  the  arteries  supplies 
chiefly  that  region  of  the  organ  in  which  the  branch  ramifies,  having  no  anasto- 
mosis  with  the  majority  of  the  other  branches. 

The  capillaries,  supported  by  the  minute  trabecular,  traverse  the  pulp  in  all 
directions,  and  terminate  either  directly  in  the  veins,  or  open  into  lacunar  spaces, 
from  which  the  veins  originate. 

The  veins  are  of  large  size,  as  compared  with  the  size  of  the  organ,  and  their 
distribution  is  limited,  like  that  of  the  arteries,  to  the  supply  of  a  particular  part 
of  the  gland ;  they  are  much  larger  and  more  numerous  than  the  arteries.  They 
originate,  1st,  as  continuations  of  the  capillaries  of  the  arteries ;  2dly,  by  inter- 
cellular spaces  communicating  with  each  other ;  3dly,  by  distinct  carcal  pouches. 
By  their  junction  they  form  from  four  to  six  branches,  which  emerge  from  the 
hilus ;  and  these,  uniting,  form  the  splenic  vein,  the  largest  branch  of  the  vena 
porta). 

The  lymphatics  form  a  deep  and  superficial  set ;  they  pass  through  the  lym- 
phatic glands  at  the  hilus,  and  terminate  in  the  thoracic  duct. 

The  nerves  are  derived  from  branches  of  the  right  and  left  semilunar  ganglia, 
and  right  pneumogastric  nerve. 


The  Thorax. 

The  Thorax  is  a  conical,  osseous  framework,  connected  with  the  middle  region 
of  the  spine.  It  is  narrow  above,  broad  below,  flattened  before  and  behind,  and 
somewhat  cordiform  on  a  transverse  section. 

Boundaries.  It  is  bounded  in  front  by  the  sternum,  the  six  upper  costal 
cartilages,  the  ribs,  and  intercostal  muscles ;  at  the  sides,  by  the  ribs  and  inter- 
costal muscles ;  and  behind,  by  the  same  structures  and  the  dorsal  portion  of  the 
vertebral  column. 

The  superior  opening  of  the  thorax  is  bounded  on  each  side  by  the  first  rib ; 
in  front,  by  the  upper  border  of  the  sternum ;  and  behind,  by  the  first  dorsal 
vertebra.  It  is  broader  from  side  to  side,  than  from  before  backwards ;  and  its 
direction  is  backwards  and  upwards. 

The  lower  opening  or  base  is  bounded  in  front  by  the  ensiform  cartilage; 
behind,  by  the  last  dorsal  vertebra ;  and  on  each  side  by  the  last  rib,  the  Dia- 
phragm filling  in  the  intervening  space.  Its  direction  is  obliquely  downwards 
and  backwards,  so  that  the  cavity  of  the  thorax  is  much  deeper  on  the  posterior 
wall,  than  on  the  anterior.  It  is  wider  transversely  than  from  before  backwards, 
and  its  general  direction  is  convex  towards  the  chest ;  but  it  is  more  flattened  at 
the  centre  than  at  the  sides,  and  rises  higher  on  the  right  than  on  the  left  side, 
corresponding  in  the  dead  body  to  the  upper  border  of  the  fifth  costal  cartilage, 
on  the  right  side ;  and  to  the  corresponding  part  of  the  sixth  cartilage  on  the  left 
side. 

The  parts  which  pass  through  the  upper  opening  of  the  thorax  are,  from  before 
backwards,  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  remains  of  the 
thymus  gland,  the  trachea,  oesophagus,  thoracic  duct,  and  the  Longi  colli  muscles ; 
on  the  sides,  the  arteria  innominata,  the  left  carotid  and  left  subclavian  arteries, 
the  internal  mammary  and  superior  intercostal  arteries,  the  right  and  left  vena? 
innominata?,  and  the  inferior  thyroid  veins,  the  pneumogastric,  sympathetic, 
phrenic,  and  cardiac  nerves,  and  the  recurrent  laryngeal  nerve  of  the  left  side. 
The  apex  of  each  lung,  covered  by  the  pleura,  also  projects  through  this  aperture, 
a  little  above  the  margin  of  the  first  rib. 

The  viscera  contained  in  the  thorax  are,  the  great  central  organ  of  circulation, 
the  heart,  inclosed  in  its  membranous  bag,  the  pericardium ;  and  the  organs  of 
respiration,  the  lungs,  invested  by  the  pleura?. 

The  Pericardium. 

The  Pericardium  is  a  conical  membranous  sac,  in  which  the  heart  and  the 
commencement  of  the  great  vessels  are  contained.  It  is  placed  behind  the  sternum, 
and  the  cartilages  of  the  fourth,  fifth,  sixth,  and  seventh  ribs  of  the  left  side,  in 
the  interval  between  the  pleurae. 

Its  apex  is  directed  upwards,  and  surrounds  the  great  vessels  about  two  inches 
above  their  origin  from  the  base  of  the  heart.  Its  base  is  attached  to  the  central 
tendon  of  the  Diaphragm,  extending  a  little  farther  to  the  left  than  the  right  side. 
In  front,  it  is  separated  from  the  sternum  by  the  remains  of  the  thymus  gland 
above,  and  a  little  loose  areolar  tissue  below ;  and  is  covered  by  the  margins  of  the 
lungs,  especially  the  left.  Behind,  it  rests  upon  the  bronchi,  the  oesophagus,  and 
the  descending  aorta.  Laterally,  it  is  covered  by  the  pleura? ;  the  phrenic  vessels 
and  nerve  descending  between  the  two  membranes  on  either  side. 

44  689 


690 


THE   THORAX. 


The  pericardium  is  a  fibre-serous  membrane,  and  consists,  therefore,  of  two  layers ; 
an  external  fibrous  and  an  internal  serous. 

The  fibrous  layer  is  a  strong,  dense,  fibrous  membrane.  Above,  it  surrounds 
the  great  vessels  arising  from  the  base  of  the  heart,  on  which  it  is  continued  in 
the  form  of  tubular  prolongations,  which  are  gradually  lost  upon  their  external 
coats;  the  strongest  being  that  which  incloses  the  aorta.  Below,  it  is  attached 
to  the  central  tendon  of  the  Diaphragm ;  and,  on  the  left  side,  to  its  muscular 
fibres. 

The  vessels  receiving  fibrous  prolongations  from  this  membrane  are  the  aorta, 
the  superior  vena  cava,  and  the  pulmonary  arteries  and  veins.  As  the  inferior 
cava  enters  the  pericardium,  through' the  central  tendon  of  the  Diaphragm,  it 
receives  no  covering  from  the  fibrous  layer. 

Fig.  351.— Front  View  of  the  Thorax.     The  Ribs  and  Sternum  are  represented 
in  Relation  to  the  Lungs,  Heart,  and  other  Internal  Organs. 


The  serous  layer  invests  the  heart,  and  is  then  reflected  on  the  inner  surface 
of  the  pericardium.  It  consists,  therefore,  of  a  visceral  and  a  parietal  portion. 
The  former  invests  the  surface  of  the  heart,  and  the  commencement  of  the  great 
vessels,  to  the  extent  of  two  inches  from  their  origin ;  from  these  it  is  reflected 
upon  the  inner  surface  of  the  fibrous  layerTtining,  below,  the  upper  surface  of  the 
central  tendon  of  the  Diaphragm.  The  serous  membrane  incloses  the  aorta  and 
pulmonary  artery  in  a  single  tube;  but  it  only  partially  covers  the  superior  and 
inferior  venae  cavse,  and  the  four  pulmonary  veins.     Its  inner  surface  is  smooth 


HEART.  691 

and  glistening,  and  secretes  a  thin  fluid,  which  serves  to  facilitate  the  movements 
of  the  contained  organ. 

The  arteries  of  the  pericardium  are  derived  from  the  internal  mammary,  the 
bronchial,  the  oesophageal,  and  the  phrenic. 

The  Heart. 

The  Heart  is  a  hollow  muscular  organ,  of  a  conical  form,  placed  between  the 
lungs,  and  inclosed  in  the  cavity  of  the  pericardium. 

Position.  The  heart  is  placed  obliquely  in  the  chest ;  the  broad  attached  end 
or  base  is  directed  upwards  and  backwards  to  the  right,  and  corresponds  to  the 
interval  between  the  fifth  and  eighth  dorsal  vertebrae ;  the  apex  is  directed  for- 
wards and  to  the  left,  and  corresponds  to  the  interspace  between  the  cartilages  of 
the  fifth  and  sixth  ribs,  one  inch  to  the  inner  side,  and  two  inches  below  the  left 
nipple.  The  heart  is  placed  beneath  the  lower  two-thirds  of  the  sternum,  and 
projects  further  into  the  left  than  into  the  right  cavity  of  the  chest,  extending 
from  the  median  line  about  three  inches  in  the  former  direction,  and  only  one  and 
a  half  in  the  latter.  Its  upper  border  would  correspond  to  a  line  drawn  across 
the  sternum,  on  a  level  with  the  upper  border  of  the  third  costal  cartilages ;  and 
its  lower  border,  to  a  line  drawn  across  the  lower  end  of  the  gladiolus,  from  the 
costo-xiphoid  articulation  of  the  right  side,  to  the  part  corresponding  to  the  apex. 
Its  anterior  surface  is  rounded  and  convex,  directed  upwards  and  forwards,  and 
formed  chiefly  by  the  right  ventricle  and  part  of  the  left.  Its  posterior  surface  is 
flattened,  and  rests  upon  the  Diaphragm.  The  right  border  is  long,  thin,  and 
sharp ;  the  left  border  short,  but  thick  and  round. 

Size.  The  heart,  in  the  adult,  measures  about  five  inches  in  length,  three  inches 
and  a  half  in  breadth  in  its  broadest  part,  and  two  inches  and  a  half  in  thickness. 
The  prevalent  weight,  in  the  male,  varies  from  ten  to  twelve  ounces,  in  the 
female,  from  eight  to  ten ;  its  proportion  to  the  body  being  as  1  to  169,  in  males, 
1  to  149  in  females.  The  heart  continues  increasing  in  weight,  and  also  in  length, 
breadth,  and  thickness,  up  to  an  advanced  period  of  life ;  and  this  is  more  marked 
in  men  than  in  women. 

Component  parts.  The  heart  is  subdivided  by  a  longitudinal  muscular  septum, 
into  two  lateral  halves,  which  are  named  respectively,  from  their  position,  right 
and  left ;  and  a  transverse  constriction  divides  each  half  of  the  organ  into  two 
cavities,  the  upper  cavity  on  each  side  being  called  the  auricle,  the  lower  the 
ventricle.  The  right  is  the  venous  side  of  the  heart,  receiving  into  its  auricle  the 
dark  venous  blood  from  the  entire  body,  by  the  superior  and  inferior  venae  cava3,  and 
coronary  sinus.  From  the  auricle,  the  blood  passes  into  the  right  ventricle ;  and 
from  the  right  ventricle,  through  the  pulmonary  artery,  into  the  lungs.  The 
blood,  arterialized  by  its  passage  through  the  lungs,  is  returned  to  the  left  side  of 
the  heart  by  the  pulmonary  veins,  which  open  into  the  left  auricle ;  from  the  left 
auricle  the  blood  passes  into  the  left  ventricle,  and  from  the  left  ventricle  is  dis- 
tributed, by  the  aorta  and  its  subdivisions,  through  the  entire  body.  This  con- 
stitutes the  circulation  of  the  blood  in  the  adult. 

This,  division  of  the  heart  into  four  cavities  is  indicated  upon  its  surface  in  the 
form  of  grooves.  Thus,  the  great  transverse  groove  separating  the  auricles  from 
the  ventricles  is  called  the  auriculo-ventricular  groove.  It  is  deficient,  in  front, 
from  being  crossed  by  the  root  of  the  pulmonary  artery,  and  contains  the  trunk 
of  the  nutrient  vessels  of  the  heart.  The  auricular  portion  occupies  the  base  of 
the  heart,  and  is  subdivided  into  two  cavities  by  a  median  septum.  The  two 
ventricles' are  also  separated  into  a  right  and  left,  by  two  longitudinal  furrows, 
which  are  situated,  one  on  its  anterior,  the  other  on  its  posterior  surface ;  these 
extend  from  the  base  to  the  apex  of  the  organ,  the  former  being  situated  nearer 
to  the  left  border  of  the  heart,  and  the  latter  to  the  right.  It  follows,  therefore, 
that  the  right  ventricle  forms  the  greater  portion  of  the  anterior  surface  of  the 
heart,  and  the  left  ventricle  more  of  its  posterior  surface. 


692  THE   THORAX. 

Each  of  these  cavities  should  now  be  separately  examined. 

The  Eight  Aueicle  is  a  little  larger  than  the  left,  its  walls  somewhat  thinner, 
measuring  about  one  line;  and  its  cavity  is  capable  of  containing  about  two 
ounces.  It  consists  of  two  parts,  a  principal  cavity  or  sinus,  and  an  appendix 
auriculae. 

The  sinus  is  the  large  quadrangular-shaped  cavity,  placed  betAveen  the  two 
venge  cavee  ;  its  walls  are  extremely  thin,  and  it  is  connected  below  with  the  right 


Fig.  352. — The  Right  Auricle  and  Ventricle  laid  open, 
the  anterior  walls  of  both  being  removed. 


Xn'stle  yarseri  th 
Jtigit  Auricula -Ymtriculaj*  evvniny 


ventricle,  and,  Internally,  with  the  left  auricle,  being  free  in  the  rest  of  its  extent. 
The  appendix  auriculae,  so  called  from  its  fancied  resemblance  to  a  dog's  ear, 
is  a  small  conical  muscular  pouch,  the  margins  of  which  present  a  dentated  edge. 
It  projects  from  the  sinus  forwards  and  to  the  left  side,  overlapping  the  root  of 
the  pulmonary  artery. 

To  examine  the  interior  of  the  auricle,  a  transverse  incision  should  be  made  along  its  ventri- 
cular margin,  from  its  right  border  to  the  appendix ;  and,  from  the  middle  of  this,  a  second  inci- 
sion should  be  carried  upwards,  along  the  inner  side  of  the  two  venae  cavae. 

The  following  parts  present  themselves  for  examination : — 

/'Superior  vena  cava.  Relics  of  Foetal  j  Annulus  ovalis. 
[Inferior  vena  cava.  structure.        \  Fossa  ovalis. 

Openings.  (Coronary  sinus.  Musculi  pectinati. 

'Foramina  Thebesii.  -rT  ■,  j  Eustachian. 

vAuriculo-ventricular.  {  Coronary. 


HEART— RIGHT   AURICLE.  693 

OPENINGS.  The  superior  vena  cava  returns  the  blood  from  the  upper  half  of 
the  body,  and  opens  into  the  upper  and  front  part  of  the  auricle,  the  direcikm  of 
its  orifice  being  downwards  and  forwards. 

The  inferior  vena  cava,  larger  than  the  superior,  returns  the  blood  from  the 
lower  half  of  the  body,  and  opens  into  the  lowest  part  of  the  auricle,  near  the 
septum,  the  direction  of  its  orifice  being  upwards  and  inwards.  The  direction  of 
a  current  of  blood  through  the  superior  vena  cava  would  consequently  be  towards 
the  auriculo-ventricular  orifice;  whilst  the  direction  of  the  blood  through  the 
inferior  cava  would  be  towards  the  auricular  septum.  This  is  the  normal  direc- 
tion of  the  two  currents  in  foetal  life. 

The  tuberculum  Lower i  is  a  small  projection  on  the  right  wall  of  the  auricle, 
between- the  two  venae  cavae.  This  is  most  distinct  in  the  hearts  of  quadrupeds ;  in 
man,  it  is  scarcely  visible.  It  was  supposed,  by  Lower,  to  direct  the  blood  from 
the  superior  vena  cava  towards  the  auriculo-ventricular  opening. 

The  coronary  sinus  opens  into  the  auricle,  between  the  inferior  vena  cava  and 
the  auriculo-ventricular  opening.  It  returns  the  blood  from  the  substance  of  the 
heart,  and  is  protected  by  a  semicircular  fold  of  the  lining  membrane  of  the  auricle, 
the  coronary  valve.  The  sinus,  before  entering  the  auricle,  is  considerably 
dilated.  Its  wall  is  partly  muscular,  and,  at  its  junction  with  the  great  coronary 
vein,  is  somewhat  constricted,  and  furnished  with  a  valve,  consisting  of  two 
unequal  segments. 

The  foramina  Thebesii  are  numerous  minute  apertures,  the  mouths  of  small 
veins  {venae  cordis  minimse),  which  open  on  various  parts  of  the  inner  surface  of  the 
auricle.  They  return  the  blood  directly  from  the  muscular  substance  of  the  heart. 
Some  of  these  foramina  are  minute  depressions  in  the  walls  of  the  heart,  presenting 
a  closed  extremity. 

The  auriculo-ventricular  opening  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle,  to  be  presently  described. 

Valves.  The  Eustachian  valve  is  situated  between  the  anterior  margin  of  the 
inferior  cava  and  the  auriculo-ventricular  orifice.  It  is  semilunar  in  form,  its 
convex  margin  being  attached  to  the  wall  of  the  vein ;  its  concave  margin,  which 
is  free,  terminating  in  two  cornua,  of  which  the  left  is  attached  to  the  anterior  edge 
of  the  annulus  ovalis ;  the  right  being  lost  on  the  wall  of  the  auricle.  The  valve 
is  formed  by  a  duplicature  of  the  lining  membrane  -of  the  auricle,  containing  a 
few  muscular  fibres. 

In  the  foetus,  this  valve  is  of  large  size,  and  serves  to  direct  the  blood  from  the 
inferior  vena  cava,  through  the  foramen  ovale,  into  the  left  auricle. 

In  the  adult,  it  is .  occasionally  persistent,  and  may  assist  in  preventing  the 
reflux  of  blood  into  the  inferior  vena  cava ;  more  commonly,  it  is  small,  and  its  free 
margin  presents  a  cribriform  or  filamentous  appearance ;  occasionally,  it  is  alto- 
gether wanting. 

The  coronary  valve  is  a  semicircular  fold  of  the  lining  membrane  of  the  auricle, 
protecting  the  orifice  of  the  coronary  sinus.  It  prevents  the  regurgitation  of  blood 
into  the  sinus  during  the  contraction  of  the  auricle.  This  valve  is  occasionally 
double. 

The  fossa  ovalis  is  an  oval  depression,  corresponding  to  the  situation  of  the 
foramen  ovale  in  the  foetus.  It  is  situated  at  the  lower  part  of  the  septum  auricu- 
larum,  above  the  orifice  of  the  inferior  vena  cava. 

The  annulus  ovalis  is  the  prominent  oval  margin  of  the  foramen  ovale.  It  is 
most  distinct  above,  and  at  the  sides;  below,  it  is  deficient.  A  small  slit-like 
valvular  opening  is  occasionally  found,  at  the  upper  margin  of  the  fossa  ovalis, 
which  leads  upwards,  beneath  the  annulus,  into  the  left  auricle ;  it  is  the  remains 
of  the  aperture  between  the  two  auricles  in  the  foetus. 

The  musculi  pectinati  are  small,  prominent  muscular  columns,  which  run  across 
the  inner  surface  of  the  appendix  auriculae,  and  adjoining  portion  of  the  wall  of 
the  sinus.  They  have  received  the  name,  pectinati,  from  the  fancied  resemblance 
they  bear  to  the  teeth  of  a  comb. 


094  THE   THORAX. 

The  Right  Ventkicle  is  triangular  in  form,  and  extends  from  the  right  auricle 
to  near  the  apex.  Its  anterior  or  upper  surface  is  rounded  and  convex,  and  forms 
the  larger  part  of  the  front  of  the  heart.  Its  posterior  or  under  surface  is  flattened, 
rests  upon  the  Diaphragm,  and  forms  only  a  small  part  of  this  surface.  Its  inner 
wall  is  formed  by  the  partition  between  the  two  ventricles,  the  septum  ventricu- 
lorum,  the  surface  of  which  is  convex,  and  bulges  into  the  cavity  of  the  right 
ventricle.  Superiorly,  the  ventricle  forms  a  conical  prolongation,  the  infundi- 
bulum  or  conus  arteriosus,  from  which  the  pulmonary  artery  arises.  The  walls  of 
the  right  ventricle  are  thinner  than  those  of  the  left,  the  proportion  between  them 
being  as  1  to  2  (Bizot).  The  thickest  part  of  the  wall  is  at  the  base,  and  it 
gradually  becomes  thinner  towards  the  apex.  Its  cavity,  which  equals  that  of  the 
left  ventricle,  is  capable  of  containing  about  two  fluid  ounces. 

To  examine  its  interior,  an  incision  should  be  made  a  little  to  the  right  of  the  anterior  ven- 
tricular groove  from  the  pulmonary  artery  to  the  apex  of  the  heart,  and  from  thence  carried  up 
along  the  right  border  of  the  ventricle,  as  far  as  the  auriculo-ventricular  opening. 

The  following  parts  present  themselves  for  examination : — 

~       .  j  Auriculo-ventricular. 

penings  .     .  j  Opening  of  the  pulmonary  artery. 
■y  i  j  Tricuspid. 

*  '     *  I  Semilunar. 

And  a  muscular  and  tendinous  apparatus  connected  with  the  tricuspid  valves : — 
Columnae  carneae.  Chordae  tendineEe. 

The  auriculo-ventricular  orifice  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle.  It  is  situated  at  the  base  of  the  ventricle,  near 
the  right  border  of  the  heart,  and  corresponds  to  the  centre  of  the  sternum 
between  the  third  costal  cartilages.  The  opening  is  about  an  inch  in  diameter, 
oval  from  side  to  side,  surrounded  by  a  fibrous  ring,  covered  by  the  lining  mem- 
brane of  the  heart,  and  is  rather  larger  than  the  corresponding  aperture  on  the 
left  side,  being  sufficiently  large  to  admit  the  ends  of  three  fingers.  It  is  guarded 
by  the  tricuspid  valve. 

The  opening  of  the  pulmonary  artery  is  circular  in  form,  and  situated  at  the 
summit  of  the  conus  arteriosus,  close  to  the  septum  ventriculorum.  It  is  placed 
on  the  left  side  of  the  auriculo-ventricular  opening,  upon  the  anterior  aspect  of 
the  heart,  and  corresponds  to  the  upper  border  of  the  third  costal  cartilage  of  the 
left  side,  close  to  the  sternum.     Its  orifice  is  guarded  by  tkje  semilunar  valves. 

The  tricuspid  valve  consists  of  three  segments  of  a  triangular  or  trapezoidal 
shape,  formed  by  a  duplicature  of  the  lining  membrane  of  the  heart,  strengthened 
by  a  layer  of  fibrous  tissue,  and  containing,  according  to  Kurschner  and  Senac, 
muscular  fibres.  These  segments  are  connected  by  their  bases  to  the  auriculo- 
ventricular  orifice,  and  by  their  sides  with  one  another,  so  as  to  form  a  continuous 
annular  membrane,  which  is  attached  round  the  margin  of  the  auriculo-ventricular 
opening,  their  free  margins  and  ventricular  surfaces  affording  attachment  to  a  num- 
ber of  delicate  tendinous  cords,  the  chordse  tendinese.  The  largest  and  most  mov- 
able segment  is  placed  towards  the  left  side  of  the  auriculo-ventricular  opening 
interposed  between  it  and  the  pulmonary  artery.  Another  segment  corresponds 
to  the  front  of  the  ventricle ;  and. a  third  to  its  posterior  wall.  The  central  part  of 
each  segment  is  thick  and  strong ;  and  the  lateral  margins  are  thin  and  indented. 
The  chordae  tendineae  are  connected  with  the  adjacent  margins  of  the  principal 
segments  of  the  valve,  and  are  further  attached  to  each  segment  in  the  following 
manner : — 1.  Three  or  four  reach  the  attached  margin  of  each  segment,  where  they 
are  continuous  with  the  auriculo-ventricular  tendinous  ring.  2.  Others,  four  to 
six  in  number,  are  attached  to  the  central  thickened  part  of  each  segment.  3.  The 
most  numerous  and  finest  are  connected  with  the  marginal  portion  of  each 
«egment. 


HEART— LEFT   AURICLE.  695 

The  columnse  carnese  are  the  rounded  muscular  columns  which  project  from 
nearly  the  whole  of  the  inner  surface  of  the  ventricle,  excepting  near  the  opening 
of  the  pulmonary  artery.  They  may  be  classified,  according  to  their  mode  of 
connection  with  the  ventricle,  into  three  sets.  The  first  set  merely  form  prominent 
ridges  on  the  inner  surface  of  the  ventricle,  being  attached  by  their  entire  length 
on  one  side,  as  well  as  by  their  extremities.  Tho  second  set  are  attached  by 
their  two  extremities,  but  are  free  in  the  rest  of  their  extent ;  whilst  the  third  set 
(columnse  papillares),  three  or  four  in  number,  are  attached  by  one  extremity  to 
the  Avail  of  the  heart,  the  opposite  extremity  giving  attachment  to  the  chordse 
tendinese. 

The  semilunar  valves,  three  in  number,  guard  the  orifice  of  the  pulmonary  artery. 
They  consist  of  three  semicircular  folds,  formed  by  a  duplicature  of  the  lining 
membrane,  strengthened  by  fibrous  tissue.  They  are  attached,  by  their  convex 
margins,  to  the  wall  of  the  artery,  at  its  junction  with  the  ventricle,  the  straight 
border  being  free,  and  directed  upwards  in  the  course  of  the  vessel,  against  the  sides 
of  which  they  are  pressed  during  the  passage  of  the  blood  along  its  canal.  The 
free  margin  of  each  is  somewhat  thicker  than  the  rest  of  the  valve,  is  strengthened 
by  a  bundle  of  tendinous  fibres,  and  presents,  at  its  middle,  a  small  projecting  fibro- 
cartilaginous nodule,  called  corpus  Arantii.  From  this  nodule,  tendinous  fibres 
radiate  through  the  valve  to  its  attached  margin,  and  these  fibres  form  a  consti- 
tuent part  of  its  substance  throughout  its  whole  extent,  excepting  two  narrow 
lunated  portions,  placed  one  on  either  side  of  the  nodule,  immediately  behind  the 
free  margin ;  here,  the  valve  is  thin,  and  formed  merely  by  the  lining  membrane. 
During  the  passage  of  the  blood  along  the  pulmonary  artery,  these  valves  are 
pressed  against  the  sides  of  its  cylinder,  and  the  course  of  the  blood  along  the  tube 
is  uninterrupted ;  but  during  the  ventricular  diastole,  when  the  current  of  blood 
along  the  pulmonary  artery  is  checked,  and  partly  thrown  back  by  its  elastic  walls, 
these  valves  become  immediately  expanded,  and  effectually  close  the  entrance  of 
the  tube.  When  the  valves  are  closed,  the  lunated  portions  of  each  are  brought 
into  contact  with  one  another  by  their  opposed  surfaces,  the  three  fibro-cartilagi- 
nous  nodules  filling  up  the  small  triangular  space  that  would  be  otherwise  left  by 
the  approximation  of  the  three  semilunar  folds. 

Between  the  semilunar  valves  and  the  commencement  of  the  pulmonary  artery 
are  three  pouches  or  dilatations,  one  behind  each  valve.  These  are  the  pulmonary 
sinuses  (sinuses  of  Valsalva).  Similar  sinuses  exist  between  the  semilunar 
valves  and  the  commencement  of  the  aorta ;  they  are  larger  than  the  pulmonary 
sinuses. 

The  Left  Auricle  is  rather  smaller  but  thicker  than  the  right,  measuring  about 
one  line  and  a  half;  it  consists  of  two  parts,  a  principal  cavity  or  sinus,  and  an 
appendix  auriculae. 

The  sinus  is  cuboidal  in  form,  and  concealed  in  front  by  the  pulmonary  artery 
and  aorta ;  internally,  it  is  separated  from  the  right  auricle  by  the  septum  auricu- 
larum ;  and  behind,  it  receives  on  each  side  the  pulmonary  veins,  being  free  in 
the  rest  of  its  extent. 

The  appendix  auriculae  is  somewhat  constricted  at  its  junction  with  the  auricle; 
it  is  longer,  narrower,  and  more  curved  than  that  of  the  right  side,  and  its  mar- 
gins more  deeply  indented,  presenting  a  kind  of  foliated  appearance.  Its  direction 
is  forwards  towards  the  right  side,  overlapping  the  root  of  the  pulmonary 
artery. 

In  order  to  examine  its  interior,  a  horizontal  incision  should  be  made  along  the  attached  border 
of  the  auricle  to  the  ventricle ;  and,  from  the  middle  of  this,  a  second  incision  should  be  carried 
upwards. 

The  following  parts  then'  present  themselves  for  examination : — 

The  openings  of  the  four  pulmonary  veins. 
Auriculo- ventricular  opening. 
Musculi  pectinati. 


696 


THE    THORAX. 


The  pulmonary  veins,  four  in  number,  open,  two  into  the  right,  and  two  into 
the  left  side  of  the  auricle.  The  two  left  veins  frequently  terminate  by  a  common 
opening.     They  are  not  provided  with  valves. 

The  auriculo-ventricular  opening  is  the  large  oval  aperture  of  communication 
between  the  auricle  and  ventricle.  It  is  rather  smaller  than  the  corresponding 
opening  on  the  opposite  side. 

The  musculi  pectinati  are  fewer  in  number  and  smaller  than  on  the  right  side ; 
they  are  confined  to  the  inner  surface  of  the  appendix. 

On  the  inner  surface  of  the  septum  auricularum  may  be  seen  a  lunated  impres- 
sion, bounded  below  by  a  crescentic  ridge,  the  concavity  of  which  is  turned 
upwards.     This  depression  is  just  above  the  fossa  ovalis  in  the  right  auricle. 


Ft* 


353. — Tlie  Left  Auricle  and  Ventricle  laid  open, 
the  Anterior  Walls  of  both  being  removed. 


passed  thro' Aortic  opening 


The  Left  Yenteicle  is  longer  and  more  conical  in  shape  than  the  right  ven- 
tricle. It  forms  a  small  part  of  the  left  side  of  the  anterior  surface  of  the  heart, 
and  a  considerable  part  of  its  posterior  surface.  It  also  forms  the  apex  of  the 
heart  by  its  projection  beyond  the  right  ventricle.  Its  walls  are  much  thicker 
than  those  of  the  right  ventricle,  the  proportion  being  as  2  to  1  (Bizot).  They 
are  also  thickest  in  the  broadest  part  of  the  ventricle,  becoming  gradually  thinner 
towards  the  base,  and  also  towards  the  apex,  which  is  the  thinnest  part. 

Its  cavity  should  be  opened  by  making  an  incision  through  its  anterior  wall  along  the  left  side 
of  the  ventricular  septum,  and  carrying  it  round  the  apex  and  along  its  posterior  surface  to  the 
auriculo-ventricular  opening. 


The  following  parts  present  themselves  for  examination : — 

Auriculo-ventricular.  y  1        i  Mitral. 

Aortic.  •  (  Semilunar 

Chordaa  tendinere.         Columnge  carneas. 


Openings 


HEART— LEFT   VENTRICLE.  697 

he  auricula-ventricular  opening  is  placed  to  the  left  of  the  aortic  orifice,  be- 
neath the  right  auriculo-ventricular  opening,  opposite  the  centre  of  the  sternum. 
It  is  a  little  smaller  than  the  corresponding  aperture  of  the  opposite  side ;  and, 
like  it,  is  broader  in  the  transverse,  than  in  the  antero-posterior,  diameter.  It  is 
surrounded  by  a  dense  fibrous  ring,  covered  by  the  lining  membrane  of  the  heart 
and  is  guarded  by  the  mitral  valve. 

The  aortic  opening  is  a  small  circular  aperture,  in  front  and  to  the  right  side  of 
the  auriculo- ventricular,  from  which  it  is  separated  by  one  of  the  segments  of  the 
mitral  valve.  Its  orifice  is  guarded  by  the  semilunar  valves.  Its  position  corre- 
sponds to  the  sternum,  on  a  line  with  the  lower  border  of  the  third  left  costal 
cartilage. 

The  mitral  valve  is  attached  to  the  circumference  of  the  auriculo-ventricular 
orifice,  in  the  same  way  that  the  tricuspid  valve  is  on  the  opposite  side.  It  is 
formed  by  a  duplicature  of  the  lining  membrane,  strengthened  by  fibrous  tissue, 
and  contains  a  few  muscular  fibres.  It  is  larger  in  size,  thicker,  and  altogether 
stronger  than  the  tricuspid,  and  consists  of  two  segments  of  unequal  size.  The 
larger  segment  is  placed  in  front,  between  the  auriculo-ventricular  and  aortic  ori- 
fices, and  is  said  to  prevent  the  filling  of  the  aorta  during  the  distension  of  the 
ventricle.  Two  smaller  segments  are  usually  found  at  the  angle  of  junction  of  the 
larger.  The  mitral  valves  are  furnished  with  chordae  tendineee ;  their  mode  of 
attachment  is  precisely  similar  to  those  on  the  right  side,  but  they  are  thicker, 
stronger,  and  less  numerous. 

The  semilunar  valves  surround  the  orifice  of  the  aorta;  they  are  similar  in 
structure,  and  in  their  mode  of  attachment,  to  those  of  the  pulmonary  artery. 
They  are,  however,  larger,  thicker,  and  stronger  than  those  of  the  right  side ;  the 
lunulas  are  more  distinct,  and  the  corpora  Arantii  larger  and  more  prominent. 
Between  each  valve  and  the  cylinder  of  the  aorta  is  a  deep  depression,  forming 
the  sinus  aortici  (sinuses  of  Valsalva) ;  they  are  larger  than  those  at  the  root  of  the 
pulmonary  artery. 

The  columnse  carnese  admit  of  a  subdivision  into  three  sets,  like  those  upon 
the  right  side ;  but  they  are  smaller,  more  numerous,  and  present  a  dense  interlace- 
ment, especially  at  the  apex,  and  upon  the  posterior  wall.  Those  attached  by  one 
extremity  only,  the  musculi  papillares,  are  two  in  number,  being  connected  one  to 
the  anterior,  the  other  to  the  posterior  wall ;  they  are  of  large  size,  and  terminate 
by  free  rounded  extremities,  from  which  the  chordas  tendineoa  arise. 

The  Endocardium  is  the  serous  membrane  which  lines  the  internal  surface  of 
the  heart ;  it  assists  in  forming,  by  its  reduplications,  the  valves  contained  in  this 
organ,  and  is  continuous  with  the  lining  membrane  of  the  great  bloodvessels. 
It  is  a  thin,  smooth,  transparent  membrane,  giving  to  the  inner  surface  of  the 
heart  its  glistening  appearance.  It  is  more  opaque  on  the  left  than  on  the  right 
side  of  the  heart,  thicker  in  the  auricles  than  in  the  ventricles,  and  thickest  in  the 
left  auricle.  It  is  thin  on  the  musculi  pectinati,  and  on  the  columnae  carneae ;  but 
thicker  on  the  smooth  part  of  the  auricular  and  ventricular  walls,  and  on  the  tips 
of  the  musculi  papillares. 

Structure  of  the  Heart.  The  heart  consists  of  muscular  fibres,  and  of 
fibrous  rings  which  serve  for  their  attachment. 

The  fibrous  rings  surround  the  auriculo-ventricular  and  arterial  orifices ;  they 
are  stronger  upon  the  left  than  on  the  right  side  of  the  heart.  The  auriculo- 
ventricular  rings  serve  for  the  attachment  of  the  muscular  fibres  of  the  auricles 
and  ventricles,  and  also  for  the  mitral  and  tricuspid  valves ;  the  left  one  is  closely 
connected,  by  its  right  margin,  with  the  aortic  arterial  ring.  Between  these  and 
the  right  auriculo-ventricular  ring,  is  a  fibro-cartilaginous  mass ;  and  in  some  of 
the  larger  animals,  as  the  ox  and  elephant,  a  portion  of  bone. 

The  fibrous  rings  surrounding  the  arterial  orifices  serve  for  the  attachment  of 
the  great  vessels  and  semilunar  valves.  Each  ring  receives,  by  its  ventricular 
margin,  the  attachment  of  the  muscular  fibres  of  the  ventricles;    its  opposite 


698  THE   THORAX. 

margin  presents  three  deep  semicircular  notches,  within  which  the  middle  coat 
of  the  artery  (which  presents  three  convex  semicircular  segments)  is  firmly  fixed; 
the  attachment  of  the  artery  to  its  fibrous  ring  being  strengthened  by  the  thin 
cellular  coat  and  serous  membrane  externally,  and  by  the  endocardium  within.  It 
is  opposite  the  margins  of  these  semicircular  notches,  in  the  arterial  rings,  that 
the  endocardium,  by  its  reduplication,  forms  the  semilunar  valves,  the  fibrous 
structure  of  the  ring  being  continued  into  each  of  the  segments  of  the  valve  at 
this  part.  The  middle  coat  of  the  artery  in  this  situation  is  thin,  and  the  sides  of 
the  vessel  dilated  to  form  the  sinuses  of  Valsalva. 

The  muscular  structure  of  the  heart  consists  of  bands  of  fibres,  which  present 
an  exceedingly  intricate  interlacement.  They  are  of  a  deep  red  color,  and  marked 
with  transverse  striae. 

The  muscular  fibres  of  the  heart  admit  of  a  subdivision  into  two  kinds,  those  of 
the  auricles,  and  those  of  the  ventricles,  which  are  quite  independent  of  one  another. 

Fibres  of  the  auricles.  These  are  disposed  in  two  layers,  a  superficial  layer 
common  to  both  cavities,  and  a  deep  layer  proper  to  each.  The  superficial  fibres 
are  most  distinct  on  the  anterior  surface  of  the  auricles,  across  the  bases  of  which 
they  run  in  a  transverse  direction,  forming  a  thin  but  incomplete  layer.  Some 
of  these  fibres  pass  into  the  septum  auricularum.  The  internal  or  deep  fibres  proper 
1  to  each  auricle  consist  of  two  sets,  looped,  and  annular  fibres.  The  looped  fibres 
pass  upwards  over  each  auricle,  being  attached  by  both  extremities  to  the  corre- 
sponding auriculo- ventricular  rings,  in  front  and  behind.  The  annular  fibres  sur- 
round the  whole  extent  of  the  appendices  auriculae,  and  are  continued  upon  the 
walls  of  the  venae  cavae  and  coronary  sinus  on  the  right  side,  and  upon  the  pul- 
monary veins  on  the  left  side,  at  their  connection  with  the  heart.  In  the  appendices, 
they  interlace  with  the  longitudinal  fibres. 

Fibres  of  the  ventricles.  These,  as  in  the  auricles,  are  disposed  in  layers,  some 
of  which'  are  common  to  both  ventricular  cavities,  whilst  others  belong  exclusively 
to  one  ventricle,  the  latter  being  chiefly  found  towards  the  base  of  the  heart. 
The  greater  majority  of  these  fibres  are  connected  by  both  ends  with  the  auriculo- 
ventricular  fibrous  rings,  either  directly  or  indirectly  through  the  chordae  ten- 
dineae ;  some,  however,  are  attached  to  the  fibrous  rings  surrounding  the  arterial 
orifices. 

The  superficial  fibres  are  either  longitudinal,  or,  more  commonly,  oblique  or  spiral 
in  their  direction,  and  towards  the  apex  are  arranged  in  the  form  of  twisted  loops ; 
the  deeper  fibres  are  circular. 

The  spiral  fibres  .are  disposed  in  layers  of  various  degrees  of  thickness ;  the 
most  superficial,  on  the  front  of  the  ventricles,  run  obliquely  from  right  to  left, 
and  from  above  downwards.  On  the  back  of  the  ventricles  they  are  directed 
more  vertically,  and  pass  from  left  to  right. 

The  superficial  fibres  coil  inwards  at  the  apex  of  the  heart,  round  which  they 
are  arranged  in  a  whorl-like  iorm,  called  the  vortex,  dipping  beneath  the  edge  of 
the  deeper  and  shorter  layers.  If  these  fibres  are  carefully  uncoiled,  in  a  heart 
previously  boiled,  the  cavity  <  f  the  left,  and  then  that  of  the  right  ventricle,  will 
be  exposed  at  this  point.  The  layers  of  fibres  successively  met  with  have  a  simi- 
lar arrangement ;  the  more  superficial  and  longer  turning  inwards,  and  including 
the  deeper  and  shorter  bands.  All  these  fibres  ascend  and  spread  out  upon  the 
inner  surface  of  the  ventricles,  forming  the  walls,  the  septum,  and  the  musculi 
papillares,  which  project  from  these  cavities ;  and  they  are  finally  inserted  into 
the  auriculo-ventricular  fibrous  rings,  or,  indirectly,  through  the  chordae  tendineae. 
Of  these  spiral  fibres,  some  enter  at  the  interventricular  furrows,  and  surround 
either  ventricle  singly ;  others  pass  across  the  furrows,  and  embrace  both  cavities. 
On  tracing  those  which  form  the  vortex,  back  into  the  interventricular  septum, 
they  become  interlaced  with  similar  fibres  from  the  right  ventricle,  and  ascend 
vertically  upon  the  right  side  of  the  septum,  as  far  as  its  base,  in  the  form  of  a 
long  and  broad  band. 

Circular  fibres.     The  circular  fibres  are  situated  deeply  in  the  substance  of 


VASCULAR   SYSTEM   OF   TIIE   FCETUS.  699 

the  heart ;  towards  the  base  they  enter  the  anterior  and  posterior  longitudinal 
furrows,  so  as  to  include  each  cavity  singly,  or,  passing  across  them,  surround 
both  ventricles,  more  fibres  passing  across  the  posterior  than  the  anterior  furrow. 
They  finally  ascend  in  the  substance  of  the  ventricle,  to  be  inserted  into  the  fibrous 
rings  at  its  base. 

Vessels  and  Nerves.  The  arteries  supplying  the  heart  are  the  anterior  and  pos- 
terior coronary. 

The  veins  accompany  the  arteries,  and  terminate  in  the  right  auricle.  They  are 
the  great  cardiac  vein,  the  small  or  anterior  cardiac  veins,  and  the  venae  cordis 
minimae  (venae  Thebesii). 

The  lymphatics  terminate  in  the  thoracic  and  right  lymphatic  ducts. 

The  nerves  are  derived  from  the  cardiac  plexuses,  which  are  formed  partly  from 
the  spinal,  and  partly  from  the  sympathetic  system.  They  are  freely  distributed 
both  on  the  surface,  and  in  the  substance  of  the  heart ;  the  separate  filaments  being 
furnished  with  small  ganglia.  These  have  been  figured  by  Remak,  but  the  more 
extended  investigations  of  Dr.  Robert  Lee  have  shown  them  tp  exist  in  great 
abundance,  both  in  the  nerves  distributed  to  the  surface,  and  in  those  in  the 
interior  of  the  organ. 

Peculiarities  in  the  Vascular  System  of  the  Foetus. 

The  chief  peculiarities  in  the  heart  of  the  foetus  are  the  direct  communication 
between  the  two  auricles  by  the  foramen  ovale,  and  the  large  size  of  the 
Eustachian  valve.  There  are  also  several  minor  peculiarities.  Thus,  the  position 
of  the  heart  is  vertical  until  the  fourth  month,  when  it  commences  to  assume  an 
oblique  direction.  Its  size  is  also  very  considerable,  as  compared  with  the  body, 
the  proportion  at  the  second  month  being  as  1  to  50 :  at  birth,  it  is  as  1  to  120 : 
whilst,  in  the  adult,  the  average  is  about  1  to  160.  At  an  early  period  of  foetal 
life,  the  auricular  portion  'of  the  heart  is  larger  than  the  ventricular,  the  right 
auricle  being  more  capacious  than  the  left ;  but,  towards  birth,  the  ventricular 
portion  becomes  the  larger.  The  thickness  of  both  ventricles  is,  at  first,  about 
equal ;  but,  towards  birth,  the  left  becomes  much  the  thicker  of  the  two. 

The  foramen  ovale  is  situated  at  the  lower  and  back  part  of  the  septum 
auricularum.  Through  it  the  auricles  communicate  with  each  other.  It  attains 
its  greatest  size  at  the  sixth  month. 

The  Eustachian  valve  is  developed  from  the  anterior  border  of  the  inferior  vena 
cava,  at  its  entrance  in  the  auricle,  and,  rising  up  on  the  left  side  of  the  opening 
of  this  vein,  serves  to  direct  the  blood  from  the  inferior  vena  cava  through  the 
foramen  ovale  into  the  left  auricle. 

The  peculiarities  in  the  arterial  system  of  the  foetus  are  the  communication 
between  the  pulmonary  artery  and  descending  aorta,  by  means  of  the  ductus 
arteriosus,  and  the  communication  between  the  internal  iliac  arteries  and  the 
placenta,  by  the  umbilical  arteries. 

The  ductus  arteriosus  is  a  short  tube,  about  half  an  inch  in  length  at  birth,  and 
of  the  diameter  of  a  goose-quill.  It  connects  the  left  branch  of  the  pulmonary 
artery  with  the  termination  of  the  arch  of  the  aorta,  just  beyond  the  origin  of  the 
left  subclavian  artery.  It  conducts  the  chief  part  of  the  blood  of  the  right  ventri- 
cle into  the  descending  aorta. 

The  umbilical  or  hypogastric  arteries  arise  from  the  internal  iliacs,  in  addition 
to  the  usual  branches  given  off'  from  these  vessels  in  the  adult.  Ascending  along 
the  sides  of  the  bladder  to  its  fundus,  they  pass  out  of  the  abdomen  at  the 
umbilicus,  and  are  continued  along  the  umbilical  cord  to  the  placenta,  coiling 
round  the  umbilical  vein.  They  return  the  blood  to  the  placenta  which  has  been 
circulated  in  the  system  of  the  foetus. 

The  peculiarity  in  the  venous  system  of  the  foetus  is  the  communication 
established  between  the  placenta  and  the  liver  and  portal  vein,  through  the 
umbilical  vein,  and  with  the  inferior  vena  cava  by  the  ductus  venosus. 


TOO 


THE   THORAX. 


Fcetal  Circulation. 

In  the  following  plan  the  figured  arrows  represent  the  kind  of  \>lood,  as  well  as  the 

direction  which  it  takes  in  the  vessels.     Thus — arterial  blood  is  figured  >» > ; 

venous  blood,  >» •••>;  mixed  (arterial  and  venous  blood),  #ti>    i     '    *if , 

Fig.  354.— Plan  of  the  Foetal  Circulation. 


Intrtml  Mac  JGC 


The  arterial  blood  destined  for  the  nutrition  of  the  foetus  is  carried  from  the 
placenta  to  the  foetus,  along  the  umbilical  cord,  by  the  umbilical  vein.  The 
umbilical  vein  enters  the  abdomen  at  the  umbilicus,  and  passes  upwards  along  the 


FCETAL   CIRCULATION.  T01 

free  margin  of  the  suspensory  ligament  of  the  liver,  to  the  under  surface  of  this 
organ,  where  it  gives  off  two  or  three  branches  to  the  left  lobe,  one  of  which  is 
of  large  size;  and  others  to  the  lobus  quadratus  and  lobus  Spigelii.  At  the 
transverse  fissure,  it  divides  into  two  branches ;  of  these,  the  larger  is  joined  by 
the  portal  vein,  and  enters  the  right  lobe ;  the  smaller  branch  continues  onwards, 
under  the  name  of  the  ductus  venosus,  and  joins  the  left  hepatic  vein  at  the 
point  of  junction  of  this  vessel  with  the  inferior  vena  cava.  The  blood,  there- 
fore, which  traverses  the  umbilical  vein,  reaches  the  inferior  vena  cava  in  three 
different  ways.  The  greater  quantity  circulates  through  the  liver  with  the  portal 
venous  blood,  before  entering  the  cava  by  the  hepatic  veins ;  some  enters  the  liver 
directly,  and  is  also  returned  to  the  inferior  cava  by  the  hepatic  veins ;  the  smaller 
quantity  passes  directly  into  the  vena  cava,  by  the  junction  of  the  ductus  venosus 
witli  the  left  hepatic  vein. 

In  the  inferior  cava,  the  blood  carried  by  the  ductus  venosus  and  hepatic  veins 
becomes  mixed  with  that  returning  from  the  lower  extremities  and  viscera  of  the 
abdomen.  It  enters  the  right  auricle,  and,  guided  by  the  Eustachian  valve,  passes 
through  the  foramen  ovale  into  the  left  auricle,  where  it  becomes  mixed  with  a 
small  quantity  of  blood  returned  from  the  lungs  by  the  pulmonary  veins.  From 
the  left  auricle  it  passes  into  the  left  ventricle ;  and,  from  the  left  ventricle,  into 
the  aorta,  from  whence  it  is  distributed  almost  entirely  to  the  head  and  upper 
extremities,  a  small  quantity  being  probably  carried  into  the  descending  aorta. 
From  the  head  and  upper  extremities,  the  blood  is  returned  by  the  branches  of 
the  superior  vena  cava  to  the  right  auricle,  where  it  becomes  mixed  with  a  small 
portion  of  the  blood  from  the  inferior  cava.  From  the  right  auricle,  it  descends 
over  the  Eustachian  valve  into  the  right  ventricle;  and,  from  the  right  ventricle, 
into  the  pulmonary  artery.  The  lungs  of  the  foetus  being  solid,  and  almost 
impervious,  only  a  small  quantity  of  blood  is  distributed  to  them,  by  the  right 
and  left  pulmonary  arteries,  which  is  returned  by  the  pulmonary  veins  to  the  left 
auricle ;  the  greater  part  passes  through  the  ductus  arteriosus  into  the  commence- 
ment of  the  descending  aorta,  where  it  becomes  mixed  with  a  small  quantity  of 
blood  transmitted  by  the  left  ventricle  into  the  aorta.  Along  this  vessel  it 
descends  to  supply  the  lower  extremities  and  viscera  of  the  abdomen  and  pelvis, 
the  chief  portion  being,  however,  conveyed  by  the  umbilical  arteries  to  the 
placenta. 

From  the  preceding  account  of  the  circulation  of  the  blood  in  the  foetus,  it  will 
be  seen: — 

1.  That  the  placenta  serves  the  double  purpose  of  a  respiratory  and  nutritive 
organ,  receiving  the  venous  blood  from  the  foetus,  and  returning  it  again  re-oxy- 
genated, and  charged  with  additional  nutritive  material. 

2.  That  nearly  the  whole  of  the  blood  of  the  umbilical  vein  traverses  the  liver 
before  entering  the  inferior  vena  cava ;  hence  the  large  size  of  this  organ,  especially 
at  an  early  period  of  foetal  life. 

3.  That  the  right  auricle  is  the  point  of  meeting  of  a  double  current,  the 
blood  in  the  inferior  vena  cava  being  guided  by  the  Eustachian  valve  into  the  left 
auricle,  whilst  that  in  the  superior  vena  cava  descends  into  the  right  ventricle.  At 
an  early  period  of  foetal  life,  it  is  highly  probable  that  the  two  streams  are  quite 
distinct ;  for  the  inferior  vena  cava  opens  almost  directly  into  the  left  auricle,  and  the 
Eustachian  valve  would  exclude  the  current  along  the  tube  from  entering  the 
right  ventricle.  At  a  later  period,  as  the  separation  between  the  two  auricles 
becomes  more  distinct,  it  seems  probable  that  some  slight  mixture  of  the  two 
streams  must  take  place. 

4.  The  blood  carried  from  the  placenta  to  the  foetus  by  the  umbilical  vein, 
mixed  with  the  blood  from  the  inferior  vena  cava,  passes  almost  directly  to  the  arch 
of  the  aorta,  and  is  distributed  by  the  branches  of  this  vessel  to  the  head  and  upper 
extremities;  hence  the  large  size  and  perfect  development  of  these  parts  at  birth. 

5.  The  blood  contained  in  the  descending  aorta,  chiefly  derived  from  that 
which  has  already  circulated  through  the  head  and  limbs,  together  with  a  small 


102  THE   THORAX. 

quantit}'-  from  the  left  ventricle,  is  distributed  to  the  lower  extremities;  hence  the 
small  size  and  imperfect  development  of  these  parts  at  birth. 

Changes  m  the  Vascular  System  at  Birth. 

At  birth,  when  respiration  is  established,  an  increased  amount  of  blood  from 
the  pulmonary  artery  passes  through  the  lungs,  which  now  perform  their  office  as 
respiratory  organs,  and,  at  the  same  time,  the  placental  circulation  is  cut  off. 
The  foramen  ovale  becomes  gradually  closed  by  about  the  tenth  day  after  birth, 
a  valvular  fold  rising  up  on  the  left  side  of  its  margin,  and  ultimately  above  its 
upper  part ;  this  valve  becomes  adherent  to  the  margins  of  the  foramen  for  the 
greater  part  of  its  circumference,  but,  above,  a  valvular  opening  is  left  between  the 
two  auricles,  which  sometimes  remains  persistent. 

The  ductus  arteriosus  begins  to  contract  immediately  after  respiration  is  estab- 
lished, becomes  completely  closed  from  the  fourth  to  the  tenth  day,  and  ultimately 
degenerates  into  an  impervious  cord,  which  serves  to  connect  the  left  pulmonary 
artery  to  the  concavity  of  the  arch  of  the  aorta. 

Of  the  umbilical  or  hypogastric  arteries,  the  portion  continued  on  to  the  bladder 
from  the  trunk  of  the  corresponding  internal  iliac  remains  pervious,  as  the  supe- 
rior vesical  artery ;  and  the  part  between  the  fundus  of  the  bladder  and  the 
umbilicus  becomes  obliterated  between  the  second  and  fifth  days  after  birth,  and 
forms  the  anterior  true  ligament  of  this  viscus. 

The  umbilical  vein  and  ductus  venosus  become  completely  obliterated  between 
the  second  and  fifth  days  after  birth,  and  ultimately  dwindle  to  fibrous  cords ;  the 
former  becoming  the  round  ligament  of  the  liver,  the  latfler  the  fibrous  cord, 
which,  in  the  adult,  may  be  traced  along  the  fissure  of  the  ductus  venosus. 


Organs  of  Voice  and  Eespiration. 


pi* 


355.— Side  View  of  the  Thyroid 
and  Cricoid  Cartilages. 


The  Larynx. 

The  Larynx  is  the  organ  of  voice,  placed  at  the  upper  part  of  the  air-passage. 
It  is  situated  between  the  trachea  and  base  of  the  tongue,  at  the  upper  and 
fore  part  of  the  neck,  where  it  forms  a  considerable  projection  in  the  middle  line. 
On  either  side  of  it  lie  the  great  vessels  of  the  neck;  behind,  it  forms  part  of 
the  boundary  of  the  pharynx,  and  is  covered  by  the  mucous  membrane  lining  this 
cavity. 

The  larynx  is  narrow  and  cylindrical  below,  but  broad  above,  where  it  presents 
the  form  of  a  triangular  box,  being  flattened  behind  and  at  the  sides,  whilst  in 
front  it  is  bounded  by  a  prominent  vertical  ridge.  It  is  composed  of  cartilages, 
connected  together  by  ligaments,  moved  by  numerous  muscles,  lined  by  mucous 
membrane,  and  supplied  with  vessels  and  nerves. 

The  cartilages  of  the  larynx  are  nine  in  number; — three  single,  and  three 
pairs : — 

Thyroid.  Two  Arytenoid. 

Cricoid.  Two  Cornicula  Laryngis. 

Epiglottis.  Two  Cuneiform. 

The  Tliyroid  (0vp«ov  dSof,  like  a  shield)  is  the  largest  cartilage  of  the  larynx. 
It  consists  of  two  lateral  lamellae  or  alae,  united  at  an  acute  angle  in  front,  forming 
a  vertical  projection  in  the  middle  line, 
which  is  prominent  above,  and  called  the 
pomum  Adami.  This  projection  is  subcu- 
taneous, more  distinct  in  the  male  than  in 
the  female,  and  occasionally  separated  from 
the  integument  by  a  bursa  mucosa. 

Each  lamella  is  quadrilateral  in  form. 
Its  outer  surface  presents  an  oblique 
ridge,  which  passes  downwards  and  for- 
wards from  a  tubercle,  situated  near  the 
root  of  the  superior  cornu.  This  ridge 
gives  attachment  to  the  Ster  no -thyroid 
and  Thyro-hyoid  muscles;  the  portion  of 
cartilage  included  between  it  and  the  poste- 
rior border,  to  part  of  the  Inferior  constric- 
tor muscle. 

The  inner  surface  of  each  ala  is  smooth, 
concave,  and  covered  by  mucous  membrane 
above  and  behind ;  but  in  front,  in  the  re- 
ceding angle  formed  by  their  junction,  are 
attached  the  epiglottis,  the  true  and  false 
chordae  vocales,  the  Thyro-arytenoid  and 
Thyro-epiglottidean  muscles. 

The  upper  border  of  the  thyroid  carti- 
lage is  deeply  notched  in  the  middle  line, 
immediately  above  the  pomum  Adami, 
whilst  on  either  side  it  is  slightly  concave. 
This  border  gives  attachment  throughout  its  whole  extent  to  the  thyro-hyoid 
membrane. 

The  lower  border  is  connected  to  the  cricoid  cartilage,  in  the  median  line,  by  the 
cri  co-thyroid  membrane ;  and,  on  each  side,  by  the  Crico-thyroid  muscle. 

703 


T04 


ORGANS   OF   YOICE   AND   RESPIRATION. 


Fig.  356.— The  Cartilajr^s  of  the  Larynx. 
Posterior  View. 


EPIGLOTTIS 


The  posterior  borders,  thick  and  rounded,  terminate,  above,  in  the  superior  cornua ; 
and,  below,  in  the  inferior  cornua.  The  two  superior  cornua  are  long  and  narrow, 
directed  backwards,  upwards,  and  inwards ;  and  terminate  in  a  conical  extremity, 
which  gives  attachment  to  the  thyro-hyoid  ligament.  The  two  inferior  cornua 
are  short  and  thick ;  they  pass  forwards  and  inwards,  and  present,  on  their  inner 
surfaces,  a  small,  oval,  articular  facet  for  articulation  with  the  side  of  the  cricoid 
cartilage.  The  posterior  border  receives  the  insertion  of  the  Stylo-ph.aryngeus 
and  Pal&to-pharyngeus  muscles  on  each  side. 

The  Cricoid  Cartilage  is  so 
called  from  its  resemblance  to 
a  signet-ring  (xpi'xoj  «5o$,  like 
a  ring).  It  is  smaller  but  thicker 
and  stronger  than  the  thyroid 
cartilage,  and  forms  the  lower 
and  back  part  of  the  cavity  of 
the  larynx. 

Its  anterior  half  is  narrow, 
convex,  affording  attachment  in 
front  and  at  the  sides  to  the 
Crico-thyroid  muscles,  and,  be- 
hind those,  to  part  of  the  Inferior 
constrictor. 

Its  posterior  half  is  very 
broad,  both  from  side  to  side 
and  from  above  downwards ;  it 
presents  in  the  middle  line  a 
vertical  ridge  for  the  attachment 
of  the  longitudinal  fibres  of  the 
oesophagus,  and  on  either  side 
of  this  is  a  broad  depression  for 
the  Crico-arytsenoideus  posticus 
muscle. 

At  the  point  of  junction  of 
the  two  halves  of  the  cartilage 
on  either  side,  is  a  small  round 
elevation,  for  articulation  with 
the  inferior  cornu  of  the  thyroid 
cartilage. 

The  lower  border  of  the  cricoid 
cartilage  is  horizontal,  and  con- 
nected to  the  upper  ring  of  the 
trachea  by  fibrous  membrane. 

Its  upper  border  is  directed  ob- 
liquely upwards  and  backwards, 
owing  to  the  great  depth  of  its 
posterior  surface.  It  gives  at- 
tachment, in  front,  to  the  crico- 
thyroid membrane  ;  at  the  sides, 
to  part  of  the  same  membrane 
and  to  the  lateral  Crico-aryte- 
noid  muscle ;  behind,  the  highest  point  of  the  upper  border  is  surmounted  on  each 
side  by  a  smooth,  oval  surface,  for  articulation  with  the  arytenoid  cartilage.  Be- 
tween the  articular  surfaces  is  a  slight  notch,  for  the  attachment  of  part  of  the 
Arytsenoideus  muscle. 

The  inner  surface  of  the  cricoid  cartilage  is  smooth,  and  lined  by  mucous  mem- 
brane. 

The  Arytenoid  Cartilages  are  so  called  from  the  resemblance  they  bear,  when 


ruKi/j^wi    CaTtlLafj, 


ARYTENOID- 


insertion  *f 
CRlCO-AfirT*NOiO 
P«ftTlCl.SkTlATi*AM» 


CRICOID 


Arl/ettla  r  facet 


Ar-t/eufftr  fnem, 
f<rr  Infer,  Ctirnu 
tf  T Ay  sold  C» 


Arytenoid  Cart9.".  Ao## 


CARTILAGES   OF   THE   LARYNX.  705 

approximated,  to  the  mouth  of  a  pitcher  (apyratva-tlSos,  like  a  pitcher).  They  are 
two  iii  number,  and  situated  at  the  upper  border  of  the  cricoid  cartilage,  at  the 
back  of  the  larynx.  Each  cartilage  is  pyramidal  in  form,  and  presents  for  ex- 
amination three  surfaces,  a  base,  and  an  apex. 

The  posterior  surface  is  triangular,  smooth,  concave,  and  lodges  part  of  the 
Arytenoid  muscle. 

The  anterior  surface,  somewhat  convex  and  rough,  gives  attachment  to  the 
Thyro-arytenoid  muscle,  and  to  the  false  vocal  cord. 

The  internal  surface  is  narrow,  smooth,  and  flattened,  covered  by  mucous  mem- 
brane, and  lies  almost  in  apposition  with  the  cartilage  of  the  opposite  side. 

The  base  of  each  cartilage  is  broad,  and  presents  a  concave  smooth  surface,  for 
articulation  with  the  cricoid  cartilage.  Of  its  three  angles,  the  external  one  is 
short,  rounded,  and  prominent,  receiving  the  insertion  of  the  posterior  and  lateral 
Crico-arytenoid  muscles.  The  anterior  one,  also  prominent,  but  more  pointed, 
gives  attachment  to  the  true  vocal  cord. 

The  apex  of  each  cartilage  is  pointed,  curved  backwards  and  inwards,  and 
surmounted  by  a  small  conical-shaped,  cartilaginous  nodule,  corniculum  laryngis 
(cartilage  of  Santorini).  This  cartilage  is  sometimes  united  to  the  arytenoid,  and 
serves  to  prolong  it  backwards  and  inwards.  To  it  is  attached  the  aryteno- 
epiglottidean  fold. 

The  cuneiform,  cartilages  (cartilages  of  Wrisberg)  are  two  small,  elongated, 
cartilaginous  bodies,  placed  one  on  each  side,  in  the  fold  of  mucous  membrane 
which  extends  from  the  apex  of  the  arytenoid  cartilage  to  the  side  of  the 
epiglottis  {aryteno-epigloltidean  fold);  they  give  rise  to  the  small  whitish  eleva- 
tions on  the  inner  surface  of  the  mucous  membrane,  just  in  front  of  the  arytenoid 
cartilages. 

The  epiglottis  is  a  thin  lamella  of  fibro-cartilage,  of  a  yellowish  color,  shaped 
like  a  leaf,  and  placed  behind  the  tongue  in  front  of  the  superior  opening  of 
the  larynx.  During  respiration,  its  direction  is  vertically  upwards,  its  free 
extremity  curving  forwards  towards  the  base  of  the  tongue ;  but  when  the  larynx 
is  drawn  up  beneath  the  base  of  the  tongue  during  deglutition,  it  is  carried 
downwards  and  backwards,  so  as  to  completely  close  the  opening  of  the  larynx. 
Its  free  extremity  is  broad  and  rounded ;  its  attached  end  is  long  and  narrow, 
and  connected  to  the  receding  angle  between  the  two  alas  of  the  thyroid  cartilage, 
just  below  the  median  notch,  by  a  long,  narrow,  ligamentous  band,  the  thyro- 
epiglottic ligament.  It  is  also  connected  to  the  posterior  surface  of  the  body  of 
the  hyoid  bone,  by  an  elastic  ligamentous  band,  the  hyo-epiglottic  ligament. 

Its  anterior  or  lingual  surface  is  curved  forwards  towards  the  tongue,  and 
covered  by  mucous  membrane,  which  is  reflected  on  to  the  sides  and  base  of 
this  organ,  forming  a  median  and  two  lateral  folds,  the  glosso-epiglottidean 
ligaments. 

Its  posterior  or  laryngeal  surface  is  smooth,  concave  from  side  to  side,  convex 
from  above  downwards,  and  covered  by  mucous  membrane;  when  this  is  removed, 
the  surface  of  the  cartilage  is  seen  to  be  studded  with  a  number  of  small  mucous 
glands,  which  are  lodged  in  little  pits  upon  its  surface.  To  its  sides  the  aryteno- 
epiglottidean  folds  are  attached. 

Structure.  The  epiglottis,  cuneiform  cartilages,  and  cornicula  laryngis  are 
composed  of  yellow  cartilage,  which  shows  little  tendency  to  ossification ;  but  the 
other  cartilages  resemble  in  structure  the  costal  cartilages,  becoming  more  or  less 
ossified  in  old  age. 

Ligaments.  The  ligaments  of  the  larynx  are  extrinsic,  as  those  connecting  the 
thyroid  cartilage  with  the  os  hyoides;  and  intrinsic,  as  those  connecting  the 
several  cartilaginous  segments  to  each  other. 

The  ligaments  connecting  the  thyroid  cartilage  with  the  os  hyoides  are 
three  in  number; — the  thyro-hyoid  membrane,  and  the  two  lateral  thyro-hyoid 
ligaments. 

The  thyro-hyoid  membrane  is  a  broad,  fibro-elastic,  membranous  layer,  attached 
45 


•706 


ORGANS   OF   VOICE    AND   RESPIRATION 


below  to  the  upper  border  of  the  thyroid  cartilage,  and  above  to  the  upper  border 
of  the  inner  surface  of  the  hyoid  bone ;  being  separated  from  the  posterior  surface 
of  the  hyoid  bone  by  a  synovial  bursa.  It  is  thicker  in  the  middle  line  than  at 
either  side,  in  which  situation  it  is  pierced  by  the  superior  laryngeal  vessels  and 
nerve. 

The  two  lateral  thyro-hyoid  ligaments  are  rounded,  elastic  cords,  which  pass 
between  the  superior  cornua  of  the  thyroid  cartilage,  to  the  extremities  of  the 
greater  cornua  of  the  hyoid  bone.  A  small  cartilaginous  nodule  (cartilago  triticea), 
sometimes  bony,  is  found  in  each. 

The  ligaments  connecting  the  thyroid  cartilage  to  the  cricoid  are  also  three  in 
number ;  the  crico-thyroid  membrane,  and  the  capsular  ligaments  and  synovial 
membrane. 

The  crico-thyroid  membrane  is  composed  mainly  of  yellow  elastic  tissue.  It  is 
of  triangular  shape ;  thick  in  front,  where  it  connects  together  the  contiguous 
margins  of  the  thyroid  and  cricoid  cartilages ;  thinner  at  each  side,  where  it  ex- 
tends from  the  superior  border  of  the  cricoid  cartilage  to  the  inferior  margin  of 
the  true  vocal  cords,  with  which  it  is  closely  united  in  front. 

The  anterior  portion  of  the  crico-thyroid  membrane  is  convex,  concealed  on 
each  side  by  the  Crico-thyroid  muscle,  subcutaneous  in  the  middle  line,  and  crossed 
horizontally  by  a  small  anastomotic  arterial  arch,  formed  by  the  junction  of  the 
crico-thyroid  branches  on  either  side. 

The  lateral  portions  are  lined  internally  by  mucous  membrane,  and  covered  by 
the  lateral  Crico-arytenoid  and  Thyro-arytenoid  muscles. 

A  capsular  ligament  incloses  the  articulation  of  the  inferior  cornu  of  the 
thyroid  with  the  side  of  the  cricoid,  on  each  side.  The  articulation  is  lined 
by  synovial  membrane. 

The  ligaments  connecting  the  arytenoid  cartilages  to  the  cricoid  are  two  thin 
and  loose  capsular  ligaments  connecting  together  the  articulating  surfaces,  lined 
internally  by  synovial  membrane,  and  strengthened  behind  by  a  strong  posterior 
crico-arytenoid  ligament,  which  extends  from  the  cricoid  to  the  inner  and  back 
part  of  the  base  of  the  arytenoid  cartilage. 

The  ligaments  of  the  epiglottis  are  the  hyo-epiglottic,  the  thyroepiglottic,  and 
the  three  glosso-epiglottic  folds  of  mucous  membrane  which  connect  the  epiglottis 
to  the  sides  and  base  of  the  tongue.     The  latter  have  been  already  described. 

The  hyo-epiglottic  ligament  is  an  elastic  fibrous  band,  which  extends  from  the 

anterior  surface  of  the  epi- 
Fig.  357.— The  Larynx  and  adjacent  parts,  glottis,  near  its  apex,  to  the 

posterior  surface  of  the  body 
of  the  hyoid  bone. 

The  thyroepiglottic  ligament 
is  a  long,  slender,  elastic  cord, 
which  connects  the  apex  of  the 
epiglottis  with  the  receding 
angle  of  the  thyroid  cartilage, 
immediately  beneath  the  me- 
dian notch,  above  the  attach- 
ment of  the  vocal  cords. 

Interior  of  the  Larynx.  The 
superior  aperture  of  the  larynx 
(fig.  357)  is  a  triangular  or 
cordiform  opening,  narrow 
in  front,  wide  behind,  and 
sloping  obliquely  downwards 
and  backwards.  It  is  bounded 
in  front  by  the  epiglottis; 
behind,  by  the  apices  of  the 
arytenoid  cartilages,  and  the  cornicula  laryngis ;  and  laterally,  by  a  fold  of  mucous 


seen  from  above. 


Arytenoid-  cart  ■ 


CAVITY   OF   LARYNX— GLOTTIS— VOCAL   CORDS. 


TOT 


membrane,  inclosing  ligamentous  and  muscular  fibres,  stretched  between  the  sides 
of  the  epiglottis  and  the  apex  of  the  arytenoid  cartilage :  these  are  the  aryteno- 
epiglottidean  folds,  on  the  margins  of  which  the  cuneiform  cartilages  form  a  more 
or  less  distinct  whitish  prominence. 

The  cavity  of  the  larynx  extends  from  the  aperture  behind  the  epiglottis  to  the 
lower  border  of  the  cricoid  cartilage.  It  is  divided  into  two  parts  by  the 
projection  inwards  of  the  vocal  cords  and  Thyro-arytenoid  muscles;  between 
the  two  cords  is  a  long  and  narrow  triangular  fissure  or  chink,  the  glottis  or  rima 
ghttidis.  The  portion  of  the  cavity  of  the  larynx  above  the  glottis  is  broad  and 
triangular  in  shape  above,  and  corresponds  to  the  interval  between  the  alas  of  the 
thyroid  cartilage ;  the  portion  below  the  glottis  is  at  first  elliptical,  and,  lower 
down,  of  a  circular  form. 

The  glottis  or  rima  ghttidis  is  the  interval  between  the  inferior  vocal  cords. 
The  two  superior  or  false  vocal  cords  are  placed  above  the  latter,  and  are  formed 
almost  entirely  hj  a  folding  inwards  of  the  mucous  membrane  ;  whilst  the  two 
inferior  or  true  vocal  cords  are  thick,  strong,  and  formed  partly  by  mucous  mem- 
brane, and  partly  by  ligamentous  fibres.  Between  the  true  and  false  vocal  cords, 
on  each  side,  is  an  oval  depression,  the  sinus  or  ventricle  of  the  larynx,  which 
leads  upwards,  on  the  outer  side  of  the  superior  vocal  cord,  into  a  csecal  pouch  of 
variable  size,  the  sacculus  laryngis. 

The  rima  ghttidis  is  the  narrow  fissure  or  chink  between  the  inferior  or  true 
vocal  cords.  It  is  the  narrowest  part  of  the  cavity  of  the  larynx,  and  cor- 
responds to  the  level  of  the  arytenoid 


K* 


358. — Vertical  Section  of  the  Larynx 
and  upper  part  of  the  Trachea. 


irybncd 
wit.' 


cartilages.  Its  length,  in  the  male, 
measures  rather  less  than  an  inch,  its 
breadth  when  dilated  varying  at  its 
widest  part  from  a  third  to  half  an 
inch.  In  the  female,  these  measure- 
ments are  less  by  two  or  three  lines. 
The  form  of  the  glottis  varies.  In  a 
quiescent  state,  it  is  a  narrow  fissure, 
a  little  enlarged  and  rounded  behind. 
In  inspiration,  it  is  widely  open,  some- 
what triangular,  the  base  of  the  triangle 
directed  backwards,  and  corresponding 
to  the  space  between  the  separated 
arytenoid  cartilages.  In  expiration, 
it  is  smaller  than  during  inspiration. 
When  sound  is  produced,  it  is  more 
narrowed,  the  margins  of  the  aryte- 
noid cartilages  being  brought  into 
contact,  and  the  edges  of  the  vocal 
cords  approximated  and  made  parallel ; 
the  degree  of  approximation  and  ten- 
sion corresponding  to  the  height  of 
the  note  produced. 

The  superior  or  false  vocal  cords,  so 
called  because  they  are  not  directly 
concerned  in  the  production  of  the 
voice,  are  two  folds  of  mucous  mem- 
brane,  inclosing    a   delicate    narrow 

fibrous  band,  the  superior  thyro-arytenoid  ligament.  This  ligament  consists  of  a 
thin  band  of  elastic  tissue,  attached  in  front  to  the  angle  of  the  thyroid  cartilage 
below  the  epiglottis,  and  behind  to  the  anterior  surface  of  the  arytenoid  cartilage. 
The  lower  border  of  this  ligament,  inclosed  in  mucous  membrane,  forms  a  free 
crescentic  margin,  which  constitutes  the  upper  boundary  of  the  ventricle  of  the 
larynx. 


708  ORGANS   OF   VOICE   AND   RESPIRATION. 

The  inferior  or  true  vocal  cords,  so  called  from  their  being  concerned  in  the 
production  of  sound,  are  two  strong  fibrous  bands  {inferior  thyro-arytenoid  liga- 
ments), covered  externally  by  a  thin  layer  of  mucous  membrane.  Each  ligament 
consists  of  a  band  of  yellow  elastic  tissue,  attached  in  front  to  the  depression 
between  the  two  alae  of  the  thyroid  cartilage,  and  behind  to  the  anterior  an°-le  of 
the  base  of  the  arytenoid.  Its  lower  border  is  continuous  with  the  thin  lateral 
part  of  the  crico-thyroid  membrane.  Its  upper  border  forms  the  lower  boundary 
of  the  ventricle  of  the  larynx.  Externally,  the  Thyro-arytaenoideus  muscle  lies 
parallel  with  it.  It  is  covered  internally  by  mucous  membrane,  which  is  extremely 
thin,  and  closely  adherent  to  its  surface. 

The  ventricle  of  the  larynx  is  an  oblong  fossa,  situated  between  the  superior 
and  inferior  vocal  cords  on  each  side,  and  extending  nearly  their  entire  length. 
This  fossa  is  bounded  above  by  the  free  crescentic  edge  of  the  superior  vocal 
cord ;  below,  by  the  straight  margin  of  the  true  vocal  cord ;  externally,  by  the 
corresponding  Thyro-arytaenoideus  muscle.  The  anterior  part  of  the  ventricle 
leads  up  by  a  narrow  opening  into  a  cascal  pouch  of  mucous  membrane  of  variable 
size,  called  the  laryngeal  pouch. 

The  sacculus  laryngis  or  laryngeal  pouch  is  a  membranous  sac,  placed  between 
the  superior  vocal  cord  and  the  inner  surface  of  the  thyroid  cartilage,  occasionally 
extending  as  far  as  its  upper  border ;  it  is  conical  in  form,  and  curved  slightly 
backwards,  resembling  in  form  a  Phrygian  cap.  On  the  surface  of  its  mucous 
membrane  are  the  openings  of  sixty  or  seventy  small  follicular  glands,  which  are 
lodged  in  the  submucous  areolar  tissue.  This  sac  is  inclosed  in  a  fibrous  capsule, 
continuous  below  with  the  superior  thyro-arytenoid  ligament;  its  laryngeal 
surface  is  covered  by  the  Arytaeno-epiglottideus  inferior  muscle  {Compressor  sac- 
culi  laryngis,  Hilton),  whilst  its  exterior  is  covered  by  the  Thyro-epiglottideus 
muscle.  These  muscles  compress  the  sacculus  laryngis,  and  discharge  the  secre- 
tion it  contains  upon  the  chordae  vocales,  the  surfaces  of  which  it  is  intended  to 
lubricate. 

Muscles  of  the  Larynx.  The  intrinsic  muscles  of  the  larynx  are  eight  in 
number ;  five  of  which  are  the  muscles  of  the  chordae  vocales  and  rima  glottidis, 
and  three  are  connected  with  the  epiglottis. 

The  five  muscles  of  the  chordae  vocales  and  rima  glottidis  are  the 

Crico-thyroid.  Arytaenoideus. 

Crico-arytaenoideus  posticus.  Thyro-arytaenoideus. 

Crico-aryta3noideus  lateralis. 

The  Crico-thyroid  is  triangular  in  form,  and  situated  at  the  fore  part  and  side 
of  the  cricoid  cartilage.  It  arises  from  the  front  and  lateral  part  of  the  cricoid 
cartilage ;  its  fibres  diverge,  passing  obliquely  upwards  and  outwards,  to  be 
inserted  into  the  lower  and  inner  borders  of  the  thyroid  cartilage ;  from  near  the 
median  line  in  front,  as  far  back  as  the  inferior  cornu. 

The  inner  borders  of  these  two  muscles  are  separated  in  the  middle  line  by  a 
triangular  interval,  occupied  by  the  crico-thyroid  membrane. 

The  Crico-arytaenoideus  posticus  arises  from  the  broad  depression  occupying 
each  lateral  half  of  the  posterior  surface  of  the  cricoid  cartilage ;  its  fibres  pass 
upwards  and  outwards,  and  converge  to  be  inserted  into  the  outer  angle  of  the 
base  of  the  arytenoid  cartilage.  The  upper  fibres  are  nearly  horizontal,  the 
middle  oblique,  and  the  lower  almost  vertical.1 

1  Dr.  Merkel,  of  Leipsic,  has  lately  described  a  muscular  slip  which  occasionally  extends 
between  the  outer  border  of  the  posterior  surface  of  the  cricoid  cartilage,  and  the  posterior  mar- 
gin of  the  inferior  cornu  of  the  thyroid  ;  this,  he  calls  the  "  Musculus  kerato-cricoideus."  It  is 
not  found  in  every  larynx,  and  when  present  exists  usually  only  on  one  side,  but  is  occasionally 
found  on  both  sides.  Mr.  Turner  (Edinburgh  Medical  Journal,  Feb.  I860)  states  that  it  is  found 
in  the  ratio  of  21.8  per  cent.  Its  action  is  to  fix  the  lower  horn  of  the  thyroid  cartilage  backwards 
and  downwards,  opposing  in  some  measure  the  part  of  the  crico-thyroid  muscle  connected  to  the 
anterior  manrin  of  the  horn. 


MUSCLES   OF   THE   LARYNX. 


709 


Fig.  359. — Muscles  of  Larynx,  Side  View. 
Eight  Ala  of  Thyroid  Cartilage  removed. 


Corni ' aila  ^ 
larvnais 


Articular  facet 
jOrlitfiruiT  Cornu.  of 
Thyroid  CartsL 


The  Crico-arytsenoideus  lateralis  is  smaller  than  the  preceding,  and  of  an 
oblong  form.  It  arises  from  the  upper  border  of  the  side  of  the  cricoid  cartilage, 
and,  passing  obliquely  upwards  and 
backwards,  is  inserted  into  the  outer 
angle  of  the  base  of  the  arytenoid 
cartilage,  in  front  of  the  preceding 
muscle. 

The  Thyro-arytsenoideus  is  a  broad, 
flat  muscle,  which  lies  parallel  with 
the  outer  side  of  the  true  vocal  cord. 
It  arises  in  front  from  the  lower 
half  of  the  receding  angle  of  the 
thyroid  cartilage,  and  from  the 
crico-thyroid  membrane.  Its  fibres 
pass  horizontally  backwards  and 
outwards,  to  be  inserted  into  the 
base  and  anterior  surface  of  the 
arytenoid  cartilage.  This  muscle 
consists  of  two  fasciculi.  The  in- 
ferior, the  thickest,  is  inserted  into 
the  anterior  angle  of  the  base  of  the 
arytenoid  cartilage,  and  into  the  ad- 
jacent portion  of  its  anterior  surface; 
it  lies  parallel  with  the  true  vocal 
cord,  to  which  it  is  occasionally  ad- 
herent. The  superior  fasciculus, 
the  thinnest,  is  inserted  into  the 
anterior  surface  and  outer  border  of 
the  arytenoid  cartilage  above  the 
preceding  fibres ;  it  lies  on  the  outer 
side  of' the  sacculus  laryngis,  imme- 
diately beneath  its  mucous  lining. 

The  Aryteenoideus  is  a  single 
muscle,  filling  up  the  posterior  con- 
cave surface  of  the  arytenoid  carti- 
lages. It  arises  from  the  posterior 
surface  and  outer  border  of  one 
arytenoid  cartilage,  and  is  inserted 
into  the  corresponding  parts  of  the 
opposite  cartilage.  It  consists  of 
three  planes  of  fibres ;  two  oblique, 
and  one  transverse.  The  oblique 
fibres,  the  most  superficial,  form 
two  fasciculi,  which  pass  from  the 
base  of  one  cartilage  to  the  apex  of 
the  opposite  one.  The  transverse 
fibres,  the  deepest  and  most  nume- 
rous, pass  transversely  across  be- 
tween the  two  cartilages ;  hence  the 
Aryteenoideus  was  formerly  con- 
sidered as  several  muscles,  under 
the  names  of  transversa  and  obliqui. 
A  few  of  the  oblique  nbres  are  oc- 
casionally continued  round  the  outer 
margin  of  the  cartilage,  and  blend 
with  the  Thyro-arytenoid  or  the 
Arytaeno-epiglottideus  muscle. 


Fig.  360. — Interior  of  the  Larynx,  seen  from 
above.     (Enlarged.) 


•riO  ORGANS   OF   VOICE   AND   RESPIRATION. 

The  muscles  of  the  epiglottis  are  the 

Thyro-epiglottideus. 
Arytseno-epiglottideus  superior. 
Arytseno-epiglottideus  inferior. 

The  TIiyro-epAglottideus  is  a  delicate  fasciculus,  which  arises  from  the  inner  surface 
of  the  thyroid  cartilage,  just  external  to  the  origin  of  the  Thyro-arytenoid  muscle, 
and.  spreading  out  upon  the  outer  surface  of  the  sacculus  laryngis,  some  of  its 
fibres  are  lost  in  the  aryteno-epiglottidean  fold,  whilst  others  are  continued  for- 
wards to  the  margin  of  the  epiglottis  {Depressor  epiglottidis). 

The  Arytseno-epiglottideus  superior  consists  of  a  few  delicate  muscular  fasciculi, 
which  arise  from  the  apex  of  the  arytenoid  cartilage,  and  become  lost  in  the  fold 
of  mucous  membrane  extending  between  the  arytenoid  cartilage  and  side  of  the 
epiglottis  (aryteno-epiglottidean  folds). 

The  Arytseno-epiglottideus  inferior  (Compressor  sacculi  laryngis,  Hilton)  arises 
from  the  arytenoid  cartilage,  just  above  the  attachment  of  the  superior  vocal  cord ; 
passing  forwards  and  upwards,  it  spreads  out  upon  the  inner  and  upper  part  of 
the  sacculus  laryngis,  and  is  inserted,  by  a  broad  attachment,  into  the  margin  of  the 
epiglottis.  This  muscle  is  separated  from  the  preceding  by  an  indistinct  areolar 
interval. 

Actions.  In  considering  the  actions  of  the  muscles  of  the  larynx,  they  may  be 
conveniently  divided  into  two  groups,  viz.:  1.  Those  which  open  and  close  the 
glottis.     2.  Those  which  regulate  the  degree  of  tension  of  the  vocal  cords. 

1.  The  muscles  which  open  the  glottis  are  the  Crico-aryttenoidei  postici ;  and 
those  which  close  it  are  the  Arytamoideus,  and  the  Crico-arytsenoidei  laterales. 
2.  The  muscles  which  regulate  the  tension  of  the  vocal  cords  are  the  Crico- 
thyroidei,  which  make  tense  and  elongate  them,  and  the  Thyro-arytsenoidei,  which 
relax  and  shorten  them.  The  Thyro-epiglottideus  is  a  depressor  of  the  epiglottis, 
and  the  Arytseno-epiglottidei  constrict  the  superior  aperture  of  the  larynx,  com- 
press the  sacculi  laryngis,  and  empty  them  of  their  contents. 

The  Crico-arytamoidei  postici  separate  the  chorda?  vocales,  and,  consequently,  open  the  glottis, 
by  rotating  the  base  of  the  arytenoid  cartilages  outwards  and  backwards  ;  so  that  their  anterior 
angles,  and  the  ligaments  attached  to  them,  become  widely  separated,  the  vocal  cords,  at  the 
same  time,  being  made  tense. 

The  Crico-arytamoidei  laterales  close  the  glottis,  by  rotating  the  base  of  the  arytenoid  carti- 
lages inwards,  so  as  to  approximate  their  anterior  angles. 

The  Arytamoideus  muscle  approximates  the  arytenoid  cartilages,  and  thus  closes  the  opening 
of  the  glottis,  especially  at  its  back  part. 

The  Crico-thyroid  muscles  effect  the  tension  and  elongation  of  the  vocal  cords,  by  drawing 
down  the  thyroid  cartilage  over  the  cricoid. 

The  Thyro-arytamoidei  muscles  draw  the  arytenoid  cartilages,  together  with  the  part  of  the 
cricoid  to  which  they  are  connected,  forwards  towards  the  thyroid,  and  thus  shorten  and  relax 
the  vocal  cords. 

The  Thyro-epiglottidei  depress  the  epiglottis,  and  assist  in  compressing  the  sacculi  laryngis. 
The  Arytazno-epiglottideus  superior  constricts  the  superior  aperture  of  the  larynx,  when  it  is 
drawn  upwards,  during  deglutition,  and  the  opening  closed  by  the  epiglottis.  The  Arylamo- 
cpiglottideus  inferior,  together  with  some  fibres  of  the  Thyro-arytaenoidei,  compress  the  sacculus 
laryngis. 

The  Mucous  Membrane  of  the  Larynx  is  continuous,  above,  with  that  lining  the 
mouth  and  pharynx,  and  is  prolonged  through  the  trachea  and  bronchi  into  the 
lungs.  It  lines  both  surfaces  of  the  epiglottis,  to  which  it  is  closely  adherent, 
and  forms  the  aryteno-epiglottidean  folds,  which  encircle  the  superior  aperture  of 
the  larynx.  It  lines  the  whole  of  the  cavity  of  the  larynx ;  forms,  by  its  redu- 
plication, the  chief  part  of  the  superior  or  false  vocal  cord ;  and,  from  the  ven- 
tricle, is  continued  into  the  sacculus  laryngis.  It  is  then  reflected  over  the  true 
vocal  cords,  where  it  is  thin,  and  very  intimately  adherent,  covers  the  inner  sur- 
face of  the  crico-thyroid  membrane,  and  cricoid  cartilage,  and  is  ultimately  con- 
tinuous with  the  lining  membrane  of  the  trachea.  It  is  covered  with  columnar 
ciliated  epithelium,  below  the  superior  vocal  cord ;  but,  above  this  point,  the  ciliae 
are  found  only  in  front,  as  high  as  the  middle  of  the  epiglottis.  In  the  rest  of  its 
extent,  the  epithelium  is  of  the  squamous  variety. 


TRACHEA. 


m 


Glands.  The  mucous  membrane  of  the  larynx  is  furnished  with  numerous 
muciparous  glands,  the  orifices  of  which  are  found  in  nearly  every  part ;  they  are 
very  numerous  upon  the  epiglottis,  being  lodged  in  little  pits  in  its  substance ; 
they  are  also  found  in  large  numbers  along  the  posterior  margin  of  the  aryteno- 
epiglottidean  fold,  in  front  of  the  arytenoid  cartilages,  where  they  are  termed  the 
arytenoid  glands.  They  exist  also  in  large  numbers  upon  the  inner  surface  of  the 
sacculus  laryugis.     None  are  found  on  the  vocal  cords. 

Vessels  and  Nerves.  The  arteries  of  the  larynx  are  the  laryngeal  branches 
derived  from  the  superior  and  inferior  thyroid.  The  veins  empty  themselves  into 
the  superior,  middle,  and  inferior  thyroid  veins.  The  lymphatics  terminate  in  the 
deep  cervical  glands.  The  nerves  are  the  superior  laryngeal,  and  the  inferior  or 
recurrent  laryngeal  branches  of  the  pneumogastric  nerves,  joined  by  filaments  from 
the  sympathetic.  The  superior  laryngeal  nerves  supply  the  mucous  membrane  of 
the  larynx,  and  the  Crico-thyroid  muscles.  The  inferior  laryngeal  nerves  supply 
the  remaining  muscles.     The  Arytenoid  muscle  is  supplied  by  both  nerves. 

The  Trachea. 
The  trachea  or  air-tube  is  a  cartilaginous  and  membranous  cylindrical  tube, 
Fig.  361. — Front  View  of  Cartilages  of  Larynx,  the  Trachea  and  Bronchi. 


712  ORGANS    OF   VOICE    AND   RESPIRATION. 

flattened  posteriorly,  extending  from  the  lower  part  of  the  larynx,  on  a  level  with 
the  fifth  cervieal  vertebra,  to  opposite  the  third  dorsal,  where  it  divides  into  the 
two  bronchi,  one  for  each  lung.  The  trachea  measures  about  four  inches  and  a 
half  in  length ;  its  diameter,  from  side  to  side,  is  from  three-quarters  of  an  inch  to 
an  inch,  being  always  greater  in  the  male  than  in  the  female. 

Relations.  The  anterior  surface  of  the  trachea  is  convex,  and  covered,  in  the 
neck,  from  above  downwards,  by  the  isthmus  of  the  thyroid  gland,  the  inferior 
thyroid  veins,  the  arteria  thyroidea  ima  (when  that  vessel  exists),  the  Sterno- 
hyoid and  Sterno-thyroid  muscles,  the  cervical  fascia  (in  the  interval  between 
these  muscles),  and,  more  superficially,  by  the  anastomosing  branches  between  the 
anterior  jugular  veins;  in  the  thorax,  it  is  covered  from  before  backwards  by  the 
first  piece  of  the  sternum,  the  remains  of  the  thymus  gland,  the  arch  of  the  aorta, 
the  innominate  and  left  carotid  arteries,  and  the  deep  cardiac  plexus.  It  lies 
upon  the  oesophagus,  which  is  directed  to  the  left,  near  the  arch  of  the  aorta ; 
laterally,  in  the  neck,  it  is  in  relation  with  the  common  carotid  arteries,  the  lateral 
lobes  of  the  thyroid  gland,  the  inferior  thyroid  arteries,  and  recurrent  laryngeal 
nerves ;  and,  in  the  thorax,  it  lies  in  the  interspace  between  the  pleuras,  having  the 
pneumogastric  nerve  on  each  side  of  it. 

The  Right  Bronchus,  wider,  shorter,  and  more  horizontal  in  direction  than  the 
left,  is  about  an  inch  in  length,  and  enters  the  right  lung,  opposite  the  fourth  dorsal 
vertebra.  The  vena  azygos  arches  over  it,  from  behind ;  and  the  right  pulmonary 
artery  lies  below,  and  then  in  front  of  it. 

The  Left  Bronchus  is  smaller,  more  oblique,  and  longer  than  the  right,  being 
nearly  two  inches  in  length.  It  enters  the  root  of  the  left  lung,  opposite  the  fifth 
dorsal  vertebra,  about  an  inch  lower  than  the  right  bronchus.  It  crosses  in  front 
of  the  oesophagus,  the  thoracic  duct,  and  the  descending  aorta ;  passes  beneath  the 
arch  of  the  aorta,  and  has  the  left  pulmonary  artery  lying  at  first  above,  and  then 
in  front  of  it.  If  a  transverse  section  is  made  across  the  trachea,  a  short  distance 
above  its  point  of  bifurcation,  and  a  bird's-eye  view  taken  of  its  interior  (fig.  362), 

the  septum  placed  at  the  bottom  of 

Fig.    362. — Transverse    Section   of  the  Trachea,  ,-,  •     ,   \  ,•  ,\       .         -i  i  • 

just  above  its   bifurcation,  with  a  bird's-eye  tn.ls  tube>  separating  the  two  bronchi, 

view  of  the  interior.  will  be  seen  to  occupy  the  left  of  the 

jn„£.  median  line,  as  was  first  shown  by  Mr. 

Goodall,  of  Dublin,  so  that  any  solid 
body  descending  the  trachea,  by  virtue 
of  the  laws  of  gravity,  would  naturally 
be  directed  towards  the  right  bronchus, 
and  this  tendency  is  undoubtedly  aided 
by  the  larger  size  of  this  tube,  as 
compared  with  its  fellow.  This  fact 
serves  to  explain  why  a  foreign  sub- 
stance in  the  trachea  almost  universally  falls  into  the  right  bronchus. 

The  trachea  is  composed  of  imperfect  cartilaginous  rings,  fibrous  membrane, 
muscular  fibres,  longitudinal  yellow  elastic  fibres,  mucous  membrane,  and  glands. 
The  Cartilages  vary  from  sixteen  to  twenty  in  number ;  each  forms  an  imper- 
fect ring,  which  surrounds  about  two-thirds  of  the  cylinder  of  the  trachea,  being 
imperfect  behind,  where  the  tube  is  completed  by  fibrous  membrane.  The  carti- 
lages are  placed  horizontally  above  each  other,  separated  by  narrow  membranous 
intervals.  They  measure  about  two  lines  in  depth,  and  half  a  line  in  thickness. 
Their  outer  surfaces  are  flattened,  but,  internally,  they  are  convex,  from  being 
thicker  in  the  middle  than  at  the  margins.  The  cartilages  are  connected  together, 
at  their  margins,  by  an  elastic  fibrous  membrane,  which  covers  both  their  surfaces ; 
and  in  the  space  between  their  extremities,  behind,  forms  a  distinct  layer.  The 
peculiar  cartilages  are  the  first  and  the  last. 

The  first  cartilage  is  broader  than  the  rest,  and  sometimes  divided  at  one  end ; 
it  is  connected  by  fibrous  membrane  with  the  lower  border  of  the  cricoid  cartilage, 
with  which,  or  with  the  succeeding  cartilage,  it  is  sometimes  blended. 


TRACHEA.  113 

The  last  cartilage  is  thick  and  broad  in  the  middle,  in  consequence  of  its  lower 
border  being  prolonged  downwards,  and,  at  the  same  time,  curved  backwards,  at 
the  point  of  bifurcation  of  the  trachea.  It  terminates  on  each  side  in  an  imper- 
fect ring,  which  incloses  the  commencement  of  the  bronchi.  The  cartilage  above 
the  last  is  somewhat  broader  than  the  rest  at  its  centre.  Two  or  more  of  the 
cartilages  often  unite,  partially  or  completely,  and  are  sometimes  bifurcated  at 
their  extremities.  They  are  highly  elastic,  and  seldom  ossify,  even  in  advanced 
life.  In  the  right  bronchus,  the  cartilages  vary  in  number  from  six  to  eight ;  in 
the  left,  from  nine  to  twelve.  They  are  shorter  and  narrower  than  those  of  the 
trachea. 

The  Muscular  Fibres  are  disposed  in  two  layers,  longitudinal  and  transverse. 
The  longitudinal  fibres  are  the  most  external,  and  arise  by  minute  tendons  from 
the  termination  of  the  tracheal  cartilages,  and  from  the  fibrous  membrane. 

The  transverse  fibres,  the  most  internal,  form  a  thin  layer,  which  extends  trans- 
versely between  the  ends  of  the  cartilages,  at  the  posterior  part  of  the  trachea. 
The  muscular  fibres  are  of  the  unstriped  variety. 

The  Elastic  Fibres  are  situated  beneath  the  mucous  membrane,  inclosing  the 
entire  cylinder  of  the  trachea;  they  are  most  abundant  at  its  posterior  part,  where 
they  are  collected  into  longitudinal  bundles. 

The  Mucous  Membrane  lining  the  tube  is  covered  with  columnar  ciliated 
epithelium.     It  is  continuous  with  that  lining  the  larynx. 

The  Tracheal  Glands  are  found  in  great  abundance  at  the  posterior  part  of  the 
trachea.  They  are  small,  flattened,  ovoid  bodies,  placed  between  the  fibrous  and 
muscular  coats,  each  furnished  with  an  excretory  duct,  which  opens  on  the  surface 
of  the  mucous  membrane.  Some  glands  of  smaller  size  are  also  found  at  the 
sides  of  the  trachea,  between  the  layers  of  fibrous  tissue  connecting  the  rings, 
and  others  immediately  beneath  the  mucous  coat.  The  secretion  from  these  glands 
serves  to  lubricate  the  inner  surface  of  the  trachea. 

Vessels  and  Nerves.  The  trachea  is  supplied  with  blood  by  the  inferior  thyroid 
arteries.  The  veins  terminate  in  the  thyroid  venous  plexus.  The  nerves  are 
derived  from  the  pneumogastric  and  its  recurrent  branches,  and  from  the  sympa- 
thetic. 

Surgical  Anatomy.  The  air-passage  may  be  opened  in  three  different  situations  ;  through  the 
crico-thyroid  membrane  (laryngotomy),  through  the  cricoid  cartilage  and  upper  ring  of  the 
trachea  (laryngo4racheotomy),  or  through  the  trachea  below  the  isthmus  of  the  thyroid  gland 
(tracheotomy).  The  student  should,  therefore,  carefully  consider  the  relative  anatomy  of  the 
air-tube  in  each  of  these  situations. 

Beneath  the  integument  of  the  laryngo-tracheal  region,  on  either  side  of  the  median  line,  are 
the  two  anterior  jugular  veins.  Their  size  and  position  vary;  there  is  nearly  always  one,  and 
frequently  two :  at  the  lower  part  of  the  neck  they  diverge,  passing  beneath  the  Sterno-mastoid 
muscles,  and  are  frequently  connected  by  a  transverse  communicating  branch.  These  veins 
should,  if  possible,  always  be  avoided  in  any  operation  on-  the  larynx  or  trachea.  If  cut  through, 
considerable  hemorrhage  is  the  result. 

Beneath  the  cervical  fascia  are  the  Sterno-hyoid  and  Sterno-thyroid  muscles,  the  contiguous 
edges  of  the  former  being  near  the  median  line,  and  beneath  these  muscles  the  following  parts 
are  met  with,  from  above  downwards ;  the  thyroid  cartilage,  the  crico-thyroid  membrane,  the 
cricoid  cartilage,  the  trachea,  and  the  isthmus  of  the  thyroid  gland. 

The  crico-thyroid  space  is  very  superficial,  and  may  be  easily  felt,  beneath  the  skin,  as  a 
depressed  spot,  about  an  inch  below  the  pomum  Adami :  it  is  crossed  transversely  by  a  small 
artery,  the  crico-thyroid,  the  division  of  which  is  seldom  accompanied  by  any  troublesome 
hemorrhage. 

The  isthmus  of  the  thyroid  gland  usually  crosses  the  second  and  third  rings  of  the  trachea ; 
above  it,  is  found  a  large  transverse  communicating  branch  between  the  superior  thyroid  veins, 
and  the  isthmus  is  covered  by  a  venous  plexus,  formed  between  the  thyroid  veins  of  opposite 
sides.  On  the  sides  of  the  thyroid  gland,  and  below  it,  the  veins  converge  to  a  single  median 
vessel,  or  to  two  trunks  which  descend  along  the  median  line  of  the  front  of  the  trachea,  to  open 
into  the  innominate  veins  by  valved  orifices.  In  the  infant,  the  thymus  gland  ascends  a  variable 
distance  along  the  front  of  the  trachea ;  and  the  innominate  artery  crosses  this  tube  obliquely  at 
the  root  of  the  neck,  from  left  to  right.  The  arteria  thyroidea  ima,  when  that  vessel  exists, 
passes  from  below  upwards  along  the  front  of  the  trachea.  The  upper  part  of  the  trachea  lies 
comparatively  superficial ;  but  the  lower  part  passes  obliquely  downwards  and  backwards,  so  as 
to  be  deeply  placed  between  the  converging  Sterno-mastoid  muscles.     In  the  child,  the  trachea 


714 


ORGANS   OF   VOICE   AND   RESPIRATION. 


is  smaller,  more  deeply  placed,  and  more  movable  than  in  the  adult.  In  fat,  or  short-necked 
people,  or  in  those  in  whom  the  muscles  of  the  neck  are  prominently  developed,  the  trachea  is 
more  deeply  placed  than  in  the  opposite  conditions. 


Fig.  363.— Surgical  Anatomy  of  Laryngotracheal  Region 
in  the  Infant. 


Cvioo-ikyroid  Minnln 
le  Artery 
Cricoid  CartUagt 
&uj>eriar  2'Ayroul  vein 


From  these  observations,  it  must  be  evident  that  laryngotomy  is  anatomically  the  most  simple 
opei'ation,  can  most  readily  be  performed,  and  should  always  be  preferred  when  particular 
circumstances  do  not  render  the  operation  of  tracheotomy  absolutely  necessary.  The  operation 
is  performed  thus:  The  head  being  thrown  back  and  steadied  by  an  assistant^  the  finger  is  passed 
over  the  front  of  the  neck,  and  the  crico-thyroid  depression  felt  for.  A  vertical  incision  is  then 
made  through  the  skin,  in  the  middle  line  over  this  spot,  and  the  crico-thyroid  membrane  is 
divided  to  a  sufficient  extent  to  allow  of  the  introduction  of  a  large  curved  tube.  The  crico- 
thyroid artery  is  the  only  vessel  of  importance  crossing  this  space.  If  it  should  be  of  large  size, 
its  division  might  produce  troublesome  hemorrhage. 

Laryngo-tracheotomy,  anatomatically  considered,  is  more  dangerous  than  tracheotomy,  on 
account  of  the  small  interspace  between  the  cricoid  cartilage  and  the  isthmus  of  the  thyroid 
gland ;  the  communicating  branches  between  the  superior  thyroid  veins,  which  cover  this  spot, 
can  hardly  fail  to  be  divided,  and  the  greatest  care  will  not,  in  some  cases,  prevent  the  division 
of  part  of  the  thyroid  isthmus.  If  either  of  these  structures  is  divided,  the  hemorrhage  will  be 
considerable. 

Tracheotomy  below  the  isthmus  of  the  thyroid  gland  is  performed  thus :  The  head  being 
thrown  back  and  steadied  by  an  assistant,  an  incision,  an  inch  and  a  half  or  two  inches  in 
length,  is  made  through  the  skin,  in  the  median  line  of  the  neck,  from  a  little  below  the  cricoid 
cartilage,  to  the  top  of  the  sternum.  The  anterior  jugular  veins  should  be  avoided,  by  keeping 
exactly  in  the  median  line ;  the  deep  fascia  should  then  be  divided,  and  the  contiguous 
borders  of  the  Sterno-hyoid  muscles  separated  from  each  other.  A  quantity  of  loose  areolar 
tissue,  containing  the  inferior  thyroid  veins,  must  then  be  separated  from  the  front  of  the 
trachea,  with  the  handle  of  the  scalpel ;  and  when  the  trachea  is  well  exposed,  it  should  be 
opened  by  inserting  the  knife  into  it,  dividing  two  or  three  of  its  rings  from  below  upwards.  It 
is  a  matter  of  the  greatest  importance  to  restrain,  if  possible,  all  hemorrhage  before  the  tube  is 
opened ;  otherwise,  blood  may  pass  into  the  trachea,  and  suffocate  the  patient. 


THE   PLEURA. 


U5 


The  Pleura. 

Each  lung  is  invested,  upon  its  external  surface,  by  an  exceedingly  delicate 
serous  membrane,  the  pleura,  which  incloses  the  organ  as  far  as  its  root,  and  is 
then  reflected  upon  the  inner  surface  of  the  thorax.     The  portion  of  the  serous 


Fig.  364.— A  Transverse  Section  of  the  Thorax,  showing  the  Relative  Position  of  the  Viscera, 
and  the  Rellections  of  the  Pleurae. 


TRIANGULARIS       STCR 
luttrnaL  JiLunmary    Vessels 


Ltft  Phrt'tie  Ittrv* 


Plcuf^i  fiulmonat** 
Pleura    CoduUis 


Mediastinum- 


Posterior 


membrane  investing  the  surface  of  the  lung  is  called  the  -pleura  pulmonalis 
(visceral  layer  of  pleura),  whilst  that  which  lines  the  inner  surface  of  the  chest 
is  called  the  pleura  costalis  (parietal  layer  of  pleura).  The  interspace  or  cavity 
between  these  two  layers  is  called  the  cavity  of  the  pleura.  Each  pleura  is 
therefore  a  shut  sac,  one  occupying  the  right,  the  other  the  left  half  of  the 
thorax;  and  they  are  perfectly  separate,  not  communicating  with  each  other.  The 
two  pleurae-  do  not  meet  in  the  middle  line  of  the  chest,  excepting  at  one  point  in 
front ;  an  interspace  being  left  between  them,  which  contains  all  the  viscera  of  the 
thorax,  excepting  the  lungs :  this  is  the  mediastinum. 

Reflections  of  the  pleura  (fig.  364).  Commencing  at  the  sternum,  the  pleura 
passes  outwards,  covers  the  costal  cartilages,  the  inner  surface  of  the  ribs  and 
Intercostal  muscles,  and  at  the  back  of  the  thorax  passes  over  the  thoracic 
ganglia  and  their  branches,  and  is  reflected  upon  the  sides  of  the  bodies  of  the 
vertebras,  where  it  is  separated  by  a  narrow  interspace  from  the  opposite  pleura, 
the  posterior  mediastinum.  From  the  vertebral  column,  the  pleura  passes  to  the 
side  of  the  pericardium,  which  it  covers  to  a  slight  extent ;  it  then  covers  the 
back  part  of  the  root  of  the  lung,  from  the  lower  border  of  which  a  triangular 
fold  descends  vertically  by  the  side  of  the  posterior  mediastinum  to  the  Diaphragm. 
This  fold  is  the  broad  ligament  of  the  lung,  the  ligamentum  latum  pulmonis,  and 
serves  to  retain  the  lower  part  of  the  organ  in   position.     From  the  root,  the 


716  ORGANS   OF   VOICE   AND   RESPIRATION". 

pleura  may  be  traced  over  the  convex  surface  of  the  lung,  the  summit  and  base, 
and  also  over  the  sides  of  the  fissures  between  the  lobes.  It  covers  its  anterioi' 
surface,  and  front  part  of  its  root,  and  is  reflected  upon  the  side  of  the  pericar- 
dium to  the  .;'Pncr-  surface  of  the  sternum.  Below,  it  covers  the  upper  surface  of 
the  Diaphragm.  Above,  its  apex  projects,  in  the  form  of  a  cul-de-sac,  through  the 
superior  opening  of  the  thorax  into  the  neck,  extending  about  an  inch  above  the 
margin  of  the  first  rib,  and  receives  the  summit  of  the  corresponding  lung ;  this 
sac  is  strengthened,  according  to  Dr.  Sibson,  by  a  dome-like  expansion  of  fascia, 
derived  from  the  lower  part  of  the  Scaleni  muscles. 

A  little  above  the  middle  of  the  sternum,  the  contiguous  surfaces  of  the 
two  pleurae  are  in  contact  for  a  slight  extent ;  but,  above  and  below  this  point, 
the  interval  left  between  them  by  their  non-approximation  forms  the  anterior 
mediastinum. 

The  inner  surface  of  the  pleura  is  smooth,  polished,  and  moistened  by  a  serous 
fluid ;  its  outer  surface  is  intimately  adherent  to  the  surface  of  the  lung,  and  to  the 
pulmonary  vessels  as  they  emerge  from  the  pericardium ;  it  is  also  adherent 
to  the  upper  surface  of  the  Diaphragm ;  throughout  the  rest  of  its  extent  it  is 
somewhat  thicker,  and  may  be  separated  from  the  adjacent  parts  with  extreme 
facility. 

The  right  pleural  sac  is  shorter,  wider,  and  reaches  higher  in  the  neck  than 
the  left. 

Vessels  and  Nerves.  The  arteries  of  the  pleura  are  derived  from  the  intercostal, 
the  internal  mammary,  the  phrenic,  inferior  thyroid,  thymic,  pericardiac,  and 
bronchial.  The  veins  correspond  to  the  arteries.  The  lymphatics  are  very 
numerous.  The  nerves  are  derived  from  the  phrenic  and  sympathetic  (Luschka). 
Kolliker  states  that  nerves  accompany  the  ramifications  of  the  bronchial  arteries 
in  the  pleura  pulmonalis. 


Mediastinum. 

The  Mediastinum  is  the  space  left  in  the  median  line  of  the  chest  by  the  non- 
approximation  of  the  two  pleurae.  It  extends  from  the  sternum  in  front  to  the 
spine  behind,  and  contains  all  the  viscera  in  the  thorax,  excepting  the  lungs. 
The  mediastinum  may  be  subdivided,  for  convenience  of  description,  into  the 
anterior,  middle,  and  posterior. 

The  anterior  mediastinum  is  bounded  in  front  by  the  sternum,  on  each  side  by 
the  pleura,  and  behind  by  the  pericardium.  Owing  to  the  oblique  position  of  the 
heart  towards  the  left  side,  this  space  is  not  parallel  with  the  sternum,  but  directed 
obliquely  from  above  downwards,  and  to  the  left  of  the  median  line ;  it  is  broad 
oelow,  narrow  above,  very  narrow  opposite  the  second  piece  of  the  sternum,  the 
contiguous  surfaces  of  the  two  pleurae  being  occasionally  united  over  a  small 
space.  The  anterior  mediastinum  contains  the  origins  of  the  Sterno-hyoid  and 
Sterno-thyroid  muscles,  the  Triangularis  sterni,  the  internal  mammary  vessels  of 
the  left  side,  the  remains  of  the  thymus  gland,  and  a  quantity  of  loose  areolar 
tissue,  containing  some  lymphatic  vessels  ascending  from  the  convex  surface  of 
the  liver. 

The  middle  mediastinum  is  the  broadest  part  of  the  interpleural  space.  It 
contains  the  heart  inclosed  in  the  pericardium,  the  ascending  aorta,  the  superior 
vena  cava,  the  bifurcation  of  the  trachea,  the  pulmonary  arteries  and  veins,  and 
the  phrenic  nerves. 

The  posterior  mediastinum  is  an  irregular  triangular  space,  running  parallel 
with  the  vertebral  column;  it  is  bounded  in  front  by  the  pericardium  and  roots  of 
the  lungs,  behind  by  the  vertebral  column,  and  on  either  side  by  the  pleura.  It 
contains  the  descending  aorta,  the  greater  and  lesser  azygos  veins  and  superior 
intercostal  vein,  the  pneumogastric  and  splanchnic  nerves,  the  oesophagus,  thoracic 
duct,  and  some  lymphatic  glands. 


THE    LUNGS. 


717 


The  Lungs. 

The  Lungs  are  the  essential  organs  of  respiration ;  they  are  two  in  number, 
placed  one  in  each  of  the  lateral  cavities  of  the  chest,  separated  from  each  other 
by  the  heart  and  other  contents  of  the  mediastinum.  Each  lung  is  conical  in 
shape,  and  presents  for  examination  an  apex,  a  base,  two  borders,  and  twc 
surfaces. 

The  apex  forms  a  tapering  cone,  which  extends  into  the  root  of  the  neck,  about 
an  inch  to  an  inch  and  a  half  above  the  level  of  the  first  rib. 

Fig.  365. — Front  View  of  the  Thorax.     The  Ribs  and  Sternum  are  represented 
in  Relation  to  the  Lungs,  Heart,  and  other  Internal  Organs. 


The  lose  is  broad,  concave,  and  rests  upon  the  convex  surface  of  the  Dia- 
phragm; its  circumference  is  thin,  and  fits  into  the  space  between  the  lower  ribs 
and  the  costal  attachment  of  the  Diaphragm,  extending  lower  down  externally 
and  behind  than  in  front. 

The  external  or  thoracic  surface  is  smooth,  convex,  of  considerable  extent, 
and  corresponds  to  the  form  of  the  cavity  of  the  chest,  being  deeper  behind  than 
in  front. 

The  inner  surface  is  concave.  It  presents,  in  front,  a  depression  corresponding 
to  the  convex  surface  of  the  pericardium,  and,  behind,  a  deep  fissure,  the  hilum 
pulmonis,  which  gives  attachment  to  the  root  of  the  lung. 


718 


ORGANS   OF   VOICE   AND   RESPIRATION 


The  posterior  border  is  rounded  and  broad,  and  is  received  in  the  deep  con- 
cavity on  either  side  of  the  spinal  column.  It  is  much  longer  than  the  anterior 
border,  and  projects  below  between  the  ribs  and  Diaphragm. 

The  anterior  border  is  thin  and  sharp,  and  overlaps  the  front  of  the  peri- 
cardium. 

The  anterior  border  of  the  right  lung  corresponds  to  the  median  line  of  the 
sternum,  and  is  in  contact  with  its  fellow,  the  pleuras  being  interposed,  as  low  as 
the  fourth  costal  cartilage ;  below  this,  the  contiguous  borders  are  separated  by  an 
irregularly-shaped  interval,  formed  at  the  expense  of  the  anterior  border  of  the 
left  lung,  and  corresponding  to  which  the  pericardium  is  exposed. 


Fig.  306. — Front  View  of  the  Heart  and  Lungs. 


Ductus  Arter/orum 


Each  lung  is  divided  into  two  lobes,  an  upper  and  lower,  by  a  long  and  deep 
fissure,  which  extends  from  the  upper  part  of  the  posterior  border  of  the  organ, 
about  three  inches  from  its  apex,  downwards  and  forwards  to  the  lower  part  of 
its  anterior  border.  This  fissure  penetrates  nearly  to  the  root.  In  the  right  lung 
the  upper  lobe  is  partially  divided  by  a  second  and  shorter  fissure,  which  extends 
from  the  middle  of  the  preceding,  forwards  and  upwards,  to  the  anterior  margin  of 
the  organ,  marking  off  a  small  triangular  portion,  the  middle  lobe. 

The  right  lung  is  the  largest ;  it  is  broader  than  the  left,  owing  to  the  inclination 
of  the  heart  to  the  left  side,  and  is  also  shorter  by  an  inch,  in  consequence  of  the 
Diaphragm  rising  higher  on  the  right  side  to  accommodate  the  liver.  The  right 
lung  has  also  three  lobes. 

The  left  lung  is  smaller,  narrower,  and  longer  than  the  right,  and  has  only  two 
lobes.  .  . 


THE   LUNGS.  719 

A  little  above  the  middle  of  the  inner  surface  of  each  lung,  and  nearer  its  pos- 
terior than  its  anterior  border,  is  its  root,  by  which  the  lung  is  connected  to  the 
heart  and  the  trachea.  It  is  formed  by  the  bronchial  tube,  the  pulmonary  artery, 
the  pulmonary  veins,  the  bronchial  arteries  and  veins,  the  pulmonary  plexus  of 
nerves,  lymphatics,  bronchial  glands,  and  areolar  tissue,  all  of  which  are  inclosed 
by  a  reflection  of  the  pleura.  The  root  of  the  right  lung  lies  behind  the  superior 
cava  and  upper  part  of  the  right  auricle,  and  below  the  vena  azygos.  That  of 
the  left  lung  passes  beneath  the  arch  of  the  aorta,  and  in  front  of  the  descending 
aorta;  the  phrenic  nerve  and  the  anterior  pulmonary  plexus  lie  in  front  of  each, 
and  the  pneumogastric  and  posterior  pulmonary  plexus  behind  each. 

The  structures  composing  the  root  of  each  lung  are  arranged  in  a  similar 
manner  from  before  backwards  on  both  sides,  viz. ; — the  pulmonary  veins  most 
anterior,  the  pulmonary  artery  in  the  middle,  and  the  bronchus,  together  with 
the  bronchial  vessels,  behind.  From  above  downwards,  on  the  two  sides,  their 
arrangement  differs,  thus: — 

On  the  right  side,  their  position  is,  bronchus,  pulmonary  artery,  pulmonary 
veins;  on  the  left  side,  their  position  is,  pulmonary  artery,  bronchus,  pulmonary 
veins :  this  is  accounted  for  by  the  bronchus  being  placed  on  a  lower  level  on 
the  left  than  on  the  right  side. 

The  weight  of  both  lungs  together  is  about  forty-two  ounces,  the  right  lung 
being  two  ounces  heavier  than  the  left ;  but  much  variation  is  met  with  according 
to  the  amount  of  blood  or  serous  fluid  they  may  contain.  The  lungs  are  heavier 
in  the  male  than  in  the  female,  their  proportion  to  the  body  being,  in  the  former, 
as  1  to  37,  in  the  latter  as  1  to  43.  The  specific  gravity  of  the  lung  tissue  varies 
from  345  to  746,  water  being  1000. 

The  color  of  the  lungs  at  birth  is  of  a  pinkish  white;  in  adult  life,  mottled  in 
patches,  of  a  dark  slate  color ;  and,  as  age  advances,  this  mottling  assumes  a 
dark  black  color.  The  coloring  matter  consists  of  granules  of  a  carbonaceous 
substance,  deposited  in  the  areolar  tissue  near  the  surface  of  the  organ.  It 
increases  in  quantity  as  age  advances,  and  is  more  abundant  in  males  than  in 
females.  The  posterior  border  of  the  lung  is  usually  darker  than  the  anterior. 
The  surface  of  the  lung  is  smooth,  shining,  and  marked  out  into  numerous  poly- 
hedral spaces,  which  represent  the  lobules  of  the  organ,  and  the  area  of  each  of 
these  spaces  is  crossed  by  numerous  lighter  lines. 

The  substance  of  the  lung  is  of  a  light,  porous,  spongy  texture ;  it  floats  in  water, 
and  crepitates  when  handled,  owing  to  the  presence  of  air  in  the  tissue.  It  is  also 
highly  elastic ;  hence  the  collapsed  state  of  these  organs  when  they  are  removed 
from  the  closed  cavity  of  the  thorax. 

Structure.  The  lungs  are  composed  of  an  external  serous  coat,  a  subserous 
areolar  tissue,  and  the  pulmonary  substance  or  parenchyma. 

The  serous  coat  is  derived  from  the  pleura;  it  is  thin,  transparent,  and  invests 
the  entire  organ  as  far  as  the  root. 

The  subserous  areolar  tissue  contains  a  large  proportion  of  elastic  fibres ;  it 
invests  the  entire  surface  of  the  lung,  and  extends  inwards  between  the  lobules. 

The  "parenchyma  is  composed  of  lobules,  which,  although  closely  connected 
together  by  an  interlobular  areolar  tissue,  are  quite  distinct  from  one  another, 
being  easily  separable  in  the  foetus.  The  lobules  vary  in  size :  those  on  the  surface 
are  large,  of  a  pyramidal  form,  the  base  turned  towards  the  surface ;  those  in  the 
interior  are  smaller,  and  of  various  forms.  Each  lobule  is  composed  of  one  of  the 
ramifications  of  the  bronchial  tube  and  its  terminal  air-cells,  of  the  ramifications 
of  the  pulmonary  and  bronchial  vessels,  lymphatics,  and  nerves;  all  of  these 
structures  being  connected  together  by  areolar  fibrous  tissue. 

The  bronchus,  upon  entering  the  substance  of  the  lung,  divides  and  subdivides 
dichotomously  throughout  the  entire  organ.  Sometimes  three  branches  arise 
together,  and  occasionally  small  lateral  branches  are  given  off  from  the  sides  of  a 
main  trunk.     Each  of  the  smaller  subdivisions  of  the  bronchi  enters  a  pulmonary 


720  ORGANS   OF   VOICE    AND   RESPIRATION. 

lobule  (lobular  bronchial  tube),  and,  again  subdividing,  ultimately  terminates  in 
the  intercellular  passages  and  air-cells  of  which  the  lobule  is  composed.  Within 
the  lungs  the  bronchial  tubes  are  circular,  not  flattened,  and  their  constituent 
elements  present  the  following  peculiarities  of  structure. 

The  cartilages  are  not  imperfect  rings,  but  consist  of  thin  laminaa,  of  varied 
form  and  size,  scattered  irregularly  along  the  sides  of  the  tube,  being  most  distinct 
at  the  points  of  division  of  the  bronchi.  They  may  be  traced  into  tubes  the  dia- 
meter of  which  is  only  one-fourth  of  a  line.  Beyond  this  point,  the  tubes  are 
wholly  membranous.  The  fibrous  coat  and  longitudinal  elastic  fibres  are  con- 
tinued into  the  smallest  ramifications  of  the  bronchi.  The  muscular  coat  is  dis- 
posed in  the  form  of  a  continuous  layer  of  annular  fibres,  which  may  be  traced 
upon  the  smallest  bronchial  tubes ;  they  consist  of  the  unstriped  variety  of  muscular 
fibre.  The  mucous  membrane  lines  the  bronchi  and  its  ramifications  throughout, 
and  is  covered  with  columnar  ciliated  epithelium. 

According  to  the  observations  of  Mr.  Rainey,1  the  lobular  bronchial  tubes,  on 
entering  the  substance  of  the  lobules,  divide  and  subdivide  from  four  to  nine  times, 
according  to  the  size  of  the  lobule,  continuing  to  diminish  in  size  until  they  attain 
a  diameter  of  ^th  to  ^Dth  of  an  inch.  They  then  become  changed  in  structure, 
losing  their  cylindrical  form,  and  are  continued  onwards  as  irregular  passages 
(intercellular  passages),  through  the  substance  of  the  lobule,  their  sides  and  ex- 
tremities being  closely  covered  by  numerous  saccular  dilatations,  the  air-cells. 
This  arrangement  resembles  most  closely  the  naked  eye  appearances  observed  in 
the  reticulated  structure  of  the  lung  of  the  tortoise,  and  other  reptilia. 

The  air-cells  are  small,  polyhedral,  alveolar  recesses,  separated  from  each  other 
by  thin  septa,  and  communicating  freely  with  the  intercellular  passages.  They 
are  well  seen  on  the  surface  of  the  lung,  and  vary  from  5^th  to  ^th  of  an  inch 
in  diameter,  being  largest  on  the  surface,  at  the  thin  borders,  and  at  the  apex, 
and  smallest  in  the  interior. 

At  the  termination  of  the  bronchial  tubes,  in  the  intercellular  passages,  their 
constituent  elements  become  changed ;  their  walls  are  formed  by  an  interlacing  of 
the  longitudinal  elastic  bundles  with  fibrous  tissue,  the  muscular  fibres  disappear, 
and  the  mucous  membrane  becomes  thin  and  delicate,  and  lined  with  a  layer  of 
squamous  epithelium.  The  latter  membrane  lines  the  air-cells,  and  forms  by  its 
reduplications  the  septa  intervening  between  them. 

The  Pulmonary  Artery  conveys  the  venous  blood  to  the  lungs ;  it  divides  into 
branches  which  accompany  the  bronchial  tubes  and  terminates  in  a  dense  capillary 
network  upon  the  walls  of  the  intercellular  passages  and  air-cells.  From  this 
network,  the  radicles  of  the  pulmonary  veins  arise ;  coalescing  into  large  branches, 
they  accompany  the  arteries,  and  return  the  blood,  purified  by  its  passage 
through  the  capillaries,  to  the  left  auricle  of  the  heart.  In  the  lung,  the  branches 
of  the  pulmonary  artery  are  usually  above  and  in  front  of  a  bronchial  tube,  the 
vein  below. 

The  Pulmonary  Capillaries  form  plexuses  which  lie  immediately  beneath  the 
mucous  membrane,  on  the  walls  and  septa  of  the  air-cells,  and  upon  the  walls  of 
the  intercellular  passages.  In  the  septa  between  the  cells,  the  capillary  network 
forms  a  single  layer.  The  capillaries  are  very  minute,  the  meshes  being  only 
slightly  wider  than  the  vessels ;  their  walls  are  also  exceedingly  thin. 

The  Bronchial  Arteries  supply  blood  for  the  nutrition  of  the  lung ;  they  are 
derived  from  the  thoracic  aorta,  and,  accompanying  the  bronchial  tubes,  are  dis- 
tributed to  the  bronchial  glands,  and  upon  the  walls  of  the  larger  bronchial  tubes 
and  pulmonary  vessels,  and  terminate-  in  the  deep  bronchial  veins.  Others  are 
distributed  in  the  interlobular  areolar  tissue,  and  terminate  partly  in  the  dee]), 
partly  in  the  superficial,  bronchial  veins.  Lastly,  some  ramify  upon  the  walls  of 
the  smallest  bronchial  tubes,  and  terminate  in  the  pulmonary  veins. 

The  Superficial  and  Deep  Bronchial  Veins  unite  at  the  root  of  the  lung,  and 

1  Medico-Chirurgical  Transactions,  vol.  xxviii.  1845. 


THYROID   GLAND.  121 

terminate  oi\  the  right  side  in  the  vena  azygos ;  on  the  left  side,  in  the  superior 
intercostal  vein. 

The  Lymphatics  consist  of  a  superficial  and  deep  set ;  they  terminate  at  the  root 
of  the  lung,  in  the  bronchial  glands. 

Nerves.  The  lungs  are  supplied  from  the  anterior  and  posterior  pulmonary 
plexuses,  formed  chiefly  by  branches  from  the  sympathetic  and  pneumogastric. 
The  filaments  from  these  plexuses  accompany  the  bronchial  tubes  upon  which  they 
are  lost.  Small  ganglia  have  been  found  by  Eemak  upon  the  smaller  branches  of 
these  nerves. 

Thyroid  Gland. 

The  Thyroid  Gland  bears  much  resemblance  in  structure  to  other  glandular 
organs,  and  is  usually  classified  together  with  the  thymus,  supra-renal  glands,  and 
spleen,  under  the  head  of  ductless  glands,  from  its  possessing  no  excretory  duct. 
Its  function  is  unknown,  but,  from  its  situation  in  connection  with  the  trachea 
and  larynx,  is  usually  described  with  these,  although  taking  no  part  in  the 
function  of  respiration.  It  is  situated  at  the  upper  part  of  the  trachea,  and 
consists  of  two  lateral  lobes,  placed  one  on  each  side  of  this  tube,  connected 
together  by  a  narrow  transverse  portion,  the  isthmus. 

Its  anterior  surface  is  convex,  and  covered  by  the  Sterno-hyoid,  Sterno-thyroid, 
and  Omo-hyoid  muscles. 

Its  lateral  surfaces,  also  convex,  lie  in  contact  with  the  sheath  of  the  common 
carotid  artery. 

Its  posterior  surface  is  concave,  and  embraces  the  trachea  and  larynx.  The 
posterior  borders  of  the  gland  extend  as  far  back  as  the  lower  part  of  the 
pharynx. 

This  gland  is  of  a  brownish-red  color.  Its  weight  varies  from  one  to  two 
ounces.  It  is  larger  in  females  than  in  males,  and  becomes  slightly  increased  in 
size  during  menstruation.  It  occasionally  becomes  enormously  hj'pertrophied,  con- 
stituting the  disease  called  bronchocele  or  goitre.  Each  lobe  is  somewhat  conical 
in  shape,  about  two  inches  in  length,  and  three-quarters  of  an  inch  in  breadth,  the 
right  lobe  being  rather  the  larger  of  the  two. 

The  isthmus  connects  the  lower  third  of  the  two  lateral  lobes  ;  it  measures  about 
half  an  inch  in  breadth,  and  the  same  in  depth,  and  usually  covers  the  second  and 
third  rings  of  the  trachea.  Its  situation  presents,  however,  many  variations,  a 
point  of  some  importance  in  the  operation  of  tracheotomy.  Sometimes  the  isthmus 
is  altogether  wanting. 

A  third  lobe,  of  conical  shape,  called  the  pyramid,  occasionally  arises  from  the 
left  side  of  the  upper  part  of  the  isthmus,  or  from  the  left  lobe,  and  ascends  as 
high  as  the  hyoid  bone.  It  is  occasionally  quite  detached,  or  divided  into  two 
parts,  or  altogether  wanting. 

A  few  muscular  bands  are  occasionally  found  attached,  above,  to  the  body  of  the 
hyoid  bone,  and,  below,  to  the  isthmus  of  the  gland,  or  its  pyramidal  process ;  these 
were  named  by  Soemmering,  the  Levator  rjlandulve  tltyroideve. 

Structure.  The  thyroid  consists  of  numerous  minute  closed  vesicles,  com- 
posed of  a  homogeneous  membrane,  inclosed  in  a  dense  capillary  plexus,  and 
connected  together  into  imperfect  lobules  by  areolar  tissue.  These  vesicles  are 
spherical  or  oblong,  perfectly  distinct,  and  contain  a  yellowish  fluid,  in  which 
are  found  floating  numerous  "dotted  corpuscles"  and  cells.  The  fluid  coa- 
gulates by  heat  or  alcohol,  but  preserves  its  transparency.  In  the  foetus 
and  in  young  subjects,  the  corpuscles  lie  in  a  single  layer,  in  contact  with 
the  inner  surface  of  these  cavities,  and  become  detached  during  the  process  of 
growth. 

Vessels  and  Nerves.     The  arteries  supplying  the  thyroid  are  the  superior  and 
inferior  thyroid,  and  sometimes  an  additional  branch  from  the  arteria  innominata, 
which  ascends  from  this  vessel  upon  the  front  of  the  trachea.     The  arteries  arc 
46 


722  ORGANS   OF   YOICE   AND   RESPIRATION. 

remarkable  for  their  large  size  and  frequent  anastomoses.  The  veins  form  a 
plexus  on  the  surface  of  the  gland,  and  on  the  front  of  the  trachea,  from  which 
arise  the  superior,  middle,  and  inferior  thyroid  veins ;  the  two  former  terminating 
in  the  internal  jugular,  the  latter  in  the  vena  innominata.  The  lymphatics  are 
numerous,  of  large  size,  and  terminate  in  the  thoracic  and  right  lymphatic  ducts. 
The  nerves  are  derived  from  the  pneumogastric,  and  from  the  middle  and  inferior 
cervical  ganglia  of  the  sympathetic. 

Chemical  Composition.  The  thyroid  gland  consists  of  albumen,  traces  of  gela- 
tin, stearin,  olein,  extractive  matter,  alkaline  and  earthy  salts,  and  water.  The 
salts  are  chloride  of  sodium,  alkaline  sulphate,  phosphate  of  potash,  lime,  mag- 
nesia, and  a  trace  of  oxide  of  iron. 

Thymus  Gland. 

The  Thymus  Gland  presents  much  resemblance  in  structure  to  other  glandular 
organs,  and  is  classified  under  the  head  of  the  ductless  glands,  from  its  possessing 
no  excretory  duct. 

The  thymus  gland  is  a  temporary  organ,  attaining  its  full  size  at  the  end  of  the 
second  year,  when  it  ceases  to  grow,  and  gradually  dwindles,  until,  at  puberty,  it 
has  almost  disappeared.  If  examined  when  its  growth  is  most  active,  it  will  be 
found  to  consist  of  two  lateral  lobes,  placed  in  close  contact  along  the  middle  line, 
situated  partly  in  the  anterior  mediastinum,  partly  in  the  neck,  and  extending 
from  the  fourth  costal  cartilage  upwards,  as  high  as  the  lower  border  of  the 
thyroid  gland.  It  is  covered  by  the  sternum,  and  by  the  origins  of  the  Sterno-hyoid 
and  Sterno -thyroid  muscles.  In  the  mediastinum,  it  rests  upon  the  pericardium, 
being  separated  from  the  arch  of  the  aorta  and  great  vessels,  by  the  thoracic 
fascia.  In  the  neck,  it  lies  on  the  front  and  sides  of  the  trachea,  behind  the 
Sterno-hyoid  and  Sterno-thyroid  muscles.  The  two  lobes  generally  differ  in 
size ;  they  are  occasionally  united  so  as  to  form  a  single  mass,  and  sometimes 
separated  by  an  intermediate  lobe.  The  thymus  is  of  a  pinkish-gray  color,  soft, 
and  lobulated  on  its  surfaces.  It  is  about  two  inches  in  length,  one  and  a  half  in 
breadth,  below,  and  about  three  or  four  lines  in  thickness.  At  birth,  it  weighs 
about  half  an  ounce. 

Structure.  Each  lateral  lobe  is  composed  of  numerous  lobules,  held  together  by 
delicate  areolar  tissue,  the  entire  gland  being  inclosed  in  an  investing  capsule  of 
a  similar,  but  denser,  structure.  The  primary  lobules  vary  in  size  from  a  pin's 
head  to  a  small  pea.  Each  lobule  contains,  in  its  interior,  a  small  cavity,  which 
is  surrounded  with  smaller  or  secondary  lobules,  which  are  also  hollow  within. 
The  cavities  of  the  secondary  and  primary  lobules  communicate ;  those  of  the 
latter  opening  into  the  great  central  cavity  or  reservoir  of  the  thymus,  which 
extends  through  the  entire  length  of  each  lateral  half  of  the  gland.  The  central 
cavity  is  lined  by  a  vascular  membrane,  which  is  prolonged  into  all  the  subordinate 
cavities,  and  contains  a  milk-white  fluid  resembling  chyle. 

If  the  investing  capsule  and  vessels,  as  well  as  the  areolar  tissue  connecting 
the  lobules,  are  removed  from  the  surface  of  either  lateral  lobe,  it  will  be  seen 
that  the  •central  cavity  is  folded  upon  itself,  and  admits  of  being  drawn  out  into  a 
lengthened  tubular  cord,  around  which  the  primary  lobules  are  attached  in  a 
spiral  manner,  like  knots  upon  a  rope.  Such  is  the  condition  of  the  organ  at  an 
early  period  of  its  development ;  for  Mr.  Simon  has  shown,  that  the  primitive 
form  of  the  thymus  is  a  linear  tube,  from  which,  as  its  development  proceeds, 
lateral  diverticula  lead  outwards,  the  tube  ultimately  becoming  obscure,  from  its 
surface  being  covered  with  numerous  lobules. 

According  to  Oesterlen  and  Mr.  Simon,  the  cavities  in  the  secondary  lobules 
are  surrounded  by  rounded  saccular  dilatations  or  vesicles,  which  open  into  it. 
These  vesicles  are  formed  of  a  homogeneous  membrane,  inclosed  in  a  dense  capil- 
lary plexus. 

The  whitish  fluid  contained  in  the  vesicles  and  central  cavity  of  the  thymus 


THYMUS   GLAND.  723 

contains  numerous  dotted  corpuscles,  similar  to  those  found  in  the  chyle.  The 
corpuscles  are  flattened  circular  disks,  measuring  about  TTyW  of  an  inch  in  dia- 
meter. 

Vessels  and  Nerves.  The  arteries  supplying  the  thymus  are  derived  from  the 
internal  mammary,  and  from  the  superior  and  inferior  thyroid.  The  veins  termi- 
nate in  the  left  vena  innominata,  and  in  the  thyroid  veins.  The  lymphatics  are 
of  large  size,  arise  in  the  substance  of  the  gland,  and  are  said  to  terminate  in  the 
internal  jugular  vein.  Sir  A.  Cooper  considered  that  these  vessels  carried  into 
the  blood  the  secretion  formed  in  the  substance  of  the  thymus.  The  nerves  are 
exceedingly  minute ;  they  are  derived  from  the  pneumogastric  and  sympathetic. 
Branches  from  the  descendens  noni  and  phrenic  reach  the  investing  capsule,  but 
do  not  penetrate  into  the  substance  of  the  gland. 

Chemical  Composition.  The  solid  animal  constituents  of  the  thymus  are  albu- 
men and  fibrin  in  large  quantities,  gelatin  and  other  animal  matters.  The  salts 
are  alkaline  and  earthy  phosphates,  with  chloride  of  potassium.  It  contains  about 
80  per  cent,  of  water. 


The  Urinary  Organs. 


The  Kidneys. 

The  Kidneys  are  two  glandular  organs,  intended  for  the  secretion  of  the  urine. 
They  are  situated  at  the  back  part  of  the  abdominal  cavity,  behind  the  peri- 
toneum, one  in  each  lumbar  region,  extending  from  the  eleventh  rib  to  near  the 
crest  of  the  ilium;  the  right  one  being  lower  than  the  left,  from  its  vicinity  to 
the  liver.  They  are  usually  surrounded  by  a  considerable  quantity  of  fat,  and 
are  retained  in  their  position  by  the  vessels  which  pass  to  and  from  them. 

Relations.  The  anterior  surface  of  the  kidney  is  convex,  partially  covered  by 
the  peritoneum,  and  is  in  relation,  on  the  right  side,  with  the  back  part  of  the 
right  lobe  of  the  liver,  the  descending  portion  of  the  duodenum,  and  ascending 
colon ;  and  on  the  left  side  with  the  great  end  of  the  stomach,  the  lower  end  of  the 
spleen,  the  tail  of  the  pancreas,  and  the  descending  colon. 

The  posterior  surface  is  flattened,  and  rests  upon  the  corresponding  crus  of  the 
Diaphragm,  in  front  of  the  eleventh  and  twelfth  ribs,  on  the  anterior  lamella  of 
the  aponeurosis  of  the  Transversalis  which  separates  it  from  the  Quadratus  lum- 
borum,  and  on  the  Psoas  magnus. 

The  superior  extremity,  directed  inwards,  is  thick  and  rounded,  and  embraced 
by  the  supra-renal  capsule.  It  corresponds,  on  the  left  side,  to  the  upper  border 
of  the  eleventh  rib,  and  on  the  right  side  to  the  lower  border. 

The  inferior  extremity,  small  and  flattened,  extends  nearly  as  low  as  the  crest 
of  the  ilium. 

The  external  border  is  convex,  and  directed  outwards  towards  the  parietes  of 
the  abdomen. 

The  internal  border  is  concave,  and  presents  a  deep  notch,  the  hilus  of  the  kidney, 
more  marked  behind  than  in  front.  At  the  hilus,  the  vessels,  excretory  duct, 
and  nerves  pass  into  or  from  the  organ ;  the  branches  of  the  renal  vein  lying  in 
front,  the  artery  and  its  branches  next,  the  excretory  duct  or  ureter  being  behind 
and  below.  On  the  vessels  the  nerves  and  lymphatics  ramify,  and  much  cellular 
tissue  and  fat  surrounds  the  whole.  The  hilus  leads  into  a  hollow  space,  the 
sinus,  which  occupies  the  interior  of  the  gland. 

Each  kidney  is  about  four  inches  in  length,  two  inches  in  breadth,  and  about 
one  inch  in  thickness ;  the  left  one  being  somewhat  longer  and  thinner  than  the 
right.  The  weight  of  the  kidney  in  the  adult  male  varies  from  4J  oz.  to  6  oz. ; 
in  the  female,  from  4  oz.  to  5|  oz.,  the  difference  between  the  two  being  about 
half  an  ounce.  The  left  is  nearly  always  heavier  than  the  right,  by  about  two 
drachms.  Their  weight  in  proportion  to  the  body  is  about  1  to  240.  The  renal 
substance  is  dense,  firm,  extremely  fragile,  and  of  a  deep  red  color. 

The  kidney  is  invested  by  a  fibrous  capsule,  formed  of  dense  fibro-areolar 
tissue.  It  is  thin,  smooth,  and  easily  removed  from  its  surface,  to  which  it  is  con- 
nected by  fine  fibrous  processes  and  vessels ;  and  at  the  hilus  is  continued  inwards, 
lining  the  sides  of  the  sinus,  and  at  the  bottom  of  that  cavity  forms  sheaths  around 
the  bloodvessels  and  the  subdivisions  of  the  excretory  duct. 

On  making  a  vertical  section  through  the  organ,  from  its  convex  to  its  concave 
border,  it  appears  to  consist  of  two  different  substances,  viz.,  an  external  or  cor- 
tical, and  an  internal  or  medullary,  substance. 

The  cortical  substance  forms  about  three-fourths  of  the  gland.  It  occupies  the 
724 


THE   KIDNEYS. 


725 


Fig.  367. — Vertical  Section  of  Kidney, 


surface  of  the  kidney,  forming  a  layer  about  two  lines  in  thickness,  where  it  covers 
the  pyramids,  and  sends  numerous  prolongations  inwards,  towards  the  sinus  between 
the  pyramids. 

The  cortical  substance  is  soft,  reddish, 
granular,  easily  lacerated,  and  contains  nu- 
merous small  red  bodies  disseminated  through 
it  in  every  part,  excepting  towards  the  free 
surface.  These  are  the  Malpighian  bodies. 
The  cortical  substance  is  composed  of  a  mass 
of  convoluted  tubuli  uriniferi,  bloodvessels, 
lymphatics,  and  nerves,  connected  together 
by  a  firm,  transparent,  granular  substance, 
which  contains  small  granular  cells. 

The  medullary  substance  consists  of  pale, 
reddish-colored,  conical  masses,  the  pyra- 
mids of  Malpighi,  varying  in  number  from 
eight  to  eighteen;  their  bases  are  directed 
towards  the  circumference  of  the  organ, 
whilst  their  apices,  which  are  free  from  the 
cortical  substance,  converge  towards  the 
sinus,  and  terminate  in  smooth,  rounded  ex- 
tremities, called  the  papillse  (mammillae)  of 
the  kidney.  Sometimes,  two  of  the  masses 
are  joined,  and  have  between  them  only  one 
papilla.  The  kidney  is  thus  seen  to  consist 
of  a  number  of  conical-shaped  masses,  each 
inclosed,  excepting  at  the  apex,  by  an  invest- 
ment of  the  cortical  substance ;  these  repre- 
sent the  separate  lobules  of  which  the  human 
kidney  in  the  foetus  consists,  a  condition 
observed  permanently  in  the  kidneys  of  many  of  the  lower  animals.  -  As  the 
human  kidney  becomes  developed,  the  adjacent  lobules  coalesce,  so  as  to  form  a 
single  gland,  the  surface  of  which,  even  in  the  adult,  occasionally  presents  faint 
traces  of  a  lobular  subdivision. 

The  medullary  substance  is  denser  in  structure  than  the  cortical,  darker  in  color, 
and  presents  a  striated  appearance,  from  being  composed  of  a  number  of  minute 
diverging  tubes  (tubuli  uriniferi).  The  tubuli  uriniferi  commence  at  the  apices  of 
the  cones  by  small  orifices,  which  vary  from 
3tf?y  to  2£ff  of  an  inch;  as  they  pass  up  in 
the  medullary  substance,  towards  the  peri- 
phery, they  pursue  a  diverging  course,  di- 
viding and  subdividing  at  very  acute  angles, 
until  they  reach  the  cortical  substance,  when 
they  become  convoluted,  anastomose  freely 
with  each  other,  and  retain  the  same  diameter. 
The  number  of  orifices  on  the  entire  surface 
of  a  single  papilla  is,  according  to  Huschke, 
about  a  thousand ;  from  four  to  five  hundred 
large,  and  as  many  smaller  ones.  The  tubuli 
uriniferi  are  formed  of  a  transparent  homo- 
geneous basement  membrane,  lined  by  sphe- 
roidal epithelium,  which  occupies  about  two- 
thirds  of  the  diameter  of  the  tube.  The 
tubes  are  separated  from  one  another,  in  the 

medullury  cones,  by  capillary  vessels,  which  form  oblong  meshes  parallel  with  the 
tubuli,  and  by  an  intermediate  parenchymatous  substance  composed  of  cells. 

As  soon  as  the  tubuli  uriniferi  enter  the  cortical  substance  (fig.  368),  they 


Fig.  368. — Minute  Structure  of  Kidney. 


>i"t# 


726  URINARY   ORGANS. 

become  convoluted,  and  anastomose  freely  with  each  other ;  they  are  sometimes 
called  the  tubes  of  Ferrein.  At  the  bases  of  the  pyramids,  the  straight  tubes  are 
described  as  being  collected  into  small  conical  bundles,  the  tortuous  tubuli  cor- 
responding to  which  are  prolonged  upwards  into  the  cortical  portion  of  the  kidney 
as  far  as  the  surface,  forming  a  number  of  small  conical  masses,  which  are  named 
the  pyramids  of  Ferrein,  several  of  which  correspond  to  each  medullary  cone  and 
its  corresponding  portion  of  cortical  substance.  According  to  Mr.  Bowman,  the 
tubuli  uriniferi  commence  in  the  cortical  substance  as  small,  dilated,  membranous 
capsules,  the  capsules  of  the  Malpighian  bodies  ;  they  also  form  loops,  either  by  the 
junction  of  adjacent  tubes,  or,  according  to  Toynbee,  by  the  union  of  two  branches 
proceeding  from  the  same  tube ;  they  have  also  been  seen  to  arise  by  free  closed 
extremities. 

The  Malpighian  bodies  are  found  only  in  the  cortical  substance  of  the  kidney. 
They  are  small  round  bodies,  of  a  deep  red  color,  and  of  the  average  diameter 
of  the  yl^  of  an  inch.  Each  body  is  composed  of  a  vascular  tuft  inclosed  in  a 
thin  membranous  capsule,  the  dilated  commencement  of  a  uriniferous  tubule.  The 
vascular  tuft  consists  of  the  ramifications  Of  a  minute  artery,  the  afferent  vessel, 
which,  after  piercing  the  capsule,  divides,  in  a  radiated  manner,  into  several 
branches,  which  ultimately  terminate  in  a  finer  set  of  capillary  vessels.  From 
these,  a  small  vein,  the  efferent  vessel,  proceeds ;  this  pierces  the  capsule  near  the 
artery,  and  forms  a  close  venous  plexus,  with  the  efferent  vessels  from  other 
Malpighian  bodies,  round  the  adjacent  tubuli. 

The  capsular  dilatation  of  the  Malpighian  body  is  not  always  placed  at  the 
commencement  of  the  tube ;  it  may  occupy  one  side  (Gerlach) :  hence  their  sub- 
division into  lateral  or  terminal.  The  membrane  composing  it  is  thicker  than  that 
of  the  tubule ;  the  epithelium  lining  its  inner  surface  is  thin,  and,  in  the  frog, 
provided  with  ciliae  at  the  neck  of  the  dilated  portion ;  but  in  the  human  subject, 
ciliae  have  not  been  detected.  According  to  Mr.  Bowman,  the  surface  of  the 
vascular  tuft  lies  free  and  uncovered  in  the  interior  of  its  capsule ;  but,  according 
to  Gerlach,  it  is  covered  with  a  thick  layer  of  nucleated  cells,  similar  to  those 
lining  the  inner  surface  of  the  capsule. 

Ducts.  The  ureter,  as  it  approaches  the  hilus,  becomes  dilated  into  a  funnel- 
shaped  membranous  sac,  the  pelvis.  It  then  enters  the  sinus,  and  subdivides 
usually  into  three  prolongations,  the  infundibula,  one  placed  at  each  extremity, 
and  one  in  the  middle  of  the  organ ;  these  subdivide  into  from  seven  to  thirteen 
smaller  tubes,  the  calyces,  each  of  which  embraces,  like  a  cup-like  pouch  or  calyx, 
the  base  of  one  of  the  papillae.  Sometimes,  a  calyx  incloses  two  or  more  papillae. 
The  ureter,  the  pelvis,  and  the  calyces  consist  of  three  coats, — fibrous,  muscular, 
and  mucous. 

The  external  or  fibro-elastic  coat  is  continuous,  round  the  bases  of  the  papillae, 
with  the  tunica  propria  investing  the  surface  of  the  organ. 

The  muscular  coat  is  placed  between  the  fibrous  and  mucous  coats.  It  consists 
of  an  external  or  longitudinal,  and  an  internal  or  circular  stratum. 

The  internal  or  mucous  coat  invests  the  papillae  of  the  kidney,  and  is  continued 
into  the  orifices  upon  their  surfaces.  It  is  lined  by  epithelium  of  the  spheroidal 
kind. 

Vessels,  and  Nerves.  The  renal  artery  is  large  in  proportion  to  the  size  of 
the  organ  which  it  supplies.  Each  vessel  divides  into  four  or  five  branches, 
which  enter  the  hilus,  and  are  invested  by  sheaths  derived  from  the  fibrous  capsule ; 
they  penetrate  the  substance  of  the  organ  between  the  papillae,  and  enter  the 
cortical  substance  in  the  intervals  between  the  medullary  cones,  dividing  and 
subdividing  in  their  course  towards  the  bases  of  the  pyramids,  where  they  form 
arches  by  their  anastomoses ;  from  these  arches,  numerous  vessels  are  distributed 
to  the  cortical  substance,  some  of  which  enter  the  Malpighian  corpuscles,  whilst 
others  form  a  capillary  network  round  the  uriniferous  tubes. 

The  veins  of  the  kidney  commence  upon  the  surface  of  the  organ,  where  they 
have  a  stellate  arrangement ;  they  pass  inwards,  and  open  into  larger  veins,  which 


URETERS  — SUPRA-RENAL  CAPSULES.        727 

unite  into  arches  round  the  bases  of  the  medullary  cones.  After  receiving  the 
venous  plexus  from  the  tubular  portion,  they  accompany  the  branches  of  the 
arteries  to  the  sinus  of  the  kidney,  where  they  finally  unite  to  form  a  single  vein, 
which  terminates  in  the  inferior  vena  cava. 

The  lymphatics  of  the  kidney  consist  of  a  superficial  and  deep  set ;  they  accom- 
pany the  bloodvessels,  and  terminate  in  the  lumbar  glands. 

The  nerves  are  derived  from  the  renal  plexus,  which  is  formed  by  filaments 
from  the  solar  plexus  and  lesser  splanchnic  nerve ;  they  accompany  the  branches 
of  the  arteries.  From  the  renal  plexus,  some  filaments  pass  to  the  spermatic- 
plexus  and  ureter. 

The  Ureters. 

The  Ureter  is  the  excretory  duct  of  the  kidney.  It  is  a  cylindrical  mem- 
branous tube,  from  sixteen  to  eighteen  inches  in  length,  and  of  the  diameter  of  a 
goose-quill.  It  is  placed  at  the  back  part  of  the  abdomen,  behind  the  peritoneum ; 
and  extends  obliquely  downwards  and  inwards,  from  the  lower  part  of  the  pelvis 
of  the  kidney,  enters  the  cavity  of  the  pelvis,  and  then  passes  downwards,  for- 
wards, and  inwards,  to  the  base  of  the  bladder,  into  which  it  opens  by  a  con- 
stricted orifice,  after  passing  obliquely,  for  nearly  an  inch,  between  its  muscular 
and  mucous  coats. 

Relations.  In  its  course  from  above  downwards,  it  rests  upon  the  Psoas 
muscle,  being  covered  by  the  peritoneum,  and  crossed  in  front  very  obliquely  by 
the  spermatic  vessels ;  the  right  ureter  lying  close  to  the  outer  side  of  the  inferior 
vena  cava.  Opposite  the  sacrum,  it  crosses  the  common  or  the  external  iliac 
artery,  lying  behind  the  ileum  on  the  right  side,  and  the  sigmoid  flexure  of  the 
colon  on  the  left.  In  the  pelvis,  it  enters  the  posterior  false  ligament  of  the 
bladder,  and  runs  below  the  obliterated  hypogastric  artery,  the  vas  deferens,  in 
the  male,  passing  between  it  and  the  bladder.  In  the  female,  the  ureter  passes 
along  the  sides  of  the  cervix  uteri  and  upper  part  of  the  vagina.  At  the  base  of 
the  bladder,  it  is  situated  about  two  inches  from  its  fellow ;  lying,  in  the  male, 
about  an  inch  and  a  half  behind  the  base  of  the  prostate,  at  the  posterior  angle  of 
the  trigone. 

Structure.  The  ureter  is  composed  of  three  coats,  fibrous,  muscular,  and 
mucous. 

The  fibrous  coat  is  continuous  with  that  surrounding  the  pelvis. 

The  muscular  coat  consists  of  two  layers  of  longitudinal  fibres,  and  an  inter- 
mediate transverse  layer. 

The  mucous  coat  is  smooth,  and  presents  a  few  longitudinal  folds,  which 
become  effaced  by  distension.  It  is  continuous  with  the  mucous  membrane  of  the 
bladder  below ;  whilst,  above,  it  is  prolonged  over  the  papillae  into  the  tubuli 
uriniferi.     The  epithelial  cells  lining  it  are  spheroidal. 

The  arteries  supplying  the  ureter  are  branches  of  the  renal,  spermatic,  internal 
iliac,  and  inferior  vesical. 

The  nerves  are  derived  from  the  inferior  mesenteric,  spermatic,  and  hypo- 
gastric plexuses. 

Supra-renal  Capsules. 

The  Supra-renal  Capsules  are  usually  classified,  together  with  the  spleen, 
thymus,  and  thyroid,  under  the  head  of  "ductless  glands,"  as  they  have  no  excre- 
tory duct.  They  are  two  small  flattened  glandular  bodies,  of  a  yellowish  color, 
situated  at  the  back  part  of  the  abdomen,  behind  the  peritoneum,  immediately  in 
front  of  the  upper  end  of  either  kidney ;  hence  their  name.  The  right  one  is 
somewhat  triangular  in  shape,  bearing  a  resemblance  to  a  cocked  hat ;  the  left  is 
more  semilunar,  and  usually  larger  and  higher  than  the  right.  They  vary  in  size 
in  different  individuals,  being  sometimes  so  small  as  to  be  scarcely  detected,  at 
other  times  large.     They  measure  from  *>n  inch  and  a  quarter  to  nearly  two 


728  URINARY   ORGANS. 

inches  in  length,  are  rather  less  in  width,  and  from  two  to  three  lines  in  thickness. 
In  weight,  they  vary  from  one  to  two  drachms. 

Relations.  The  anterior  surface  of  the  right  supra-renal  capsule  is  in  relation 
with  the  under  surface  of  the  liver ;  that  of  the  left  with  the  pancreas  and  spleen. 
The  posterior  surface  rests  upon  the  crus  of  the  Diaphragm,  opposite  the  tenth 
dorsal  vertebra.  Their  upper  thin  convex  border  is  directed  upwards  and  inwards. 
Their  lower  thick  concave  bonier  rests  upon  the  upper  end  of  the  kidneys,  to  which 
they  are  connected  by  areolar  tissue.  Their  inner  borders  are  in  relation  with  the 
great  splanchnic  nerves  and  semilunar  ganglia,  and  lie  in  contact  on  the  right  side 
with  the  inferior  vena  cava,  and  on  the  left  side  with  the  aorta.  The  surface  of 
the  supra-renal  gland  is  surrounded  by  areolar  tissue  containing  much  fat,  and 
closely  invested  by  a  thin  fibrous  coat,  which  is  difficult  to  remove,  on  account 
of  the  numerous  fibrous  processes  and  vessels  which  enter  the  organ  through  the 
furrows  on  its  anterior  surface  and  base. 

Structure.  On  making  a  perpendicular  section,  the  gland  is  seen  to  consist  of 
two  substances,  external  or  cortical,  and  internal  or  medullary. 

The  cortical  substance  forms  the  chief  part  of  the  organ ;  it  is  of  a  deep  yellow 
color,  andv  consists  of  narrow  columnar  masses  placed  perpendicularly  to  the 
surface. 

The  medullary  substance  is  soft,  pulpy,  and  of  a  dark  brown  or  black  color ; 
hence  the  name,  atrabiliary  capsules,  given  to  these  organs.  In  its  centre  is  often 
seen  a  space  formed  by  the  breaking  down  of  its  component  parts. 

According  to  the  researches  of  Oesterlen  and  Mr.  Simon,  the  narrow  columnar 
masses  of  which  the  cortical  substance  is  composed  measure  about  T  J  ^th  of  an 
inch  in  diameter,  and  consist  of  small  closed  parallel  tubes  of  limitary  membrane 
containing  dotted  nuclei,  together  with  much  granular  matter,  oil  globules,  and 
nucleated  cells.  According  to  Ecker,  the  apparent  tubular  canals  consist  of  rows 
of  closed  vesicles  placed  endwise,  so  as  to  resemble  tubes ;  whilst  Kolliker  states, 
that  these  vesicles  are  merely  loculi  or  spaces  in  the  stroma  of  the  organ,  having 
no  limitary  membrane,  and,  from  being  situated  endwise,  present  the  appearance 
of  linear  tubes.  Nucleated  cells  exist  in  large  numbers  in  the  supra-renal  glands 
of  ruminants,  but  more  sparingly  in  man  and  other  animals,  but  the  granular 
matter  appears  to  form  their  chief  constituent;  the  granules  vary  in  size,  and  they 
present  the  singular  peculiarity  of  undergoing  no  change  when  acted  upon  by 
most  of  the  chemical  reagents.  The  columnar  masses  are  surrounded  by  a  close 
capillary  network,  which  runs  parallel  with  them. 

The  medullary  substance  consists  of  nuclei  and  granular  matter,  uniformly 
scattered  throughout  a  plexus  of  minute  veins. 

The  arteries  supplying  the  supra-renal  glands  are  numerous  and  of  large  size, 
and  are  derived  from  the  aorta,  the  phrenic,  and  the  renal ;  they  subdivide  into 
numerous  minute  branches  previous  to  entering  the  substance  of  the  gland. 

The  supra-renal  vein  returns  the  blood  from  the  medullary  venous  plexus,  and 
receives  several  branches  from  the  cortical  substance ;  it  opens  on  the  right  side 
into  the  inferior  vena  cava,  on  the  left  side  into  the  renal  vein. 

The  lymphatics  terminate  in  the  lumbar  glands. 

The  nerves  are  exceedingly  numerous;  they  are  derived  from  the  solar  and  renal 
plexuses,  and,  according  to  Bergmann,  from  the  phrenic  and  pneumogastric  nerves. 
They  have  numerous  small  ganglia  developed  upon  them. 

The  Pelvis. 

The  Cavity  of  the  Pelvis  is  that  part  of  the  general  abdominal  cavity  which  is 
below  the  level  of  the  linea  ilio-pectinea  and  the  promontory  of  the  sacrum. 

Boundaries.  It  is  bounded,  behind,  by  the  sacrum,  the  coccyx,  and  the  great 
sacro-sciatic  ligaments ;  in  front  and  at  the  sides,  by  the  pubes  and  ischia,  covered 
by  the  Obturator  muscles;  above,  it  communicates  with  the  cavity  of  the  abdomen; 
and  below,  it  is  limited  by  the  Levatores  ani  and  Coccygei  muscles,  and  the 


BLADDER. 


729 


visceral  layer  of  the  pelvic  fascia,  which  is  reflected  from  the  wall  of  the  pelvis 
on  to  the  viscera. 

Contents.  The  viscera  contained  in  this  cavity  are  the  urinary  bladder,  the 
lower  end  of  the  rectum,  and  some  of  the  generative  organs  peculiar  to  each 
sex ;  they  are  partially  covered  by  the  peritoneum,  and  supplied  with  blood  and 
lymphatic  vessels  and  nerves. 


The  Bladder. 

The  Bladder  is  the  reservoir  for  the  urine.  It  is  a  musculo-membranous  sac, 
situated  in  the  pelvis,  behind  the  pubes,  and  in  front  of  the  rectum  in  the  male, 
the  uterus  and  vagina  intervening  between  it  and  that  intestine  in  the  female. 
The  shape,  position,  and  relations  of  the  bladder  are  greatly  influenced  by  age, 
sex,  and  the  degree  of  distension  of  the  organ.  During  infancy,  it  is  conical  in 
shape,  and  projects  above  the  upper  border  of  the  pubes  into  the  hypogastric 
region.     In  the  adult,  when  quite  empty  and  contracted,  it  is  a  small  triangular 


Fig.  369. — Vertical  Section  of  Bladder,  Penis,  and  Urethra. 


Covftr'k    CI 


Prtpuo* 


sac,  placed  deeply  in  the  pelvis,  flattened  from  before  backwards,  its  apex  reaching 
as  high  as  the  upper  border  of  the  symphysis  pubis.  When  slightly  distended,  it 
has  a  rounded  form,  and  partially  fills  the  pelvic  cavity;  when  greatly  distended  it 
is  ovoid  in  shape,  rising  into  the  abdominal  cavity,  often  extending  upwards  nearly 
as  high  as  the  umbilicus.  It  is  larger  in  its  vertical  diameter  than  from  side  to 
side,  and  its  long  axis  is  directed  from  above  obliquely  downwards  and  backwards 
in  a  line  directed  from  some  point  between  the  pubes  and  umbilicus  (according  to 
its  distension)  to  the  end  of  the  coccyx.  The  bladder,  when  distended,  is  slightly 
curved  forwards  towards  the  anterior  wall  of  the  abdomen,  so  as  to  be  more 


130  URINARY   ORGANS. 

convex  behind  than  in  front.  In  the  female,  it  is  larger  in  the  transverse  than 
in  the  vertical  diameter,  and  its  capacity  is  said  to  be  greater  than  in  the  male. 
"When  moderately  distended,  it  measures  about  five  inches  in  length,  and  three 
inches  across,  and  the  ordinary  amount  which  it  contains  is  about  a  pint. 

The  bladder  is  divided  into  a  summit,  body,  base,  and  neck. 

The  summit  or  apex  of  the  bladder  is  rounded  and  directed  forwards  and 
upwards ;  it  is  connected  to  the  umbilicus  by  a  fibro-muscular  cord,  the  urachus, 
and  also  by  means  of  two  rounded  fibrous  cords,  the  obliterated  portions  of  the 
hypogastric  arteries,  which  are  placed  one  on  each  side  of  the  urachus.  The 
summit  of  the  bladder  behind  the  urachus  is  covered  by  peritoneum,  whilst  the 
portion  in  front  is  uncovered  by  it,  and  rests  upon  the  abdominal  wall. 

The  urachus  is  the  obliterated  remains  of  a  tubular  canal  existing  in  the  embryo, 
which  connects  the  cavity  of  the  bladder  with  a  membranous  sac  placed  external 
to  the  abdomen,  opposite  the  umbilicus,  called  the  allantois.  In  the  infant  at 
birth,  it  is  occasionally  found  pervious,  so  that  the  urine  escapes  at  the  umbilicus, 
and  calculi  have  been  found  in  its  canal. 

The  body  of  the  bladder  in  front  is  not  covered  by  peritoneum,  and  is  in 
relation  with  the  triangular  ligament  of  the  urethra,  the  posterior  surface  of  the 
symphysis  pubis,  the  Internal  obturator  muscles,  and,  when  distended,  with  the 
abdominal  parietes. 

The  posterior  surface  is  covered  by  peritoneum  throughout.  It  corresponds, 
in  the  male,  with  the  rectum ;  in  the  female,  with  the  uterus,  some  convolutions  of 
the  small  intestine  being  interposed. 

The  side  of  the  bladder  is  crossed  obliquely  from  below,  upwards  and  forwards, 
by  the  obliterated  hypogastric  artery ;  above  and  behind  this  cord,  the  bladder  is 
covered  by  peritoneum,  but,  below  and  in  front  of  it,  the  serous  covering  is 
wanting,  and  it  is  connected  to  the  pelvic  fascia.  The  vas  deferens  passes,  in  an 
arched  direction,  from  before  backwards,  along  the  side  of  the  bladder,  towards 
its  base,  crossing  in  its  course  the  obliterated  hypogastric  artery,  and  passing  along 
the  inner  side  of  the  ureter. 

The  base  or  fundus  of  the  bladder  is  directed  downwards  and  backwards.  It 
varies  in  extent  according  to  the  state  of  distension  of  the  organ,  being  very 
broad  when  full,  but  much  narrower  when  empty.  In  the  male,  it  rests  upon  the 
second  portion  of  the  rectum,  from  which  it  is  separated  by  a  reflection  of  the 
recto- vesical  fascia.  It  is  covered  posteriorly,  for  a  slight  extent,  by  the  peri- 
toneum, which  is  reflected  from  it  upon  the  rectum,  forming  the  recto-vesical  fold. 
The  portion  of  the  bladder  in  relation  with  the  rectum  corresponds  to  a  triangular 
space,  bounded  behind  by  the  recto-vesical  fold ;  on  either  side,  by  the  vesicula 
seminalis  and  vas  deferens;  and,  in  front,  by  the  prostate  gland.  When  the 
bladder  is  very  full,  the  peritoneal  fold  is  raised  with  it,  and  the  distance  between 
its  reflection  and  the  anus  is  about  four  inches,  but  this  distance  is  much 
diminished  when  the  bladder  is  empty  and  contracted.  In  the  female,  the  base 
of  the  bladder  lies  in  contact  with  the  lower  part  of  the  cervix  uteri,  is  adherent 
to  the  anterior  wall  of  the  vagina,  and  separated  from  the  upper  part  of  the 
anterior  surface  of  the  cervix  uteri  by  a  fold  of  the  peritoneum. 

The  cervix  or  neck  of  the  bladder  is  the  constricted  portion  continuous  with 
the  urethra.  In  the  male,  its  direction  is  oblique  in  the  erect  posture,  and  it  is 
surrounded  by  the  prostate  gland.  In  the  female,  its  direction  is  obliquely  down- 
wards and  forwards. 

Ligaments.  The  bladder  is  retained  in  its  place  by  ligaments,  which  are  divided 
into  true  and  false.  The  true  ligaments  are  five  in  number,  two  anterior  and  two 
lateral,  formed  by  the  recto-vesical  fascia,  and  the  urachus.  The  false  ligaments, 
also  five  in  number,  are  formed  by  folds  of  the  peritoneum. 

The  anterior  ligaments  (pubo-prostatic)  extend  from  the  back  of  the  pubes,  one 
on  each  side  of  the  symphysis,  to  the  front  of  the  neck  of  the  bladder,  and  upper 
surface  of  the  prostate  gland.  These  ligaments  contain  a  few  muscular  fibres, 
prolonged  from  the  bladder. 


STRICTURE   OF   THE   BLADDER.  731 

The  lateral  ligaments,  broader  and  thinner  than  the  preceding,  are  attached  to 
the  lateral  parts  of  the  prostate,  and  to  the  sides  of  the  base  of  the  bladder. 

The  urachus  is  the  fibro-muscular  cord  already  mentioned,  extending  between 
the  summit  of  the  bladder  and  the  umbilicus.  It  is  broad  below,  at  its  attachment 
to  the  bladder,  and  becomes  narrower  as  it  ascends. 

The  false  ligaments  of  the  bladder  are,  two  posterior,  two  lateral,  and  one 
superior. 

The  two  posterior  pass  forwards,  in  the  male,  from  the  sides  of  the  rectum  ;  in 
the  female,  from  the  sides  of  the  uterus,  to  the  posterior  and  lateral  aspect  of  the 
bladder :  they  form  the  lateral  boundaries  of  the  recto- vesical  fold  of  peritoneum, 
and  contain  the  obliterated  hypogastric  arteries,  the  ureters,  and  vessels  and 
nerves. 

The  two  lateral  ligaments  are  reflections  of  the  peritoneum,  from  the  iliac  fossae 
to  the  sides  of  the  bladder. 

The  superior  ligament  is  the  prominent  fold  of  peritoneum  extending  from  the 
summit  of  the  bladder  to  the  umbilicus.  It  covers  the  urachus,  and  the  obliterated 
hypogastric  arteries. 

Structure.  The  bladder  is  composed  of  four  coats : — a  serous,  a  muscular,  a  cel- 
lular, and  a  mucous  coat. 

The  serous  coat  is  partial,  and  derived  from  the  peritoneum.  It  invests  the 
posterior  surface,  from  opposite  the  termination  of  the  two  ureters  to  its  summit, 
and  is  reflected  from  this  point  and  from  the  sides,  on  to  the  abdominal  and  pelvic 
walls. 

The  muscular  coat  consists  of  two  layers  of  unstriped  muscular  fibre,  an 
external  layer,  composed  of  longitudinal  fibres,  and  an  internal  layer  of  circular 
fibres. 

The  longitudinal  fibres  are  most  distinct  on  the  anterior  and  posterior  surfaces 
of  the  organ.  They  arise,  in  front,  from  the  anterior  ligaments  of  the  bladder, 
from  the  neck  of  the  bladder,  and,  in  the  male,  from  the  adjacent  portion  of  the 
prostate  gland.  They  spread  out,  and  form  a  plexiform  mesh,  on  the  anterior 
surface  of  the  bladder,  being  continued  over  the  posterior  surface  and  base  of 
the  organ  to  the  neck,  where  they  are  inserted  into  the  prostate  in  the  male,  and 
into  the  vagina  in  the  female. 

Other  longitudinal  fibres  arise,  in  the  male,  from  the  sides  of  the  prostate,  and 
spread  out  upon  the  sides  of  the  bladder,  intersecting  with  one  another. 

The  circular  fibres  are  very  thinly  and  irregularly  scattered  on  the  body  of 
the  organ ;  but,  towards  its  lower  part,  round  the  cervix  and  commencement  of  the 
urethra,  they  are  disposed  as  a  thick  circular  layer,  forming  the  sphincter  vesicae, 
which  is  continuous  with  the  muscular  fibres  of  the  prostate  gland. 

Two  bands  of  oblique  fibres,  originating  behind  the  orifices  of  the  ureters, 
converge  to  the  back  part  of  the  prostate  gland,  and  are  inserted,  by  means  of  a 
fibrous  process,  into  the  middle  lobe  of  this  organ.  They  are  the  muscles  of  the 
ureters,  described  by  Sir  C.  Bell,  who  supposed  that,  during  the  contraction  of 
the  bladder,  they  served  to  retain  the  oblique  direction  of  the  ureters,  and  so 
prevent  the  reflux  of  urine  into  them. 

The  cellular  coat  consists  of  a  layer  of  areolar  tissue,  connecting  together  the 
muscular  and  mucous  coats,  being  intimately  connected  with  the  latter. 

The  mucous  coat  is  thin,  smooth,  and  of  a  pale  rose  color.  It  is  continuous 
through  the  ureters  with  the  lining  membrane  of  the  uriniferous  tubes,  and,  below, 
with  the  urethra.  It  is  connected  loosely  to  the  muscular  coat,  by  a  layer  of 
areolar  tissue,  excepting  at  the  trigone,  where  its  adhesion  is  more  close.  It  is 
provided  with  a  few  mucous  tollicles,  and  numerous  small  racemose  glands, 
lined  with  columnar  epithelium,  exist  near  the  neck  of  the  organ.  The  epithe- 
lium covering  it  is  intermediate  in  form  between  the  columnar  and  squamous 
varieties. 

Interior  of  the  bladder.  Upon  the  inner  surface  of  the  base  of  the  bladder, 
immediately  behind  the  urethral  orifice,  is  a  triangular,  smooth  surface,  the  apex 


T32 


"URINARY   ORGANS. 


Fig.  370.— The  Bladder  and  Urethra  laid  open. 
Seen  from  above. 


Cwp"'>  Gl* 


of  which  is  directed  forwards;  this  is  the  trigonum  vesicse  or  trigone  vesicale.  It 
's  paler  in  color  than  the  rest  of  the  mucous  membrane,  and  never  presents  any 
rugae,  even  in  the  collapsed  condition  of  the  organ,  owing  to  its  intimate  adhesion 
to  the  subjacent  tissues.  It  is  bounded  on  each  side  by  two  slight  ridges,  which 
pass  backwards  and  outwards  to  the  orifices  of  the  ureters,  and  correspond  with 
the  muscles  of  these  tubes ;  and  at  each  posterior  angle,  by  the  orifices  of  the 
ureters,  which  are  placed  nearly  two  inches  from  each  other,  and  about  an  inch 
and  a  half  behind  the  orifice  of  the  urethra.     The  trigone  corresponds  with  the 

interval  at  the  base  of  the  bladder, 
bounded  by  the  prostate  in  front,  and 
the  vesicula3  and  vasa  deferentia  on 
the  sides.  Projecting  from  the  lower 
and  anterior  part  of  the  bladder,  into 
the  orifice  of  the  urethra,  is  a  slight 
elevation  of  mucous  membrane,  called 
the  uvula  vesicse.  It  is  formed  by  a 
thickening  of  the  prostate. 

The  arteries  supplying  the  bladder 
are  the  superior,  middle,  and  inferior 
vesical,  in  the  male,  with  additional 
branches  from  the  uterine,  in  the  female. 
They  are  all  derived  from  the  anterior 
trunk  of  the  internal  iliac. 

The  veins  form  a  complicated  plexus 
round  the  neck,  sides,  and  base  of  the 
bladder,  and  terminate  in  the  internal 
iliac  veins. 

The  lymphatics  accompany  the 
bloodvessels,  passing  through  the 
glands  surrounding  them. 

The  nerves  are  derived  from  the 
hypogastric  and  sacral  plexuses;  the 
former  supplying  the  upper  part  of 
the  organ,  the  latter  its  base  and 
neck. 

Male  Urethra. 


The  Urethra  extends  from  the  neck 

of  the  bladder  to  the  meatus  urinarius. 

It  is  curved   in    its  course,  so  as  to 

resemble,  in  its  flaccid  state,  the  Italic 

letter  /;  but  in  the  erect  state  it  forms 

only  a  single  curve,  the  concavity  of 

which  is  directed  upwards.     Its  length 

varies  from  eight  to  nine  inches ;  and 

it  is  divided  into  three  portions,  the 

prostatic,    membranous,    and    spongy, 

the  structure  and  relations  of  which 

are  essentially  different. 

The  Prostatic  portion  is  the  widest  and  most  dilatable  part  of  the  canal.     It 

passes  through  the  prostate  gland,  from  its  base  to  its  apex,  lying  nearer  its  upper 

than  its  lower  surface.     It  is  about  an  inch  and  a  quarter  in  length,  and  the  form 

of  the  canal  is  spindle-shaped,  being  wider  in  the  middle  than  at  either  extremity, 

and  narrowest  in  front,  where  it  joins  the  membranous  portion.     A  transverse 

section  of  the  canal  in  this  situation  is  triangular,  the  apex  directed  downwards. 

Upon  the  floor  of  the  canal  is  a  narrow  longitudinal  ridge,  the  veru  montanum 


Ottflcr*  cf  Juct*. 

s/'Coitytrs  Glands 


URETHRA.  733 

or  caput  yallinaginis,  formed  by  an  elevation  of  the  mucous  membrane  and  its. 
subjacent  tissue.  It  is  eight  or  nine  lines  in  length,  and  a  line  and  a  half  in 
height,  and  contains,  according  to  Kobelt,  muscular  and  erectile  tissues.  When 
distended,  it  may  serve  to  prevent  the  passage  of  the  semen  backwards  into  the 
bladder.  On  each  side  of  the  veru  montanum  is  a  slightly  depressed  fossa,  the 
prostatic  sinus,  the  floor  of  which  is  perforated  by  numerous  apertures,  the  orifices 
of  the  prostatic  ducts,  the  ducts  of  the  middle  lobe  opening  behind  the  crest.  At 
the  fore  part  of  the  veru  montanum,  in  the  middle  line,  is  a  depression,  the  sinus 
pocularis  or  vesicula  prostalica;  and  upon  or  within  its  margins  are  the  slit-like 
openings  of  the  ejaculatory  ducts.  The  sinus  pocularis  forms  a  cul-de-sac  about 
a  quarter  of  an  inch  in  length,  which  runs  upwards  and  backwards  in  the  sub- 
stance of  the  prostate,  beneath  the  middle  lobe ;  its  prominent  upper  wall  partly 
forms  the  veru  montanum.  Its  walls  are  composed  of  fibrous  tissue,  muscular 
fibres,  and  mucous  membrane ;  and  numerous  small  glands  open  on  its  inner  sur- 
face. It  has  been  called  by  Weber,  who  discovered  it,  the  uterus  masculinus, 
from  its  supposed  homology  with  the  female  organ. 

The  Membranous  portion  of  the  urethra  extends  between  the  apex  of  the  pros- 
tate, and  the  bulb  of  the  corpus  spongiosum.  It  is  the  narrowest  part  of  the  canal 
(excepting  the  orifice),  and  measures  three-quarters  of  an  inch  along  its  upper, 
and  half  an  inch  along  its  lower  surface,  in  consequence  of  the  bulb  projecting 
backwards  beneath  it  below.  Its  upper  concave  surface  is  placed  about  an  inch 
beneath  the  pubic  arch,  from  which  it  is  separated  by  the  dorsal  vessels  and  nerves 
of  the  penis,  and  some  muscular  fibres.  Its  lower  convex  surface  is  separated 
from  the  rectum  by  a  triangular  space,  which  constitutes  the  perineum.  The 
membranous  portion  of  the  urethra  perforates  the  deep  perineal  fascia ;  and  two 
layers  from  this  membrane  are  prolonged  round  it,  the  one  forwards,  the  other 
backwards ;  it  is  also  surrounded  by  the  Compressor  urethraa  muscle.  Its  cover- 
ings are  mucous  membrane,  elastic  fibrous  tissue,  a  thin  layer  of  erectile  tissue, 
muscular  fibres,  and  a  prolongation  from  the  deep  perineal  fascia. 

The  Spongy  portion  is  the  longest  part  of  the  urethra,  and  is  contained  in  the 
corpus  spongiosum.  It  is  about  six  inches  in  length,  and  extends  from  the  termi- 
nation of  the  membranous  portion  to  the  meatus  urinarius.  Commencing  below 
the  symphysis  pubis,  it  ascends  for  a  short  distance,  and  then  curves  downwards. 
It  is  narrow,  and  of  uniform  size  in  the  body  of  the  penis,  measuring  about  a 
quarter  of  an  inch  in  diameter  ;  being  dilated  behind,  within  the  bulb,  where  it 
forms  the  bulbous  portion,  and  again  anteriorly,  within  the  glans  penis,  forming 
the  fossa  navicularis.  A  cross  section  of  this  canal  in  the  body  has  its  diameter 
transverse,  but  in  the  glans  the  diameter  is  directed  vertically. 

The  meatus  urinarius  is  the  most  contracted  part  of  the  urethra ;  it  is  a  vertical 
slit,  about  three  lines  in  length,  bounded  on  each  side  by  two  small  labia.  The 
inner  surface  of  the  lining  membrane  of  the  urethra,  especially  on  the  floor  of  the 
spongy  portion,  presents  the  orifices  of  numerous  mucous  glands  and  follicles, 
situated  in  the  submucous  tissue,  and  named  the  glands  of  Littre.  They  vary  in 
size,  and  their  orifices  are  directed  forwards,  so  that  they  may  easily  intercept  the 
point  of  a  catheter  in  its  passage  along  the  canal.  One  of  these  lacunte,  larger 
than  the  rest,  is  situated  on  the  upper  surface  of  the  fossa  navicularis,  about  an 
inch  and  a  half  from  the  orifice ;  it  is  called  the  lacuna  magna.  Into  the  bulbous 
portion  are  found  opening  the  ducts  of  Cowper's  glands. 

Structure.  The  urethra  is  composed  of  three  coats :  a  mucous,  muscular,  and 
erectile. 

The  mucous  coat  forms  part  of  the  genito-urinary  mucous  membrane.  It  is 
continuous  with  the  mucous  membrane  of  the  bladder,  ureters,  and  kidneys, 
externally,  with  the  integument  covering  the  glans  penis ;  and  is  prolonged  into 
the  ducts  of  the  numerous  glands  which  open  into  the  urethra,  viz.,  Cowper's 
glands,  and  the  prostate  gland ;  and,  through  the  ejaculatory  ducts,  is  continued  into 
the  vasa  deferentia  and  vesiculse  seminales.  In  the  spongy  and  membranous 
portions,  the  mucous  membrane  is  arranged  in  longitudinal  folds  when  the  organ 


734  URINARY   ORGANS. 

is  contracted.  Small  papillae  are  found  upon  it,  near  the  orifice ;  and  its  epithe- 
lial lining  is  of  the  columnar  variety,  excepting  near  the  meatus,  where  it  is 
laminated. 

The  muscular  coat  consists  of  two  layers  of  plain  muscular  fibres,  an  external 
longitudinal  layer,  and  an  internal  circular.  The  muscular  tissue  is  most  abundant 
in  the  prostatic  portion  of  the  canal. 

A  thin  layer  of  erectile  tissue  is  continued  from  the  corpus  spongiosum  round 
the  membranous  and  prostatic  portions  of  the  urethra  to  the  neck  of  the  bladder. 


Male  Generative  Organs. 

Prostate  Gland. 

The  Prostate  Gland  (rtpoCat^fii,  to  stand  before)  is  a  pale,  firm,  glandular  body, 
which  surrounds  the  neck  of  the  bladder  and  commencement  of  the  urethra.  It 
is  placed  in  the  pelvic  cavity,  behind  and  below  the  symphysis  pubis,  posterior 
to  the  deep  perineal  fascia,  and  upon  the  rectum,  through  which  it  may  be  distinctly 
felt,  especially  when  enlarged.     In  shape  and  size  it  resembles  a  horse-chestnut. 

Its  base  is  directed  backwards  towards  the  neck  of  the  bladder. 

The  apex  is  directed  forwards  to  the  deep  perineal  fascia,  which  it  touches. 

Its  under  surface  is  smooth,  and  rests  on  the  rectum,  to  which  it  is  connected 
by  a  dense  areolar  fibrous  tissue. 

Its  upper  surface  is  flattened,  marked  by  a  slight  longitudinal  furrow,  and  placed 
about  three-quarters  of  an  inch  below  the  pubic  symphysis. 

It  measures  about  an  inch  and  a  half  in  its  transverse  diameter  at  the  base,  an 
inch  in  its  antero-posterior  diameter,  and  three-quarters  of  an  inch  in  depth; 
and  its  weight  is  about  six  drachms.  It  is  held  in  its  position  by  the  anterior 
ligaments  of  the  bladder  (pubo-prostatic) ;  by  the  posterior  layer  of  the  deep 
perineal  fascia,  which  invests  the  commencement  of  the  membranous  portion  of 
the  urethra  and  prostate  gland ;  and  by  the  anterior  portion  of  the  Levator  ani 
muscle  {levator  prostatae),  which  passes  down  on  each  side  from  the  symphysis  pubis 
and  anterior  ligament  of  the  bladder  to  the  sides  of  the  prostate. 

The  prostate  consists  of  three  lobes ;  two  lateral  and  a  middle  lobe. 

The  two  lateral  lobes  are  of  equal  size,  separated  behind  by  a  deep  notch,  and 
marked  by  a  slight  furrow  upon  their  upper  and  lower  surface,  which  indicates 
the  bi-lobed  condition  of  the  organ  in  some  animals. 

The  third  or  middle  lobe  is  a  small,  transverse  band,  occasionally  a  rounded  or 
triangular  prominence,  placed  between  the  two  lateral  lobes  at  the  under  and 
posterior  part  of  the  organ.  It  lies  immediately  beneath  the  neck  of  the  bladder, 
behind  the  commencement  of  the  urethra,  and  above  the  ejaculatory  ducts.  Its 
existence  is  not  constant,  but  it  is  occasionally  found  at  an  early  period  of  life,  as 
well  as  in  adults,  and  in  old  age.  In  advanced  life  it  often  becomes  considerably 
enlarged,  and  projects  into  the  bladder,  so  as  to  impede  the  evacuation  of  the  urine. 

The  prostate  gland  is  perforated  by  the  urethra  and  common  seminal  ducts. 
The  urethra  usually  lies  about  one-third  nearer  its  upper  than  its  lower  surface ; 
occasionally,  the  prostate  surrounds  only  the  lower  three-fourths  of  this  tube,  and 
it  more  rarely  runs  through  the  lower  than  the  upper  part  of  the  gland.  The 
ejaculatory  ducts  pass  forwards  obliquely  through  a  conical  canal,  situated  in  the 
lower  part  of  the  prostate,  and  open  into  the  prostatic  portion  of  the  urethra. 

Structure.  The  prostate  is  inclosed  in  a  thin  but  firm  fibrous  capsule,  distinct 
from  that  derived  from  the  posterior  layer  of  the  deep  perineal  fascia,  and  sepa- 
rated from  it  by  a  plexus  of  veins.  Its  substance  is  of  a  pale,  reddish-gray  color, 
very  friable,  but  of  great  density.  It  consists  of  glandular  substance  and  muscular 
tissue. 

The  glandular  substance  is  composed  of  numerous  follicular  pouches,  opening 
into  elongated  canals,  which  join  to  form  from  twelve  to  twenty  small  excretory 
ducts.  The  follicles  are  connected  together  by  areolar  tissue,  supported  by  pro- 
longations from  the  fibrous  capsule,  and  inclosed  in  a  delicate  capillary  plexus. 
The  epithelium  lining  the  canals  is  columnar,  whilst  that  in  the  terminal  vesicles 
is  of  the  squamous  variety. 

The  muscular  tissue  of  the  prostate  is  arranged  in  the  form  of  circular  bands 

735 


736  MALE    GENERATIVE    ORGANS. 

round  the  urethra ;  it  is  continuous  behind  with  the  circular  fibres  of  the  sphincter 
vesicae,  and  in  front  with  the  circular  fibres  of  the  urethra.  The  muscular  fibres 
are  of  the  involuntary  kind.  The  prostatic  ducts  open  into  the  floor  of  the 
prostatic  portion  of  the  urethra. 

Vessels  and  Nerves.  The  arteries  supplying  the  prostate  are  derived  from  the 
internal  pudic,  vesical,  and  hemorrhoidal.  Its  veins  form  a  plexus  around  the 
sides  and  base  of  the  gland ;  they  communicate  in  front  with  the  dorsal  vein  of 
the  penis,  and  terminate  in  the  internal  iliac  vein.  The  nerves  are  derived  from 
the  hypogastric  plexus. 

The  Prostatic  Secretion  is  a  milky  fluid,  having  an  acid  reaction,  and  presenting, 
on  microscopic  examination,  molecular  matter,  the  squamous  and  columnar  forms 
of  epithelium,  and  granular  nuclei.  In  old  age,  this  gland  is  liable  to  be  enlarged, 
and  its  ducts  are  often  filled  with  innumerable  small  concretions,  of  a  brownish-red 
color,  and  of  the  size  of  a  millet-seed,  composed  of  carbonate  of  lime  and  animal 
matter. 

Cowper's  Glands. 

Cowper's  Glands  are  two  small  rounded  and  somewhat  lobulated  bodies,  of  a 
yellowish  color,  about  the  size  of  peas,  placed  beneath  the  fore  part  of  the 
membranous  portion  of  the  urethra,  between  the  two  layers  of  the  deep  perineal 
fascia.  They  lie  close  behind  the  bulb,  and  are  inclosed  by  the  transverse  fibres 
of  the  Compressor  urethras  muscle.  Each  gland  consists  of  several  lobules,  held 
together  by  a  fibrous  investment.  The  excretory  duct  of  each  gland,  nearly  an 
inch  in  length,  passes  obliquely  forwards  beneath  the  mucous  membrane,  and 
opens  by  a  minute  orifice  on  the  floor  of  the  bulbous  portion  of  the  urethra. 
Their  existence  is  said  to  be  constant ;  they  gradually  diminish  in  size  as  age 
advances. 

The  Penis. 

The  Penis  is  the  organ  of  copulation,  and  contains  in  its  interior  the  larger 
portion  of  the  urethra.  It  consists  of  a  root,  body,  and  the  extremity  or  glans 
penis. 

The  root  is  broad  and  firmly  connected  to  the  rami  of  the  pubes  by  two  strong 
tapering  fibrous  processes,  the  crura,  and  to  the  front  of  the  symphysis  pubis  by 
a  fibrous  membrane,  the  suspensory  ligament. 

The  extremity  or  glans  penis  presents  the  form  of  an  obtuse  cone,  flattened  from 
above  downwards.  At  its  summit  is  a  vertical  fissure,  the  orifice  of  the  urethra, 
meatus  urinarius  ;  and  at  the  back  part  of  this  orifice  a  fold  of  mucous  membrane 
passes  backwards  to  the  bottom  of  a  depressed  raphe,  where  it  is  continuous  with 
the  prepuce ;  this  fold  is  termed  the  froenum  preputii.  The  base  of  the  glans  forms 
a  rounded  projecting  border,  the  corona  glandis  ;  and  behind  the  corona  is  a  deep 
constriction,  the  cervix.  Upon  both  of  these  parts  numerous  small  lenticular 
sebaceous  glands  are  found,  the  glandulse  Tysonii  sou  odoriferve.  They  secrete  a 
sebaceous  matter  of  very  peculiar  odor,  which  probably  contains  casein,  and 
becomes  easily  decomposed. 

The  body  of  the  penis  is  the  part  between  the  root  and  the  extremity.  In  the 
flaccid  condition  of  the  organ  it  is  cylindrical,  but  when  erect  has  a  triangular 
prismatic  form  with  rounded  angles,  the  broadest  side  being  turned  upwards,  and 
called  the  dorsum.  It  is  covered  by  integument  remarkable  for  its  thinness,  its 
dark  color,  its  looseness  of  connection  with  the  deeper  parts  of  the  organ,  and 
from  containing  no  adipose  tissue.  At  the  root  of  the  penis  the  integument  is 
continuous  with  that  upon  the  pubes  and  scrotum ;  and  at  the  neck  of  the  glans 
it  leaves  the  surface,  and  becomes  folded  upon  itself  to  form  the  prepuce. 

The  internal  layer  of  the  prepuce,  which  also  becomes  attached  to  the  cervix, 
approaches  in  character  to  a  mucous  membrane ;  it  is  reflected  over  the  glans 
penis,  and  at  the  meatus  urinarius  is  continuous  with  the  mucous  lining  of  the 
urethra. 


PE^IS.  T37 

Tlie  mucous  membrane  covering  the  glans  penis  contains  no  sebaceous  glands ; 
but  projecting  from  its  free  surface  are  a  number  of  small,  highly  sensitive 
papillae.    , 

The  penis  is  composed  of  a  mass  of  erectile  tissue,  inclosed  in  three  cylindrical 
fibrous  compartments.  Two  of  these,  the  corpora  cavernosa,  are  placed  side  by 
side  along  the  upper  part  of  the  organ ;  the  third  or  corpus  spongiosum  incloses 
the  urethra,  and  is  placed  below. 

The  Corpora  Cavernosa  form  the  chief  part  of  the  body  of  the  penis.  They 
consist  of  two  fibrous  cylindrical  tubes,  placed  side  by  side,  and  intimately  con- 
nected along  the  median  line  for  their  anterior  three-fourths,  their  posterior  fourth 
being  separated  to  form  the  two  crura,  by  which  the  penis  is  connected  to  the 
rami  of  the  pubes.  Each  crus  commences  by  a  thick-pointed  process  in  front  of 
the  tuberosity  of  the  ischium ;  and,  near  its  junction  with  its  fellow,  presents  a 
slight  enlargement,  named,  by  Kobelt,  the  bulb  of  the  corpus  cavernosum.  Just 
beyond  this  point  they  become  constricted,  and  retain  an  equal  diameter  to  their 
anterior  extremity,  where  they  form  a  single  rounded  end,  which  is  received 
into  a  fossa  in  the  base  of  the  glans  penis.  A  median  groove  on  the  upper  surface 
lodges  the  dorsal  vein  of  the  penis,  and  the  groove  on  the  under  surface  receives 
the  corpus  spongiosum.  The  root  of  the  penis  is  connected  to  the  symphysis 
pubis  by  the  suspensory  ligament. 

Structure.  Each  corpus  cavernosum  consists  of  a  strong  fibrous  envelop, 
inclosing  a  fibrous  reticular  structure,  containing  erectile  tissue  in  its  meshes.  It 
is  separated  from  its  fellow  by  an  incomplete  fibrous  septum. 

The  fibrous  investment  is  extremely  dense,  of  considerable  thickness,  and  highly 
elastic ;  it  not  only  invests  the  surface  of  the  organ,  but  sends  off  numerous  fibrous 
bands  (trabeculse)  from  its  inner  surface,  as  well  as  from  the  surface  of  the  septum, 
which  cross  its  interior  in  all  directions,  subdividing  it  into  a  number  of  separate 
compartments,  which  present  a  spongy  structure,  in  which  the  erectile  tissue  is 
contained. 

The  trabecular  structure  fills  the  interior  of  the  corpora  cavernosa.  Its  com- 
ponent fibres  are  larger  and  stronger  round  the  circumference  than  at  the  centre 
of  the  corpora  cavernosa;  they  are  also  thicker  behind  than  in  front.  The  inter- 
spaces, on  the  contrary,  are  larger  at  the  centre  than  at  the  circumference,  their 
long  diameter  being  directed  transversely ;  and  they  are  largest  anteriorly.  They 
are  lined  by  a  layer  of  squamous  epithelium. 

The  fibrous  septum  forms  an  imperfect  partition  between  the  two  corpora  caver- 
nosa ;  it  is  thick  and  complete  behind,  but  in  front  it  is  incomplete,  and  consists  of 
a  number  of  vertical  bands  of  fibrous  tissue,  which  are  arranged  like  the  teeth  of 
a  comb ;  hence  the  name,  septum  pectiniforme.  These  bands  extend  between  the 
dorsal  and  urethral  surface  of  the  corpora  cavernosa. 

The  fibrous  investment  and  septum  consist  of  longitudinal  bands  of  white  fibrous 
tissue,  with  numerous  elastic  and  muscular  fibres.  The  trabecule  also  consist  of 
white  fibrous  tissue,  elastic  fibres,  and  plain  muscular  fibres,  and  inclose  arteries 
and  nerves. 

The  Corpus  Spongiosum  incloses  the  urethra,  and  is  situated  in  the  groove  on 
the  under  surface  of  the  corpora  cavernosa.  It  commences  posteriorly  in  front 
of  the  deep  perineal  fascia,  between  the  diverging  crura  of  the  corpora  cavernosa, 
where  it  forms  a  rounded  enlargement,  the  bulb ;  and  terminates,  anteriorly,  in 
another  expansion,  the  glans  penis,  which  overlays  the  anterior  rounded  extremity 
of  the  corpora  cavernosa ;  its  central  portion  or  body  is  cylindrical,  and  tapers 
slightly  from  behind  forwards. 

The  bulb  varies  in  size  in  different  subjects ;  it  receives  a  fibrous  investment 
from  the  anterior  layer  of  the  deep  perineal  fascia,  and  is  surrounded  by  the 
Accelerator  urinse  muscle.  The  urethra  enters  the  bulb  nearer  its  upper  than  its 
lower  surface,  being  surrounded  by  a  layer  of  erectile  tissue,  named,  by  Kobelt, 
the  colliculi  bulbi,  a  thin  prolongation  of  which  is  continued  backwards  round 
the  membranous  and  prostatic  portions  of  the  canal  to  the  neck  of  the  bladder, 
47 


738  MALE    GENERATIVE   ORGANS. 

lying  immediately  beneath  the  mucous  membrane.  The  portion  of  the  bulb 
below  the  urethra  presents  a  partial  division  into  two  lobes,  being  marked 
externally  by  a  linear  raphe,  whilst  internally  there  projects  inwards,  for  a  short 
distance,  a  thin  fibrous  septum,  most  distinct  in  early  life. 

Structure.  The  corpus  spongiosum  consists  of  a  strong  fibrous  envelop,  inclosing 
a  trabecular  structure,  which  contains  in  its  meshes  erectile  tissue.  The  fibrous 
envelop  is  thinner,  whiter  in  color,  and  more  elastic  than  that  of  the  corpus 
cavernosum.  The  trabeculse  are  delicate,  uniform  in  size,  and  the  meshes  between 
them  small ;  their  long  diameter,  for  the  most  part,  corresponding  with  that  of 
the  penis.  A  thin  layer  of  muscular  fibres,  continuous  behind  with  those  of  the 
bladder,  forms  part  of  the  outer  coat  of  the  corpus  spongiosum. 

Erectile  tissue  consists  essentially  of  an  intricate  venous  plexus,  lodged  in  the 
interspaces  between  the  trabeculse.  The  veins  forming  this  plexus  are  so 
numerous,  and  communicate  so  freely  with  one  another,  as  to  present  a  cellular 
appearance  when  examined  by  means  of  a  section;  their  walls  are  extremely  thin, 
and  lined  by  squamous  epithelium.  The  veins  are  smaller  in  the  glans  penis, 
corpus  spongiosum,  and  circumference  of  the  corpora  cavernosa,  than  in  the  central 
part  of  the  latter,  where  they  are  of  large  size,  and  much  dilated.  They  return 
the  blood  by  a  series  of  vessels,  some  of  which  emerge  in  considerable  numbers 
from  the  base  of  the  glans  penis,  and  converge  on  the  dorsum  of  the  organ  to  form 
the  dorsal  vein ;  others  pass  out  on  the  upper  surface  of  the  corpora  cavernosa, 
and  join  the  dorsal  vein ;  some  emerge  from  the  under  surface  of  the  corpora 
cavernosa,  and,  receiving  branches  from  the  corpus  spongiosum,  wind  round  the 
sides  of  the  penis  to  terminate  in  the  dorsal  vein ;  but  the  greater  number  pass 
out  at  the  root  of  the  penis,  and  join  the  prostatic  plexus  and  pudendal  veins. 

The  arteries  of  the  penis  are  derived  from  the  internal  pudic.  Those  supplying 
the  corpora  cavernosa  are  the  arteries  of  the  corpora  cavernosa,  and  branches  from 
the  dorsal  artery  of  the  penis,  which  perforate  the  fibrous  capsule  near  the  fore 
part  of  the  organ.  Those  to  the  corpus  spongiosum  are  the  arteries  of  the  bulb. 
Additional  branches  are  described,  by  Kobelt,  as  arising  from  the  trunk  of  the 
internal  pudic ;  they  enter  the  bulbous  enlargement  on  the  corpora  cavernosa  and 
corpus  spongiosum.  The  arteries,  on  entering  the  cavernous  structure,  divide  into 
branches,  which  are  supported  and  inclosed  by  the  trabecular ;  according  to  Muller, 
some  of  these  branches  terminate  in  a  capillary  network,  which  communicates  with 
the  veins  as  in  other  parts;  whilst  others  are  more  convoluted,  and  assume  a  tendril- 
like appearance;  hence  the  name,  helicine  arteries,  which  is  given  to  these  peculiar 
vessels.  The  helicine  arteries  are  most  abundant  in  the  back  part  of  the  corpora 
cavernosa  and  corpus  spongiosum ;  they  have  not  been  seen  in  the  glans  penis. 
The  existence  of  these  vessels  is  denied  by  Valentin,  who  describes  the  smallest 
branches  of  the  arteries  as  terminating  by  wide,  funnel-shaped  orifices,  which  open 
directly  into  the  venous  cavities. 

The  lymphatics  of  the  penis  consist  of  a  superficial  and  deep  set ;  the  former 
terminate  in  the  inguinal  glands,  the  latter  emerge  from  the  corpora  cavernosa 
and  corpus  spongiosum,  and,  passing  beneath  the  pubic  arch,  join  the  deep  lym- 
phatics of  the  pelvis. 

The  nerves  are  derived  from  the  internal  pudic  nerve  and  the  hypogastric  plexus. 
On  the  glans  and  bulb,  some  filaments  of  the  cutaneous  nerves  have  Pacinian 
bodies  connected  with  them. 

The  Testes. 

The  Testes  are  two  small  glandular  organs,  which  secrete  the  semen ;  they  are 
situated  in  the  scrotum,  being  suspended  by  the  spermatic  cords.  Each  is  of  an 
oval  form,  compressed  laterally  and  behind,  and  having  an  oblique  position  in  the 
scrotum ;  the  upper  extremity  being  directed  forwards  and  a  little  outwards ;  the 
lower,  backwards  and  a  little  inwards;  the  anterior  convex  border  looks  forwards 
and  downwards,  the  posterior  or  straight  border,  to  which  the  cord  is  attached, 
backwards  and  upwards. 


COVERINGS   OF   THE   TESTES.  739 

The  anterior  and  lateral  surfaces,  as  well  as  both  extremities  of  the  organ,  are 
convex,  free,  smooth,  and  invested  by  a  serous  covering  called  the  tunica  vaginalis. 
The  posterior  border,  to  which  the  cord  is  attached,  receives  only  a  partial  invest- 
ment from  this  membrane.  Lying  upon  the  outer  edge  of  this  border,  is  a  long, 
narrow,  flattened  body,  named,  from  its  relation  to  the  testis,  the  epididymis  («« 
AiSi^o;,  testis).  It  consists  of  a  central  portion  or  body,  an  upper  enlarged  ex- 
tremity, the  globus  major  or  head ;  and  a  lower  pointed  extremity,  the  tail  or 
globus  minor.  The  globus  major  is  intimately  connected  with  the  upper  end  of 
the  testicle  by  means  of  its  efferent  ducts ;  and  the  globus  minor  is  connected 
with  its  lower  end  by  cellular  tissue,  and  a  reflection  of  the  tunica  vaginalis.  The 
outer  surface  and  upper  and  lower  ends  of  the  epididymis  are  free  and  covered  by 
serous  membrane ;  the  body  is  also  completely  invested  by  it,  excepting  along  its 
posterior  border,  and  connected  to  the  back  of  the  testis  by  a  fold  of  the  serous 
membrane.  Attached  to  the  upper  end  of  the  testis,  or  to  the  epididymis,  is  a 
small  pedunculated  body,  the  use  of  which  is  unknown. 

Size  and  Weight.  The  average  dimensions  of  this  gland  are  from  one  and  a 
half  to  two  inches  in  length,  one  inch  in  breadth,  and  an  inch  and  a  quarter  in 
the  antero-posterior  diameter ;  and  the  weight  varies  from  six  to  eight  drachms, 
the  left  testicle  being  a  little  the  larger. 

Coverings.  At  an  early  period  of  foetal  life,  the  testes  are  contained  in  the  abdo- 
minal cavity,  behind  the  peritoneum.  Before  birth,  they  descend  to  the  inguinal 
canal,  along  which  they  pass  with  the  spermatic  cord,  and,  emerging  at  the  external 
abdominal  ring,  they  descend  into  the  scrotum,  becoming  invested  in  their  course 
by  numerous  coverings,  derived  from  the  serous,  muscular,  and  fibrous  layers  of 
the  abdominal  parietes,  as  well  as  by  the  scrotum.  The  coverings  of  the  testis 
are  the 

Skin      )  G      , 
-p.     ,        \  Scrotum. 
Dartos    j 

Intercolumnar  or  External  spermatic  fascia. 

Cremaster  muscle. 

Infundibuliform  fascia,  Fascia  propria  or  Internal  spermatic  fascia. 

Tunica  vaginalis. 

The  Scrotum  is  a  cutaneous  pouch,  which  contains  the  testes  and  part  of  the 
spermatic  cords.  It  is  divided  into  two  lateral  halves,  by  a  median  line  or  raphe, 
which  is  continued  forwards  along  the  under  surface  of  the  penis,  and  backwards 
along  the  middle  line  of  the  perineum  to  the  anus.  Of  these  two  lateral  portions, 
the  left  is  longer  than  the  right,  and  corresponds  with  the.  greater  length  of  the 
spermatic  cord  on  the  left  side.  Its  external  aspect  varies  under  different 
circumstances ;  thus,  under  the  influence  of  warmth,  and  in  old  and  debilitated 
persons,  it  becomes  elongated  and  flaccid ;  but,  under  the  influence  of  cold,  and 
in  the  young  and  robust,  it  is  short,  corrugated,  and  closely  applied  to  the  testes 

The  scrotum  consists  of  two  layers,  the  integument  and  the  darto;-;. 

The  integument  is  very  thin,  of  a  brownish  color,  and  generally  thrown  into 
folds  or  rugae.  It  is  provided  with  sebaceous  follicles,  the  secretion  of  which  has 
a  peculiar  odor,  and  is  beset  with  thinly-scattered,  crisp  hairs,  the  roots  of  which 
are  seen  through  the  skin. 

The  dartos  is  a  thin  layer  of  loose  reddish  tissue,  endowed  with  contractility ; 
it  forms  the  proper  tunic  of  the  scrotum,  is  continuous,  around  the  base  of  the 
scrotum,  with  the  superficial  fascia  of  the  groin,  perineum,  and  inner  side  of  the 
thighs,  and  sends  inwards  a  distinct  septum,  septum  scroti,  which  divides  it  into 
two  cavities  for  the  two  testes,  the  septum  extending  between  the  raphe  and  under 
surface  of  the  penis,  as  far  as  its  root. 

The  dartos  is  closely  united  to  the  skin  externally,  but  connected  with  the 
subjacent  parts  by  delicate  areolar  tissue,  upon  which  it  glides  with  the  greatest 
facility.  The  dartos  is  very  vascular,  and  consists  of  a  loose  areolar  tissue,  con- 
taining unstriped  muscular  fibre.  Its  contractility  is  slow,  and  excited  by  cold 
and  mechanical  stimuli,  but  not  by  electricity. 


?40 


MALE   GENERATIVE   ORGANS. 


Fig.  371.— The  Testis  in  Situ  :  the  Tunica 
Vaginalis  having  been  laid  open. 


Artery 
of  Cord 


The  intercolumnar  fascia  is  a  thin  membrane,  derived  from  the  margin  of  the 
pillars  of  the  external  abdominal  ring,  during  the  descent  of  the  testis  in  the 
foetus,  being  prolonged  downwards  around  the  surface  of  the  cord  and  testis.  It 
is  separated  from  the  dartos  by  loose  areolar  tissue,  which  allows  of  considerable 
movement  of  the  latter  upon  it,  but  is  intimately  connected  with  the  succeeding 
layer. 

The  cremasteric  fascia  consists  of  scattered  bundles  of  muscular  fibres  (  Cremaster 
muscle),  derived  from  the  lower  border  of  the  Internal  oblique  muscle,  during  the 
descent  of  the  testis. 

The  fascia  propria  is  a  thin  membranous  layer,  which  loosely  invests  the 
surface  of  the  cord.  It  is  a  continuation  downwards  of  the  infundibuliform  pro- 
cess of  the  fascia  transversalis,  and  is  also  derived  during  the  descent  of  the  testis 
in  the  foetus. 

The  tunica  vaginalis  is  described  more  appropriately,  as  one  of  the  proper 
coverings  of  the  testis.     A  more  detailed  account  of  the  coverings  just  described 
may  be  found  in  the  description  of  the  surgical  anatomy  of  inguinal  hernia. 
Proper  coverings  or  investments  of  the  Testis.     The  testis  is  invested  by  three 

tunics,  the  tunica  vaginalis,  tunica  albu- 
ginea,  and  tunica  vasculosa. 

The  Tunica  Vaginalis  is  the  serous 
covering  of  the  testis.  It  is  a  pouch  of 
serous  membrane,  derived  from  the  peri- 
toneum during  the  descent  of  the  testis, 
in  the  foetus,  from  the  abdomen  into  the 
scrotum.  After  its  descent,  that  portion 
of  the  pouch  which  extends  from  the 
internal  ring  to  near  the  upper  part  of 
the  gland  becomes  obliterated,  the  lower 
portion  remaining  as  a  shut  sac,  which 
invests  the  outer  surface  of  the  testis,  and 
is  reflected  on  the  internal  surface  of  the 
scrotum ;  hence  it  may  be  described  as 
consisting  of  a  visceral  and  parietal  por- 
tion. 

The  visceral  portion  {tunica  vaginalis 
propria)  covers  the  outer  surface  of  the 
testis,  as  well  as  the  epididymis,  con- 
necting the  latter  to  the  testis  by  means 
of  a  distinct  fold.  From  the  posterior 
border  of  the  gland,  it  is  reflected  on  to  the  internal  surface  of  the  scrotum. 

The  parietal  portion  of  the  serous  membrane  (tunica  vaginalis  reflexa)  is  far 
more  extensive  than  the  visceral  portion,  extending  upwards  for  some  distance  in 
front,  and  on  the  inner  side  of  the  cord,  and  reaching  below  the  testis.  The  inner 
surface  of  the  tunica  vaginalis  is  free,  smooth,  and  covered  by  a  layer  of  squamous 
epithelium.  The  interval  between  the  visceral  and  parietal  layers  of  this  mem- 
brane constitutes  the  cavity  of  the  tunica  vaginalis. 

The  Tunica  ATbuginea  is  the  fibrous  covering  of  the  testis.  It  is  a  dense  fibrous 
membrane,  of  a  bluish- white  color,  composed  of  bundles  of  white  fibrous  tissue, 
which  interlace  in  every  direction.  Its  outer  surface  is  covered  by  the  tunica 
vaginalis,  except  along  its  posterior  border,  and  at  the  points  of  attachment  of 
the  epididymis ;  hence  the  tunica  albuginea  is  usually  considered  as  a  fibro-serous 
membrane,  like  the  dura  mater  and  pericardium.  This  membrane  surrounds  the 
glandular  structure  of  the  testicle,  and,  at  its  posterior  and  upper  border,  is 
reflected  into  the  interior  of  the  gland,  forming  an  incomplete  vertical  septum, 
called  the  mediastinum  testis  {corpus  Highmorianum). 

The  mediastinum  testis  extends  from  the  upper,  nearly  to  the  lower,  border  of 
<Jie  gland,  and  is  wider  above  than  below.     From  the  front  and  sides  of  this 


Tun/ra  Vaginalis  ^ 
parietal  layer 


SPERMATIC    CORD  — TESTIS. 


741 


Fig.  372.— Vertical  Section  of  the  Tes- 
ticle, to  show  the  arrangement  of  the 
Ducts. 


septum,  numerous  slender  fibrous  cords  (trabecule)  are  given  off,  which  pass  to  be 
attached  to  the  inner  surface  of  the  tunica  albuginea ;  they  serve  to  maintain  the 
form  of  the  testis,  and  join,  with  similar  cords  given  off  from  the  inner  surface  of 
the  tunica  albuginea,  to  form  spaces  which  inclose  the  separate  lobules  of  the  organ. 
The  mediastinum  supports  the  vessels  and  ducts  of  the  testis  in  their  passage  to 
and  from  the  substance  of  the  gland. 

The  Tunica  Vasculosa  (pia  mater  testis)  is  the  vascular  layer  of  the  testis, 
consisting  of  a  plexus  of  bloodvessels,  held  together  by  a  delicate  areolar  tissue. 
It  covers  the  inner  surface  of  the  tunica  albuginea,  sending  off  numerous  processes 
between  the  lobules,  which  are  supported  by  the  fibrous  prolongations  from  the 
mediastinum  testis. 

Structure  of  the  Testis.  The  glandular  structure  of  the  testis  consists  of  nume- 
rous lobules  {lobuli  testis).  Their  number,  in  a  single  testis,  is  estimated  by  Berres 
at  250,  and  by  Krause  at  400.  They  differ  in  size  according  to  their  position, 
those  in  the  middle  of  the  gland  being  larger  and  longer.  Each  lobule  is  conical 
in  shape,  the  base  being  directed  towards  the  circumference  of  the  organ,  the  apex 
towards  the  mediastinum.  Each  lobule  is  contained  in  one  of  the  intervals  between 
the  fibrous  cords  and  vascular  processes,  which  extend  between  the  mediastinum 
testis  and  the  tunica  albuginea,  and  consists  of  from  one  to  three,  or  more, 
minute  convoluted  tubes,  the  tubuli  seminiferi.  The  tubes  may  be  separately 
unravelled,  by  careful  dissection  under  water,  and  may  be  seen  to  commence 
either  by  free  cgecal  ends,  or  by  anasto- 
motic loops.  The  total  number  of  tubes 
is  considered  by  Monro  to  be  about  300, 
and  the  length  of  each  about  sixteen  feet ; 
by  Lauth,  their  number  is  estimated  at 
840,  and  their  average  length  two  feet 
and  a  quarter.  Their  diameter  varies 
from  3£&th  to  T50th  of  an  inch.  The 
tubuli  are  pale  in  color  in  early  life,  but, 
in  old  age,  they  acquire  a  deep  yellow 
tinge,  from  containing  much  fatty  matter. 
They  consist  of  a  basement  membrane, 
lined  by  epithelium,  consisting  of  nucle- 
ated granular  corpuscles,  and  are  inclosed 
in  a  delicate  plexus  of  capillary  vessels. 
In  the  apices  of  the  lobules,  the  tubuli 
become  less  convoluted,  assume  a  nearly 
straight  course,  and  unite  together  to  form 
from  twenty  to  thirty  larger  ducts,  of 
about  5'0th  of  an  inch  in  diameter,  and 
these,  from  their  straight  course,  are  called 
vasa  recta. 

The  vasa  recta  enter  the  fibrous  tissue 
of  the  mediastinum,  and  pass  upwards  and 
backwards,  forming,  in  their  ascent,  a 
close  network  of  anastomosing  tubes,  with 

exceedingly  thin  parietes ;  this  constitutes  the  rete  testis.  At  the  upper  end  of  the 
mediastinum,  the  vessels  of  the  rete  testis  terminate  in  from  twelve  to  fifteen  or 
twenty  ducts,  the  vasa  efferentia:  they  perforate  the  tunica  albuginea,  and  carry 
the  seminal  fluid  from  the  testis  to  the  epididymis.  Their  course  is  at  first 
straight ;  they  then  become  enlarged,  and  exceedingly  convoluted,  and  form  a 
series  of  conical  masses,  the  cord  vasculosi,  which,  together,  constitute  the  globus 
major  of  the  epididymis.  Each  cone  consists  of  a  single  convoluted  duct,  from 
six  to  eight  inches  in  length,  the  diameter  of  which  gradually  decreases  from  the 
testis  to  the  epididymis.  Opposite  the  bases  of  the  cones,  the  efferent  vessels 
open  at  narrow  intervals  into  a  single  duct,  which  constitutes,  by  its  complex 


742  MALE   GENERATIVE   ORGANS. 

convolutions,  the  body  and  globus  minor  of  the  epididymis.  "When  the  convolu- 
tions of  this  tube  are  unravelled,  it  measures  upwards  of  twenty  feet  in  length, 
and  increases  in  breadth  and  thickness  as  it  approaches  the  vas  deferens.  The 
convolutions  are  held  together  by  fine  areolar  tissue,  and  by  bands  of  fibrous 
tissue.  A  long  narrow  tube,  the  vasculum  aberrans  of  Haller,  is  occasionally  found 
connected  with  the  lower  part  of  the  canal  of  the  epididymis,  or  with  the  com- 
mencement of  the  vas  deferens,  and  extending  up  into  the  cord  for  about  two  or 
three  inches,  where  it  terminates  by  a  blind  extremity,  which  is  occasionally 
bifurcated.  Its  length  varies  from  an  inch  and  a  half  to  fourteen  inches,  and 
sometimes  it  becomes  dilated  towards  its  extremity ;  more  commonly,  it  retains 
the  same  diameter  throughout.  Its  structure  is  similar  to  that  of  the  vas  deferens. 
Occasionally,  it  is  found  unconnected  with  the  epididymis. 

Vas  Deferens.  The  Vas  Deferens,  the  excretory  duct  of  the  testis,  is  the 
continuation  of  the  epididymis.  Commencing  at  the  lower  part  of  the  globus 
minor,  it  ascends  along  the  posterior  and  inner  side  of  the  testis  and  epididymis, 
and  along  the  back  part  of  the  spermatic  cord,  through  the  spermatic  canal,  to  the 
internal  abdominal  ring.  From  the  ring  it  descends  into  the  pelvis,  crossing  the 
external  iliac  vessels,  and  curves  round  the  outer  side  of  the  epigastric  artery ;  at 
the  side  of  the  bladder,  it  arches  backwards  and  downwards  to  its  base,  crossing 
outside  the  obliterated  hypogastric  artery,  and  to  the  inner  side  of  the  ureter.  At 
the  base  of  the  bladder,  it  lies  between  it  and  the  rectum,  running  along  the  inner 
border  of  the  vesicula  seminalis.  In  this  situation,  it  becomes  enlarged  and  sac- 
culated ;  and,  becoming  narrowed,  at  the  base  of  the  prostate,  unites  with  the  duct 
of  the  vesicula  seminalis  to  form  the  ejaculatory  duct.  The  vas  deferens  presents 
a  hard  and  cordy  sensation  to  the  fingers,  is  about  two  feet  in  length,  of  cylin- 
drical form,  and  about  a  line  and  a  quarter  in  diameter.  Its  Avails  are  of  extreme 
density  and  thickness,  measuring  one-third  of  a  line ;  and  its  canal  is  extremely 
small,  measuring  about  half  a  line. 

In  structure,  the  vas  deferens  consists  of  three  coats ;  an  external  or  cellular 
coat ;  a  muscular  coat,  which  is  thick,  dense,  elastic,  and  consists  of  two  longitu- 
dinal layers,  and  an  intermediate  circular  layer  of  muscular  fibres,  and  an  internal 
or  mucous  coat,  which  is  pale,  and  arranged  in  longitudinal  plicae :  its  epithelial 
covering  is  of  the  columnar  variety. 

Vessels  and  Nerves  of  the  Testes.  The  arteries  supplying  the  coverings  of  the 
testes  are  the  superficial  and  deep  external  pudic  from  the  femoral ;  the  superficial 
perineal  branch  of  the  internal  pudic,  and  the  cremasteric  branch  from  the  epi- 
gastric. The  veins  follow  the  course  of  the  corresponding  arteries.  The  lymphatics 
terminate  in  the  inguinal  glands.  The  nerves  are  the  ilio-inguinal  and  ilio- 
hypogastric branches  of  the  lumbar  plexus,  the  two  superficial  perineal  branches 
of  the  internal  pudic  nerve,  the  inferior  pudenal  branch  of  the  small  sciatic  nerve, 
and  the  genital  branch  of  the  genito-crural  nerve. 

Spermatic  Cord.  The  Spermatic  Cord  extends  from  the  internal  abdominal 
ring,  where  the  structures  of  which  it  is  composed  converge,  to  the  back  part  of 
the  testicle.  It  is  composed  of  arteries,  veins,  lymphatics,  nerves,  and  the  excre- 
tory duct  of  the  testicle,  connected  together  by  areolar  tissue,  and  invested  by  its 
proper  coverings.  In  the  abdominal  wall,  it  passes  obliquely  along  the  inguinal 
canal,  lying  at  first  beneath  the  Internal  oblique,  and  upon  the  fascia  transversalis ; 
but,  nearer  the  pubes,  it  rests  upon  Poupart's  ligament,  having  the  aponeurosis 
of  the  External  oblique  in  front  of  it,  and  the  conjoined  tendon  behind  it.  It  then 
escapes  at  the  external  ring,  and  descends  nearly  vertically  into  the  scrotum.  The 
left  cord  is  rather  longer  than  the  right,  consequently  the  left  testis  hangs  some- 
what lower  than  its  fellow. 

The  arteries  of  the  cord  are  the  spermatic,  from  the  aorta ;  the  artery  of  the 
vas  deferens,  from  the  superior  vesical ;  and  the  cremasteric,  from  the  epigastric 
artery. 

The  spermatic  artery  supplies  the  testicle.  On  approaching  this  gland,  some 
branches  supply  the  epididymis,  others  perforate  the  tunica  albuginea  behind,  and 


YAS   DEFERENS— YESICTTL^E    SEMINALES. 


743 


spread  out  on  its  inner  surface,  or  pass  through  the  fibrous  septum  in  its  interior, 
to  be  distributed  on  the  membranous  septa,  between  the  separate  lobes. 

The  artery  of  the  vas  deferens  is  a  long  slender  vessel,  which  accompanies  the 
vas  deferens,  ramifying  upon  the  coats  of  this  duct,  and  anastomosing  with  the 
spermatic  artery  near  the  testis. 

The  cremasteric  branch  from  the  epigastric  supplies  the  Cremaster  muscle,  and 
other  coverings  of  the  cord. 

The  spermatic  veins  leave  the  back  part  of  the  testis,  and,  receiving  branches 
from  the  epididymis,  unite  to  form  a  plexus  {pampiniform  plexus),  which  forms 
the  chief  mass  of  the  cord.  They  pass  up  in  front  of  the  vas  deferens,  and  unite 
to  form  a  single  trunk,  which  terminates,  on  the  right  side  in  the  inferior  vena 
cava,  on  the  left  side  in  the  left  renal  vein. 

The  lymphatics  are  of  large  size,  accompany  the  bloodvessels,  and  terminate 
in  the  lumbar  glands. 

The  nerves  are  the  spermatic  plexus  from  the  sympathetic.  This  plexus  is 
derived  from  the  renal  and  aortic  plexuses,  joined  by  filaments  from  the  hypogastric 
plexus,  which  accompany  the  artery  of  the  vas  deferens. 

Yesicul^:  Seminales. 

The  Seminal  Yesicles  are  two  lobulated  membranous  pouches,  placed  between 
the  base  of  the  bladder  and  the  rectum,  serving  as  reservoirs  for  the  semen,  and 


Fig.  373. — Base  of  the  Bladder,  with  the  Vasa  Deferentia 
and  Vesicular  Seuiiuales. 


Bight  Ej'aruUtory 


secreting  some  fluid  to  be  added  to  that  of  the  testicles.  Each  sac  is  somewhat 
pyramidal  in  form,  the  broad  end  being  directed  backwards,  and  the  narrow  end 
forwards  towards  the  prostate.  They  measure  about  two  and  a  half  inches  in 
length,  about  five  lines  in  breadth,  and  from  two  to  three  lines  in  thickness. 
They  vary,  however,  in  size,  not  only  in  different  individuals,  but  also  in  the  same 
individual  on  the  two  sides.  Their  upper  surface  is  in  contact  with  the  base  of 
the  bladder,  extending  from  near  the  termination  of  the  ureters  to  the  base  of  the 
prostate  gland.  Their  under  surface  rests  upon  the  rectum,  from  which  they  are 
separated  by  the  recto-vesical  fascia.     Their  posterior  extremities  diverge  back- 


144  MALE   GENERATIVE    ORGANS: 

wards  and  outwards  from  each  other.  The  anterior  extremities  are  pointed,  and 
converge  towards  the  base  of  the  prostate  gland,  where  each  joins  witli  the 
corresponding  vas  deferens  to  form  the  ejaculatory  duct.  Along  the  inner  margin 
of  each  vesicula  runs  the  enlarged  and  convoluted  vas  deferens.  The  inner  border 
of  the  vesicula,  and  the  corresponding  vas  deferens,  form  the  lateral  boundary  of 
a  triangular  space,  limited  behind  by  the  recto-vesical  peritoneal  fold ;  the  portion 
of  the  bladder  included  in  this  space  rests  on  the  rectum,  and  corresponds  with 
the  trigonum  vesicae  in  its  interior. 

Structure.  Each  vesicula  consists  of  a  single  tube,  coiled  upon  itself,  and  giving 
off  several  irregular  cascal  diverticula ;  the  separate  coils,  as  well  as  the  diverticula, 
being  connected  together  by  fibrous  tissue.  When  uncoiled,  this  tube  is  about 
the  diameter  of  a  quill,  and  varies  in  length  from  four  to  six  inches ;  it  terminates 
posteriorly  in  a  cul-de-sac,  but  its  anterior  extremity  becomes  constricted  into  a 
narrow  straight  duct,  which  joins  on  its  inner  side  with  the  corresponding  vas 
deferens,  and  forms  the  ejaculatory  duct. 

The  ejaculatory  ducts,  two  in  number,  one  on  each  side,  are  formed  by  the 
junction  of  the  duct  of  the  vesicula  seminalis  with  the  vas  deferens.  Each  duct 
is  about  three  quarters  of  an  inch  in  length ;  it  commences  at  the  base  of  the 
prostate,  and  runs  forwards  and  upwards  in  a  canal  in  its  substance,  and  along 
the  side  of  the  utriculus,  to  terminate  by  a  separate  slit-like  orifice  upon  or  within 
the  margins  of  the  sinus  pocularis.  The  ducts  diminish  in  size,  and  converge 
towards  their  termination. 

Structure.  The  vesiculaa  seminales  are  composed  of  three  coats : — external  or 
fibro-cellular,  derived  from  the  recto-vesical  fascia ;  middle  or  fibrous  coat,  which 
is  firm,  dense,  fibrous  in  structure,  somewhat  elastic,  and  contains,  according  to 
E.  H.  Weber,  muscular  fibres ;  and  an  internal  or  mucous  coat,  which  is  pale,  of  a 
whitish-brown  color,  and  presents  a  delicate  reticular  structure,  like  that  seen  in 
the  gall-bladder,  but  the  meshes  are  finer.  It  is  lined  by  squamous  epithelium. 
The  coats  of  the  ejaculatory  ducts  are  extremely  thin,  the  outer  fibrous  layer  being 
almost  entirely  lost  after  their  entrance  into  the  prostate,  a  thin  layer  of  muscular 
fibres  and  the  mucous  membrane  forming  the  only  constituent  parts  of  these 
tubes. 

Vessels  and  Nerves.  The  arteries  supplying  the  vesiculas  seminales  are  derived 
from  the  inferior  vesical  and  middle  hemorrhoidal.  The  veins  and  lymphatics 
accompany  the  arteries.     The  nerves  are  derived  from  the  Irypogastric  plexus. 

The  Semen  is  a  thick  whitish  fluid,  having  a  peculiar  odor.  It  consists  of  a 
fluid  called  the  liquor  seminis,  and  solid  particles,  viz : — the  seminal  granules  and 
spermatozoa. 

The  liquor  seminis  is  transparent,  colorless,  and  of  an  albuminous  compo- 
sition, containing  particles  of  squamous  and  columnar  epithelium,  with  oil  globules 
and  granular  matter  floating  in  it,  besides  the  above-mentioned  solid  elements. 

The  seminal  granules  are  round  finely-granular  corpuscles,  measuring  1TJVtfth 
of  an  inch  in  diameter. 

The  spermatozoa  or  spermatic  filaments  are  the  essential  agents  in  producing 
fecundation.  They  are  minute  elongated  particles,  consisting  of  a  small  flattened 
oval  extremity  or  body,  and  a  long  slender  caudal  filament.  A  small  circular 
spot  is  observed  in  the  centre  of  the  body,  and  at  its  point  of  connection  with 
the  tail  there  is  frequently  seen  a  projecting  rim  or  collar.  The  movements  of 
these  bodies  are  remarkable,  and  consist  of  a  lashing  or  undulatory  motion  of  the 
tail. 

Descent  of  the  Testes. 

The  Testes,  at  an  early  period  of  foetal  life,  are  placed  at  the  back  part  of  the 
abdominal  cavity,  behind  the  peritoneum,  in  front  of,  and  a  little  below,  the  kidneys. 
The  anterior  surface  and  sides  are  invested  by  peritoneum;  the  bloodvessels  and 
efferent  ducts  are  connected  with  their  posterior  surface ;  and  attached  to  the 


DESCENT   OP   THE   TESTES.  745 

lower  end  is  a  peculiar  structure,  the  gubernaculum  testis,  which  is  said  to  assist 
in  their  descent. 

The  Gubernaculum  Testis  attains  its  full  development  between  the  fifth  and 
sixth  months ;  it  is  a  conical-shaped  cord,  attached  above  to  the  lower  end  of  the 
epididymis,  and  below  to  the  bottom  of  the  scrotum.  It  is  placed  behind  the 
peritoneum,  lying  upon  the  front  of  the  Psoas  muscle,  and  completely  filling  the 
inguinal  canal.  It  consists  of  a  soft  transparent  areolar  tissue  within,  which  often 
appears  partially  hollow,  surrounded  by  a  layer  of  striped  muscular  fibres,  the 
Cremaster,  which  ascends  upon  this  body  to  be  attached  to  the  testis.  According 
to  Mr.  Curling,  the  gubernaculum,  as  well  as  these  muscular  fibres,  divides  below 
into  three  processes ;  the  external  and  broadest  process  is  connected  with  Poupart's 
ligament  in  the  inguinal  canal ;  the  middle  process  descends  along  the  inguinal  canal 
to  the  bottom  of  the  scrotum,  where  it  joins  the  dartos ;  the  internal  one  is  firmly 
attached  to  the  os  pubis  and  sheath  of  the  Pectus  muscle;  some  fibres,  moreover, 
are  reflected  from  the  Internal  oblique  on  to  the  front  of  the  gubernaculum.  Up 
to  the  fifth  month,  the  testis  is  situated  in  the  lumbar  region,  covered  in  front  and 
at  the  sides  by  peritoneum,  and  supported  in  its  position  by  a  fold  of  this  mem- 
brane, the  mesorchium ;  between  the  fifth  and  sixth  months  the  testis  descends  to 
the  iliac  fossa,  the  gubernaculum  at  the  same  time  becoming  shortened ;  during 
the  seventh  month,  it  enters  the  internal  abdominal  ring,  a  small  pouch  of  perito- 
neum (processus  vaginalis)  preceding  the  testis  in  its  course  through  the  canal. 
By  the  end  of  the  eighth  month,  the  testis  has  descended  into  the  scrotum,  carry- 
ing down  with  it  a  lengthened  pouch  of  peritoneum,  which  communicates  by  its 
upper  extremity  with  the  peritoneal  cavity.  Just  before  birth,  the  upper  part  of 
this  pouch  becomes  closed,  and  this  obliteration  extends  gradually  downwards  to 
within  a  short  distance  of  the  testis.  The  process  of  peritoneum  surrounding  the 
testis,  which  is  now  entirely  cut  off  from  the  general  peritoneal  cavity,  constitutes 
the  tunica  vaginalis. 

Mr.  Curling  considers  that  the  descent  of  the  testis  is  effected  by  means  of  the 
muscular  fibres  of  the  gubernaculum ;  those  fibres  which  proceed  from  Poupart's 
ligament  and  the  Obliquus  internus  are  said  to  guide  the  organ  into  the  inguinal 
canal ;  those  attached  to  the  pubis  draw  it  below  the  external  abdominal  ring ;  and 
those  attached  to  the  bottom  of  the  scrotum  complete  its  descent.  During  the 
descent  of  the  organ  these  muscular  fibres  become  gradually  everted,  forming  a 
muscular  layer,  which  becomes  placed  external  to  the  process  of  peritoneum, 
surrounding  the  gland  and  spermatic  cord,  and  constitutes  the  Cremaster.  In  the 
female,  a  small  cord,  corresponding  to  the  gubernaculum  in  the  male,  descends  to 
the  inguinal  region,  and  ultimately  forms  the  round  ligament  of  the  uterus.  A 
pouch  of  peritoneum  accompanies  it  along  the  inguinal  canal,  analogous  to  the 
processus  vaginalis  in  the  male ;  it  is  called  the  canal  of  Nuch. 


Female  Organs  of  Generation. 

The  External  Organs  of  Generation  in  the  female  are  the  mons  Veneris,  the 
labia  majora  and  minora,  the  clitoris,  the  meatus  urinarius,  and  the  orifice  of  the 
vagina.  The  term  "  vulva"  or  "  pudendum,"  as  generally  applied,  includes  all 
these  parts. 

The  mons  veneris  is  the  rounded  eminence  in  front  of  the  pubes,  formed  by  a 
collection  of  fatty  tissue  beneath  the  integument.  It  surmounts  the  vulva,  and  is 
covered  with  hair  at  the  time  of  puberty. 

Fig.  374.— The  Vulva.     External  Female  Organs  of  Generation. 


The  labia  majora  are  two  prominent  longitudinal  cutaneous  folds,  extending 
downwards  from  the  mons  Veneris  to  the  anterior  boundary  of  the  perineum,  and 
inclosing  an  elliptical  fissure,  the  common  urino-sexual  opening.  Each  labium  is 
formed  externally  of  integument,  covered  with  hair ;  internally,  of  mucous  mem- 
brane, which  is  continuous  with  the  genito-urinary  mucous  tract ;  and  between 
the  two,  of  a  considerable  quantity  of  areolar  tissue,  fat,  and  a  tissue  resembling 
746 


VULYA.  ui 

the  dartos  of  the  scrotum,  besides  vessels,  nerves,  and  glands.  _  The  labia  are 
thicker  in  front  than  behind,  and  joined  together  at  each  extremity,  forming  the 
anterior  and  posterior  commissures.  The  interval  left  between  the  posterior  com- 
missure and  the  margin  of  the  anus  is  about  an  inch  in  length,  and  constitutes  the 
perineum.  Just  within  the  posterior  commissure  is  a  small,  transverse  fold,  the 
frsenulum  pudencU  or  fourchette,  which  is  commonly  ruptured  in  the  first  partu- 
rition, and  the  space  between  it  and  the  commissure  is  called  the  fossa  navicularis. 
The  labia  are  analogous  to  the  scrotum  in  the  male. 

The  labia  minora  or  nymphse  are  two  small  folds  of  mucous  membrane,  situated 
within  the  labia  majora,  and  extending  from  the  clitoris  obliquely  downwards 
and  outwards  for  about  an  inch  and  a  half  on  each  side  of  the  orifice  of  the 
vagina,  on  the  sides  of  which  they  are  lost.  They  are  continuous  externally  with 
the  labia  majora,  internally  with  the  inner  surface  of  the  vagina.  As  they  con- 
verge towards  the  clitoris  in  front,  each  labium  divides  into  two  folds,  which  sur- 
round the  glans  clitoridis,  the  superior  folds  uniting  to  form  the  praeputium  clito- 
ridis,  the  inferior  folds  being  attached  to  the  glans,  and  forming  the  frasnum.  The 
nymphae  are  composed  of  mucous  membrane,  covered  by  a  thin  epithelial  layer. 
They  contain  a  plexus  of  vessels  in  their  interior,  and  are  provided  with  numer- 
ous large  mucous  crypts  which  secrete  abundance  of  sebaceous  matter. 

The  clitoris  is  an  erectile  structure,  analogous  to  the  corpora  cavernosa  of  the 
penis.  It  is  situated  beneath  the  anterior  commissure,  partially  hidden  between 
the  anterior  extremities  of  the  labia  minora.  It  is  an  elongated  organ,  connected 
to  the  rami  of  the  pubes  and  ischia  on  each  side  by  two  crura ;  the  body  is  short, 
and  concealed  beneath  the  labia ;  its  free  extremity,  the  glans  clitoridis,  is  a  small 
rounded  tubercle,  consisting  of  spongy  erectile  tissue,  and  highly  sensitive.  The 
clitoris  consists  of  two  corpora  cavernosa,  composed  of  erectile  tissue  inclosed  in 
a  dense  layer  of  fibrous  membrane,  united  together  along  their  inner  surfaces  by 
an  incomplete  fibrous  pectiniform  septum.  It  is  provided,  like  the  penis,  with 
a  suspensory  ligament,  and  with  two  small  muscles,  the  Erectores  clitoridis,  which 
are  inserted  into  the  crura  of  the  corpora  cavernosa. 

Between  the  clitoris  and  the  entrance  of  the  vagina  is  a  triangular  smooth 
surface,  bounded  on  each  side  by  the  nymphas ;  this  is  the  vestibule. 

The  orifice  of  the  urethra  {meatus  urinarius)  is  situated  at  the  back  part  of  the 
vestibule,  about  an  inch  below  the  clitoris,  and  near  the  margin  of  the  vagina, 
surrounded  by  a  prominent  elevation  of  the  mucous  membrane.  Below  the 
meatus  urinarius  is  the  orifice  of  the  vagina,  an  elliptical  aperture,  more  or  less 
closed  in  the  virgin  by  a  membranous  fold,  the  hymen. 

The  hymen  is  a  thin  semilunar  fold  of  mucous  membrane,  stretched  across  the 
lower  part  of  the  orifice  of  the  vagina ;  its  concave  margin  being  turned  upwards 
towards  the  pubes.  Sometimes  this  membrane  forms  a  complete  septum  across 
the  orifice  of  the  vagina,  which  constitutes  an  imperforate  hymen.  Occa- 
sionally, it  forms  a  circular  septum,  perforated  in  the  centre  by  a  round  open 
ing;  sometimes  it  is  cribriform,  or  its  free  margin  forms  a  membranous  fringe, 
or  it  may  be  entirely  absent.  The  hymen  cannot,  consequently,  be  considered  as 
a  proof  of  virginity.  Its  rupture,  or  the  rudimentary  condition  of  the  membrane 
above  referred  to,  gives  rise  to  those  small  rounded  elevations  which  surround 
the  opening  of  the  vagina,  the  carunculse  myrtiformes. 

Glands  of  Bartholine.  On  each  side  of  the  commencement  of  the  vagina  is  a 
round,  or  oblong  body,  of  a  reddish-yellow  color,  and  of  the  size  of  a  horse  bean, 
analogous  to  Cowper's  gland  in  the  male.  It  is  called  the  gland  of  Bartholine. 
Each  gland  opens  by  means  of  a  long  single  duct,  upon  the  inner  side  of  the 
nymphaa,  external  to  the  hymen.  Extending  from  the  clitoris,  along  either  side  of 
the  vestibule,  and  lying  a  little  behind  the  nymphee,  are  two  large  oblong  masses, 
about  an  inch  in  length,  consisting  of  a  plexus  of  veins,  inclosed  in  a  thin  layer 
of  fibrous  membrane.  These  bodies  are  narrow  in  front,  rounded  below,  and  are 
connected  with  the  crura  of  the  clitoris  and  rami  of  the  pubes ;  they  are  termed 
by  Kobelt,  the  bulbi  vestibuli,  and  he  considers  them  analogous  to  the  bulb  of 


748 


FEMALE   ORGANS   OP   GENERATION. 


the  corpus  spongiosum  in  the  male.  Immediately  in  front  of  these  bodies  is  a 
smaller  venous  plexus,  continuous  with  the  bulbi  vestibuli  behind,  and  the  glans 
clitoridis  in  front ;  it  is  called  by  Kobelt,  the  pars  intermedia,  and  is  considered 
by  him  as  analogous  to  that  part  of  the  body  of  the  corpus  spongiosum  which 
immediately  succeeds  the  bulb. 

Fig.  375. — Section  of  Female  Pelvis,  showing  position  of  Viscera. 


Bladder. 

The  Bladder  is  situated  at  the  anterior  part  of  the  pelvis.  It  is  in  relation, 
in  front,  with  the  os  pubis ;  behind,  with  the  uterus,  some  convolutions  of  the 
small  intestine  being  interposed ;  its  base  lies  in  contact  with  the  neck  of  the 
uterus,  and  with  the  anterior  wall  of  the  vagina.  The  bladder  is  larger  in  the 
female  than  in  the  male,  and  very  broad  in  its  transverse  diameter. 

Urethra. 

The  Urethra  is  a  narrow  membranous  canal,  about  an  inch  and  a  half  in  length, 
extending  from  the  neck  of  the  bladder  to  the  meatus  urinarius.  It  is  placed 
beneath  the  symphysis  pubis,  imbedded  in  the  anterior  wall  of  the  vagina ;  and 
its  direction  is  obliquely  downwards  and  forwards,  its  course  being  slightly 
curved,  the  concavity  directed  upwards.  Its  diameter,  when  undilated,  is  about 
a  quarter  of  an  inch.  The  urethra  perforates  the  triangular  ligament,  precisely 
as  in  the  male,  and  is  surrounded  by  the  muscular  fibres  of  the  Compressor 
urethrse. 

Structure.     The  urethra  consists  of  three  coats  ;  muscular  erectile,  and  mucous. 

The  muscular  coat  is  continuous  with  that  of  the  bladder :  it  extends  the  whole 
length  of  the  tube,  and  consists  of  a  thick  stratum  of  circular  fibres. 


VAGINA.  U9 

A  thin  layer  of  spongy,  erectile  tissue,  intermixed  with  much  elastic  tissue, 
lies  immediately  beneath  the  mucous  coat. 

The  mucous  coat  is  pale,  continuous,  externally,  with  the  vulva,  and  internally 
with  that  of  the  bladder.  It  is  thrown  into  longitudinal  folds,  one  of  which, 
placed  along  the  floor  of  the  canal,  resembles  the  veru  montanum  in  the  male 
urethra.  It  is  lined  by  laminated  epithelium,  which  becomes  spheroidal  at  the 
bladder.     Its  external  orifice  is  surrounded  by  a  few  mucous  follicles. 

The  urethra,  from  not  being  surrounded  by  dense  resisting  structures,  as  in  the 
male,  admits  of  considerable  dilatation,  which  enables  the  surgeon  to  remove  with 
considerable  facility,  calculi,  or  other  foreign  bodies,  from  the  cavity  of  the 
bladder. 

Kectum. 

The  Kectum  is  more  capacious,  and  less  curved  in  the  female,  than  in  the  male. 

The  first  portion  extends  from  the  left  sacro-iliac  symphysis  to  the  middle  of 
the  sacrum.     Its  connections  are  similar  to  those  in  the  male. 

The  second  portion  extends  to  the  tip  of  the  coccyx.  It  is  covered  in  front  by 
the  peritoneum,  but  only  for  a  short  distance,  at  its  upper  part,  and  is  in  relation 
with  the  posterior  wall  of  the  vagina. 

The  third  portion  curves  backwards,  from  the  vagina  to  the  anus,  leaving  a 
space  which  corresponds  on  the  surface  of  the  body  to  the  perineum.  Its  ex- 
tremity is  surrounded  by  the  Sphincter  muscles,  and  its  sides  are  supported  by 
the  Levatores  ani. 

The  Vagina. 

The  Vagina  is  a  membranous  canal,  extending  from  the  vulva  to  the  uterus. 
It  is  situated  in  the  cavity  of  the  pelvis,  behind  the  bladder,  and  in  front  of 
the  rectum.  Its  direction  is  curved  forwards  and  downwards,  following  at  first 
the  line  of  the  axis  of  the  cavity  of  the  pelvis,  and  afterwards  that  of  the  outlet. 
It  is  cylindrical  in  shape,  flattened  from  before  backwards,  and  its  walls  are 
ordinarily  in  contact  with  each  other.  Its  length  is  about  four  inches  along  its 
anterior  wall,  and  between  five  or  six  along  its  posterior  wall.  It  is  constricted 
at  its  commencement,  and  becomes  dilated  near  the  uterine  extremity ;  it  surrounds 
the  vaginal  portion  of  the  cervix  uteri,  a  short  distance  from  the  os,  and  its  at- 
tachment extends  higher  up  on  the  posterior  than  on  the  anterior  wall. 

Relations.  Its  anterior  surface  is  concave,  and  in  relation  with  the  base  of  the 
bladder,  and  with  the  urethra.  Its  posterior  surface  is  convex,  and  connected  to 
the  anterior  wall  of  the  rectum,  for  the  lower  three-fourths  of  its  extent,  the 
upper  fourth  being  separated  from  that  tube  by  the  recto-uterine  fold  of  peri- 
toneum, which  forms  a  cul-de-sac  between  the  vagina  and  rectum.  Its  sides  give 
attachment  superiorly  to  the  broad  ligaments,  and  inferiorly  to  the  Levatores  ani 
muscles  and  recto-vesical  fascia. 

Structure.  The  vagina  consists  of  an  external  or  muscular  coat,  a  layer  of 
erectile  tissue,  and  an  internal  mucous  lining. 

The  muscular  coat  consists  of  longitudinal  fibres,  which  surround  the  vagina, 
and  are  continuous  with  the  superficial  muscular  fibres  of  the  uterus.  The 
strongest  fasciculi  are  those  attached  to  the  recto-vesical  fascia  on  each  side. 

The  erectile  tissue  is  inclosed  between  two  layers  of  fibrous  membrane :  it  is 
more  abundant  at  the  lower  than  at  the  upper  part  of  the  vagina. 

The  mueom  membrane  is  continuous,  above,  with  that  lining  the  uterus,  and 
below,  with  the  integument  covering  the  labia  majora.  Its  inner  surface  presents, 
along  the  anterior  and  posterior  walls,  a  longitudinal  ridge  or  raphe,  called  the 
column  of  the  vagina,  and  numerous  transverse  ridges  or  rugae  extend  outwards 
from  the  raphe  on  each  side.  These  rugae  are  most  distinct  near  the  orifice  of 
the  vagina,  especially  in  females  before  parturition.  They  indicate  its  adaptation 
for  dilatation,  and  are  calculated  to  facilitate  its  enlargement  during  parturition. 
The  mucous  membrane  is  covered  with  conical  and  filiform  papillae,  and  provided 


750  FEMALE    ORGANS    OF    GENERATION. 

with  mucous  glands  and  follicles,  which  are  especially  numerous  in  its  upper  part, 
and  around  the  cervix  uteri. 

The  Uterus. 

The  Uterus  is  the  organ  of  gestation,  receiving  the  fecundated  ovum  in  its 
cavity,  retaining  and  supporting  it  during  the  development  of  the  foetus,  and  the 
principal  agent  in  its  expulsion  at  the  time  of  parturition. 

In  the  virgin  state  it  is  pear-shaped,  flattened  from  before  backwards,  and 
situated  in  the  cavity  of  the  pelvis,  between  the  bladder  and  rectum ;  it  is  re- 
tained in  its  position  by  the  round  and  broad  ligaments  on  each  side,  and  projects 
into  the  upper  end  of  the  vagina  below.  Its  upper  end  or  base  is  directed 
upwards  and  forwards ;  its  lower  end  or  apex  downwards  and  backwards,  in  the 
line  of  the  axis  of  the  inlet  of  the  pelvis,  forming  an  angle  with  the  vagina,  the 
direction  of  which  corresponds  to  the  cavity  and  outlet  of  the  pelvis.  The  uterus 
measures  about  three  inches  in  length,  two  in  breadth,  at  its  upper  part,  and  an 
inch  in  thickness,  and  it  weighs  from  an  ounce  to  an  ounce  and  a  half. 

The  fundus  is  the  upper  broad  extremity  of  the  organ ;  it  is  convex,  covered 
by  peritoneum,  and  placed  on  a  line  below  the  level  of  the  brim  of  the  pelvis. 

The  body  gradually  narrows  from  the  fundus  to  the  neck.  Its  anterior  surface 
is  flattened,  covered  by  peritoneum  in  the  upper  three-fourths  of  its  extent,  and 
separated  from  the  bladder  by  some  convolutions  of  the  small  intestine :  the  lower 
fourth  is  connected  with  the  bladder.  Its  posterior  surface  is  convex,  covered 
by  peritoneum  throughout,  and  separated  from  the  rectum  by  some  convolutions 
of  the  intestine.  Its  lateral  margins  are  concave,  and  give  attachment  to  the 
Fallopian  tube  above,  the  round  ligament  below  and  in  front  of  this,  and  the 
ligament  of  the  ovary  behind  and  below  these. 

The  cervix  is  the  lower  rounded  and  constricted  portion  of  the  uterus :  around 
its  circumference  is  attached  the  upper  end  of  the  vagina,  which  extends  upwards 
a  greater  distance  behind  than  in  front. 

At  the  vaginal  extremity  of  the  uterus  is  a  transverse  aperture,  the  os  uteri, 
bounded  by  two  lips,  an  anterior  one,  which  is  thick,  and  a  posterior,  narrow  and 

Ligaments.  The  ligaments  of  the  uterus  are  six  in  number :  two  anterior,  two 
posterior,  and  two  lateral.     They  are  formed  of  peritoneum. 

The  two  anterior  ligaments  (vesico-uterine)  are  two  semilunar  folds,  which 
pass  between  the  neck  of  the  uterus  and  the  posterior  surface  of  the  bladder. 

The  two  posterior  ligaments  (recto-uterine)  pass  between  the  sides  of  the  uterus 
and  rectum. 

The  two  lateral  or  broad  ligaments  pass  from  the  sides  of  the  uterus  to  the 
lateral  walls  of  the  pelvis,  forming  a  septum  across  the  pelvis,  which  divides  this 
cavity  into  two  portions.  In  the  anterior  part  are  contained  the  bladder,  urethra, 
and  vagina ;  in  the  posterior  part,  the  rectum. 

The  cavity  of  the  uterus  is  small  in  comparison  with  the  size  of  the  organ : 
that  portion  corresponding  to  the  body  is  triangular,  flattened  from  before  back- 
wards, so  that  its  walls  are  closely  approximated,  and  having  its  base  directed 
upwards  towards  the  fundus.  At  each  superior  angle  is  a  funnel-shaped  cavity, 
which  constitutes  the  remains  of  the  division  of  the  body  of  the  uterus  into  two 
cornua ;  and  at  the  bottom  of  each  cavity  is  the  minute  orifice  of  the  Fallopian 
tube.  At  the  inferior  angle  of  the  uterine  cavity  is  a  small  constricted  opening, 
the  internal  orifice  (ostium  internum),  which  leads  into  the  cavity  of  the  cervix. 
The  cavity  of  the  cervix  is  somewhat  cylindrical,  flattened  from  before  backwards, 
broader  at  the  centre  than  at  either  extremity,  and  communicates,  below,  with  the 
vagina.  Each  wall  of  the  canal*  presents  a  longitudinal  column,  from  which 
proceed  a  number  of  small  oblique  columns,  giving  the  appearance  of  branches 
from  the  stem  of  a  tree,  and  hence  the  name  arbor  vitve  xderinus,  applied  to  it. 
These  folds  usually  become  very  indistinct  after  the  first  labor. 


UTERUS.  151 

Structure.  The  uterus  is  composed  of  three  coats :  an  external  serous  coat,  a 
middle  or  muscular  layer,  and  an  internal  mucous  coat. 

The  serous  coat  is  derived  from  the  peritoneum ;  it  invests  the  fundus  and  the 
whole  of  the  posterior  surface  of  the  body  of  the  uterus ;  but  only  the  upper 
three-fourths  of  its  anterior  surface. 

The  muscular  coat  forms  the  chief  bulk  of  the  substance  of  the  uterus.  In  the 
unimpregnated  state,  it  is  dense,  firm,  of  a  grayish  color,  and  cuts  almost  like 
cartilage.  It  is  thick  opposite  the  middle  of  the  body  and  fundus,  and  thin  at 
the  orifices  of  the  Fallopian  tubes.  It  consists  of  bundles  of  unstriped  muscular 
fibres,  disposed  in  layers,  intermixed  with  areolar  tissue,  blood,  and  lymphatic 
vessels  and  nerves.  In  the  impregnated  state,  the  muscular  tissue  becomes  more 
prominently  developed,  and  is  disposed  in  three  layers ; — external,  middle,  and 
internal. 

The  external  layer  is  placed  beneath  the  peritoneum,  disposed  as  a  thin  plane  on 
the  anterior  and  posterior  surfaces.  It  consists  of  fibres,  which  pass  transversely 
across  the  fundus,  and,  converging  at  each  superior  angle  of  the  uterus,  are  con- 
tinued on  the  Fallopian  tubes,  the  round  ligament,  and  ligament  of  the  ovary ; 
some  passing  at  each  side  into  the  broad  ligament,  and  others  running  backwards 
from  the  cervix  into  the  recto-uterine  ligaments. 

The  middle  layer  of  fibres  presents  no  regularity  in  its  arrangement,  being 
disposed  longitudinally,  obliquely,  and  transversely. 

The  internal  or  deep  layer  consists  of  circular  fibres  arranged  in  the  form  of 
two  hollow  cones,  the  apices  of  which  surround  the  orifices  of  the  Fallopian  tubes, 
their  bases  intermingling  with  one  another  on  the  middle  of  the  body  of  the  uterus. 
At  the  cervix,  these  fibres  are  disposed  transversely. 

The  mucous  membrane  is  thin,  smooth,  and  closely  adherent  to  the  subjacent 
tissue.  It  is  continuous,  through  the  fimbriated  extremity  of  the  Fallopian  tubes, 
with  the  peritoneum ;  and,  through  the  os  uteri,  with  the  mucous  lining  of  the 
vagina. 

In  the  body  of  the  uterus,  it  is  smooth,  soft,  of  a  reddish  color,  lined  by 
columnar-ciliated  epithelium,  and  presents,  when  viewed  with  a  lens,  the  orifices 
of  numerous  tubular  follicles  arranged  perpendicularly  to  the  surface.  They  are 
of  small  size  in  the  unimpregnated  uterus,  but  shortly  after  impregnation  they  are 
enlarged,  elongated,  presenting  a  contorted  or  waved  appearance  towards  their 
closed  extremities  which  occasionally  dilate  into  two  or  three  sacculated  extremities. 
The  circular  orifices  of  these  glands  may  be  seen  on  the  inner  surface  of  the 
mucous  membrane,  many  of  which  during  the  early  period  of  pregnancy  are 
surrounded  by  a  whitish  ring  formed  of  epithelium  which  lines  the  follicles. 

In  the  cervix,  the  mucous  membrane  between  the  ruga3  and  around  the  os  uteri 
is  provided  with  numerous  mucous  follicles  and  glands.  The  small,  transparent, 
vesicular  elevations,  so  often  found  within  the  os  and  cervix  uteri,  are  due  to 
closure  of  the  mouths  of  these  follicles,  and  their  distension  with  their  proper 
secretion.  They  were  called  the  ovula  of  Naboth.  The  mucous  membrane 
covering  the  lower  half  of  the  cervix  presents  numerous  papillae. 

Vessels  and  Nerves.  The  arteries  of  the  uterus  are  the  uterine,  from  the 
internal  iliac,  and  the  ovarian,  from  the  aorta.  They  are  remarkable  for  their 
tortuous  course  in  the  substance  of  the  organ,  and  for  their  frequent  anastomoses. 
The  veins  are  of  large  size,  and  correspond  with  the  arteries.  In  the  impregnated 
uterus,  these  vessels  are  termed  the  uterine  sinuses,  consisting  of  the  lining  mem- 
brane of  the  veins  adhering  to  the  walls  of  canals  channelled  through  the  substance 
of  the  uterus.  They  terminate  in  the  uterine  plexuses.  The  lymphatics  are  of 
large  size  in  the  impregnated  uterus,  and  terminate  in  the  pelvic  and  lumbar 
glands.  The  nerves  are  derived  from  the  inferior  hypogastric  and  spermatic 
plexuses,  and  from  the  third  and  fourth  sacral  nerves. 

The  form,  size,  and  situation  of  the  uterus,  vary  at  different  periods  of  life,  and  under  different 
circumstances. 


Y52  FEMALE   ORGANS   OF   GENERATION. 

In  tliefcetus,  the  uterus  is  contained  in  the  abdominal  cavity,  projecting  beyond  the  brim  of  the 
pelvis.     The  cervix  is  considerably  larger  than  the  body. 

At  puberty,  the  uterus  is  pyriform  in  shape,  and  weighs  from  eight  to  ten  drachms.  It  has 
descended  into  the  pelvis,  the  fundus  being  just  below  the  level  of  the  brim  of  this  cavity.  The 
arbor  vita?  is  distinct,  and  extends  to  the  upper  part  of  the  cavity  of  the  organ. 

During  and  after  menstruation,  the  organ  is  enlarged,  and  more  vascular,  its  surfaces  rounder; 
the  os  externum  is  rounded,  its  labia  swollen,  and  the  lining  membrane  of  the  body  thickened, 
softer,  and  of  a  darker  color. 

During  pregnancy,  the  uterus  increases  in  weight  from  one  pound  and  a  half  to  three  pounds. 
It  becomes  enormously  enlarged,  and  projects  into  the  hypogastric  and  lower  part  of  the  umbili- 
cal regions.  This  enlargement,  which  continues  up  to  the  sixth  month  of  gestation,  is  partially 
clue  to  increased  development  of  pre-existing  and  new-formed  muscular  tissue.  The  round  liga- 
ments are  enlarged,  and  the  broad  ligaments  become  encroached  upon  by  the  uterus  making  its 
way  between  their  laminae.  The  mucous  membrane  becomes  more  vascular,  its  mucous  follicles 
and  glands  enlarged ;  the  rugae  and  folds  in  the  canal  of  the  cervix  become  obliterated ;  the 
bloodvessels  and  lymphatics  as  well  as  the  nerves,  according  to  the  researches  of  Dr.  Lee, 
become  greatly  enlarged. 

After  parturition,  the  uterus  nearly  regains  its  usual  size,  weighing  from  two  to  three  ounces, 
but  its  cavity  is  larger  than  in  the  virgin  state ;  the  external  orifice  is  more  marked,  and  assumes 
a  transverse  direction ;  its  edges  present  a  fissured  surface ;  its  vessels  are  tortuous ;  and  its 
muscular  layers  are  more  defined. 

In  old  age,  the  uterus  becomes  atrophied,  and  paler  and  denser  in  texture ;  a  more  distinct 
constriction  separates  the  body  and  cervix.  The  ostium  internum,  and,  occasionally,  the  vaginal 
orifice,  often  become  obliterated,  and  its  labia  almost  entirely  disappear. 

Appendages  of  the  Uterus. 

The  appendages  of  the  uterus  are  the  Fallopian  tubes,  the  ovaries  and  their 
ligaments,  and  the  round  ligaments.  These  structures,  together  with  their  nutrient 
vessels  and  nerves,  and  some  scattered  muscular  fibres,  are  inclosed  between  the 
two  folds  of  peritoneum,  which  constitute  the  broad  ligaments ;  they  are  placed  in 
the  following  order :  in  front  is  the  round  ligament ;  the  Fallopian  tube  occupies 
the  free  margin  of  the  broad  ligament ;  the  ovary  and  its  ligament  are  behind 
and  below  the  latter. 

The  Fallopian  Tubes  or  oviducts  convey  the  ova  from  the  ovaries  to  the 
cavity  of  the  uterus.  They  are  two  in  number,  one  on  each  side,  situated  in  the 
free  margin  of  the  broad  ligament,  extending  from  each  superior  angle  of  the 
uterus  to  the  sides  of  the  pelvis.  Each  tube  is  about  four  inches  in  length ;  its 
canal  is  exceedingly  minute,  and  commences  at  the  superior  angle  of  the  uterus 
by  a  minute  orifice,  the  ostium  internum,  which  will  hardly  admit  a  fine  bristle ; 
it  continues  narrow  along  the  inner  half  of  the  tube ;  it  then  gradually  widens 
into  a  trumpet-shaped  extremity,  which  becomes  contracted  at  its  termination. 
This  orifice  is  called  the  ostium  ahdominale,  and  communicates  with  the  peritoneal 
cavity.  Its  margins  are  surrounded  by  a  series  of  fringe-like  processes,  termed 
fimbriae,  and  one  of  these  processes  is  connected  with  the  outer  end  of  the  ovary. 
To  this  part  of  the  tube  the  name  fimbriated  extremity  is  applied ;  it  is  also  called 
morsus  diaboli,  from  the  peculiar  manner  in  which  it  embraces  the  surface  of  the 
ovary  during  sexual  excitement. 

Structure.  The  Fallopian  tube  consists  of  three  coats,  serous,  muscular,  and 
mucous. 

The  external  or  serous  coat  is  derived  from  the  peritoneum. 

The  middle  or  muscular  coat  consists  of  an  external  longitudinal  and  an  internal 
or  circular  layer  of  muscular  fibres  continuous  with  those  of  the  uterus. 

The  internal  or  mucous  coat  is  continuous  with  the  mucous  lining  of  the  uterus, 
and  at  the  free  extremity  of  the  tube  with  the  peritoneum.  It  is  thrown  into 
longitudinal  folds  in  the  outer  part  of  the  tube,  which  indicate  its  adaptation  for 
dilatation,  and  is  covered  by  columnar-ciliated  epithelium.  This  form  of  epithe- 
lium is  also  found  on  the  inner  and  outer  surfaces  of  the  fimbriae. 

The  Ovaries  (testes  muliebres,  Galen)  are  analogous  to  the  testes  in  the  male. 
Thev  are  oval-shaped  bodies,  of  an  elongated  form,  flattened  from  above  downwards, 
situated  one  on  each  side  of  the  uterus  in  the  posterior  part  of  the  broad  ligament, 


FALLOPIAN   TUBE  —  OVARY. 


753 


behind  and  below  the  Fallopian  tubes.  Each  ovary  is  connected,  by  its  anterior 
margin,  with  the  broad  ligament ;  by  its  inner  extremity  to  the  uterus  by  a  proper 
ligament,  the  ligament  of  the  ovary ;    and   by  its  outer  end  to  the  fimbriated 


Fig.  376. — The  Uterus  and  its  Appendages.    Anterior  View. 


-**£ 


EriVc  passed  throvO^ 

k'.UUM   it  I'll 


Fig.  377. — Section  of  the  Ovary  of  a  Virgin, 

showing  the  Stroma  and  Graafian 

Vesicles. 


extremity  of  the  Fallopian  tube  by  a  short  ligamentous  cord.  The  ovaries  are  of 
a  whitish  color,  and  present  either  a  smooth  or  puckered  uneven  surface.  They 
are  each  about  an  inch  and  a  half  in  length,  three-quarters  of  an  inch  in  width, 
and  about  a  third  of  an  inch  thick ;  and  weigh  from  one  to  two  drachms.  The 
surfaces  and  posterior  convex  border  are  free,  the  anterior  straight  border  being 
attached  to  the  broad  ligament. 

Structure.  The  ovary  is  invested  by  peritoneum,  excepting  along  its  anterior 
attached  margin ;  beneath  this,  is  the  proper  fibrous  covering  of  the  organ,  the 
tunica  albuginea,  which  is  extremely 
dense  and  firm  in  structure,  and  incloses 
a  peculiar  soft  fibrous  tissue  or  stroma, 
abundantly  supplied  with  bloodvessels 
(fig.  377).  Imbedded  in  the  meshes  of 
this  tissue  are  numerous  small,  round, 
transparent  vesicles  in  various  stages  of 
development ;  they  are  the  Graafian  vesi- 
cles, the  ovisacs  containing  the  ova.  In 
women  who  have  not  borne  children, 
they  vary,  in  number,  from  ten  to  fifteen 

or  twenty,  and,  in  size,  from  a  pin's  head  to  a  pea ;  but  Dr.  Martin  Barry  has 
shown,  that  a  large  number  of  microscopic  ovisacs  exist  in  the  parenchyma  of  the 
organ,  few  of  which  produce  ova.  These  vesicles  have  thin,  transparent  walls, 
and  are  filled  with  a  clear,  colorless,  albu- 
minous fluid. 

The  Graafian  vesicles  are,  during  their 
early  development,  small,  and  deeply  seat- 
ed in  the  substance  of  the  ovary ;  as  they 
enlarge,  they  approach  the  surface ;  and, 
when  mature,  form  small  projections  on 
the  exterior  of  the  ovary  beneath  the 
peritoneum.  Each  vesicle  consists  of  an 
external  fibro- vascular  coat,  connected  with 
the  surrounding  stroma  of  the  ovary  by 


Fig.  378. — Section  of  the  Graafian  Vesicle. 
(After  Von  Baer.) 


1ni:  tLicd-  vtitel*         v    1 

mtmeranA 

ttlM—'fH 


154  FEMALE   ORGANS   OF   GENERATION. 

a  network  of  bloodvessels ;  and  an  internal  coat,  named  the  ovi-capsule,  which  ig 
lined  by  a  layer  of  nucleated  cells,  called  the  membrana  granulosa.  The  fluid 
contained  in  the  interior  of  the  vesicles  is  transparent  and  albuminous,  and  in  it 
is  suspended  the  ovum. 

The  Ovum  is  a  small  spherical  body,  situated,  in  immature  vesicles,  near  their 
centre ;  but,  in  the  mature  ones,  in  contact  with  the  membrana  granulosa,  at  that 
part  of  the  vesicle  which  projects  just  beneath  the  surface  of  the  ovary.  Accu- 
mulated round  the  ovum,  in  greater  number  than  at  any  other  point,  are  the  cells 
of  the  membrana  granulosa,  forming  a  kind  of  granular  zone,  the  discus  proli- 
gerus. 

The  human  ovum  is  extremely  minute,  measuring  from  u\-$  to  T2Tr  of  an  inch 
in  diameter.  It  consists,  externally,  of  a  transparent  envelop,  the  zona  pellucida 
or  vitelline  membrane ;  within  this,  and  in  close  contact  with  it,  is  the  yelk  or 
vitellus ;  imbedded  in  the  substance  of  the  yelk,  is  a  small  vesicular  body,  the 
germinal  vesicle,  which  contains  the  germinal  spot. 

The  zona  pellucida   or   vitelline   membrane   is   a   thick,  colorless,  transparent 

membrane,  which  appears  under  the  mi- 
Fig.  379.— Ovum  of  the  Sow.  croscope  as  a  bright  ring,  bounded  ex- 
(    ter    any.)  ternally  and  internally  by  a  dark  outline. 
7^ZMTSk'  It  corresponds  to  the  chorion  of  the  im- 
"^u»sf^'           pregnated  ovurn. 

The  yelk  consists  of  granules  and  glo- 
bules of  various  sizes,  imbedded  in  a  more 
or  less  viscid  fluid.  The  smaller  gra- 
nules resemble  pigment ;  the  larger  gra- 
nules, which  are  in  greatest  number  at 
the  periphery  of  the  yelk,  resemble  fat- 
globules.  In  the  human  ovum,  the  number  of  granules  is  comparatively  small. 
The  germinal  vesicle  consists  of  a  fine,  transparent,  structureless  membrane, 
containing  a  watery  fluid,  in  which  are  occasionally  found  a  few  granules.  It  is 
about  730-  of  an  incn  in  diameter,  and,  in  immature  ova,  lies  nearly  in  the  centre 
of  the  yelk ;  but,  as  the  ovum  becomes  developed,  it  approaches  the  surface,  and 
enlarges  much  less  rapidly  than  the  yelk. 

The  germinal  spot  occupies  that  part  of  the  periphery  of  the  germinal  vesicle 
which  is  nearest  to  the  periphery  of  the  yelk.  It  is  opaque,  of  a  yellow  color, 
and  finely-granular  in  structure,  measuring  from  si^s  to  54VTT  of  an  inch. 

The  formation,  development,  and  maturation  of  the  Graafian  vesicles  and  ova 
continue  uninterruptedly  from  infancy  to  the  end  of  the  fruitful  period  of 
woman's  life.  Before  puberty,  the  ovaries  are  small,  the  Graafian  vesicles  con- 
tained in  them  minute,  and  few  in  number ;  and  few,  probably,  ever  attain  full 
development,  but  shrink  and  disappear,  their  ova  being  incapable  of  impregnation. 
At  puberty,  the  ovaries  enlarge,  are  more  vascular,  the  Graafian  vesicles  are 
developed  in  greater  abundance,  and  their  ova  capable  of  fecundation. 

Discharge  of  the  Ovum..  The  Graafian  vesicles,  after  gradually  approaching  the 
surface  of  the  ovary,  burst;  the  ovum  and  fluid  contents  of  the  vesicles  are 
liberated,  and  escape  on  the  exterior  of  the  ovary,  passing  from  thence  into  the 
Fallopian  tube,  the  fimbriated  processes  of  which  are  supposed  to  grasp  the  ovary, 
the  aperture  of  the  tube  being  applied  to  the  part  corresponding  to  the  matured 
and  bursting  vesicle.  In  the  human  subject,  and  most  mammalia,  the  maturation 
and  discharge  of  ova  occur  at  regular  periods  only,  and  are  indicated,  in  the  mam- 
malia, by  the  phenomena  of  heat  or  rut;  and,  in  the  human  female,  by  menstruation. 
Sexual  desire  is  more  intense  in  females  at  this  period,  and,  if  the  union  of  the 
sexes  takes  place,  the  ovum  may  be  fecundated. 

Corpus  Luteum.  Immediately  after  the  rupture  of  a  Graafian  vesicle,  and  the 
escape  of  its  ovum,  the  vesicle  is  filled  with  blood-tinged  fluid ;  and  in  a  short 
time  the  circumference  of  the  vesicle  is  occupied  by  a  firm,  yellow  substance, 
which  is  probably  formed  from  plasma  exuded  from  its  walls.     Dr.  Lee  believes 


CORPUS   LUTEUM.  ?55 

that  this  yellow  matter  is  deposited  outside  both  the  membranes  of  the  follicle ; 
Montgomery  regards  it  as  placed  between  the  layers;  while  Kolliker  considers  it 
MB  a  thickening  of  the  inner  layer  of  the  outer  coat  of  the  follicle.  The  exudation 
is  at  first  of  a  dark  brown  or  brownish-red  color,  but  it  soon  becomes  paler,  and 
its  consistence  more  dense. 

For  every  follicle  in  the  ovary  from  which  an  ovum  is  discharged,  a  corpus 
luteum  will  be  found.  But  the  characters  it  exhibits,  and  the  changes  produced 
in  it,  will  be  determined  by  the  circumstance  of  the  ovum  being  impregnated 
or  not. 

Although  there  is  little  doubt  of  corpora  lutea  existing  in  the  ovaries  after  the 
escape  of  ova,  independent  of  coitus,  or  impregnation,  it  appears  that  the  corpus 
luteum  of  pregnancy  (true  corpora  lutea)  possesses  characters  by  which  it  may  be 
distinguished  from  one  formed  in  a  follicle,  from  which  an  ovum  has  been  dis- 
charged without  subsequent  impregnation  (false  corpora  lutea). 

The  true  corpora  lutea  are  of  large  size,  often  as  large  as  a  mulberry ;  of  a 
rounded  form,  and  project  from  the  surface  of  the  ovary,  the  summit  of  the  pro- 
jection presenting  a  triangular  depression  or  cicatrix,  where  the  peritoneum 
appears  to  have  been  torn.  They  contain  a  small  cavity  in  their  centre  during  the 
early  period  of  their  formation,  which  becomes  contracted,  and  exhibits  a  stellate 
cicatrix  during  the  latter  stages  of  pregnancy.  Its  vascularity,  lobulated  or 
puckered  appearance,  its  firm  consistence,  and  yellow  color,  are  also  characteristic 
marks. 

False  corpora  lutea  are  of  small  size,  do  not  project  from  the  surface  of  the 
ovary,  are  angular  in  form,  seldom  present  any  cicatrix,  contain  no  cavity  in  their 
centre ;  the  material  composing  it  is  not  lobulated,  its  consistence  is  usually  soft, 
often  resembling  coagulated  blood ;  the  yellow  matter  exists  in  the  form  of  a  very 
thin  layer,  or,  more  commonly,  is  entirely  wanting.  False  corpora  lutea  most 
frequently  result  from  the  effusion  of  serum  or  blood  into  the  cavities  of  the 
Graafian  vesicles,  which  subsequently  undergo  various  changes,  and  is  ultimately 
removed.  Dr.  Lee  states,  that  in  the  false  corpora  lutea  the  yellow  substance  is 
contained  within,  or  attached  to,  the  inner  surface  of  the  Graafian  vesicle,  and 
does  not  surround  it,  as  is  the  case  in  the  true  corpora  lutea. 

In  the  foetus,  the  ovaries  are  situated,  like  the  testes,  in  the  lumbar  region,  near 
the  kidneys.  They  may  be  distinguished  from  those  bodies  at  an  early  period  by 
their  elongated  and  flattened  form,  and  by  their  position,  which  is  at  first  oblique, 
and  then  nearly  transverse.     They  gradually  descend  into  the  pelvis. 

The  Ligament  of  the  Ovary  is  a  rounded  cord,  which  extends  from  each  superior 
angle  of  the  uterus  to  the  inner  extremity  of  the  ovary ;  it  consists  of  fibrous 
tissue,  and  a  few  muscular  fibres  derived  from  the  uterus. 

The  Round  Ligaments  are  two  rounded  cords,  between  four  and  five  inches  in 
length,  situated  between  the  layers  of  the  broad  ligament,  in  front  of  and  below 
the  Fallopian  tube.  Commencing  on  each  side  at  the  superior  angle  of  the  uterus, 
each  ligament  passes  forwards  and  outwards  through  the  internal  abdominal  ring, 
along  the  inguinal  canal  to  the  labia  majora,  in  which  it  becomes  lost.  Each  liga- 
ment consists  of  areolar  tissue,  vessels,  and  nerves,  besides  a  dense  bundle  of  fibrous 
tissue,  and  muscular  fibres  prolonged  from  the  uterus,  inclosed  in  a  duplicature  of 
peritoneum,  which,  in  the  foetus,  is  prolonged  in  the  form  of  a  tubular  process  for 
a  short  distance  into  the  inguinal  canal ;  this  process  is  called  the  canal  of  Nuck. 
It  is  generally  obliterated  in  the  adult,  but  sometimes  remains  pervious  even  in 
advanced  life.  It  is  analogous  to  the  peritoneal  pouch  which  accompanies  the 
descent  of  the  testes. 

Vessels  and  Nerves.  The  arteries  of  the  ovaries  and  Fallopian  tubes  are  the 
ovarian  from  the  aorta.  They  anastomose  with  the  termination  of  the  uterine 
arteries,  and  enter  the  attached  border  of  the  ovary.  The  veins  follow  the  course 
of  the   arteries ;   they  form  a  plexus  near  the  ovary,  the  pampiniform  plexus. 

The  nerves  are  derived  from  the  spermatic  plexus,  the  Fallopian  tube  receiving  a 
branch  from  one  of  the  uterine  nerves. 


15G  FEMALE   ORGANS   OF   GENERATION. 


Mammary  Glands. 

The  Mammas  or  breasts  are  accessory  glands  of  the  generative  system,  which 
secrete  the  milk.  They  exist  in  the  male  as  well  as  in  the  female ;  but  in  the 
former  only  in  a  rudimentary  state,  unless  their  growth  is  excited  by  peculiar 
circumstances.  They  are  two  large  hemispherical  eminences,  situated  towards 
the  lateral  aspect  of  the  pectoral  region,  corresponding  to  the  interval  between 
the  third  and  sixth  or  seventh  ribs,  and  extending  from  the  side  of  the  sternum 
to  the  axilla.  Their  weight  and  dimensions  differ  at  different  periods  of  life,  and 
in  different  individuals.  Before  puberty  they  are  of  small  size,  but  enlarge  as 
the  generative  organs  become  more  completely  developed.  They  increase  during 
pregnancy,  and  especially  after  delivery,  and  become  atrophied  in  old  age.  The 
left  mamma  is  generally  a  little  larger  than  the  right.  Their  base  is  nearly 
circular,  flattened  or  slightly  concave,  and  having  their  long  diameter  directed 
upwards  and  outwards  towards  the  axilla ;  they  are  separated  from  the  Pectoral 
muscles  by  a  thin  layer  of  superficial  fascia.  The  outer  surface  of  the  mamma  is 
convex,  and  presents,  just  below  the  centre,  a  small  conical  prominence,  the 
mammilla  or  nipple.  The  surface  of  the  nipple  is  dark-colored,  and  surrounded 
by  an  areola  having  a  colored  tint.  In  the  virgin,  the  areola  is  of  a  delicate 
rosy  hue ;  about  the  second  month  of  impregnation,  it  enlarges,  and  acquires  a 
darker  tinge,  which  increases  as  pregnancy  advances,  becoming,  in  some  cases, 
a  dark  brown  or  even  black  color.  This  color  diminishes  as  soon  as  lactation 
is  oyer,  but  is  never  entirely  lost  through  life.  These  changes  in  the  color  of  the 
areola  are  of  extreme  importance  in  forming  a  conclusion  in  a  case  of  suspected 
pregnancy. 

The  nijjple  is  a  cylindrical  or  conical  eminence,  capable  of  undergoing  a  sort  of 
erection  from  mechanical  excitement.  It  is  of  a  pink  or  brownish  hue,  its  surface 
wrinkled  and  provided  with  papillae,  and  its  summit  perforated  by  numerous 
orifices,  the  apertures  of  the  lactiferous  ducts.  Near  the  base  of  the  nipple,  and 
upon  the  surface  of  the  areola,  are  numerous  sebaceous  glands,  which  become  much 
enlarged  during  lactation,  and  present  the  appearance  of  small  tubercles  beneath 
the  skin.  These  glands  secrete  a  peculiar  fatty  substance,  which  serves  as  a  pro- 
tection to  the  integument  of  the  nipple  in  the  act  of  sucking.  The  nipple  consists 
of  numerous  vessels,  which  form  a  kind  of  erectile  tissue,  intermixed  with  plain 
muscular  fibres. 

Structure.  The  mamma  consists  of  gland  tissue ;  of  fibrous  tissue,  connecting 
its  lobes ;  and  of  fatty  tissue  in  the  intervals  between  the  lobes.  The  mammary 
gland,  free  from  cellular  tissue  and  fat,  is  of  a  pale  reddish  color,  firm  in  texture, 
circular  in  form,  flattened  from  before  backwards,  thicker  in  the  centre  than  at 
the  circumference,  and  presenting  several  inequalities  on  its  surface,  especially  in 
front.  It  consists  of  numerous  lobes,  and  these  are  composed  of  lobules,  connected 
together  by  areolar  tissue,  bloodvessels,  and  ducts.  The  smallest  lobules  consist 
of  a  cluster  of  rounded  vesicles,  which  open  into  the  smallest  branches  of  the 
lactiferous  ducts ;  these  ducts,  uniting,  form  larger  ducts,  which  terminate  in  a 
single  canal,  corresponding  with  one  of  the  chief  subdivisions  of  the  gland.  The 
number  of  excretory  ducts  vceries  from  fifteen  to  twenty ;  they  are  termed  the 
tubuli  lactiferi  seu  galactophori.  They  converge  towards  the  areola,  beneath  which 
they  form  dilatations  or  ampullae,  which  serve  as  reservoirs  for  the  milk,  and,  at 
the  base  of  the  nipple,  become  contracted,  and  pursue  a  straight  course  to  its 
summit,  perforating  it  by  separate  orifices  considerably  narrower  than  the  ducts 
themselves.  The  ducts  are  composed  of  areolar  tissue,  with  longitudinal  and 
transverse  elastic  fibres,  and  longitudinal  muscular  fibres;  their  mucous  lining  is 
continuous,  at  the  point  of  the  nipple,  with  the  integument;  its  epithelial  lining  is 
of  the  tessellated  or  scaly  variety. 

The  fibrous  tissue  invests  the  entire  surface  of  the  breast,  and  sends  down  septa 
between  its  lobes,  connecting  them  together. 


MAMMARY  GLANDS.  757 

The  fatty  tissue  surrounds  the  surface  of  the  gland,  and  occupies  the  intervals 
between  its  lobes  and  lobules.  It  usually  exists  in  considerable  abundance,  and 
determines  the  form  and  size  of  the  gland.  There  is  no  fat  immediately  beneath 
the  areola  and  nipple. 

Vessels  and  Nerves.  The  arteries  supplying  the  mammas  are  derived  from  the 
thoracic  branches  of  the  axillary,  the  intercostals,  and  internal  mammary.  The 
veins  describe  an  anastomotic  circle  round  the  base  of  the  nipple,  called,  by  Haller, 
the  circulus  venosus.  From  this,  large  branches  transmit  the  blood,  to  the  cir- 
cumference of  the  gland,  and  end  in  the  axillary  and  internal  mammary  veins. 
The  lymphatics  run  along  the  lower  border  of  the  Pectoralis  major  to  the  axillary 
glands.  The  nerves  are  derived  from  the  anterior  and  lateral  cutaneous  nerves  of 
the  thorax. 


The  Surgical  Anatomy  of  Inguinal  Hernia. 

Dissection  (fig.  380).  For  the  dissection  of  the  parts  concerned  in  inguinal  hernia,  a  male 
subject,  free  from  fat,  should  always  be  selected.  The  body  should  be  placed  in  the  prone  posi- 
tion, the  abdomen  and  pelvis  raised  by  means  of  blocks  placed  beneath  them,  and  the  lower 
extremities  rotated  outwards,  so  as  to  make  the  parts  as  tense  as  possible.  If  the  abdominal 
walls  are  flaccid,  the  cavity  of  the  abdomen  should  be  inflated  by  an  aperture  through  the  umbi- 
licus. An  incision  should  be  made  along  the  middle  line,  from  the  umbilicus  to  the  pubes,  and 
continued  along  the  front  of  the  scrotum  ;  and  a  second  incision,  from  the  anterior  superior  spine 
of  the  ilium  to  just  below  the  umbilicus.  These  incisions  should  divide  the  integument ;  and  the 
triangular-shaped  flap  included  between  them  should  be  reflected  downwards  and  outwards,  when 
the  superficial  fascia  will  be  exposed. 

The  superficial  fascia  in  this  region  consists  of  two  layers,  .between  which  are 
found  the  superficial  vessels  and  nerves,  and  the  inguinal  lymphatic  glands. 

The  superficial  layer  is  thick,  areolar  in  texture,  containing  adipose  tissue  in 
its  meshes,  the  quantity  of  which  varies  in  different  subjects.  Below,  it  passes 
over  Poupart's  ligament,  and  is  continuous  with  the  outer  layer  of  the  superficial 
fascia  of  the  thigh.  This  fascia  is  continued  as  a  tubular  prolongation  around 
the  outer  surface  of  the  cord  and  testis.  In  this  situation,  it  changes  its  character ; 
it  becomes  thin,  destitute  of  adipose  tissue,  and  of  a  pale  reddish  color,  and 
assists  in  forming  the  dartos.  From  the  scrotum,  it  may  be  traced  backwards  to 
be  continuous  with  the  superficial  fascia  of  the  perineum.  This  layer  should  be 
removed,  by  dividing  it  across  in  the  same  direction  as  the  external  incision,  and 
reflecting  it  downwards  and  outwards,  when  the  following  vessels  and  nerves  will 
be  exposed: — 

The  superficial  epigastric,  circumflex  iliac,  and  external  pudic  vessels ;  the  ter- 
minal filaments  of  the  ilio-hypogastric  and  ilio-inguinal  nerves  ;  and  the  upper 
chain  of  inguinal  lymphatic  glands. 

The  superficial  epigastric  artery  crosses  Poupart's  ligament,  and  ascends  obliquely 
towards  the  *  umbilicus,  lying  midway  between  the  spine  of  the  ilium  and  the 
pubes.  It  supplies  the  integument,  and  anastomoses  with  the  deep  epigastric. 
This  vessel  is  a  branch  of  the  common  femoral  artery,  and  pierces  the  fascia  lata, 
below  Poupart's  ligament.  Its  accompanying  vein  empties  itself  into  the  internal 
saphenous,  piercing  previously  the  cribriform  fascia. 

The  superficial  external  pudic  artery  passes  transversely  inwards  across  the 
spermatic  cord,  and  supplies  the  integument  of  the  hypogastric  region,  and  of  the 
penis  and  scrotum.  This  vessel  is  usually  divided  in  the  first  incision  made  in  the 
operation  for  inguinal  hernia,  and  occasionally  requires  the  application  of  a  ligature 
to  suppress  the  hemorrhage. 

The  circumflex  iliac  artery  passes  outwards  towards  the  crest  of  the  ilium.  The 
veins  accompanying  the  latter  vessels  are  usually  much  larger  than  the  arteries ; 
they  terminate  in  the  internal  saphenous  vein. 

Lymphatic  vessels  are  found,  taking  the  same  course  as  the  bloodvessels ;  they 
return  the  lymph  from  the  superficial  structures  in  the  lower  part  of  the  abdomeu, 
the  scrotum,  penis,  and  external  surface  of  the  buttock,  and  terminate  in  a  small 
chain  of  lymphatic  glands,  three  or  four  in  number,  which  lie  on  a  level  with, 
Poupart's  ligament. 

Nerves.  The  terminal  branch  of  the  ilio-inguinal  nerve  emerges  at  the  external 
abdominal  ring ;  and  the  hypogastric  branch  of  the  ilio-hypogastric  nerve  perfo- 
rates the  aponeurosis  of  the  external  oblique  above  and  to  the  outer  side  of  the 
external  ring. 

The  Deep  layer  of  superficial  fascia  should  be  divided  across  in  the  same 
758 


INGUINAL   HERNIA— SUPERFICIAL   DISSECTION.      759 

direction  as  the  external  incisions,  separated  from  the  aponeurosis  of  the  External 
oblique,  to  which  it  is  connected  by  delicate  areolar  tissue,  and  reflected  down- 
wards and  outwards.  It  is  thin,  aponeurotic  in  structure,  and  of  considerable 
strength.  It  is  intimately  adherent,  in  the  middle  line,  to  the  linea  alba,  and, 
below,  to  the  whole  length  of  Poupart's  ligament  and  upper  part  of  the  fascia 
lata.  It  forms  a  thin  tubular  prolongation  round  the  outer  surface  of  the  cord, 
which  blends  with  the  superficial  layer,  and  is  continuous  with  the  dartos  of  the 
scrotum.  From  the  back  of  the  scrotum,  the  conjoined  layers  maybe  traced  into 
the  perineum,  where  they  are  continuous  with  the  deep  layer  of  the  superficial 
fascia  in  this  region,  which  is  attached,  behind,  to  the  triangular  ligament,  and,  on 
each  side,  to  the  ramus  of  the  pubes  and  ischium.  The  connections  of  this  fascia 
serve  to  explain  the  course  taken  by  the  urine  in  extravasation  of  this  fluid  from 
rapture  of  the  urethra ;  passing  forwards  from  the  perineum  into  the  scrotum, 
it  ascends  on  to  the  abdomen,  but  is  prevented  extending  into  the  thighs  by  the 
attachment  of  the  fascia  to  the  ramus  of  the  pubes  and  ischium,  on  each  side,  and 
to  Poupart's  ligament  in  front. 


Fig.  380. — Inguinal  Hernia.     Superficial  Dissection. 


Exttmnl 

AbUomiaalRing 


The  aponeurosis  of  the  External  oblique  muscle  is  exposed  on  the  removal  of  thi3 
fascia.  It  is  a  thin,  strong,  membranous  aponeurosis,  the  fibres  of  which  are 
directed  obliquely  downwards  and  inwards.  It  is  attached  to  the  anterior  superior 
spinous  process  of  the  ilium,  the  spine  of  the  pubes,  the  pectineal  line,  front  of  the 
pubes,  and  linea  alba.     That  portion  of  the  aponeurosis  which  extends  from  the 


7G0         SURGICAL   ANATOMY   OF   INGUINAL   HERNIA. 

anterior  superior  spine  of  the  ilium,  to  the  spine  of  the  pubes,  is  termed  Poupart's 
ligament  or  the  crural  arch ;  and  that  portion  which  is  inserted  into  the  pectineal 
line,  is  termed  Gimbernat's  ligament. 

Just  above  and  to  the  outer  side  of  the  crest  of  the  pubes,  a  triangular  interval 
is  seen  in  the  aponeurosis  of  the  External  oblique,  called  the  external  abdominal 
ring ;  it  transmits  the  spermatic  cord  in  the  male,  and  the  round  ligament  in  the 
female.  This  aperture  is  oblique  in  direction,  somewhat  triangular  in  form,  and 
corresponds  with  the  course  of  the  fibres  of  the  aponeurosis.  It  usually  measures 
from  base  to  apex  about  an  inch,  and  transversely  about  half  an  inch.  It  is 
bounded  below  by  the  crest  of  the  os  pubis ;  above,  by  a  series  of  curved  fibres, 
the  inter  columnar,  which  pass  across  the  upper  angle  of  the  ring  so  as  to  increase 
its  strength ;  and  on  either  side,  by  the  free  borders  of  the  aponeurosis,  which  are 
called  the  columns  or  pillars  of  the  ring. 

The  external  pillar,  which,  at  the  same  time,  is  inferior  from  the  obliquity  of 
its  direction,  is  the  strongest ;  it  is  formed  by  that  portion  of  Poupart's  ligament, 
which  is  inserted  into  the  spine  of  the  pubes ;  it  is  curved  round  the  spermatic 
cord,  so  as  to  form  a  kind  of  groove,  upon  which  it  rests. 

The  internal  or  superior  pillar  is  a  broad,  thin,  flat  band,  which  interlaces  with 
its  fellow  of  the  opposite  side,  in  front  of  the  symphysis  pubis,  that  of  the  right 
side  being  superficial. 

The  external  abdominal  ring  gives  passage  to  the  spermatic  cord  in  the  male, 
and  round  ligament  in  the  female ;  it  is  much  larger  in  men  than  women  on 
account  of  the  large  size  of  the  spermatic  cord,  and  hence  the  greater  frequency 
of  inguinal  hernia  in  the  former  sex. 

The  intercolumnar  fibres  are  a  series  of  curved  tendinous  fibres,  which  arch 
across  the  lower  part  of  the  aponeurosis  of  the  External  oblique.  They  have 
received  their  name  from  stretching  across  between  the  two  pillars  of  the  external 
ring;  they  increase  the  strength  of  the  membrane  which  bounds  the  upper  part 
of  this  aperture,  and  prevent  the  divergence  of  the  pillars  from  one  another.  They 
are  thickest  below,  where  they  are  connected  to  the  outer  third  of  Poupart's 
ligament,  and  taking  a  curvilinear  course,  the  convexity  of  which  is  directed 
downwards,  are  inserted  into  the  linea  alba.  They  are  much  thicker  and  stronger 
at  the  outer  angle  of  the  external  ring  than  internally,  and  are  more  strongly 
developed  in  the  male  than  in  the  female.  These  fibres  are  continuous  with  a  thin 
fascia,  which  is  closely  connected  to  the  margins  of  the  external  ring,  and  has 
received  the  name  of  the  intercolumnar  or  external  spermatic  fascia ;  it  forms  a 
tubular  prolongation  around  the  outer  surface  of  the  cord  and  testis,  and  incloses 
them  in  a  distinct  sheath.  The  sac  of  an  inguinal  hernia,  in  passing  through  the 
external  abdominal  ring,  receives  an  investment  from  the  intercolumnar  fascia. 

The  finger  should  be  introduced  a  slight  distance  into  the  external  ring,  and,  if 
the  limb  is  extended  and  rotated  outwards,  the  aponeurosis  of  the  External  oblique, 
together  with  the  iliac  portion  of  the  fascia  lata,  will  be  felt  to  become  tense,  and 
the  external  ring  much  contracted ;  if  the  limb  is,  on  the  contrary,  flexed  upon 
the  pelvis  and  rotated  inwards,  this  aponeurosis  will  become  lax~  and  the  external 
ring  sufficiently  enlarged  to  admit  the  finger  with  comparative  ease ;  hence  the 
latter  position  should  always  be  assumed  in  cases  where  the  taxis  is  applied  for 
the  reduction  of  an  inguinal  hernia,  in  order  that  the  abdominal  walls  may  be  as 
much  relaxed  as  possible. 

The  aponeurosis  of  the  External  oblique  should  be  removed  by  dividing  it  across  in  the  same 
direction  as  the  external  incisions,  and  reflecting  it  outwards ;  great  care  is  requisite  in  separating 
it  from  the  aponeurosis  of  the  muscle  beneath.  The  lower  part  of  the  Internal  oblique  and  the 
Cremaster  are  then  exposed,  together  with  the  inguinal  canal,  which  contains  the  spermatic  cord 
(fig.  381).  The  mode  of  insertion  of  Poupart's  and  Gimbernat's  ligaments  into  the  pubes  should 
also  be  examined. 

Poupart's  ligament  or  the  crural  arch  extends  from  the  anterior  superior  spine 
of  the  ilium  to  the  spine  of  the  pubes.  It  is  also  attached  to  the  pectineal  line 
to  the  extent  of  about   an  inch,  forming  Gimbernat's  ligament.     Its  general 


INTERNAL   OBLIQUE  — CREM ASTER. 


761 


direction  is  curved  towards  the  thigh,  where  it  is  continuous  with  the  fascia  lata. 
Its  outer  half  is  rounded,  oblique  in  its  direction,  and  continuous  with  the  iliac 
fascia.  Its  inner  half  gradually  widens  at  its  attachment  to  the  pubes,  is  more 
horizontal  in  direction,  and  lies  beneath  the  spermatic  cord. 

&imbernai's  ligament  is  that  portion  of  the  aponeurosis  of  the  External  oblique 
which  is  inserted  into  the  pectineal  line;  it  is  thin,  membranous  in  structure, 
triangular  in  shape,  the  base  directed  outwards,  and  passes  upwards  and  backwards 
beneath  the  spermatic  cord,  from  the  spine  of  the  os  pubis  to  the  pectineal  line,  to 
the  extent  of  about  half  an  inch. 

The  triangular  ligament  is  a  band  of  tendinous  fibres,  of  a  triangular  shape, 
which  is  continued  from  Poupart's  ligament  at  its  attachment  to  the  pectineal  line 
upwards  and  inwards,  beneath  the  inner  pillar  of  the  external  ring,  to  the  linea 
alba. 

The  Internal  oblique  muscle  has  already  been  described  (p.  283).  The  part  which 
is  now  exposed  is  partly  muscular  and  partly  tendinous  in  structure.  Those  fibres 
which  arise  from  the  outer  part  of  Poupart's  ligament  are  thin,  pale  in  color, 
curve  downwards,  and  terminate  in  an  aponeurosis,  which  passes  in  front  of  the 
Rectus  and  Pyramidalis  muscles,  to  be  inserted  into  the  crest  of  the  os  pubis  and 


Fig.  3S1.- 


-Inguinal  Hernia,  showing  the  Internal  Oblique, 
Cremaster,  and  Spermatic  Canal. 


f\ 


pectineal  line,  to  the  extent  of  half  an  inch,  in  common  with  that  of  the  Trans, 
versalis  muscle,  forming  by  their  junction  the  conjoined  tendon.  This  tendon  is 
placed  immediately  behind  Gimbernat's  ligament  and  the  external  abdominal  ring, 
and  serves  to  strengthen  what  would  otherwise  be  a  very  weak  point  in  the 
abdominal  wall.  When  the  pouch  of  inguinal  hernia  passes  directly  through  the 
external  ring,  forming  what  is  called  direct  inguinal  hernia,  the  conjoined  tendon 
usually  forms  one  of  its  coverings. 

The  Cremaster  is  a  slender  muscular  fasciculus,  which  arises  from  the  middle  of 


162  SURGICAL   ANATOMY   OF   INGUINAL   HERNIA. 

Poupart's  ligament  at  the  inner  side  of  the  Internal  oblique,  being  connected  with 
that  muscle,  and  also  occasionally  with  the  Transversalis.  It  passes  along  the 
outer  side  of  the  spermatic  cord,  descends  with  it  through  the  external  ring  upon 
the  front  and  sides  of  the  cord,  and  forms  a  series  of  loops,  which  differ  in  thick- 
ness and  length  in  different  subjects.  Those  at  the  upper  part  of  the  cord  are 
exceedingly  short,  but  they  become  in  succession  longer  and  longer,  the  longest 
reaching  down  as  low  as  the  testicle,  where  a  few  are  inserted  into  the  tunica 
vaginalis.  These  loops  are  united  together  by  areolar  tissue,  and  form  a  thin 
covering  over  the  cord,  the  fascia  cremasterica.  The  fibres  ascend  along  the  inner 
side  of  the  cord,  and  are  inserted,  by  a  small  pointed  tendon,  into  the  crest  of  the 
os  pubis  and  front  of  the  sheath  of  the  Rectus  muscle. 

It  will  be  observed,  that  the  origin  and  insertion  of  the  Cremaster  are  precisely 
similar  with  those  of  the  lower  fibres  of  the  Internal  oblique.  This  fact  affords  an 
easy  explanation  of  the  manner  in  which  the  testicle  and  cord  are  invested  by 
this  muscle.  At  an  early  period  of  foetal  life,  the  testis  is  placed  at  the  lower 
and  back  part  of  the  abdominal  cavity,  but,  during  its  descent  towards  the  scrotum, 
which  takes  place  before  birth,  it  passes  beneath  the  arched  border  of  the  Internal 
oblique.  In  its  passage  beneath  this  muscle  some  fibres  are  derived  from  its 
lower  part,  which  accompany  the  testicle  and  cord  into  the  scrotum. 

It  occasionally  happens  that  the  loops  of  the  Cremaster  surround  the  cord, 
some  lying  behind  as  well  as  in  front.  It  is  probable  that,  under  these  circum- 
stances, the  testis,  in  its  descent,  passed  through,  instead  of  beneath,  the  fibres  of 
the  Internal  oblique. 

In  the  descent  of  an  oblique  inguinal  hernia,  which  takes  the  same  course  as 
the  spermatic  cord,  the  Cremaster  muscle  forms  one  of  its  coverings.  This  muscle 
becomes  largely  developed  in  cases  of  hydrocele  and  large  old  scrotal  hernia?. 
No  such  muscle  exists  in  the  female,  but  an  analogous  structure  is  developed  in 
those  cases  where  an  oblique  inguinal  heimia  descends  beneath  the  margin  of  the 
Internal  oblique. 

The  Internal  oblique  should  be  detached  from  Poupart's  ligament,  separated  from  the  Trans- 
versalis to  the  same  extent  as  in  the  previous  incisions,  and  reflected  inwards  on  to  the  sheath  of 
the  Rectus  (fig.  385).  The  circumflexa  ilii  vessels,  which  lie  between  these  two  muscles,  form  a 
valuable  guide  to  their  separation. 

The  Transversalis  muscle  has  been  previously  described  (p.  284).  Its  lower  part 
is  partly  fleshy  and  partly  tendinous  in  structure ;  this  portion  arises  from  the 
outer  third  of  Poupart's  ligament,  and  arching  downwards  and  inwards  over  the 
cord,  terminates  in  an  aponeurosis,  which  is  inserted  into  the  linea  alba,  the  crest 
of  the  pubes,  and  into  the  pectineal  line  to  the  extent  of  an  inch,  forming  together 
with  the  Internal  oblique,  the  conjoined  tendon.  Between  the  lower  border  of 
this  muscle  and  Poupart's  ligament,  a  space  is  left  in  which  is  seen  the  fascia 
transversalis. 

The  inguinal  or  spermatic  canal  contains  the  spermatic  cord  in  the  male,  and 
the  round  ligament  in  the  female.  It  is  an  oblique  canal,  about  an  inch  and  a 
half  in  length,  directed  downwards  and  inwards,  and  placed  parallel  with,  and 
a  little  above,  Poupart's  ligament.  It  communicates,  above,  with  the  cavity  of 
the  abdomen,  by  means  of  the  internal  abdominal  ring,  which  is  the  point  where 
the  cord  enters  the  spermatic  canal ;  and  terminates,  below,  at  the  external  ring. 
It  is  bounded,  in  front,  by  the  integument,  the  superficial  fascia,  and  by  the  apo- 
neurosis of  the  External  oblique  throughout  its  whole  length,  and  by  the  Internal 
oblique  for  its  outer  third ;  behind,  by  the  conjoined  tendon  of  the  Internal 
oblique  and  Transversalis,  the  triangular  ligament,  transversalis  fascia,  and  the 
sub-peritoneal  fat  and  peritoneum ;  above,  by  the  arched  fibres  of  the  Internal 
oblique  and  Transversalis ;  below,  by  the  union  of  the  fascia  transversalis  with 
Poupart's  ligament.  That  form  of  protrusion  in  which  the  intestine  follows  the 
course  of  the  spermatic  cord  along  the  spermatic  canal,  is  called  oblique  inguinal 
hernia. 


SPERMATIC    CANAL  — INTERNAL   RING. 


763 


The  fascia  transversalis  is  a  thin  aponeurotic  membrane,  which  lies  between 
the  inner  surface  of  the  Transversalis  muscle  and  the  peritoneum.  It  forms  part 
of  the  general  layer  of  fascia  which  lines  the  interior  of  the  abdominal  and  pelvic 
cavities,  and  is  directly  continuous  with  the  iliac  and  pelvic  fasciae. 

In  the  inguinal  region,  the  transversalis  fascia  is  thick  and  dense  in  structure, 
and  joined  by  fibres  from  the  aponeurosis  of  the  Transversalis ;  but  it  becomes 
thin  and  cellular  as  it  ascends  to  the  Diaphragm.  Below,  it  has  the  following 
attachments :  external  to  the  femoral  vessels,  it  is  connected  to  the  posterior  margin 
of  Poupart's  ligament,  and  is  there  continuous  with  the  iliac  fascia ;  internal  to 
these  vessels  it  is  thin,  and  attached  to  the  pubes  and  pectineal  line,  behind  the 
conjoined  tendon,  with  which  it  is  united ;  and,  corresponding  to  the  point  where 
the  femoral  vessels  pass  into  the  thigh,  this  fascia  descends  in  front  of  them, 
forming  the  anterior  wall  of  the  crural  sheath. 


Fig.  382.- 


-Inguinal  Hernia,  showing  the  Transversalis  Muscle,  the  Transversalis  Fascia,  and  the 
Internal  Abdominal  Ring. 


The  Internal  Abdominal  ring  is  situated  in  the  transversalis  fascia,  midway 
between  the  anterior  superior  spine  of  the  ilium  and  the  spine  of  the  pubes,  and 
about  half  an  inch  above  Poupart's  ligament.  It  is  of  an  oval  form,  the  extremi- 
ties of  the  oval  directed  upwards  and  downwards,  varies  in  size  in  different 
subjects,  and  is  much  larger  in  the  male  than  the  female.  It  is  bounded,  above, 
by  the  arched  fibres  of  the  Transversalis  muscle,  and,  internally,  by  the  epigastric 
vessels.  It  transmits  the  spermatic  cord  in  the  male,  and  the  round  ligament  in 
the  female;  and  from  its  circumference,  a  thin,  funnel-shaped  membrane,  the 
infundibuliform  or  transversalis  fascia  is  continued  round  the  cord  and  testis, 
inclosing  them  in  a  distinct  pouch.  When  the  sac  of  an  oblique  inguinal  hernia 
passes  through  the  internal  ring,  the  transversalis  fascia  forms  one  of  its 
coverings. 

Bet-ween  the  transversalis  fascia  and  the  peritoneum  is  a  quantitv  of  loose 
areolar  tissue.     In  some  subjects  it  is  of  considerable  thickness,  and  loaded  with 


?64  SURGICAL   ANATOMY   OF   INGUINAL   HERNIA. 

adipose  tissue.  Opposite  the  internal  ring  it  is  continued  round  the  surface  of 
the  cord,  forming  for  it  a  loose  sheath. 

The  epigastric  artery  bears  a  very  important  relation  to  the  internal  abdominal 
ring.  This  vessel  lies  between  the  transversalis  fascia  and  peritoneum,  and  passes 
obliquely  upwards  and  inwards,  from  its  origin  from  the  external  iliac,  to  the 
margin  of  the  sheath  of  the  Rectus  muscle.  In  this  course,  it  lies  along  the  lower 
and  inner  margin  of  the  internal  ring,  and  beneath  the  commencement  of  the 
spermatic  cord,  the  vas  deferens  curving  round  it  as  it  passes  from  the  ring  into 
the  pelvis. 

The  peritoneum,  corresponding  to  the  inner  surface  of  the  internal  ring,  pre- 
sents a  well-marked  depression,  the  depth  of  which  varies  in  different  subjects. 
A  thin  fibrous  band  is  continued  from  it  along  the  front  of  the  cord,  for  a  variable 
distance,  and  becomes  ultimately  lost.  This  is  the  remains  of  the  pouch  of 
peritoneum  which,  in  the  foetus,  accompanies  the  cord  and  testis  into  the  scrotum, 
the  obliteration  of  which  commences  soon  after  birth.  In  some  cases,  the  fibrous 
band  can  only  be  traced  a  short  distance ;  but  occasionally  it  may  be  followed,  as 
a  fine  cord,  as  far  as  the  upper  end  of  the  tunica  vaginalis.  Sometimes  the  tube 
of  peritoneum  is  only  closed  at  intervals,  and  presents  a  sacculated  appearance ; 
or  a  single  pouch  may  extend  along  the  whole  length  of  the  cord,  which  may  be 
closed  above ;  or  the  pouch  may  be  directly  continuous  with  the  peritoneum  by 
an  opening  at  its  upper  part. 

Inguinal  Hernia. 

Inguinal  Hernia  includes  that  form  of  protrusion  which  makes  its  way  through 
the  abdomen  in  the  inguinal  region. 

There  are  two  principal  varieties  of  inguinal  hernia :  external  or  oblique,  and 
internal  or  direct. 

External  or  oblique  inguinal  hernia,  the  most  frequent  of  the  two,  is  that  form 
of  jjrotrusion  which  takes  the  same  course  as  the  spermatic  cord.  It  is  called 
external,  from  the  neck  of  the  sac  being  on  the  outer  or  iliac  side  of  the  epigastric 
artery. 

Internal  or  direct  inguinal  hernia  is  that  form  of  protrusion  which  does  not 
follow  the  same  course  as  the  cord,  but  protrudes  through  the  abdominal  wall  on 
the  inner  or  pubic  side  of  the  epigastric  artery. 

Oblique  Inguinal  Hernia. 

In  Oblique  Inguinal  Hernia,  the  intestine  escapes  from  the  abdominal  cavity  at 
the  internal  ring,  pushing  before  it  a  pouch  of  peritoneum,  which  forms  the  hernial 
sac.  As  it  enters  the  inguinal  canal,  it  receives  an  investment  from  the  subserous 
areolar  tissue,  and  is  inclosed  in  the  infundibuliform  process  of  the  transversalis 
fascia.  In  passing  along  the  inguinal  canal,  it  displaces  upwards  the  arched  fibres 
of  the  Transversalis  and  Internal  oblique  muscles,  and  is  surrounded  by  the  fibres 
of  the  Cremaster.  It  then  passes  along  the  front  of  the  cord,  and  escapes  from 
the  inguinal  canal  at  the  external  ring,  receiving  an  investment  from  the  inter- 
columnar  fascia.  Lastly,  it  descends  into  the  scrotum,  receiving  coverings  from 
the  superficial  fascia  and  the  integument. 

The  various  coverings  of  this  form  of  hernia,  after  it  has  passed  through  the 
external  ring,  are,  from  without  inwards,  the  integument,  superficial  fascia,  inter- 
columnar  fascia,  Cremaster  muscle,  transversalis  fascia,  subserous  cellular  tissue, 
and  peritoneum. 

This  form  of  hernia  lies  in  front  of  the  vessels  of  the  spermatic  cord,  and 
seldom  extends  below  the  testis,  on  account  of  the  intimate  adhesions  of  the  cover- 
ings of  the  cord  to  the  tunica  vaginalis. 

The  seat  of  stricture  in  oblique  inguinal  hernia  is  either  at  the  external  ring,  in 
the  inguinal  canal,  caused  by  the  fibres  of  the  Internal  oblique  or  Transversalis, 


VARIETIES   OF   INGUINAL   HERNIA.  T65 

or  at  the  internal  ring ;  more  frequently  in  the  latter  situation.  If  it  is  situated  at 
the  external  ring,  the  division  of  a  few  fibres  at  one  point  of  its  circumferenee  is 
all  that  is  necessary  for  the  replacement  of  the  hernia.  If  in  the  inguinal  canal, 
or  at  the  internal  ring,  it  will  be  necessary  to  divide  the  aponeurosis  of  the  Ex- 
ternal oblique  so  as  to  lay  open  the  inguinal  canal.  In  dividing  the  stricture, 
the  direction  of  the  incision  should  be  directly  upwards. 

When  the  intestine  passes  along  the  spermatic  canal,  and  escapes  from  the 
external  ring  into  the  scrotum,  it  is  called  common  oblique  inguinal  or  scrotal  hernia. 
If  the  intestine  does  not  escape  from  the  external  ring,  but  is  retained  in  the 
inguinal  canal,  it  is  called  incomplete  inguinal  hernia  or  bubonocele.  In  each  of 
these  cases,  the  coverings  which  invest  it  will  depend  upon  the  extent  to  which 
it  descends  in  the  inguinal  canal. 

There  are  two  other  varieties  of  oblique  inguinal  hernia : — the  congenital  and 
infantile. 

Congenital  hernia  is  liable  to  occur  in  those  cases  where  the  pouch  of  perito- 
neum which  accompanies  the  cord  and  testis  in  its  descent  in  the  foetus  remains 
unclosed,  and  communicates  directly  with  the  peritoneum.  The  intestine  descends 
along  this  pouch  into  the  cavity  of  the  tunica  vaginalis,  and  lies  in  contact  with 
the  testis.  This  form  of  hernia  has  no  proper  sac,  being  contained  within  the 
tunica  vaginalis. 

In  infantile  hernia,  the  hernial  sac  descends  along  the  inguinal  canal  into  the 
scrotum,  behind  the  pouch  of  peritoneum  which  accompanies  the  cord  and  testis 
into  the  same  part.  The  abdominal  aperture  of  this  pouch  is  closed,  but  the 
portion  contained  in  the  inguinal  canal  remains  unobliterated.  The  hernial  sac 
is  consequently  invested,  more  or  less  completely,  by  the  posterior  layer  of  the 
tunica  vaginalis,  from  which  it  is  separated  by  a  little  loose  areolar  tissue ;  so  that 
in  operating  upon  this  variety  of  hernia,  three  layers  of  peritoneum  would  require 
division,  the  first  and  second  being  the  layers  of  the  tunica  vaginalis,  the  third 
the  anterior  layer  of  the  hernial  sac. 

Dieect  Inguinal  Hernia. 

In  Direct  Inguinal  Hernia,  the  protrusion  makes  its  way  through  some  part  of 
the  abdominal  wall  internal  to  the  epigastric  artery,  and  passes  directly  through 
the  abdominal  parietes  and  external  ring.  At  the  lower  part  of  the  abdominal 
wall  is  a  triangular  space  (Hesselbach's  triangle),  bounded,  externally,  by  the 
epigastric  artery;  internally,  by  the  margin  of  the  Rectus  muscle;  below,  by 
Poupart's  ligament.  The  conjoined  tendon  is  stretched  across  the  inner  two- 
thirds  of  this  space,  the  remaining  portion  of  the  space  being  filled  in  by  the 
transversalis  fascia. 

In  some  cases  [more  often,  perhaps,  than  is  generally  supposed],  the  hernial 
protrusion  escapes  from  the  abdomen  on  the  outer  side  of  the  conjoined  tendon, 
pushing  before  it  the  peritoneum,  the  subserous  cellular  tissue,  and  the  transver- 
salis fascia.  It  then  enters  the  inguinal  canal,  passing  along  nearly  its  whole 
length,  and  finally  emerges  from  the  external  ring,  receiving  an  investment  from 
the  intercolumnar  fascia.  The  coverings  of  this  form  of  hernia  are  precisely 
similar  to  those  investing  the  oblique  form  of  protrusion. 

In  other  cases,  and  this  is  the  more  frequent  variety,  the  intestine  is  either 
forced  through  the  fibres  of  the  conjoined  tendon,  or  the  tendon  is  gradually  dis- 
tended in  front  of  it,  so  as  to  form  a  complete  investment  for  it.  The  intestine 
then  enters  the  lower  end  of  the  inguinal  canal,  escapes  at  the  external  ring,  lying 
on  the  inner  side  of  the  cord,  and  receives  additional  coverings  from  the  super- 
ficial fascia  and  the  integument.  This  form  of  hernia  has  the  same  coverings  as 
the  oblique  variety,  excepting  that  the  conjoined  tendon  is  substituted  for  the 
Cremaster,  and  the  infundibuliform  fascia  is  replaced  by  a  part  of  the  general 
fascia  transversalis. 

The  seat  of  stricture  in  both  varieties  of  direct  hernia  is  most  frequently  at  the 


T66  SURGICAL   ANATOMY   OF   FEMORAL   HERNIA. 

neck  of  the  sac,  or  at  the  external  ring.  In  that  form  of  hernia  which  perforates 
the  conjoined  tendon,  it  not  unfrequently  occurs  at  the  edges  of  the  fissure  through 
which  the  gut  passes.  In  dividing  the  stricture,  the  incision  should  in  all  cases 
be  directed  upwards. 

If  the  hernial  protrusion  passes  into  the  inguinal  canal,  but  does  not  escape 
from  the  external  abdominal  ring,  it  forms  what  is  called  incomplete  direct  hernia. 
This  form  of  hernia  is  usually  of  small  size,  and,  in  corpulent  persons,  very  diffi- 
cult of  detection. 

Direct  inguinal  hernia  is  of  much  less  frequent  occurrence  than  the  oblique, 
their  comparative  frequency  being,  according  to  Cloquet,  as  one  to  five.  It  occurs 
far  more  frequently  in  men  than  women,  on  account  of  the  larger  size  of  the 
external  ring  in  the  former  sex.  It  differs  from  the  oblique  in  its  smaller  size 
and  globular  form,  dependent  most  probably  on  the  resistance  offered  to  its  pro- 
gress by  the  transversalis  fascia  and  conjoined  tendon.  It  differs  also  in  its  posi- 
tion, being  placed  over  the  pubes,  and  not  in  the  course  of  the  inguinal  canal. 
The  epigastric  artery  runs  along  the  outer  or  iliac  side  of  the  neck  of  the  sac,  and 
the  spermatic  cord  along  its  external  and  posterior  side,  not  directly  behind  it,  as 
tin  oblique  inguinal  hernia. 


SURGICAL  ANATOMY  OF  FEMORAL  HERNIA. 

Dissection  (fig.  383).  The  dissection  of  the  parts  comprised  in  the  anatomy  of  femoral  hernia 
should  be  performed,  if  possible,  upon  a  female  subject  free  from  fat.  The  subject  should  lie 
upon  its  back  ;  a  block  is  first  placed  under  the  pelvis,  the  thigh  everted,  and  the  knee  slightly 
bent,  and  retained  in  this  position.  An  incision  should  then  be  made  from  the  anterior  superior 
spinous  process  of  the  ilium  along  Poupart's  ligament  to  the  symphysis  pubis ;  a  second  incision 
should  be  carried  transversely  across  the  thigh  about  six  inches  beneath  the  preceding;  and 
these  are  to  be  connected  together  by  a  vertical  one  carried  along  the  inner  side  of  the  thigh. 
These  several  incisions  should  divide  merely  the  integument ;  this  is  to  be  reflected  outwards, 
when  the  superficial  fascia  will  be  exposed. 

The  superficial  fascia  at  the  upper  part  of  the  thigh  consists  of  two  layers, 
between  which  are  found  the  cutaneous  vessels  and  nerves,  and  numerous  lym- 
phatic glands. 

The  superficial  layer  is  a  thick  and  dense  cellulo-fibrous  membrane,  in  the  meshes 
of  which  is  found  a  considerable  amount  of  adipose  tissue,  which  varies  in  quantity 
in  different  subjects ;  this  layer  may  be  traced  upwards  over  Poupart's  ligament 
to  be  continuous  with  the  superficial  fascia  of  the  abdomen ;  whilst  below,  and  on 
the  inner  and  outer  sides  of  the  limb,  it  is  continuous  with  the  superficial  fascia 
covering  the  rest  of  the  thigh. 

This  layer  should  be  detached  by  dividing  it  across  in  the  same  direction  as  the  external 
incisions  ;  its  removal  will  be  facilitated  by  commencing  at  the  lower  and  inner  angle  of  the 
space,  detaching  it  at  first  from  the  front  of  the  internal  saphenous  vein,  and  dissecting  it  off 
from  the  anterior  surface  of  this  vessel  and  its  branches  ;  it  should  then  be  reflected  outwards, 
in  the  same  manner  as  the  integument.  The  cutaneous  vessels  and  nerves,  and  superficial 
inguinal  glands,  are  then  exposed,  lying  upon  the  deep  layer  of  superficial  fascia.  These  are 
the  internal  saphenous  vein,  and  the  superficial  epigastric,  superficial  circumflexa  ilii,  and  super- 
ficial pudic  vessels,  as  well  as  numerous  lymphatics  ascending  with  the  saphenous  vein  to  the 
inguinal  glands. 

The  internal  saphenous  vein  i's  a  vessel  of  considerable  size,  which  ascends  obliquely 
upwards  along  the  inner  side  of  the  thigh,  below  Poupart's  ligament.  It  passes 
through  the  saphenous  opening  in  the  fascia  lata  to  terminate  in  the  femoral  vein. 
This  vessel  is  accompanied  by  numerous  lymphatics,  which  return  the  lymph 
from  the  dorsum  of  the  foot  and  inner  side  of  the  leg  and  thigh  ;  they  terminate 
in  the  inguinal  glands,  which  surround  the  saphenous  opening.  Converging 
towards  the  same  point  are  the  superficial  epigastric  vessels,  which  run  across 
Pou  part's  ligament,  obliquely  upwards  and  inwards,  to  the  lower  part  of  the 


FEMORAL   HERNIA  — SUPERFICIAL   DISSECTION.       T6> 

abdomen ;  the  circumflexa  ilii  vessels  pass  obliquely  outwards  along  Poupart's 
ligament  to  the  crest  of  the  ilium ;  and  the  superficial  external  pudic  vessels  pass 
inwards  to  the  perineal  and  scrotal  regions.  These  vessels  supply  the  subcutaneous 
areolar  tissue  and  the  integument,  and  are  accompanied  by  numerous  lymphatic 
vessels,  which  return  the  lymph  from  the  same  parts  to  the  inguinal  glands. 
"  The  superficial  inguinal  glands  are  arranged  in  two  groups,  one  of  which  is 
disposed  parallel  with  Poupart's  ligament ;  the  other  is  placed  below  this  ligament, 
surrounding  the  termination  of  the  saphenous  vein,  and  following  (occasionally) 
the  course  of  this  vessel  a  short  distance  along  the  thigh.  The  upper  chain 
receives  the  lymphatic  vessels  from  the  penis,  scrotum,  lower  part  of  the  abdomen, 
perineum,  and  buttock ;  the  lower  chain  receives  the  lymphatic  vessels  from  the 
lower  extremity. 

The  nerves  supplying  the  integument  of  this  region  are  derived  from  the  ilio- 


Fig.  383.— Femoral  Hernia.     Superficial  Dissection. 


inguinal,  the  genito-crural,  and  anterior  crural.  The  ilio-inguinal  nerve  may  be 
found  on  the  inner  side  of  the  internal  saphenous  vein,  the  terminal  branch  of  the 
genito-crural  nerve  outside  the  vein,  and  the  middle  and  external  cutaneous  nerves 
more  external. 

The  deep  layer  of  superficial  fascia  should  be  divided  in  the  same  direction 
as  the  external  incisions,  and  separated  from  the  fascia  lata ;  this  is  easily  effected, 
from  its  extreme  thinness.  It  is  a  thin  but  dense  membrane,  placed  beneath  the 
subcutaneous  vessels  and  nerves,  and  upon  the  surface  of  the  fascia  lata.     It  is 


768 


SURGICAL   ANATOMY   OF   FEMORAL   HERNIA. 


intimately  adherent  above  to  the  lower  margin  of  Poupart's  ligament,  and  about 
one  inch  below  this  ligament  covers  the  saphenous  opening  in  the  fascia  lata, 
is  closely  united  to  its  circumference,  and  is  connected  to  the  sheath  of  the 
femoral  vessels  corresponding  to  its  under  surface.  The  portion  of  fascia  covering 
this  aperture  is  perforated  by  the  internal  saphenous  vein,  and  by  numerous  blood- 
vessels and  lymphatics ;  hence  it  has  been  termed,  from  its  sieve-like  appearance, 
the  cribriform  fascia.  A  femoral  hernia,  in  passing  through  the  saphenous  open- 
ing, receives  the  cribriform  fascia  as  one  of  its  coverings. 

The  deep  layer  of  superficial  fascia,  together  with  the  cribriform  fascia,  having 
been  removed,  the  fascia  lata  is  exposed. 

The  Fascia  Lata,  already  described  (p.  328),  is  a  dense  fibrous  aponeurosis, 
which  forms  a  uniform  investment  for  the  whole  of  this  region  of  the  limb.  At 
the  upper  and  inner  part  of  the  thigh,  a  large  oval-shaped  aperture  is  observed  in 
it ;  it  transmits  the  internal  saphenous  vein  and  other  small  vessels,  and  is  called 
the  saphenous  opening.     In  order  the  more  correctly  to  consider  the   mode  of 

Fig.  3S4.—  Femoral  Hernia,  showing  Fascia  Lata  and  Saphenous  Opening. 


formation  of  this  aperture,  the  fascia  lata  in  this  part  of  the  thigh  is  described  as 
consisting  of  two  portions,  an  iliac  portion  and  a  pubic  portion. 

The  iliac  portion  of  the  fascia  lata  is  situated  on  the  outer  side  of  the  saphenous 
opening,  covering  the  outer  surface  of  the  Sartorius,  the  Rectus,  and  the  Psoas 
and  Iliacus  muscles.  It  is  attached  externally  to  the  crest  of  the  ilium  and  its 
anterior  superior  spine,  to  the  whole  length  of  Poupart's  ligament  as  far  internally 
as  the  spine  of  the  pubes,  and  to  the  pectineal  line  in  conjunction  with  Gimber- 


FASCIA   LATA— SAPHENOUS   OPENING.  T69 

nat's  ligament,  where  it  becomes  continuous  with  the  pubic  portion.  From  the 
spine  of  the  pubes,  it  is  reflected  downwards  and  outwards,  forming  an  arched 
margin,  the  outer  boundary  {superior  cornu)  of  the  saphenous  opening.  This  is 
sometimes  called  the  falciform  process  of  the  fascia  lata  or  femoral  ligament  of 
Hey ;  it  overlies,  and  is  adherent  to  the  sheath  of  the  femoral  vessels  beneath ; 
to  its  edge  is  attached  the  cribriform  fascia,  and  it  is  continuous  below  with'  th.e 
pubic  portion  of  the  fascia  lata  by  a  well-defined  curved  margin. 

The  pubic  portion  of  the  fascia  lata  is  situated  at  the  inner  side  of  the  saphe- 
nous opening ;  at  the  lower  margin  of  this  aperture,  it  is  continuous  with  the  iliac 
portion ;  traced  upwards,  it  covers  the  surface  of  the  Pectineus,  Adductor  longus, 
and  Gracilis  muscles;  and  passing  behind  the  sheath  of  the  femoral  vessels,  to 
which  it  is  closely  united,  is  continuous  with  the  sheath  of  the  Psoas  and  Iliacus 
muscles,  and  is  finally  lost  in  the  fibrous  capsule  of  the  hip-joint.  This  fascia  is 
attached  above  to  the  pectineal  line,  and  internally  to  the  margin  of  the  pubic 
arch.  It  may  be  observed  from  this  description,  that  the  iliac  portion  of  the 
fascia  lata  passes  in  front  of  the  femoral  vessels,  the  pubic  portion  behind  them ; 
an  apparent  aperture  consequently  exists  between  the  two,  through  which  the 
internal  saphenous  joins  the  femoral  vein. 

The  Saphenous  Opening  is  an  oval-shaped  aperture,  measuring  about  an  inch 
and  a  half  in  length,  and  half  an  inch  in  width.  It  is  situated  at  the  upper  and 
inner  part  of  the  thigh,  below  Poupart's  ligament,  on  the  pubic  side  of  its  centre, 
and  is  directed  obliquely  downwards  and  outwards. 

Its  outer  margin  is  of  a  semilunar  form,  thin,  strong,  sharply  defined,  and  lies 
on  a  plane  considerably  anterior  to  the  inner  margin.  If  this  edge  is  traced 
upwards,  it  will  be  seen  to  form  a  curved  elongated  process  or  cornu,  the  superior 
cornu  ox  falciform  process  of  Burns,  which  ascends  in  front  of  the  femoral  vessels, 
and  curving  inwards  is  attached  to  Poupart's  ligament  and  to  the  spine  of  the 
pubis  and  pectineal  line,  where  it  is  continuous  with  the  pubic  portion.  If  traced 
downwards,  it  is  found  continuous  with  another  curved  margin,  the  concavity  of 
which  is  directed  upwards  and  inwards ;  this  is  the  inferior  cornu  of  the  saphenous 
opening,  and  is  blended  with  the  pubic  portion  of  the  fascia  lata  covering  the 
Pectineus  muscle. 

The  inner  doundary  of  the  opening  is  on  a  plane  posterior  to  the  outer  margin, 
and  behind  the  level  of  the  femoral  vessels ;  it  is  much  less  prominent  and  defined 
than  the  outer,  from  being  stretched  over  the  subjacent  Pectineus  muscle.  It 
is  through  the  saphenous  opening  that  a  femoral  hernia  passes  after  descending 
along  the  crural  canal. 

If  the  finger  is  introduced  into  the  saphenous  opening  while  the  limb  is  moved 
in  different  directions,  the  aperture  will  be  found  to  be  greatly  constricted  on 
extending  the  limb,  or  rotating  it  outwards,  and  to  be  relaxed  on  flexing  the  limb 
and  inverting  it :  hence  the  necessity  of  placing  the  limb  in  the  latter  position  in 
employing  the  taxis  for  the  reduction  of  a  femoral  hernia. 

The  iliac  portion  of  the  fascia  lata,  together  with  its  falciform  process,  should  now  be  removed, 
by  detaching  it  from,  the  lower  margin  of  Poupart's  ligament,  carefully  dissecting  it  from  the 
subjacent  structures,  and  turning  it  aside,  when  the  sheath  of  the  femoral  vessels  is  exposed 
descending  beneath  Poupart's  ligament  (fig.  385). 

The  Crural  Arch  or  PouparCs  Ligament  is  the  lower  border  of  the  aponeurosis 
of  the  External  oblique  muscle,  which  stretches  across  between  the  anterior  supe- 
rior spine  of  the  ilium  to  the  spine  of  the  os  pubis  and  pectineal  line ;  the  portion 
corresponding  to  the  latter  insertion  is  called  Gimbernafs  ligament.  Its  direction 
is  curved  downwards  towards  the  thigh ;  its  outer  half  being  oblique,  its  inner  half 
nearly  horizontal.  Nearly  the  whole  of  the  space  included  between  the  crural 
arch  and  innominate  bone  is  filled  in  by  the  parts  which  descend  from  the  abdo- 
men into  the  thigh.  The  outer  half  of  this  space  is  occupied  by  the  Iliacus  and 
Psoas  muscles,  together  with  the  external  cutaneous  and  anterior  crural  nerves. 
The  pubic  side  of  the  space  is  occupied  by  the  femoral  vessels  included  in  their 
49 


no 


SURGICAL  ANATOMY  OF  FEMORAL  HERNIA. 


sheath,  a  small  oval-shaped  interval  existing  between  the  femoral  vein  and  the 
inner  wall  of  the  sheath,  which  is  occupied  merely  by  a  little  loose  areolar  tissue, 
and  occasionally  a  small  lymphatic  gland ;  this  is  the  crural  canal,  along  which  a 
portion  of  gut  descends  in  femoral  hernia. 

Qimbernais  Ligament  (fig.  386)  is  that  part  of  the  aponeurosis  of  the  External 
oblique  muscle,  which  is  reflected  downwards  and  outwards  to  be  inserted  into 
the  pectineal  line  of  the  os  pubis.  It  is  about  an  inch  in  length,  larger  in  the 
male  than  in  the  female,  almost  horizontal  in  direction  in  the  erect  posture,  and 
of  a  triangular  form,  the  base  directed  outwards.  Its  base  or  outer  margin  is 
concave,  thin  and  sharp,  lies  in  contact  with  the  crural  sheath,  and  is  blended  with 
the  pubic  portion  of  the  fascia  lata.  Its  apex  corresponds  to  the  spine  of  the  pubes. 
Its  posterior  margin  is  attached  to  the  pectineal  line.  Its  anterior  margin  is  con- 
tinuous with  Poupart's  ligament. 


Fig.  385. — Femoral  Hernia ;  Iliac  Portion  of  Fascia  Lata  having  been  removed,  and 
Sheath  of  Femoral  Vessels  and  Femoral  Canal  exposed. 


Crural  Sheath.  If  Poupart's  ligament  is  divided,  the  femoral  or  crural  sheath 
may  be  demonstrated  as  a  continuation  downwards  of  the  fasciae  that  line  the 
abdomen,  the  transversalis  fascia  passing  down  in  front  of  the  femoral  vessels,  and 
the  iliac  fascia  descending  behind  them ;  these  fasciae  are  directly  continuous  on 
the  iliac  side  of  the  femoral  artery,  but  a  small  space  exists  between  the  femoral 
vein  and  the  point  where  they  are  continuous  on  the  pubic  side  of  this  vessel, 
which  constitutes  the  femoral  or  crural  canal.     The  femoral  sheath  is  closely 


CRURAL   CANAL— FEMORAL   RING.  Ill 

adherent  to  the  contained  vessels  about  an  inch  below  the  saphenous  opening, 
becoming  blended  with  the  areolar  sheath  of  the  vessels,  but  opposite  Poupart's 
ligament  it  is  much  larger  than  is  required  to  contain  them ;  hence  the  funnel- 
shaped  form  which  it  presents.  The  outer  border  of  the  sheath  is  perforated  by 
the  genito-crural  nerve.  Its  inner  border  is  pierced  by  the  internal  saphenous  vein, 
and  numerous  lymphatic  vessels.  In  front  it  is  covered  by  the  iliac  portion  of  the 
fascia  lata ;  and,  behind  it,  is  the  pubic  portion  of  the  same  fascia. 

Deep  Crural  Arch.  Passing  across  the  front  of  the  crural  sheath,  and  closely 
connected  with  it,  is  a  thickened  band  of  fibres,  called  the  deep  crural  arch.  It 
is  apparently  a  thickening  of  the  fascia  transversalis,  joined  externally  to  the 
centre  of  Poupart's  ligament,  and  arching  across  the  front  of  the  crural  sheath, 
to  be  inserted  by  a  broad  attachment  into  the  pectineal  line,  behind  the  conjoined 
tendon.  In  some  subjects,  this  structure  is  not  very  prominently  marked,  and  not 
unfrequently  it  is  altogether  wanting. 

If  the  anterior  wall  of  the  sheath  is  removed,  the  femoral  artery  and  vein  are 
seen  lying  side  by  side,  a  thin  septum  separating  the  two  vessels,  and  another 
septum  separating  the  vein  from  the  inner  wall  of  the  sheath ;  the  septa  are  stretched 
between  the  anterior  and  posterior  walls  of  the  sheath,  so  that  each  vessel  is 
inclosed  in  a  separate  compartment.  The  interval  left  between  the  vein  and  the 
inner  wall  of  the  sheath  is  not  filled  up  by  any  structure,  excepting  a  little  loose 
areolar  tissue,  a  few  lymphatic  vessels,  and  occasionally  a  lymphatic  gland ;  this 
is  the  femoral  or  crural  canal,  through  which  a  portion  of  intestine  descends  in 
femoral  hernia. 

The  crural  canal  is  the  narrow  interval  between  the  femoral  vein  and  the  inner 
wall  of  the  crural  sheath.  Its  length  is  from  a  quarter  to  half  an  inch,  and  it 
extends  from  Gimbernat's  ligament  to  the  upper  part  of  the  saphenous  opening. 

Its  anterior  wall  is  very  narrow,  and  formed  by  the  fascia  transversalis,  Pou- 
part's ligament,  and  the  falciform  process  of  the  fascia  lata. 

Its  posterior  wall  is  formed  by  the  iliac  fascia  and  the  pubic  portion  of  the 
fascia  lata. 

Its  outer  wall  is  formed  by  the  fibrous  septum  covering  the  inner  side  of  the 
femoral  vein. 

Its  inner  wall  is  formed  by  the  junction  of  the  transversalis  and  iliac  fasciae, 
which  forms  the  inner  side  of  the  femoral  sheath  and  covers  the  outer  edge  of 
Gimbernat's  ligament. 

This  canal  has  two  orifices :  a  lower  one,  the  saphenous  opening,  closed  by  the 
cribriform  fascia;  an  upper  one,  the  femoral  or  crural  ring,  closed  by  the  septum 
crurale. 

The  femoral  or  crural  ring  (fig.  386)  is  the  upper  opening  of  the  femoral  canal, 
and  leads  into  the  cavity  of  the  abdomen.  It  is  bounded  in  front  by  Poupart's 
ligament  and  the  deep  crural  arch ;  behind,  by  the  pubes,  covered  by  the  Pectineus 
muscle,  and  the  pubic  portion  of  the  fascia  lata;  internally,  by  Gimbernat's 
ligament,  the  conjoined  tendon,  the  transversalis  fascia,  and  the  deep  crural  arch ; 
externally,  by  the  femoral  vein,  covered  by  its  sheath.  The  femoral  ring  is  of  an 
oval  form,  its  long  diameter,  directed  transversely,  measures  about  half  an  inch, 
and  it  is  larger  in  the  female  than  in  the  male ;  hence  one  of  the  reasons  of  the 
greater  frequency  of  femoral  hernia  in  the  former  sex. 

Position  of  Parts  around  the  Ring.  The  spermatic  cord  in  the  male,  and  round 
ligament  in  the  female,  lie  immediately  above  the  anterior  margin  of  the  femoral 
ring,  and  may  be  divided  in  an  operation  for  femoral  hernia  if  the  incision  for 
the  relief  of  the  stricture  is  not  of  limited  extent.  In  the  female  this  is  of  little 
importance,  but  in  the  male  the  spermatic  artery  and  vas  deferens  may  be  divided. 

The  femoral  vein  lies  on  the  outer  side  of  the  ring. 

The  epigastric  artery,  in  its  passage  inwards  from  the  external  iliac  to  the 
umbilicus,  passes  across  the  upper  and  outer  angle  of  the  crural  rinjr,  and  is 
consequently  in  great  danger  of  being  wounded  if  the  stricture  is  divided  in  a 
direction  upwards  and  outwards. 


772         -SURGICAL   ANATOMY   OP   FEMORAL   HERNIA. 

The  communicating  branch  between  the  epigastric  and  obturator  lies  in  front 
of  the  ring. 

The  circumference  of  the  ring  is  thus  seen  to  be  bounded  by  vessels  in  every 
part  excepting  internally  and  behind.  It  is  in  the  former  position  that  the  stric- 
ture is  divided  in  cases  of  strangulated  femoral  hernia. 


Fig.  3S(5. — Hernia.     The  Relations  of  the  Femoral  and  Internal  Abdominal  Rings, 
seen  from  within  the  Abdomen.     Right  Side. 


The  obturator  artery,  when  it  arises  by  a  common  trunk  with  the  epigastric, 
which  occurs  once  in  every  three  subjects  and  a  half,  bears  a  very  important 
relation  to  the  crural  ring.  In  some  cases  (fig.  387)  it  descends  on  the  inner  side 
of  the  external  iliac  vein  to  the  obturator  foramen,  and  will  consequently  lie  on 
the  outer  side  of  the  crural  ring,  where  there  is  little  danger  of  its  being  wounded 
in  the  operation  for  dividing  the  stricture  in  femoral  hernia.     Occasionally,  how- 


Variations  in  Origin  and  Course  of  Obturator  Artery. 
Fig.  387.  Fig.  388. 


ever,  this  vessel  curves  along  the  free  margin  of  Gimbernat's  ligament  in  its 
passage  to  the  obturator  foramen ;  it  would,  consequently,  skirt  along  the  greater 
part  of  the  circumference  of  the  crural  canal,  and  could  hardly  fail  in  being 
wounded  in  the  operation  (fig.  388). 

Septum  Crurale.  The  femoral  ring  is  closed  by  a  layer  of  condensed  areolar 
tissue,  called,  by  J.  Cloquet,  the  septum  crurale.  This  serves  as  a  barrier  to  the 
protrusion  of  a  hernia  through  this  part.     Its  upper  surface  is  slightly  concave, 


DESCENT   AND   COVERINGS   OF   FEMORAL   HERNIA.     773 

and  supports  a  small  lymphatic  gland,  by  which  it  is  separated  from  the  subserous 
areolar  tissue  and  peritoneum.  Its  under  surface  is  turned  towards  the  femoral 
canal.  The  septum  crurale  is  perforated  by  numerous  apertures  for  the  passage 
of  lymphatic  vessels,  connecting  the  deep  inguinal  glands  with  those  surrounding 
the  external  iliac  artery. 

The  size  of  the  femoral  canal,  the  degree  of  tension  of  its  orifices,  and,  conse- 
quently, the  degree  of  constriction  of  a  hernia,  vary  according  to  the  position  of 
the  limb.  If  the  leg  and  thigh  are  extended,  abducted,  or  everted,  the  femoral 
canal  and  its  orifices  are  extremely  tense  from  the  traction  on  these  parts  by 
Poupart's  ligament  and  the  fascia  lata,  as  may  be  ascertained  by  passing  the 
finger  along  it.  If,  on  the  contrary,  the  thigh  is  flexed  upon  the  pelvis,  and,  at 
the  same  time,  adducted  and  rotated  inwards,  the  femoral  canal  and  its  orifices 
become  considerably  relaxed ;  for  this  reason,  the  limb  should  always  be  placed 
in  the  latter  position  when  the  application  of  the  taxis  is  made  in  attempting  the 
reduction  of  a  femoral  hernia. 

The  septum  crurale  is  separated  from  the  peritoneum  by  a  quantity  of  loose 
subserous  areolar  tissue.  In  some  subjects  this  tissue  contains  a  considerable 
amount  of  adipose  substance,  which,  when  protruded  forwards  in  front  of  the  sac 
of  a  femoral  hernia,  may  be  mistaken  for  a  portion  of  omentum. 

Descent  of  the  Hernia.  From  the  preceding  description,  it  follows,  that  the 
femoral  ring  must  be  a  weak  point  in  the  abdominal  wall ;  hence  it  is,  that  when 
violent  or  long-continued  pressure  is  made  upon  the  abdominal  viscera,  a  portion 
of  intestine  may  be  forced  into  it,  constituting  a  femoral  hernia ;  and  the  larger 
size  of  this  aperture  in  the  female  serves  to  explain  the  frequency  of  this  form 
of  hernia  in  women. 

When  a  portion  of  intestine  is  forced  through  the  femoral  ring,  it  carries  before 
it  a  pouch  of  peritoneum,  which  forms  what  is  called  the  hernial  sac  ;  it  receives 
an  investment  from  the  subserous  areolar  tissue,  and  from  the  septum  crurale,  and 
descends  vertically  along  the  crural  canal  in  the  inner  compartment  of  the  sheath 
of  the  femoral  vessels  as  far  as  the  saphenous  opening ;  at  this  point,  it  changes 
its  course,  being  prevented  extending  further  down  the  sheath,  on  account  of  its 
greater  narrowness  and  close  contact  with  the  vessels,  and  also  from  the  close 
attachment  of  the  superficial  fascia  and  crural  sheath  to  the  lower  part  of  the 
circumference  of  the  saphenous  opening ;  it  is,  consequently,  directed  forwards, 
pushing  before  it  the  cribriform  fascia,  and  curves  upwards  on  to  the  falciform 
process  of  the  fascia  lata  and  lower  part  of  the  tendon  of  the  External  oblique, 
being  covered  by  the  superficial  fascia  and  integument.  While  the  hernia  is 
contained  in  the  femoral  canal,  it  is  usually  of  small  size,  owing  to  the  resisting 
nature  of  the  surrounding  parts ;  but  when  it  has  escaped  from  the  saphenous 
opening  into  the  loose  areolar  tissue  of  the  groin,  it  becomes  considerably  enlarged. 
The  direction  taken  by  a  femoral  hernia  in  its  descent  is  at  first  downwards,  then 
forwards  and  upwards ;  this  should  be  borne  in  mind,  as  in  the  application  of  the 
taxis  for  the  reduction  of  a  femoral  hernia,  pressure  should  be  directed  precisely 
in  the  reverse  order. 

Coverings  of  the  Hernia.  The  coverings  of  a  femoral  hernia  from  within  out- 
wards are  peritoneum,  subserous  areolar  tissue,  the  septum  crurale,  crural  sheath, 
cribriform  fascia,  superficial  fascia,  and  integument. 

Varieties  of  Femoral  Hernia.  If  the  intestine  descends  along  the  femoral  canal 
only  as  far  as  the  saphenous  opening,  and  does  not  escape  from  this  aperture,  it  is 
called  incomplete  femoral  hernia.  The  small  size  of  the  protrusion  in  this  form 
of  hernia,  on  account  of  the  firm  and  resisting  nature  of  the  canal  in  which  it  is 
contained,  renders  it  an  exceedingly  dangerous  variety  of  the  disease,  from  the 
extreme  difficulty  of  detecting  the  existence  of  the  swelling,  especially  in  corpulent 
subjects.  The  coverings  of  an  incomplete  femoral  hernia  would  be,  from  without 
inwards,  integument,  superficial  fascia,  falciform  process  of  fascia  lata,  fascia 
propria,  septum  crurale,  subserous  cellular  tissue,  and  peritoneum.  When,  how- 
ever, the  hernial  tumour  protrudes  through  the  saphenous  opening,  and  directs 


m    SURGICAL  ANATOMY  OF  FEMORAL  HERNIA. 

itself  forwards  and  upwards,  it  forms  a  complete  femoral  hernia.  Occasionally,  the 
hernial  sac  descends  on  the  iliac  side  of  the  femoral  vessels,  or  in  front  of  these 
vessels,  or  even  sometimes  behind  them. 

The  seat  of  stricture  of  a  femoral  hernia  varies :  it  may  be  in  the  peritoneum 
at  the  neck  of  the  hernial  sac ;  in  the  greater  number  of  cases  it  would  appear  to 
be  at  the  point  of  junction  of  the  falciform  process  of  the  fascia  lata  with  the 
lunated  edge  of  Gimbernat's  ligament ;  or  at  the  margin  of  the  saphenous  opening 
in  the  thigh.  The  stricture  should  in  every  case  be  divided  in  a  direction 
upwards  and  inwards ;  and  the  extent  necessary  in  the  majority  of  cases  is  about 
two  or  three  lines.  By  these  means,  all  vessels  or  other  structures  of  importance 
in  relation  with  the  neck  of  the  hernial  sac  will  be  avoided. 


Surgical  Anatomy  of  the  Perineum  and 
Ischio-Rectal  Region. 

Dissection.  The  student  should  select  a  well-developed  muscular  subject,  free  from  fat ;  and 
the  dissection  should  be  commenced  early,  in  order  that  the  parts  may  be  examined  in  as 
recent  a  state  as  possible.  A  staff  having  been  introduced  into  the  bladder,  and  the  subject 
placed  in  the  position  shown  in  fig.  389,  the  scrotum  should  be  raised  upwards,  and  retained  in 
that  position,  and  the  rectum  moderately  distended  with  tow. 

The  space  which  is  now  exposed,  corresponds  to  the  inferior  aperture  or  outlet 
of  the  pelvis.  Its  deep  boundaries  are,  in  front,  the  pubic  arch  and  sub-pubic 
ligament ;  behind,  the  tip  of  the  coccyx ;  and  on  each  side,  the  ramus  of  the  pubes 
and  ischium,  the  tuberosity  of  the  ischium,  and  great  sacro-sciatic  ligament.  The 
space  included  by  these  boundaries  is  somewhat  lozenge-shaped,  and  is  limited  on 
the  surface  of  the  body  by  the  scrotum  in  front,  by  the  buttocks  behind,  and  on 
each  side  by  the  inner  side  of  the  thighs.  It  measures,  from  before  backwards, 
about  four  inches,  and  about  three  in  the  broadest  part  of  its  transverse  diameter, 
between  the  ischial  tuberosities.  A  line  drawn  transversely  between  the  anterior 
part  of  the  tuberosity  of  the  ischium,  on  either  side,  in  front  of  the  anus,  sub- 
divides this  space  into  two  portions.  The  anterior  portion  contains  the  penis  and 
urethra,  and  is  called  the  perineum.  The  posterior  portion  contains  the  termina- 
tion of  the  rectum,  and  is  called  the  ischio-rectal  region. 

Ischiorectal  Kegiojst. 

The  Ischio-rectal  region  corresponds  to  the  portion  of  the  outlet  of  the  pelvis 
situated  immediately  behind  the  perineum:  it  contains  the  termination  of  the 
rectum.  A  deep  fossa,  filled  with  fat,  is  seen  on  either  side  of  the  intestine, 
between  it  and  the  tuberosity  of  the  ischium:  this  is  called  the  ischiol-rectal 
fossa. 

The  ischio-rectal  region  presents,  in  the  middle  line,  the  aperture  of  the  anus : 
around  this  orifice  the  integument  is  thrown  into  numerous  folds,  which  are 
obliterated  on  distension  of  the  intestine.  The  integument  is  of  a  dark  color, 
continuous  with  the  mucous  membrane  of  the  rectum,  and  provided  with  numerous 
follicles,  which  occasionally  inflame  and  suppurate,  and  may  be  mistaken  for 
fistulas.  The  veins  around  the  margin  of  the  anus  are  occasionally  much  dilated, 
forming  a  number  of  hard,  pendent  masses,  of  a  dark  bluish  color,  covered  partly 
by  mucous  membrane,  and  partly  by  the  integument.  These  tumors  constitute 
the  disease  called  external  piles. 

Dissection.  Make  an  incision  through  the  integument,  along  the  median  line,  from  the  base 
of  the  scrotum  to  the  anterior  extremity  of  the  anus ;  carry  it  round  the  margins  of  this  aperture 
to  its  posterior  extremity,  and  continue  it  backwards  about  an  inch  behind  the  tip  of  the  coccyx. 
A  transverse  incision  should  now  be  carried  across  the  base  of  the  scrotum,  joining  the  anterior 
extremity  of  the  preceding ;  a  second,  carried  in  the  same  direction,  should  be  made  in  front  of 
the  anus  ;  and  a  third,  at  the  posterior  extremity  of  the  gut.  These  incisions  should  be  sufficiently 
extensive  to  enable  the  dissector  to  raise  the  integument  from  the  inner  side  of  the  thighs.  The 
flaps  of  skin  corresponding  to  the  ischio-rectal  region  (figs.  389 — 392)  should  now  be  removed.  In 
dissecting  the  integument  from  this  region,  great  care  is  required,  otherwise  the  External  sphincter 
will  be  removed,  as  it  is  intimately  adherent  to  the  skin. 

The  superficial  fascia  is  exposed  on  the  removal  of  the  skin ;  it  is  very  thick, 
areolar  in  texture,  and  contains  much  fat  in  its  meshes.   In  it  are  found  ramifying 

775 


TtG 


SURGICAL   ANATOMY   OF   THE   PERINEUM. 


two  or  three  cutaneous  branches  of  the  small  sciatic  nerve ;  these  turn  round  the 
inferior  border  of  the  Gluteus  maximus,  and  are  distributed  to  the  integument 
in  this  region. 


Fig.  389. — Dissection  of  Perineum  and  Ischio-rectal  Region. 


The  External  sphincter  is  a  thin  flat  plane  of  muscular  fibres,  elliptical  in 
shape,  and  intimately  adherent  to  the  integument  surrounding  the  margin  of  the 
anus.  It  measures  about  three  or  four  inches  in  length,  from  its  anterior  to  its 
posterior  extremity,  being  about  an  inch  in  breadth,  opposite  the  anus.  It  arises 
from  the  tip  of  the  coccyx,  by  a  narrow  tendinous  band,  and  from  the  superficial 
fascia  in  front  of  that  bone ;  and  is  inserted  into  the  tendinous  centre  of  the 
perineum,  joining  with  the  Trans  versus  perinei,  and  the  other  muscles  inserted 
into  this  part.  Like  other  sphincter  muscles,  it  consists  of  two  planes  of  muscular 
fibre,  which  surround  the  margin  of  the  anus,  and  join  at  the  commissure  before 
and  behind. 

Relations.  By  its  superficial  surface,  with  the  integument ;  by  its  deep  surface  it 
is  in  contact  with  the  Internal  sphincter  ;  and  is  separated  from  the  Levator  ani 
by  loose  areolar  tissue. 

The  Sphincter  ani  is  a  voluntary  muscle,  supplied  by  the  hemorrhoidal  branch 
of  the  fourth  sacral  nerve.  This  muscle  is  divided  in  the  operation  for  fistula  in 
ano ;  and  also  in  some  cases  of  fissure  of  the  rectum,  especially  if  attended  with 
much  pain  or  spasm.  The  object  of  its  division  is  to  keep  the  parts  at  rest  and 
in  contact  during  the  healing  process. 

The  Internal  sphincter  is  a  muscular  ring,  about  half  an  inch  in  breadth,  which 
surrounds  the  lower  extremity  of  the  rectum,  about  an  inch  from  the  margin  of 
the  anus.  This  muscle  is  about  two  lines  in  thickness,  and  is  formed  by  an 
aggregation  of  the  involuntary  circular  fibres  of  the  intestine.  It  is  paler  in 
color,  and  less  coarse  in  texture,  than  the  External  sphincter. 

The  Ischio-rectal  Fossa  is  situated  'between  the  end  of  the  rectum  and  the 
tuberosity  of  the  ischium  on  each  side.  It  is  triangular  in  shape,  its  base 
directed  to  the  surface  is  formed  by  the  integument  of  the  ischio-rectal  region  ;  its 
apex,  directed  upwards,  corresponds  to  the  point  of  division  of  the  obturator 
fascia,  and  the  thin  membrane  given  off  from  it,  which  covers  the  outer  surface 
of  the  Levator  ani  (ischio-rectal  fascia).  Its  dimensions  are  about  an  inch  in 
breadth,  at  the  base,  and  about  two  inches  in  depth,  being  deeper  behind  than  in 
front.  It  is  bounded,  internally,  by  the  Sphincter  ani,  Levator  ani,  and  Coccygeus 
muscles ;  externally,  by  the  tuberosity  of  the  ischium,  and  the  obturator  fascia, 
which  covers  the  inner  surface  of  the  Obturator  intern  us  muscle ;  in  front,  it  is 
limited  by  the  line  of  junction  of  the  superficial  and  deep  perineal  fascia ;  and 
behind,  by  the   margin  of  the  Gluteus    maximus,  and   the   great   sacro-sciatic 


ISCHIO-RECTAL   FOSSA— PERINEUM.  m 

ligament.  This  space  is  filled  with  a  large  mass  of  adipose  substance,  which 
explains  the  frequency  with  which  abscesses  in  the  neighborhood  of  the  rectum 
burrow  to  a  considerable  depth. 

If  the  subject  has  been  injected,  on  placing  the  finger  on  the  outer  wall  of  this 
fossa,  the  internal  pudic  artery,  with  its  accompanying  veins  and  nerve,  will  be 
felt  about  an  inch  and  a  half  above  the  margin  of  the  ischial  tuberosity,  but 
approaching  nearer  the  surface  as  they  pass  forwards  along  the  inner  margin  of  the 
pubic  arch.  These  structures  are  inclosed  in  a  sheath  formed  by  the  obturator 
fascia,  the  pudic  nerve  lying  below  the  artery.  Crossing  the  space  transversely, 
about  its  centre,  are  the  inferior  hemorrhoidal  vessels  and  nerves,  branches  of  the 
pudic ;  they  are  distributed  to  the  integument  of  the  anus,  and  to  the  muscles  of 
the  lower  end  of  the  rectum.  These  vessels  are  occasionally  of  large  size,  and 
may  give  rise  to  troublesome  hemorrhage,  when  divided  in  the  operation  of  litho- 
tomy, or  for  fistula  in  ano.  At  the  back  part  of  this  space  may  be  seen  a  branch 
of  the  fourth  sacral  nerve ;  and,  at  the  fore  part  of  the  space,  a  cutaneous  branch 
of  the  perineal  nerve. 

Perineum. 

The  Perineal  Space'  is  of  a  triangular  form ;  its  deep  boundaries  are  limited, 
laterally,  by  the  rami  of  the  pubes  and  ischia,  meeting  in  front  at  the  pubic  arch ; 
behind,  by  an  imaginary  transverse  line,  extending  between  the  tuberosity  of  the 
ischium  on  either  side.  The  lateral  boundaries  vary,  in  the  adult,  from  three 
inches  to  three  inches  and  a  half  in  length,  and  the  base  from  two  to  three  inches 
and  a  half  in  breadth;  the  average  diameter  being  two  inches  and  three-quarters. 
The  variations  in  the  diameter  of  this  space  are  of  extreme  interest  in  connection 
with  the  operation  of  lithotomy,  and  the  extraction  of  a  stone  from  the  cavity  of 
the  bladder.  In  those  cases  where  the  tuberosities  of  the  ischia  are  approximated, 
it  would  be  necessary  to  make  the  incisions  in  the  lateral  operation  of  lithotomy 
much  less  oblique,  than  if  the  tuberosities  were  widely  separated,  and  the  perineal 
space,  consequently,  wider.  The  perineum  is  subdivided  by  the  median  raphe 
into  two  equal  parts.  Of  these,  the  left  is  the  one  usually  selected  to  commence 
the  primary  incisions  in  the  operation  of  lithotomy. 

In  the  middle  line,  the  perineum  is  convex,  and  corresponds  to  the  bulb  of  the 
urethra.  The  skin  covering  it  is  of  a  dark  color,  thin,  freely  movable  upon  the 
subjacent  parts,  and  covered  with  sharp  crisp  hairs,  which  should  be  removed 
before  the  dissection  of  the  part  is  commenced.  In  front  of  the  anus,  a  prominent 
line  commences,  the  raphe,  continuous  in  front  with  the  raphe  of  the  scrotum. 
The  flaps  of  integument  corresponding  to  this  space  having  been  removed,  in  the 
manner  shown  in  figs.  388 — 391,  the  superficial  fascia  is  exposed. 

The  Superficial  Fascia  consists  of  two  layers,  as  in  other  regions  of  the  body, 
superficial  and  deep. 

The  superficial  layer  is  thick,  loose,  areolar  in  texture,  and  contains  much 
adipose  tissue  in  its  meshes,  the  amount  of  which  varies  in  different  subjects. 
In  front,  it  is  continuous  with  the  dartos  of  the  scrotum ;  behind,  it  is  continuous 
with  the  subcutaneous  areolar  tissue  surrounding  the  anus ;  and,  on  either  side, 
with  the  same  fascia  on  the  inner  side  of  the  thighs.  This  layer  should  be 
carefully  removed,  after  it  has  been  examined,  when  the  deep  layer  will  be 
exposed. 

The  deep  layer  of  superficial  fascia  (superficial  perineal  fascia)  is  thin,  aponeu- 
rotic in  structure,  and  of  considerable  strength,  serving  to  bind  down  the  muscles 
of  the  root  of  the  penis.  It  is  continuous,  in  front,  with  the  dartos  of  the  scrotum ; 
on  either  side,  it  is  firmly  attached  to  the  margins  of  the  rami  of  the  pubes  and 
ischium,  external  to  the  crus  penis,  and  as  far  back  as  the  tuberosity  of  the 
ischium ;  posteriorly,  it  curves  down  behind  the  Transversus  perinei  muscles  to 
join  the  lower  margin  of  the  deep  perineal  fascia.  This  fascia  not  only  covers  the 
muscles  in  this  region,  but  sends  down  a  vertical  septum  from  its  under  surface 


778 


SURGICAL   ANATOMY   OF   THE   PERINEUM. 


which,  separates  the  back  part  of  the  subjacent  space  into  two,  being  incomplete 
in  front. 

In  rupture  of  the  anterior  portion  of  the  urethra,  accompanied  by  extravasation 
of  urine,  the  fluid  makes  its  way  forwards,  beneath  this  fascia,  into  the  areolar 


Fig.  390. — The  Perineum  :  the  Integument  and  Superficial  Layer  of 
Superficial  Fascia  being  reflected. 


tissue  of  the  scrotum,  penis,  and  anterior  and  lateral  portions  of  the  abdomen ;  it 
rarely  extends  into  the  areolar  tissue  on  the  inner  side  of  the  thighs,  or  backwards 
around  the  anus.  This  limitation  of  the  extravasated  fluid  to  the  parts  above- 
named  is  easy  of  explanation,  when  the  attachments  of  the  deep  layer  of  the 
superficial  fascia  are  considered.  "When  this  fascia  is  removed,  the  muscles  con- 
nected with  the  penis  and  urethra  will  be  exposed ;  these  are,  in  the  middle  line, 
the  Accelerator  urinae ;  on  each  side,  the  Erector  penis ;  and  behind,  the  Trans- 
versa perinei. 

The  Accelerator  urinse  is  placed  in  the  middle  line  of  the  perineum,  immediately 
in  front  of  the  anus.  It  consists  of  two  symmetrical  halves,  united  along  the  median 
line  by  a  tendinous  raphe.  It  arises  from  the  central  tendon  of  the  perineum, 
and  from  the  median  raphe  in  front.  From  this  point,  its  fibres  diverge  like  the 
plumes  of  a  pen ;  the  most  posterior  form  a  thin  layer,  which  are  lost  on  the 
anterior  surface  of  the  triangular  ligament ;  the  middle  fibres  encircle  the  bulb  and 
adjacent  part  of  the  corpus  spongiosum,  and  join  with  the  muscle  of  the  opposite 
side,  on  the  upper  part  of  this  body,  in  a  strong  aponeurosis ;  the  anterior  fibres, 
the  longest  and  most  distinct,  spread  out  over  the  sides  of  the  corpus  cavernosum, 
to  be  inserted  partly  into  this  body,  anterior  to  the  Erector  penis ;  partly  termi- 
nating in  a  tendinous  expansion,  which  covers  the  dorsal  vessels  of  the  penis. 
The  latter  fibres  are  best  seen  by  dividing  the  muscle  longitudinally,  and  dissecting 
"ft  outwards  from  the  surface  of  the  urethra.  . 

Action.     This  muscle  may  serve  to  accelerate   the   flow  of  urine   or   semen 


MUSCLES   OF   THE   PERINEUM. 


no 


along  the  canal  of  the  urethra.  The  middle  fibres  are  supposed,  by  Krause,  to 
assist  in  the  erection  of  the  corpus  spongiosum,  by  compressing  the  erectile  tissue 
of  the  bulb.  The  anterior  fibres,  according  to  Tyrrel,  also  contribute  to  the 
erection  of  the  penis,  as  they  are  inserted  into,  and  continuous  with,  the  fascia 
penis,  compressing  the  dorsal  vein  during  the  contraction  of  the  muscle. 


Fig.  391.— The  Superficial  Muscles  and  Vessels  of  the  Perineum. 


C-rT  Saero  Sriaiie  Zigf- 


Superficial  Perineal  A  rttry 
Superficia.  I  Perineal  Aer  ve 
Internal  Pudie  Nerve 
Infernal  Pudic  Arte  ry 


The  Erector  Penis  covers  the  unattached  part  of  the  crus  penis.  It  is  an 
elongated  muscle,  broader  in  the  middle  than  at  either  extremity,  and  situated  on 
either  side  of  the  lateral  boundary  of  the  perineum.  It  arises  by  tendinous  and 
fleshy  fibres  from  the  inner  surface  of  the  tuberosity  of  the  ischium,  behind  the 
crus  penis,  from  the  surface  of  the  crus,  and  from  the  adjacent  portion  of  the 
ramus  of  the  pubes.  From  these  points,  fleshy  fibres  succeed,  which  end  in  an 
aponeurosis  which  is  inserted  into  the  sides  and  under  surface  of  the  crus  penis. 
This  muscle  compresses  the  crus  penis,  and  thus  serves  to  maintain  this  organ 
erect. 

The  Transversus  Perinei  is  a  narrow  muscular  slip,  which  passes  more  or  less 
transversely  across  the  back  part  of  the  perineal  space.  It  arises  by  a  small 
tendon  from  the  inner  side  of  the  ascending  ramus  of  the  ischium,  and,  passing 
obliquely  forwards  and  inwards,  is  inserted  into  the  central  tendinous  point  of  the 
perineum,  joining  in  this  situation  with  the  muscle  of  the  opposite  side,  the 
Sphincter  ani  behind,  and  the  Accelerator  urinae  in  front. 

Between  the  muscles  just  examined,  a  triangular  space  exists,  bounded  internally 
by  the  Accelerator  urinae.  externally  by  the  Erector  penis,  the  base  corresponding 
to  the  Transversus  perinei.  The  floor  of  this  space  is  formed  by  the  triangular 
ligament  of  the  urethra  (deep  perineal  fascia),  and,  running  from  behind  forwards 
in  it,  are  the  superficial  perineal  vessels  and  nerves,  the  transversus  perinei  artery 
coursing  along  the  posterior  boundary  of  the  space,  resting  upon  the  Transversus 
perinei  muscle. 


180 


SURGICAL   ANATOMY   OF   THE   PERINEUM. 


In  the  lateral  operation  of  lithotomy,  the  knife  is  carried  obliquely  across  the 
back  part  of  this  space,  downwards  and  outwards,  into  the  ischio-rectal  fossa, 
dividing  the  Transversus  perinei  muscle  and  artery;  the  posterior  fibres  of  the 
Accelerator  urinae,  the  superficial  perineal  vessels  and  nerve,  and,  more  posteriorly, 
the  external  hemorrhoidal  vessels. 

The  superficial  and  transverse  perineal  arteries  are  described  at  p.  434  ■  and 
the  superficial  perineal  and  inferior  pudendal  nerves,  at  pp.  586,  588. 

The  Accelerator  urinae  and  Erector  penis  muscles  should  now  be  removed,  when  the  deep 
perineal  fascia  will  be  exposed,  stretching  across  the  front  part  of  the  outlet  of  the  pelvis.  The 
urethra  is  seen  perforating  its  centre,  just  behind  the  bulb  ;  and  on  either  side  is  the  crus  penis, 
connecting  the  corpus  cavernosum  with  the  ramus  of  the  ischium  and  pubes. 


Fig.  392. — Deep  Perineal  Fascia.     On  the  left  side,  the  anterior  layer 
has  been  removed. 


Anterior  layer  ef 
Dffp  Perineal. Fascia  Ttmcvtdi 
Shewing 

COMPRESSOR      URETHRA 

Internal  Pudic  Arty. 
Arty  ef  tie  Ba,lt 
Conqu'r*   Gland 


The  muscles  of  the  perineum  in  the  female  are  the 


Sphincter  vagina?. 
Erector  clitoridis. 
Transversus  perinei. 


Compressor  urethra?. 
Sphincter  ani. 
Levator  ani. 


Coccygeus. 


The  Sphincter  Vaginse  surrounds  the  orifice  of  the  vagina,  and  is  analogous  to 
the  Accelerator  urinae  in  the  male.  It  is  attached,  posteriorly,  to  the  central 
tendon  of  the  perineum,  where  it  blends  with  the  Sphincter  ani.  Its  fibres  pass 
forwards  on  each  side  of  the  vagina,  to  be  inserted  into  the  corpora  cavernosa  and 
body  of  the  clitoris. 

The  Erector  Clitoridis  resembles  the  Erector  penis  in  the  male,  but  is  smaller 
than  it. 

The  Transversus  Perinei  is  inserted  into  the  side  of  the  Sphincter  vaginas,  and 


DEEP   PERINEAL   FASCIA.  181 

the  Levator  ani  into  the  side  of  the  vagina.     The  other  muscles  are  precisely 
similar  to  those  in  the  male. 

The  Deep  Perineal  Fascia  (triangular  ligament)  is  a  dense  membranous  lamina, 
which  closes  the  front  part  of  the  outlet  of  the  pelvis.  It  is  triangular  in  shape, 
about  an  inch  and  a  half  in  depth,  attached  above,  by  its  apex,  to  the  under 
surface  of  the  symphysis  pubis  and  sub-pubic  ligament ;  and,  on  each  side,  to  the 
rami  of  the  ischia  and  pubes,  beneath  the  crura  penis.  Its  inferior  margin  or 
base  is  directed  towards  the  rectum,  and  connected  to  the  central  tendinous  point 
of  the  perineum.  It  is  continuous  with  the  deep  layer  of  the  superficial  fascia, 
in  front  of  the  Transversus  perinei  muscle,  and  with  a  thin  fascia,  which  covers 
the  outer  surface  of  the  Levator  ani  muscle. 

The  deep  perineal  fascia  is  perforated  by  the  urethra,  about  an  inch  below  the 
symphysis  pubis.  The  aperture  is  circular  in  form,  and  about  three  or  four  lines 
in  diameter.  Above  this  is  the  aperture  for  the  dorsal  vein  of  the  penis ;  and 
outside  the  latter,  the  puclic  nerve  and  artery  pierce  it. 

The  deep  perineal  fascia  consists  of  two  layers,  anterior  and  posterior :  these 
are  separated  above,  but  united  below. 

The  anterior  layer  is  continued  forwards,  around  the  anterior  part  of  the  mem- 
branous portion  of  the  urethra,  becoming  lost  upon  the  bulb. 

The  posterior  layer  is  derived  from  the  pelvic  fascia :  it  is  continued  backwards 
around  the  posterior  part  of  the  membranous  portion  of  the  urethra,  and  the 
outer  surface  of  the  prostate  gland. 

If  the  anterior  layer  of  this  fascia  is  detached  on  either  side,  the  following 
parts  are  seen  between  it  and  the  posterior  layer :  the  sub-pubic  ligament  above, 
close  to  the  pubes ;  the  dorsal  vein  of  the  penis ;  the  membranous  portion  of  the 
urethra,  and  the  muscles  of  the  urethra ;  Cowper's  glands,  and  their  ducts ;  the 
pudic  vessels  and  nerve;  the  artery  and  nerve  of  the  bulb,  and  a  plexus  of 
veins. 

The  Compressor  Urethrse  (constrictor  urethral)  surrounds  the  whole  length  of 
the  membranous  portion  of  the  urethra,  and  is  contained  between  the  two  layers 
of  the  deep  perineal  fascia.  It  arises  by  aponeurotic  fibres,  from  the  upper  part 
of  the  ramus  of  the  pubes  on  each  side,  to  the  extent  of  half  or  three  quarters  of 
an  inch ;  each  segment  of  the  muscle  passes  inwards,  and  divides  into  two 
fasciculi,  which  surround  the  urethra  from  the  prostate  gland  behind,  to  the 
bulbous  portion  of  the  urethra  in  front ;  and  unite,  at  the  upper  and  lower  sur-^ 
faces  of  this  tube,  with  the  muscle  of  the  opposite  side,  by  means  of  a  tendinous 
raphe. 

Circular  muscular  fibres  surround  the  membranous  portion  of  the  urethra,  from 
the  bulb  in  front  to  the  prostate  gland  behind :  they  are  placed  immediately  beneath 
the  transverse  fibres  already  described,  and  are  continuous  with  the  circular  fibres 
of  the  bladder.     These  fibres  are  involuntary. 

Cowpers  Glands  are  situated  immediately  below  the  membranous  portion  of  the 
urethra,  close  behind  the  bulb,  and  below  the  artery  of  the  bulb  (p.  736). 

The  Pudic  vessels  and  Nerves  are  placed  along  the  inner  margin  of  the  pubic  arch 

The  Artery  of  the  Bulb  passes  transversely  inwards  from  the  internal  pudic  along 
the  base  of  the  triangular  ligament,  between  the  two  layers  of  fascia,  accompanied 
by  a  branch  of  the  pudic  nerve  (p.  434). 

If  the  posterior  layer  of  the  deep  perineal  fascia  is  removed,  and  the  crus 
penis  of  one  side  detached  from  the  bone,  the  under  or  perineal  surface  of  the 
Levator  ani  is  brought  fully  into  view.  This  muscle,  with  the  triangular  ligament 
in  front  and  the  Coccygeus  and  Pyriformis  behind,  closes  in  the  outlet  of  the 
pelvis. 

The  Levator  ani  is  a  broad  thin  muscle,  situated  on  each  side  of  the  pelvis.  It 
is  attached  to  the  inner  surface  of  the  sides  of  the  true  pelvis,  and,  descending, 
unites  with  its  fellow  of  the  opposite  side  to  form  the  floor  of  the  pelvic  cavity. 
It  supports  the  viscera  in  this  cavity,  and  surrounds  the  various  structures  which 


T82  SURGICAL   ANATOMY   OF   THE   PERINEUM. 

pass  through  it.  It  arises,  in  front,  from  the  posterior  surface  of  the  body  and 
ramus  of  the  pubes,  on  the  outer  side  of  the  symphysis ;  posteriorly,  from  the 
inner  surface  of  the  spine  of  the  ischium ;  and,  between  these  two  points,  from 
the  angle  of  division  between  the  obturator  and  recto- vesical  layers  of  the  pelvic 
fascia  at  their  under  part :  the  fibres  pass  downwards  to  the  middle  line  of  the 
floor  of  the  pelvis,  and  are  inserted,  the  most  posterior  fibres  into  the  sides  of  the 
apex  of  the  coccyx ;  those  placed  more  anteriorly  unite  with  the  muscle  of  the 
opposite  side,  in  a  median  fibrous  raphe,  which  extends  between  the  coccyx  and 
the  margin  of  the  anus.  The  middle  fibres,  which  form  the  larger  portion  of  the 
muscle,  are  inserted  into  the  side  of  the  rectum,  blending  with  the  fibres  of  the 
Sphincter  muscles :  lastly,  the  anterior  fibres,  the  longest,  descend  upon  the  side 
of  the  prostate  gland  to  unite  beneath  it  with  the  muscle  of  the  opposite  side, 
blending  with  the  fibres  of  the  External  sphincter  and  Transversus  perinei 
muscles,  at  the  tendinous  centre  of  the  perineum. 

The  anterior  portion  is  occasionally  separated  from  the  rest  of  the  muscle  by 
cellular  tissue.  From  this  circumstance,  as  well  as  from  its  peculiar  relation  with 
the  prostate  gland,  descending  by  its  side  and  surrounding  it  as  in  a  sling,  it  has 
been  described  by  Santorini  and  others  as  a  distinct  muscle,  under  the  name  of 
the  Levator  prostatas.  In  the  female,  the  anterior  fibres  of  the  Levator  ani  descend 
upon  the  sides  of  the  vagina. 

Relations.  By  its  upper  or  pelvic  surface  with  the  reCto-vesical  fascia,  which 
separates  it  from  the  viscera  of  the  pelvis  and  from  the  peritoneum.  By  its  outer 
or  perineal  surface,  it  forms  the  inner  boundary  of  the  ischio-rectal  fossa ;  is 
covered  by  a  quantity  of  fat,  and  by  a  thin  layer  of  fascia  continued  fron*  the 
obturator  fascia.  Its  posterior  border  is  continuous  with  the  Coccygeus  muscle. 
Its  anterior  border  is  separated  from  the  muscle  of  the  opposite  side  by  a  triangular 
space,  through  which  the  urethra,  and,  in  the  female,  the  vagina  passes  from  the 
pelvis. 

Actions.  This  muscle  supports  the  lower  end  of  the  rectum  and  vagina,  and 
also  the  bladder  during  the  efforts  of  expulsion. 

The  Coccygeus  is  situated  behind  and  parallel  with  the  preceding.  It  is  a 
triangular  plane  of  muscular  and  tendinous  fibres,  arising,  by  its  apex,  from  the 
spine  of  the  ischium  and  lesser  sacro-sciatic  ligament,  and  is  inserted,  by  its  base, 
into  the  margin  of  the  coccyx  and  into  the  side  of  the  lower  piece  of  the  sacrum. 
This  muscle  is  continuous  with  the  posterior  border  of  the  Levator  ani,  and  closes 
in  the  back  part  of  the  outlet  of  the  pelvis. 

Relations.  By  its  inner  or  pelvic  surface,  with  the  rectum.  By  its  .external 
surface,  with  the  lesser  sacro-sciatic  ligament.  By  its  posterior  border,  with  the 
Pyriformis. 

Action.  The  Coccygei  muscles  raise  and  support  the  coccyx  after  it  has  been 
pressed  backwards  during  defecation  or  parturition. 

Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis.  Divide  the  central  tendinous  point  of  the 
perineum,  and  separate  the  rectum  from  its  connections  by  dividing  the  fibres  of  the  Levator  ani, 
which  descend  upon  the  sides  of  the  prostate  gland,  turn  it  backwards  towards  the  coccyx,  when 
the  under  surface  of  the  prostate  gland,  the  neck  and  base  of  the  bladder,  the  vesicuhe  seminales, 
and  vasa  deferentia  will  be  exposed. 

The  Prostate  Gland  is  placed  immediately  in  front  of  the  neck  of  the  bladder, 
around  the  prostatic  portion  of  the  urethra,  its  base  being  turned  backwards,  and 
its  under  surface  towards  the  rectum.  It  is  retained  in  its  position  by  the  Levator 
prostatas  and  by  the  pubo-prostatic  ligaments,  and  is  invested  by  a  dense  fibrous 
covering,  continued  from  the  posterior  layer  of  the  deep  perineal  fascia,  The 
longest  diameters  of  this  gland  are  in  the  antero-posterior  direction,  and  trans- 
versely at  its  base ;  and  hence  the  greatest  extent  of  incision  that  can  be  made 
in  it,  without  dividing  its  substance  completely  across,  is  obliquely  outwards  and 
backwards.  This  is  the  direction  in  which  the  incision  is  made  through  it  in 
the  operation  of  lithotomy,  the  extent  of  which  should  seldom  exceed  an  inch  in 
length.     The  relations  of  the  prostate  to  the  rectum  should  be  noticed :  by  means 


POSITION   OF   VISCERA   AT   OUTLET   OF   PELVIS.       783 

of  the  finger  introduced  into  the  gut,  the  surgeon  readily  detects  enlargement  or 
other  disease  of  this  organ,  and  he  is  enabled  by  the  same  means,  to  direct  the 
point  of  a  catheter  when  its  introduction  is  attended  with  much  difficulty,  either 
from  injury  or  disease  of  the  membranous  or  prostatic  portions  of  the  urethra. 

Behind  the  prostate  is  the  posterior  surface  of  the  neck  and  base  of  the  bladder ; 
a  small  triangular  portion  of  this  organ  is  seen,  bounded,  in  front,  by  the  prostate 
gland ;  behind,  by  the  recto-vesical  fold  of  the  peritoneum ;  on  either  side,  by  the 
vesiculae  seminales  and  vasa  deferentia ;  and  separated  from  direct  contact  with  the 
rectum  by  the  recto-vesical  fascia.  The  relation  of  this  portion  of  the  bladder  to 
the  rectum  is  of  extreme  interest  to  the  surgeon.  In  cases  of  retention  of  urine, 
this  portion  of  the  organ  is  found  projecting  into  the  rectum,  between  three  and 
four  inches  from  the  margin  of  the  anus,  and  may  be  easily  perforated  during  life 
without  injury  to  any  important  parts ;  this  portion  of  the  bladder  is,  consequently, 


Fig.  393. — A  View  of  the  Position  of  the  Viscera  at  the  Outlet  of  the  Pelvis. 


Artery  of  Corpus  Caverntitum 
iiorsa I  Artery  of  Tenia 


Artery  if  .Bnft, 
Tntertnl  Pudie  Artery 


Coirper'a   IZanJ-^ 


frequently  selected  for  the  performance  of  the  operation  of  tapping  the  bladder. 
If  the  finger  is  introduced  into  the  bowel,  the  surgeon  may  learn  the  position,  as 
well  as  the  size  and  weight,  of  a  calculus  in  the  bladder ;  and  in  the  operation 
for  its  removal,  if,  as  is  not  unfrequently  the  case,  it  should  be  lodged  behind  an 
enlarged  prostate,  it  may  be  easily  displaced  from  its  position  by  pressing  upwards 
the  base  of  the  bladder  from  the  rectum. 

Parts  concerned  in  the  Ojieration  of  Lithotomy.  The  triangular  ligament  must  be 
replaced,  the  rectum  drawn  forwards  so  as  to  occupy  its  normal  position,  and  the 
student  should  then  consider  the  position  of  the  various  parts  in  reference  to  the 
lateral  operation  of  lithotomy.  This  operation  is  usually  performed  on  the  left 
side  of  the  perineum,  as  it  is  most  convenient  for  the  right  hand  of  the  operator. 
A  staff  having  been  introduced  into  the  bladder,  the  first  incision  is  commenced 
about  an  inch  and  a  half  in  front  of  the  anus,  a  little  on  the  left  side  of  the  raphe, 
and  carried  obliquely  backwards  and  outwards  to  midway  between  the  anus  and 
tuberosity  of  the  ischium.     This  incision  divides  the  integument  and  superficial 


m 


SURGICAL  ANATOMY  OP  THE  PERINEUM. 


fascia,  the  external  hemorrhoidal  vessels  and  nerves,  and  the  superficial  and  trans- 
verse perineal  vessels ;  if  the  forefinger  of  the  left  hand  is  thrust  upwards  and 
forwards  into  the  wound,  pressing  at  the  same  time  the  rectum  inwards  and  back- 
wards, the  staff  may  be  felt  in  the  membranous  portion  of  the  urethra.  The  finder 
is  fixed  upon  the  staff,  and  the  structures  covering  it  are  divided  with  the  point 
of  the  knife,  which  must  be  directed  along  the  groove  towards  the  bladder,  the  edge 
of  the  knife  being  carried  outwards  and  backwards,  dividing  in  its  course  the 
membranous  portion  of  the  urethra,  and  part  of  the  left  lobe  of  the  prostate  gland, 
to  the  extent  of  about  an  inch.  The  knife  is  then  withdrawn,  and  the  forefinger 
of  the  left  hand  passed  along  the  staff  into  the  bladder ;  the  staff  having  been 
withdrawn,  and  the  position  of  the  stone  determined  upon,  the  forceps  are  intro- 
duced over  the  finger  into  the  bladder.  If  the  stone  is  very  large,  the  opposite 
side  of  the  prostate  should  be  notched  before  the  forceps  is  introduced ;  the  finger 
is  now  withdrawn,  the  blades  of  the  forceps  opened,  and  made  to  grasp  the  stone, 
which  must  be  extracted  by  slow  and  cautious  undulating  movements. 

Parts  divided  in  the  operation.  The  various  structures  divided  in  this  operation 
are  as  follows ;  the  integument,  superficial  fascia,  external  hemorrhoidal  vessels 
and  nerve,  the  posterior  fibres  of  the  Accelerator  urinte,  the  Trans  versus  perinei 
muscle  and  artery  (and,  probably,  the  superficial  perineal  vessels  and  nerves),  the 
deep  perineal  fascia,  the  anterior  fibres  of  the  Levator  ani,  part  of  the  Compressor 
urethras,  the  membranous  and  prostatic  portions  of  the  urethra,  and  part  of  the 
prostate  gland. 


Fig.  394. — A  Transverse  Section  of  the  Pelvis  ;  showing  the  Pelvic  Fascia. 


AnteriorCruralJVcn<e 

Femoral  Vessels. 


OhturafoT-  Fascia. 


Internal  Pudic  VisseU  &.  A> 


***  <!fl 


Parts  to  be  avoided  in  the  operation.  In  making  the  necessary  incisions  in  the 
perineum  for  the  extraction  of  a  calculus,  the  following  rules  should  be  observed: 
The  primary  incision  should  not  be  made  too  near  the  middle  line,  for  fear  of 
wounding  the  bulb  of  the  corpus  spongiosum  or  rectum ;  nor  too  far  externally, 
otherwise  the  pudic  artery  may  be  implicated  as  it  ascends  along  the  inner  border 
of  the  pubic  arch.  If  the  incisions  are  carried  too  far  forward,  the  artery  of  the 
bulb  may  be  divided ;  if  carried  too  far  backwards,  the  entire  breadth  of  the 


PELVIC   FASCIA. 


185 


prostate  and  neck  of  the  bladder  may  be  cut  through,  which  allows  of  infiltration 
of  urine  behind  the  pelvic  fascia  into  the  loose  cellular  tissue  between  the  bladder 
and  rectum,  instead  of  escaping  externally ;  diffuse  inflammation  is  consequently 
set  up,  and  peritonitis  from  the  close  proximity  of  the  recto-vesical  peritoneal 
fold  is  the  consequence.  If,  on  the  contrary,  the  prostate  is  divided  in  front  of 
the  base  of  the  gland,  the  urine  makes  its  way  externally,  and  there  is  no  danger 
of  any  infiltration  taking  place. 

During  the  operation,  it  is  of  great  importance  that  the  finger  should  be  passed 
into  the  bladder  before  the  staff  is  removed ;  if  this  is  neglected,  and  the  incision 
made  through  the  prostate  and  neck  of  the  bladder  be  too  small,  great  difficulty 
may  be  experienced  in  introducing  it  afterwards ;  and  in  the  child,  where  the 
connections  of  the  bladder  to  the  surrounding  parts  are  very  loose,  the  force  made 
in  the  attempt  is  sufficient  to  displace  the  bladder  up  into  the  abdomen,  out  of  the 
reach  of  the  operator.  Such  a  proceeding  has  not  unfrequently  occurred,  pro- 
ducing the  most  embarrassing  results,  and  total  failure  of  the  operation. 

Fig.  395. — Side  View'of  the  Pelvic  Viscera  of  the  Male  Subject,  showing  the  Pelvic 

and  Perineal  Fasciae. 


It  is  necessary  to  bear  in  mind  that  the  arteries  in  the  perineum  occasionally 
take  an  abnormal  course.  Thus,  the  artery  of  the  bulb,  when  it  arises,  as  some- 
times happens,  from  the  pudic,  opposite  the  tuber  ischii,  is  liable  to  be  wounded 
in  the  operation  for  lithotomy,  in  its  passage  forwards  to  the  bulb.  The  accessory 
pudic  may  be  divided  near  the  posterior  border  of  the  prostate  gland,  if  this  is 
completely  cut  across;  and  the  prostatic  veins,  especially  in  people  advanced  in 
life,  are  of  large  size,  and  give  rise  when  divided  to  troublesome  hemorrhage. 


Pelvic  Fascia. 

The  Pelvic  Fascia  is  a  thin  membrane  which  lines  the  whole  of  the  cavity  01 
the  pelvis,  and  is  continuous  with  the  transversalis  and  iliac  fasciae.     It  is  attached 
50 


786  PELYIC   FASCIA. 

to  the  brim  of  the  pelvis  for  a  short  distance  at  the  side  of  this  cavity,  and  to  the 
inner  surface  of  the  bone  round  the  attachment  of  the  Obturator  internus.  At 
the  posterior  border  of  this  muscle,  it  is  continued  backwards  as  a  very  thin 
membrane  in  front  of  the  Pyriformis  muscle  and  sacral  nerves,  behind  the  branches 
of  the  internal  iliac  artery  and  vein  which  perforate  it,  to  the  front  of  the  sacrum. 
In  front,  it  follows  the  attachment  of  the  Obturator  internus  to  the  bone,  arches 
beneath  the  obturator  vessels,  completing  the  orifice  of  the  obturator  canal,  and 
at  the  front  of  the  pelvis  is  attached  to  the  lower  part  of  the  symphysis  pubis ; 
being  continuous  below  the  pubes  with  the  fascia  of  the  opposite  side  so  as  to 
close  the  front  part  of  the  outlet  of  the  pelvis,  blending  with  the  posterior  layer 
of  the  triangular  ligament.  At  the  level  of  a  line  extending  from  the  lower 
part  of  the  symphysis  pubis  to  the  spine  of  the  ischium,  is  a  thickened  whitish 
band ;  this  marks  the  attachment  of  the  Levator  ani  muscle  to  the  pelvic  fascia, 
and  corresponds  to  its  point  of  division  into  two  layers,  the  obturator  and  recto- 
vesical. 

The  obturator  fascia  descends  and  covers  the  Obturator  internus  muscle.  It  is 
a  direct  continuation  of  the  pelvic  fascia  below  the  white  line  above  mentioned, 
and  is  attached  to  the  pubic  arch  and  to  the  margin  of  the  great  sacro-sciatic 
ligament.  This  fascia  forms  a  canal  for  the  pudic  vessels  and  nerve  in  their 
passage  forwards  to  the  perineum,  and  is  continuous  with  a  thin  membrane  which 
covers  the  perineal  aspect  of  the  Levator  ani  muscle,  called  the  isckio-rectal  or  anal 
fascia. 

The  recto-vesical  fascia  (visceral  layer  of  the  pelvic  fascia)  descends  into  the 
pelvis  upon  the  upper  surface  of  the  Levator  ani  muscle,  and  invests  the  prostate, 
bladder,  and  rectum.  From  the  inner  surface  of  the  symphysis  pubis  a  short 
rounded  band  is  continued  to  the  upper  surface  of  the  prostate  and  neck  of  the 
bladder,  forming  the  pubo-prostatic  or  anterior  true  ligaments  of  the  bladder.  At 
the  side,  this  fascia  is  connected  to  the  side  of  the  prostate,  inclosing  this  gland 
and  the  vesical  prostatic  plexus,  and  is  continued  upwards  on  the  surface  of  the 
bladder,  forming  the  lateral  true  ligaments  of  the  organ.  Another  prolongation 
invests  the  vesiculas  seminales,  and  passes  across  between  the  bladder  and  rectum, 
being  continuous  with  the  same  fascia  of  the  opposite  side.  Another  thin  pro- 
longation is  reflected  round  the  surface  of  the  lower  end  of  the  rectum.  The 
Levator  ani  muscle  arises  from  the  point  of  division  of  the  pelvic  fascia ;  the 
visceral  layer  descending  upon  and  being  intimately  adherent  to  the  upper  surface 
of  this  muscle,  while  the  under  surface  is  covered  by  a  thin  layer  derived  from 
the  obturator  fascia,  called  the  ischio-rectal  or  anal  fascia.  In  the  female,  the 
vagina  perforates  the  recto-vesical  fascia,  and  receives  a  prolongation  from  it. 


INDEX.1 


Abdomen,  658 

apertures  found  in,  659 

boundaries  of,  658 

lymphatics  of,  490 

muscles  of,  281 

regions  of,  659 

viscera  of,  659 
Abdominal  aorta.     See  Aorta, 
abdominal. 

muscles,  281 

ring,  external.  282,  760 
internal,  763 

viscera,  position  of,  659 
Absorbent  glands,  482 
Absorbents,  481 
Acervulus  cerebri,  528 
Acetabulum,  154 
Air-cells,  720 
Air-tubes,  711 
Alae  of  nose,  580 

of  vomer,  92 
Alimentary  canal,  643 

subdivisions  of,  643. 
See  also   Stomach,   Intes- 
tines, &c. 
Allantois,  721 
Alveoli,  formation  of,  651 

of  lower  jaw,  93 

of  stomach,  666 

of  upper  jaw,  85 
Amphiarthrosis,  185 
Ampullae   of   semicircular    ca- 
nals, 638 

of  tubuli  lactiferi,  756 
Amygdalae,  653 

of  cerebellum,  531,  532 
Anastomosis  of  arteries,  358 
Anatomy,  descriptive,  33 

surgical,  33.    See  also  Surgi- 
cal anatomy. 
Angle  of  jaw,  95 

nasal,  81 

of  pubes,  153 

of  rib,  117 

sacro-vertebral,  50 
Angular  movement,  187 
Animal  constituent  of  bone,  33 
Ankle-joint,  228 

arteries  of,  229 

bones  of,  228 

ligaments  of,  228 

relations  of  tendons  and  ves- 
sels, in  front  of,  229 
behind,  229 


Annulus  ovalis,  693 
Antihelix,  629 
fossa  of,  62 9 
Antitragus,  629 
Antrum  of  Highmore,  84 
Anus,  775 

muscles  of,  776 
Aorta,  361 

divisions  of,  361 
sinuses  of,  362 
abdominal,  418 
aneurism  of,  420 
branches  of,  420 
surgical  anatomy  of,  420 
arch  of,  361 

aneurism  of,  364 
ascending  part  of,  362 
branches  of,  365 
descending  part  of,  364 
peculiarities  of,  364 
of  branches  of,  365 
of  conformation  of,  364 
of  direction  of,  364 
surgical  anatomy  of,  364 
transverse  portion  of,  363 
descending,  416 
thoracic,  417 
aneurism  of,  417 
branches  of,  417 
surgical  anatomy  of,  417 
Aortic  opening.     *Sfee  Opening, 
aortic, 
valves.     See  Valves. 
Apertura  scalae  vestibuli  coch- 
lea, 638 
Aperture  of  iter  chordae  ante- 
rius,  632 

posterius,  632 
of  larynx,  707 
of  posterior  nares,  109 
See  also  Apertura  and  Open- 
ings. 
Aponeurosis,  237 
of  deltoid,  299 
of  external  oblique,  in  ingui- 
nal region,  759 
infraspinous,  300 
of  insertion,  238 
of  investment,  238 
of  occipito-frontalis,  241 
of  soft  palate,  653 
pharyngeal,  656 
subscapular,  299 
supra-spinous,  300 


Aponeurosis — 

vertebral,  274 
Apophysis,  35 
Apparatus,  lachrymal,  627 

ligamentosus  colli,  195 
Appendages  of  eye,  625 
of  skin,  605 
of  uterus,  752 
Appendices  epiploicae,  603,  673 
Appendix  of  left  auricle,  695 
of  right  auricle,  692 
vermiformis,  671 
Aqua  labyrinthi,  640 
Aquaeduetus  cochleae,  70,  638 
Fallopii,  633 
Sylvii,  528 
vestibuli,  70,  638 
Aqueous    chamber,    epithelial 
lining  of,  623 
humor,  622 

secreting  membrane  of,  623 
Arachnoid  membrane  of  brain, 
508 
parietal  layer  of,  508 
structure  of,  508 
visceral  layer  of,  509 
of  cord,  501 
cavity  of,  501 
Arbor  vitae  of  cerebellum,  533 

uterinus,  750 
Arch  of  aorta.   See  Aorta,  arch 
of. 
of  colon,  672 
crural,  760 
femoral,  760 
deep,  771 
nasal,  458 
palmar,  deep,  411 
superficial,  414 
plantar,  452 
of  pubes,  157 
supraorbital,  64 
of  vertebra,  40 
zygomatic,  105 
Arciform  fibres  of  medulla  ob- 
longata, 511 
Areola  of  breast,  756 
Arm,  arteries  of,  405 
bones  of,  129 
fascia  of,  302 
muscles  of  back  of,  304 

front  of,  302 
nerves  of,  569 
veins  of,  467 


1  Each  Artery,  Nerve,  Muscle,  Ac,  is  placed  in  the  Index  under  the  head  of  Artery,  Nerve,  Muscle,  Ac. 
Carotid  artery,  for  example,  being  found  under  Artery,  carotid;  Median  nerve,  under  Nerve,  median  ;  Ac. 

787 


788 


INDEX. 


Arnold's  ganglion,  554 
nerve,  559 

canal  for,  71 
Arteria  or  Arteriae.     See  Ar- 
tery. 
A-rteriae  receptaculi,  387 
Artery  or  Arteries,  358 
anastomoses  of,  358 
capillary,  360 
coats  of,  359 

areolar,  359 

contractile,  359 

elastic,  359 

external,  359 

fenestrated,  359 

internal,  359 

middle,  359 
distribution  of,  358 
epithelial  lining  of,  360 
mode  of  division  of,  358 

of  origin  of  branches  of,  358 
nerves  of,  360 
physical  properties  of,  360 
sheath  of,  360 
structure  of,  361 
subdivision  of,  358 
surgical  anatomy  of,  361 
tortuosity  of,  359 
vessels  of,  360 

abdominal,  of  lumbar,  428 
accessory  pudic,  433 
acromial  thoracic,  404 
alar  thoracic,  405 
alveolar,  381 

anastomotica  magna  of  bra- 
chial, 409 

of  femoral,  443 
angular,  376 
anterior  auricular,  379 

carpal,  412,  416 

cerebellar,  397 

cerebral,  390 

choroid,  391 

ciliary,  390,  624 

circumflex,  405 

communicating,  390 

intercostal,  400,  418 

interosseous,  416 

meningeal,  387 

peroneal,  452 

spinal,  396 

temporal,  375 

ulnar  recurrent,  415 
aorta.     See  Aorta, 
articular,   of   knee,    inferior 
external,  446 
internal,  446 
superior  external,  446 
internal,  445 

of  sciatic,  436 
ascending  cervical,  398 

pharyngeal,  377 
auditory,  397,  642 
auricular,  anterior,  379 

posterior,  377 
axillary,  402 

branches  of,  404 

peculiarities  of,  404 

surgical  anatomy  of,  404 
azygos  articular  of  knee,  446 


Artery  or  Arteries — 
basilar,  397 
brachial,  405 
branches  of,  408 
peculiarities  of,  407 
surgical  anatomy  of,  408 
bronchial,  418,  720 
buccal,  381 

of  bulb  of  urethra,  434,  781 
calcanean,  internal,  452 
carotid,  367 
common,  367 
left,  relations  of,  368 
peculiarities  of.  370 
surgical  anatomy  of,  370 
external,  371 

surgical  anatomy  of,  371 
internal,  385 

cavernous  portion,  386 
cerebral  portion,  386 
cervical  portion,  386 
petrous  portion,  386 
surgical  anatomy  of,  386 
carpal,  anterior  of  radial,  412 
of  ulnar,  416 
posterior  of  radial,  412 
<»f  ulnar,  416 
of  cavernous  body,  434,  738 
centralis  modioli,  639 

retina?,  390,  622 
cerebellar,  anterior,  397 
inferior,  397 
superior,  397 
cerebral,  anterior,  390 
middle,  390 
posterior,  397 
cervical,  ascending,  398 
superficial,  398 
princeps,  377 
profunda,  400 
choroid,  anterior,  391 

posterior,  397 
ciliary,  390 

anterior,  390,  624 
long,  390,  624 
short,  390,  624 
circle  of  Willis,  397 
circumflex  of  arm,  405 
anterior,  405 
posterior,  405 
iliac,  438 

superficial,  441 
of  thigh,  442 

ascending   branches   of, 

442 
descending  branches  of, 

442 
external,  442 
internal,  442 
transverse  branches  of, 
442 
cochlear,  642 
coccygeal,  435 
cceliac  axis,  421 
colica  dextra,  425 
media,  425 
sinistra,  425 
comes  nervi  ischiadici,  435 

phrenici.  399 
communicating,   anterior,  of 
brain,  390 


Artery  or  Arteries — 

posterior  of  brain,  390 
communicating     branch     of 
dorsalis  pedis,  449 
of  ulnar,  416 
coronary,  of  heart,  365 
inferior,  375 
left,  366 

peculiarities  of,  366 
right,  365 
superior,  376 
of  upper  lip,  376 
of  lower  lip,  375 
of  corpus  cavernosum,  434 
cremasteric,  438 
crico-thyroid,  373 
cutaneous,  445 
cystic,  423 

deep  branch  of  ulnar,  416 
cervical,  400 
palmar  arch,  411 
temporal,  381 
deferent,  432 
dental,  inferior,  381 

superior,  381 
descending  palatine,  382 
digital,  of  plantar,  453 

of  ulnar,  416 
dorsal,  of  lumbar,  428 
of  penis,  434      - 
of  scapula,  405.    See  also 
Artery,  dorsalis. 
dorsalis  hallucis,  449 
indicis,  412 
linguae,  373 
pedis,  448 

branches  of,  449 
peculiarities  of,  449 
surgical  anatomy  of,  449 
penis,  434 
pollicis,  412 
scapulae,  405 
epigastric,  437 

peculiarities  of,  438 
relation  of,  to   external 
ring,  771 
to  internal  ring,  764 
superior,  400 
superficial,  411 
ethmoidal,  388 
external   articular   of   knee, 
445 
carotid,  371 
circumflex,  442 
hemorrhoidal,  434 
iliac,  436 
malleolar,  448 
obturator,  433 
plantar,  452 
pudic,  442 
facial,  374 

peculiarities  of,  376 
surgical  anatomy  of,  376 
transverse,  378 
femoral,  438 

branches  of,  441 
peculiarities  of,  440 
surgical  anatomy  of,  440 
deep,  442 
frontal,  389 
gastric,  421 


INDEX. 


789 


Artery  or  Arteries — 

of  splenic,  423 
gastro-duodenalis,  422 

epiploica  dextra,  422 
gastro  epiploica  sinistra,  423 
gluteal,  436 

deep,  436 

inferior,  435 

superficial,  436 
helicine,  738 
hemorrhoidal,  external,  434 

inferior,  434 

middle,  432 

superior,  425 
hepatic,  421,  678 
hyoid  branch  of  lingual.  373 

of  superior  thyroid,  372 
hypogastric,  in  foetus,  699, 701 

how  obliterated,  702 
ileo-colic,  425 
iliac,  428 

circumflex,  438 

common,  428 
left,  428 
right,  428 

peculiarities  of,  429 
surgical  anatomy  of,  429 

external,  436 

surgical  anatomy  of,  437 

internal  430 
at  birth,  431 
peculiarities  of,  in  foetus, 

430 
surgical  anatomy  of,  431 
of  ilio-lumbar,  436 
inferior  cerebellar,  397 

coronary,  375 

dental,  381 

gluteal,  435 

hemorrhoidal,  434 

labial,  375 

laryngeal,  373 

meningeal,  377 

mesenteric,  425 

palatine,  375 

perforating,  443 

profunda,  409 

p'idic,  442 

pyloric,  422 

thyroid,  398 

vesical,  432 
infra-orbital,  381 
innominate,  366 

peculiarities  of,  366 
surgical  anatomy  of,  367 
intercostal,  400,  418 

anterior,  400,  418 

dorsal,  418 

superior,  400,  418 
internal  auditory,  642 

calcanean,  452 

carotid,  385 

circumflex  of  thigh,  442 

iliac,  430 

malleolar,  448 

mammary,  399 

maxillary,  379 

obturator,  433 

plantar,  452 

pudic,  433 
interosseous  of  ulnar,  415 


Artery  or  Arteries — 

dorsal  of  foot,  452 
of  hand,  415 
anterior,  416 
posterior,  416 
of  radial,  412 
intestini  tenuis,  424 
labial,  375 

inferior,  375 
lachrymal,  388 
laryngeal,  398 

inferior,  373 

superior,  373 
lateral  sacral,  436 

spinal,  396 
lateralis  nasi,  376 
lingual,  373 

surgical  anatomy  of,  374 
long  ciliary,  370,  624 

thoracic,  405 
lumbar,  427 

ilio-lumbar  of  the,  436 
malleolar,  448 

external,  448 

internal,  448 
mammary,  internal,  399 
masseteric,  381 
maxillary,  internal,  379 
median,  397,  416 

of  forearm,  416 

of  spinal  cord,  397 
mediastinal,  400 

posterior,  418 
meningeal,    from    ascending 
pharyngeal,  378 

anterior,  from  carotid,  387 

inferior,  from  occipital.  377 

middle,  from  internal  max- 
illary, 379 

posterior,  from  vertebral, 
396 

small,  from  internal  max- 
illary, 380 
mesenteric,  inferior,  425 

superior,  423 
metacarpal,  412 
metatarsea,  449 
metatarsal,  449 
middle  cerebral,  390 

sacral,  428 
musculo-phrenic,  400 
mylo-hyoid,  381 
nasal,  382 

of  ophthalmic,  389 

of  septum,  375 
nutrient  of  femur,  443 

fibula,  452 

humerus,  409 

radius,  416 

tibia,  452 

ulna,  416 
obturator,  432 

external,  433 

internal,  433 

peculiarities  of,  433 

relations  of,  in  hernia,  772 
occipital,  376 
oesophageal,  398,  418 
ophthalmic,  387 
orbital,  380 
ovarian,  427 


Artery  or  Arteries — 
palatine,  ascending,  375 

d3scending,  382 

inferior,  375 

of  pharyngeal,  378 

posterior,  382 
palmar  arch,  deep,  411 
superficial,  414 

interosseae,  413 
palpebral,  388 
pancreatic,  423 
pancreatica  magnae,  423 

parvae,  423 
pancreatico-duodenalis,  423 

inferior,  424 
perforating,   313,   400.     See 

Perforating  arteries, 
pericardiac,  400,  417 
perineal,  superficial,  434 

transverse,  434 
peroneal,  451 

anterior,  452 
pharyngea  ascendens,  377 
phrenic,  427 

superior,  399 
plantar,  452 

external,  452 

internal,  452 
popliteal,  444 

branches  of,  445 

peculiarities  of,  445 

surgical  anatomy  of,  445 
posterior  auricular,  377 

carpal,  412,  416 

cerebral,  397 

choroid,  397 

circumflex  of  arm,  405 

communicating,  390 

interosseous,  416 

meningeal,  396 

palatine,  382 

recurrent  interosseous,  41 G 

spinal,  397 

scapular,  399 

temporal,  378 

ulnar  recurrent,  415 
princeps  cervicis,  377 

pollicis,  413 
profunda  of  arm.  inferior,  409 
superior.  409 

cervicis,  400 

femoris,  442 
pterygoid,  381 
pterygopalatine,  382 
pubic,  438 
pudic,  accessory,  433 

external,  442 
deep,  442 
inferior,  442 
superficial,  442 
superior,  442 

internal,  433 

peculiarities  of,  433 
in  female,  435 
pulmonary,  453,  694,  720 
pyloric,  422 

inferior,  422 

of  hepatic,  422 
radial,  410 

branches  of,  412 

peculiarities  of,  411 


790 


INDEX. 


Artery  or  Arteries — 

relations  of,  in  forearm,  411 
in  hand,  411 

surgical  anatomy  of,  411 
radialis  indicis,  413 
ranine,  373 

recurrent  interosseous,  poste- 
rior, 416 

radial,  412 

tibial,  448 

ulnar,  anterior,  415 
posterior,  415 
renal,  426,  726 
sacra  media,  428 
sacral,  lateral,  436 

middle,  428 
scapular,  posterior,  399 
sciatic,  435 

short  ciliary,  390,  624 
sigmoid,  425 
spermatic,  427,  740 
spheno-palatine,  382 
spinal,  anterior,  396 

from  the  intercostal,  418 

in  the  loins,  436 

in  the  neck,  396 

in  the  thorax,  418 

lateral,  396 

from  the  lumbar,  428 

median,  397 

posterior,  397 

from  the  vertebral,  396 
splenic,  423,  688 
sterno-mastoid,  372 
stylo-mastoid,  377 
subclavian,  391 

branches  of,  395 

first  part  of  left,  392 

left,  392 

peculiarities  of,  393 

right,  392 

second  portion  of,  392 

surgical  anatomy  of,  393 

third  portion  of,  393 
sublingual,  373 
submaxillary,  375 
submental,  375 
subscapular,  405 
superficial  cervical,  398 

circumflex  iliac,  441 

epigastric,  441 

palmar  arch,  414 

perineal,  434 
superficialis  volse,  412 
superior  cerebellar,  397 

coronary,  376 

dental,  381 

epigastric,  400 

hemorrhoidal,  425 

intercostal,  400,  418 

laryngeal,  373 

mesenteric,  423 

perforating,  443 

phrenic,  399 

profunda,  409 

pudic,  442 

thoracic,  404 

thyroid,  372 

vesical,  432 
supra-orbital,  388 

-renal,  426 


Artery  or  Arteries — ■ 
supra-scapular,  398 
sural,  445 
tarsal,  449 
tarsea,  449 
temporal,  378 
anterior,  378 
deep,  381 
middle,  378 
posterior,  378 
surgical  anatomy  of,  379 
thoracic,  acromial,  404 
alar,  405 
aorta,  417 
long,  405 
superior,  404 
thyroid,  inferior,  398 
superior,  372 
surgical  anatomy  of,  373 
axis,  398 
tibial,  anterior,  446 
branches  of,  448 
peculiarities  of,  447 
surgical  anatomy  of,  447 
posterior,  450 
branches  of,  451 
peculiarities  of,  450 
surgical  anatomy  of,  450 
recurrent,  448 
tonsillar,  375 
transverse  of  basilar,  397 

facial,  378 
transversalis  colli,  398 
tympanic,  from  internal  caro- 
tid, 387 
from  internal  maxillary,  37  9 
ulnar,  413 

branches  of,  415 
peculiarities  of,  414 
relations  of,  in  forearm, 
413 
in  hand,  414 
in  -wrist,  414 
surgical  anatomy  of,  414 
recurrent,  anterior,  415 
posterior,  415 
umbilical  in  £cetus,  699,  701 

how  obliterated,  702 
uterine,  432 
vaginal,  432 

vasa  aberrantia  of  arm,  407 
brevia,  423 
intestini  tenuis,  424 
vertebral,  396 
vesical,  inferior,  432 
middle,  432 
superior,  432 
vestibular,  642 
Vidian,  382 
Arthrodia,  185 
Articular  cartilage,  181 

lamella  of  bone,  181 
Articulations,  181 

acromioclavicular,  208 
ankle,  228 
astragalo-calcanoal,  230 

-scaphoid,  232 
atlo-axoid,  191 
calcaneo-astragaloid,  230 
-cuboid,  230 
-scaphoid,  231 


Articulations — 
carpal,  217 

carpo-metacarpal,  218 
classification  of,  186 
coccygeal,  205 
costo-clavicular,  208 
-sternal,  200 
-transverse,  199 
-vertebral,  197 
elbow,  211 
femoro-tibial,  223 
of  foot,  229 
hand, 217 
hip,  221 
immovable,  184 
knee,  223 
larynx,  705 
lower  extremity,  221 
metacarpal,  209 
metacarpophalangeal,  220 
metatarsal,  233 
metatarso-phalangeal,  233 
mixed,  185 
movable,  185 
movements  of,  187 
occipito-atloid,  194 

-axoid,  195 
of  pelvis,  204 

with  spine,  203 
phalanges,  234 
pubic,  205 
radio-carpal,  216 
-ulnar,  inferior.  214 
middle,  214 
superior,  213 
sacro-coccvgeal,  205 
-iliac,  204 
-sciatic,  204 
-vertebral,  203 
scapuloclavicular,  208 

humeral,  210 
shoulder,  210 

of  spine  with  cranium,  193 
sterno-clavicular,  207 
of  sternum,  202 
tarsal,  229 

tarso-metatarsal,  233 
temporo- maxillary,  195 
tibio-fibular,  inferior,  227 
middle,  227 
superior,  226 
of  the  trunk, 188 
of  tympanic  bones,  635 
of  upper  extremity,  207 
of  vertebral  column,  188 
wrist,  216 
Ary  teno-epiglottidean  folds,707 
Astragalus,  173 
Atlas,  42 

development  of,  49 
Atrabiliary  capsules,  729 
Auditory    canal.      See   Canal, 
auditory, 
meatus,  external,  69 
internal,  70 
Auricle  of  ear,  628 

cartilage  of,  629 
ligaments  of,  629 
structure  of,  62 'J 
of  heart,  691,  696 

appendix  of,  692,  695 


INDEX. 


191 


Auricle  of  ear — 
left,  695 

openings  in,  693,  696 
right,  092 
einus  of,  692,  695 
valves  in,  693,  696 
Auriculo-ventricular  groove  of 
heart,  691 
opening,  left,  696,  697 
right,  093.  094 
Axes  of  the  pelvis,  157 
Axilla,  401 

dissection  of,  293 
Axillary  space,  401 

surgical  anatomy  of,  401 
Axis,  43 

development  of,  49 
cerebro-spinal,  495 
cceliac,  421 
thyroid,  398 
Axis-cylinder  of  nerve  tubes, 
496 

Back,  muscles  of,  first  layer,  209 
second  layer,  272 
third  layer,  273 
fourth  layer,  276 
fifth  layer,  278 
Bartholine,  duct  of,  655 

gland  of,  747 
Base  of  brain,  517 

of  skull,  external  surface,  102 
internal  surface,  100 
Bauhin,  valve  of,  671 
Beale's  researches  on  the  liver, 

680 
Bend  of  elbow,  407 
Berzelius's  analysis  of  bone,  34 
Bicuspid  teeth,  046 
Biliary  ducts.    See  Ducts,  bili- 
ary. 
Bladder,  729 
arteries  of,  732 
base  of,  730 
body  of,  730 
cervix  of,  730 
false  ligaments  of,  731 
female,  relations  of,  748 
fundus  of,  730 
interior  of,  731 
ligaments  of,  730 
lymphatics  of,  492,  732 
neck  of,  730 
nerves  of,  732 
shape,  position,  and  relations 

of,  729 
structure  of,  731 
summit  of,  730 
surgical  anatomy  of,  730 
trigonum  vesicae  of,  732 
true  ligaments  of,  730 
uvula  vesicae,  732 
veins  of,  732 
Blood,  circulation  of,  in  adult, 
691 
in  foetus,  700 
Body  of  a  tooth,  645 

of  a  vertebra,  41 
Bone,  affected  with  rickets,  ana- 
lysis of,  34 
animal  constituent  of,  33 


Bone — 

arteries  of,  37 
apophyses  of,  35 
articular  eminences  of,  35 
canaliculi  of,  37 
cancellous  tissue  of,  33 
chemical  analysis  of,  33 
compact  tissue  of.  33 
development  of,  38 
diploe  of,  35 

earthy  constituent  of,  33 
eminences    and    depressions 

of,  35 
epiphyses  of,  35 
general  properties  of,  33 
growth  of,  40 
Haversian  canals  of,  36 

systems  of,  36 

spaces  of,  37 
inorganic  constituent  of,  33 
lymphatics  of,  38 
marrow  of,  38 
medullary  canal  of,  38 

membrane  of,  38 
microscopic  structure  of,  36 
nerves  of,  38 
number  of,  40 
organic  constituent  of,  33 
ossification  of,  38 

intra-cartilaginous,  39 

intra-membranous,  39 

period  of,  39 
ossific    centres,  number  of, 
39 

mode  of  union  of,  39 
periosteum  of,  38 
spongy  tissue  of,  33 
structure  of,  33 

of  the  extremities  of,  35 

of  the  shaft  of,  35 
surfaces  of,  35 
veins  of,  37 
vessels  of,  37 

ankle,  228 

astragalus,  173 

atlas,  42 

axis,  43 

calcaneum,  170 

carpal,  140 

clavicle,  121 

coccyx,  54 

cranial,  57 

cuboid,  173 

cuneiform  of  carpus,  141 

of  tarsus,  175 
ear,  634 
ethmoid,  77 
facial,  57,  80 
femur,  158 
fibula,  168 
finger,  147 
flat,  34 
foot,  170 
forms  of,  34 
frontal,  63 
hand,  140 
humerus.  129 
hyoid,  111 
ilium,  149 
incus,  034 


Bone — 
inferior  maxillary,  92 

turbinated,  91 
innominate,  149 
irregular,  35 
ischium,  152 
lachrymal,  86 
lesser  lachrymal,  86 
lingual,  111 
long,  35 
magnum,  145 
malar,  87 
malleus.  634 
maxillary,  inferior,  92 

superior,  81 
metacarpal,  146 
metatarsal,  177 
mixed,  35 
nasal,  81 
navicular,  of  carpus,  1^1 

of  tarsus,  175 
occipital,  57 
orbicular,  634 
palate,  88 
parietal,  01 
patella,  104 
pelvic,  155 
phalanges,  of  foot,  178 

of  hand,  147 
pisiform,  143 
pubic,  153 
radius,  138 
ribs,  116 
sacrum,  50 
scaphoid  of  carpus,  141 

of  tarsus,  175 
scapula,  123 
semilunar,  141 
sesamoid,  179 
short,  35 
sphenoid,  72 
sphenoidal  spongy,  76 
spongy,  91 
stapes,  634 
sternum,  112 
superior  maxillary,  81 
supernumerary,  80 
tarsal,  170 
temporal,  67 
tibia,  165 
trapezium,  143 
trapezoid,  143 
triquetral,  80 
turbinated,  inferior,  91 

middle,  78 

superior,  78 
tympanic,  634 
ulna,  133 
unciform,  145 
ungual,  147 
vertebra  dentata,  43 

prominens,  44 
vertebrae,  cervical,  41 

coccygeal,  54 

dorsal,  44 

lumbar,  47 

sacral,  50 
vomer,  92 
Wormian,  80 
Bostock's  analysis  of  a  rickety 

bone,  34 


792 


INDEX. 


Bowman  on  structure  of  kidney, 

725 
Brachia  of  optic  lobes,  529 
Brain,  507.    See  also  Cerebrum. 

arachnoid  of,  508 

base  of,  517 

dura  mater  of,  507 

interior  of,  519 

lateral  ventricles  of,  522 

lobe  of,  anterior,  517 
middle  of,  517 
posterior  of,  517 

membranes  of,  507 

pia  mater  of,  509 

subdivision  into  parts,  507 

under  surface  of,  517 

upper  surface  of,  517 

weight  of,  507. 
Breasts,  756 
Brim  of  pelvis,  155 
Bronchi,  712 

mode  of  subdivision  in  lung, 
719 

septum  of,  712 

structure  of,  in   lobules    of 
lung,  719 
Brunner's  glands,  669 
Bubonocele,  765 
Bulb,  artery  of,  434,  781 

of  corpus  cavernosum,  434, 
738 

of  corpus  spongiosum,  434, 
738 

olfactory,  535 
Bulbi  vestibuli,  747 
Bulbous  portion  of  urethra,  733 
Bulbs  of  the  fornix,  519 
Bursa?  mucosae,  184 
Bursal  synovial  membranes,  184 

Cecum,  670 

Calamus  scriptorius,  512 
Calcaneum,  170 
Calyces  of  kidney,  726 
Canal  or  Canals — 
accessory  palatine,  88 
alimentary,  643 
anterior  dental,  83 
palatine,  85,  102 
for  Arnold's  nerve,  71 
auditory,  631 

cartilaginous    portion    of. 

631 
external,  69,  631 
internal,  70,  642 
osseous  portion  of,  631 
carotid,  70 

central  of  modiolus,  639 
for  chorda  tympani,  68,  631 
of  cochlea,  638 
crural,  771 
dental,  anterior,  83 
inferior,  94 
posterior,  82 
ethmoidal,  anterior,  66,  78 

posterior,  66,  78 
femoral,  771 
Haversian,  of  bene,  36 
incisive,  102 
infraorbital,  83 
inguinal,  762 


Canal  or  Canals — 

for  Jacobson's  nerve,  71 

lachyrmal,  83,  628 

malar,  88 

nasal,  81 

naso-palatine,  82 

of  Nuck,  745 

palatine,  accessory,  88 
anterior,  90 
posterior,  88 

of  Petit,  624 

portal,  680 

pterygoid,  75 

pterygopalatine,  74 

sacral,  53 

spermatic,  762 

of  spinal  cord,  506 

spiral,  of  cochlea,  639 
of  modiolus,  639 

semicircular,      See   Semicir- 
cular canals. 

for  tensor  tympani,  634 

vertebral,  57 

Vidian,  75 

of  Wirsung,  683 
Canaliculi  of  bone,  37 

of  eyelids,  628 
Canalis  spiralis  modioli,  640 
Cancellous  tissue  of  bone,  33 
Canthi  of  eyelids,  625 
Capillaries,  360 

diameter  of,  360 
form  of,  360 
number  of,  361 
structure  of,  361 

pulmonary,  720 
Capitula  laryngis,  705 
Capsule,  atrabiliary,  728 

of  Glisson,  678 

of  the  lens,  623 
in  foetus,  623 

of  Malpighian  bodies  of  kid- 
ney, 726 

supra-renal,  727 
Caput  cornu  posterius,  505 

gallinaginis,  733 
Carpus,  140 

articulations  of,  217 

development  of,  148 
Cartilage  or  Cartilages — 

articular,  181,  182 

arytenoid,  704 

of  auricle,  629 

of  bronchi,  720 

cells  of,  181 

circumferential,  183 

connecting,  183 

costal,  120 

cricoid,  704 

cuneiform,  705 

of  ear,  629 

ensiform,  114 

of  epiglottis,  705 

fibro-,  183.     See  Fibro-carti- 
lage. 

intcrarticular,  183 

intercellular  substance  of,  182 

interosseous,  183 

of  larynx,  703 
structure  of,  705 

of  the  nose,  612 


Cartilage  or  Cartilages — 

of  the  pinna,  629 

of  Santorini,  705 

palpebral,  625 

permanent,  181 

reticular,  182 

semilunar  of  knee,  225 

of  septum  of  nose,  612 

spongy,  182 

stratiform,  183 

structure  of,  181 

tarsal,  625 

temporary,  38,  181 

thyroid,  703 

of  trachea,  712 

of  Wrisberg,  705 

xiphoid,  114 

yellow,  182 
Cartilagines  minores   of  nose, 

612 
Cartilago  triticea,  706 
Caruncle,  lachrymal,  626 
Caruncula  lacrymalis,  626 

mammillaris,  536 
Caruncula?  myrtiformes,  747 
Casserian  ganglion,  546 
Cauda  equina,  502,  584 
Cava,  vena.     iSee  Vena  cava. 
Cavernous  body,  artery  of,  434, 

738 
Cavities  of  reserve  of  the  teeth, 

651 
Cavity,  cotyloid.  153 

digital  of  fifth  ventricle,  523 
of  lateral  ventricle,  523 

glenoid,  127 

of  pelvis,  156 

sigmoid,  135,  139 
of  radius,  139 
of  ulna,  135 
Cells  of  bone,  37 

ethmoidal,  78 

hepatic,  679,  680 

mastoid,  69 
Cement  of  teeth,  649 

formation  of,  651  ' 
Centres  of  ossification,  39 
Centrum  ovale  majus,  521 

minus,  520 
Cerebelli  incisura  anterior.  531 

posterior,  531 
Cerebellum,  530 

corpus  dentatum  of,  533 

ganglion  of,  533 

hemispheres  of,  530 

lamina?  of,  531,  533 

lobes  of,  531 

lobulus  centralis,  530 

median  lobe  of,  529 

peduncles  of,  529,  533,  534 

structure  of,  533 

under  surface  of,  531 

upper  surface  of,  530 

valley  of,  531 

ventricle  of,  533 

weight  of,  530 
Cerebro-spinal  axis,  495 

fluid,  501,  509 

nerves,  498 
Cerebrum,  515 

base  of,  517 


INDEX. 


793 


Cerebrum — 
commissures  of,  528 
convolutions  of,  515 
cortical  substance  of,  515 
crura  of,  520 
fibres  of,  529 
fissure  of  Sylvius,  518 

longitudinal,  517 
general  arrangement  of  its 

parts,  520 
gray  matter  of,  515 
hemispheres  of,  515 
interior  of,  520 
labia  of,  521 
lobes  of,  517 
peduncles  of,  519 
structure  of,  529 
sulci,  515,  516 

tmperior  ganglia  of,  523,  527 
nnder  surface  of,  517 
upper  surface  of,  515 
ventricles  of,  522 
Cervix  cornu  posterius,  505 

uteri,  750 
Chambers  of  the  eye,  622 
Cheek,  muscles  of,  248 
Cheeks,  644 

structure  of,  644 
Chemical  analysis  of  bone,  33 
of  cerebro-spinal  fluid,  509 
of  dentine  or  ivory,  648 
of  enamel,  648 
of  nervous  substance,  495 
of  synovia,  184 
of  thymus  gland,  723 
of  thyroid  gland,  722 
Chest,  muscles  of  front  of,  294 

muscles  of  side  of,  298 
Chiasma  or  optic  commissure, 

537 
Chorda  tympani,  542,  637 
Chordae  tendineae  of  left  ventri- 
cle 697 
of  right,  694,  695 
vocales,  707,  708 
Willisii,  463 
Choroid  coat  of  eye,  617 
structure  of,  618 
plexus    of   fourth  ventricle, 
532 
of  lateral  ventricle,  523 
of  third  ventricle,  526 
Chyli  receptaculum,  481 
Cilia  or  evelashes,  626 
Circle  of  Willis,  397 
Circulation  of  blood  in  adults, 
358,  691 
in  foetus,  699-702 
pulmonic,  358 
systemic,  358 
Circulus  tonsillaris,  557 
Circumduction,  187 
Cistern  of  Pecquet,  683 
Clarke,  Lockhart,  researches  on 

the  spinal  cord,  505,  506 
Clavicle,  121 
articulations  of,  123 
attachments  of  muscles  to, 

123 
development  of,  123 
fracture  of,  320 


Clavicle — 

of  acromial  end  of,  321 
of  sternal  end  of,  321 
peculiarities  of,  123 
structure  of,  123 
Clitoris,  747 
fraenum  of,  747 
lymphatics  of,  491 
muscles  of,  747,  780 
prepuce  of,  747 
structure  of,  747 
Coccyx,  54 

articulations  of,  55 
attachment  of  muscles  to,  55 
cornua  of,  55 
development  of,  55 
Cochlea,  639 

aqueduct  of,  70,  640 
arteries  of,  642 
central  axis  of,  639 
cupola  of,  639 
denticulate  lamina  of,  640 
hamular  process  of,  640 
infundibulum  of,  639 
lamina  spiralis  of,  639 
membranous  zone  of,  639 
modiolus  of,  639 
nerves  of,  642 
osseous  zone  of,  640 
scala  tympani  of,  640 

vestibuli  of,  640 
scalae  of,  640 
spiral  canal  of,  639 
veins  of,  642 
Collateral  circulation  after  liga- 
tion of  brachial,  409 
common  carotid,  371 
femoral,  441 
iliac,  common,  430 
external,  437 
internal,  431 
subclavian,  395 
Colles's  fracture,  324 
Colliculus  bulbi  urethras,  737 
Colon,  672 
ascending,  672 
descending,  672 
sigmoid  flexure  of,  672 
transverse,  672 
Columella  cochleae,  639 
Column,  posterior  vesicular  of 

spinal  cord,  505 
Columnae  carneae  of  left  ventri- 
cle, 697 
of  right  ventricle,  695 
papillares,  695,  697 
Columnar  layer  of  retina,  621 
Columns  of  abdominal  ring,  760 
of  medulla  oblongata,  511 
of  rectum,  674 
of  spinal  cord,  504 
of  vagina,  749 
Commissura  brevis  of  cerebel- 
lum, 531 
simplex  of  cerebellum,  531 
Commissure  of  flocculus,  531 

optic,  519 
Commissures  of  brain,  anterior, 
528 
middle,  528 
posterior,  528 


Commissures  of  brain — 
soft,  528 
of  spinal  cord,  gray,  504 
white,  504 
Compact  tissue  of  bone,  33 
Conarium,  528 
Concha,  629 

Condyles  of  bones.    See  Bones. 
Congenital  fissures  in  cranium, 

80 
Coni  vasculosi,  741 
Conjoined   tendon   of  internr.l 
oblique  and  transversals, 
284,  761 
Conjunctiva,  626 

palpebral  folds  of,  627 
Conjunctival  epithelium,  616 
Conus  arteriosus,  694 
Convolution  of  corpus  callosum, 
517 
of  longitudinal  fissure,  517 
supra-orbital,  517 
Convolutions  of  cerebrum,  cor- 
tical substance  of,  515 
structure  of,  515 
white  matter  of,  515 
Cord,  spermatic.     See  Sperm- 
atic cord, 
spinal.     See  Spinal  Cord. 
Cordiform  tendon,  291 
Cords,  vocal.    See  Yocal  cords. 
Corium  of  skin,  603 
Cornea,  616 
arteries  and  nerves  of,  617 
elastic  laminae  of,  616 
proper  substance  of,  616 
structure  of,  616 
Cornicula  laryngis,  705 
Cornu  Ammonis,  524 
Cornua  of  the  coccyx,  55 
of  hyoid  bone,  112 
of  sacrum,  51 
of  thyroid  cartilage,  704 
Corona  glandis,  736 
Corpora  albicantia,  519 
Arantii,  695,  697 
cavernosa  clitoridis,  747 
penis,  737 
crura  of,  737 
structure  of,  737 
geniculata,  529 
lutca.     See  Corpus  luteum. 
olivaria,  511 
pyramidalia,  511 
quadrigemina,  529 
restiformia,511 
striata,  523 
veins  of,  463 
Corpus  Arantii,  695,  697 
callosum,  517,  518,  521 
convolution  of,  517 
genu  of,  521 
peduncles  of,  518,  522 
rostrum  of,  521 
ventricle  of,  521 
cavernosura.      See    Corpora 

cavernosa, 
colliculi  bulbi,  737 
dentatum  of  cerebellum,  533 

of  olivary  body,  513 
fimbriatum,  524,  525,  526 


794 


INDEX. 


Corpus — 
geniculaturn  externum,  529 

internum,  529 
Highmorianum,  740 
luteum,  754 

structure  of,  755 
false,  755 
true,  755 
spongiosum,  737 
arteries  of,  738 
structure  of,  738 
>See  also  Corpora. 
Corpuscles,  Malpighian,  of  kid- 
ney, 726 
of  spleen,  68G 
C  ortical  substance  of  brain,  495 
of  cerebral  convolutions,  515 
of  kidney,  725 

of  supra-renal  capsules,  728 
of  teeth,  649 
Costal  cartilages,  120 
Coverings  of  hernia.     See  Her- 
nia, 
of  testis.     See  Testis. 
Cowper's  glands,  736,  781 
Cranial  bones,  57 
articulations  of,  97.  • 
See  also  Bones,  cranial. 
Cranial  nerves,  535 
classification  of,  535 
nerves  of  special  sense,  535 
of    common     sensation, 

545 
of  motion,  537 
mixed,  560 
first  pair,  535 
second,  536 
third,  537 
fourth,  538 
fifth,  545 
sixth,  539 
seventh,  soft  portion,  537 

hard  portion,  540 
eighth,     glosso- pharyngeal, 
555 
spinal  accessory,  560 
vagus,  557 
ninth,  544 
Cranium,  articulations  of,  79 
development  of  bones  of,  57 
See  also  Skull, 
('rest,  frontal,  65 
of  ilium,  150 
nasal,  81 
occipital,  58 

internal,  60 
of  pubes,  153 
of  tibia,  166 
turbinated,  of  palate,  88 
of  superior  maxillary,  85 
Cricoid  cartilage,  704 
Crista  galli,  77 
ilii,  150 
pubis,  153 
Crown  of  tooth,  645 
Crura  cerebelli,  533 
cerebri,  519 
of  clitoris,  747 
of  corpora  cavernosa,  737 
of  diaphragm,  290 
of  fornix,  526 


Crural  canal.     See  Canal,  cru- 
ral, 
ring.     See  Ring,  crural. 

Crusta  petrosa  of  teeth,  648 

Crypts  of  Lieberkiihn,  669 

Crystalline    lens.      See    Lens, 
crystalline. 

Cuboid  bone,  173 

Cuneiform  bone  of  foot,  175 
of  hand,  141 
external,  176 
internal,  175 
middle,  176 

Cupola  of  cochlea,  639 

Curling  on  the  development  of 
the  testes,  745 

Curvatures  of  the  spine,  55 

Cutaneous  nerves.    Sec  Nerves, 
cutaneous. 

Cuticle,  604 

Cutis  vera,  603 

Dartos,  739 

Decussation   of   optic   nerves, 
537 

of  pyramids,  511 
Deciduous  teeth,  645 
Dens  sapientise,  647 
Dentine,  648 

chemical  composition  of,  648 

formation  of,  650 
Depression  of  bones,  35 

coronoid,  132 

for  Pacchionian  bodies,  62 
Derma  or  true  skin,  603 
Descent  of  testicle,  745 
Development  of  atlas,  49 

axis,  49 

bone,  38 

carpus,  148 

clavicle,  122 

coccyx,  54 

cranium,  79 

ethmoid,  78 

femur,  163 

fibula,  170 

foot,  179 

frontal  bone,  66 

hand,  148 

hurnerus,  132 

hyoid  bone,  112 

inferior  turbinated  bone,  91 

lachrymal  bone,  86 

lower  jaw,  95 

lumbar  vertebra?,  49 

malar  bone,  88 

metacarpus,  148 

metatarsus,  179 

nasal  bone,  81 

occipital  bone,  61 

os  innominatum,  154 

palate  bone,  90 

parietal  bone,  63 

patella,  164 

permanent  teeth,  651 

phalanges  of  foot,  179 
of  hand,  148 

radius,  140 

ribs,  118 

sacrum,  54 

scapula,  127 


Development — 

seventh  cervical  vertebra,  49 

sphenoid,  76 

sternum,  114 

superior  maxillary  bone,  85 

tarsus,  178 

teeth,  649 

temporal  bone,  71 

temporary  teeth,  649 

tibia,  168 

ulna,  138 

vertebra;,  48 

vomer,  92 

Wormian  bones,  80 
Diameters  of  pelvis,  156 
Diaphragm,  289 

aortic  opening  of,  291 

lymphatics  of,  494 

serous  membranes  of,  291 
Diaphysis,  39 
Diarthrosis,  185 

rotatorius,  186 
Digestion,  organs  of,  643 
Diploe,  35 

veins  of,  461 
Direct    inguinal    hernia.      See 

Hernia. 
Discharge  of  ovum,  754 
Discus  proligerus,  754 
Dissection  of  muscles,  regions, 
hernia,  &c.     See  Mus«l<?a, 
Eegions,  Hernia,  &c. 
Dorsum  of  penis,  736 

of  scapula,  118 
Duct  or  Ducts — 

aberrant  of  testis,  742 

of  Bartholine,  655 

biliarv.  682 
glands  of,  682 
structure  of,  682 

common  choledoch,  688 

of  Cowper's  gland,  7~6 

cystic,  682 
valve  of,  682 

ejaculatory,  744 

galactophorous,  756 

hepatic,  680.  6.^1 

of  kidney.  726 

lactiferous,  756 

of  liver,  6v  0 

lymphatic,  right,  484 

nasal,  628 

of  pancreas,  683 

parotid,  654 

seminal,  744 

Steno's,  654 

thoracic,  483 

Whartonian,  655 
Ductless  glands.     See  Glands, 

ductless. 
Ductus  arteriosus,  699,  701 
how  obliterated  in  foetus. 
702 

communis  choledochus,  682 

pancreaticus  minor,  684 

lliviniani.  655 

venosus,  699,  701 
how  obliterated,  702 
Duodenum,  667 

vessels  and  nerves  of.  668 
Dura  mater  of  brain,  507 


INDEX. 


795 


Dura  mater — 

arteries  of,  507 
nerves  of,  507 
processes  of,  508 
structure  of,  507 
veins  of,  507 
of  cord,  500 
peculiarities  of,  501 

Ear,  628 

arteries  of,  631,  636,  642 

auditory  canal,  631 

auricle  of,  628 

cochlea,  639 

external,  628 

helix  of,  629 

internal,  637 

labyrinth,  637 
membranous,  640 

middle,  632 

muscles  of,  241,  630,  636 
of  auricle,  241,  630 
of  tympanum,  636 

ossicula  of,  634 

pinna,  628 

semicircular  canals,  638 

tympanum,    632.      See    also 
Tympanum. 

vestibule,  637 
Earthy    constituent    of   bone, 

33 
Ecker  on  supra-renal  capsules, 

728 
Eighth  pair  of  nerves,  555 
Ejaculatory  ducts,  744 

structure  of,  744 
Elbow,  bend  of,  407 

joint,  211 

vessels  and  nerves  of,  212, 
213 
Eminence  of  aquaxluctus  Fal- 
lopii,  633 

of  bones,  35 

canine,  82 

frontal,  64 

ilio-pectineal,  153 

jugular,  59 

nasal,  67 

parietal,  61 
Eminentia  articularis,  67 

collateralis,  523,  525 
Enamel  of  teeth,  649 

chemical  composition  of,  649 

formation  of,  651 

membrane,  651 

organ,  651 

rods,  649 
Enarthrosis,  185 
Endocardium,  697 
Endolymph,  642 
Ensiform  appendix,  114 
Epidermis,  604 

development  of,  664 

growth  of,  064 

structure  of,  664 
Epididymis,  739 
Epiglottic  glands,  711 
Epiglottis,  705 

muscles  of,  710 
Epiphyses,  35 

separation  of,  40 


Epithelium  of  skin,  tongue,  &c. 

See  Skin,  Tongue,  &c. 
Erectile  tissue,  structure  of,  738 
of  penis,  738 
of  vulva,  747 
Eruption  of  the  teeth,  651 
Ethmoid  bone,  77 
articulations  of,  78 
cribriform  plate  of,  77 
development  of,  78 
lateral  masses  of,  78 
perpendicular  plate  of,  77 
os  planum  of,  78 
unciform  process  of,  78 
Eustachian  tube,  634 

tympanic  orifice  of,  634 
valve,  693 

in  foetal  heart.  699 
Eye,  614 

appendages  of,  625 
arteries  of,  624,  625 
chambers  of,  622 
ciliary  ligament,  620 
muscle,  620 
processes,  618 
humors  of,  622 
aqueous,  622 
crystalline  lens,  623 
vitreous,  623 
membrana  pupillaris,  620 
membranes  of,  615 
choroid,  618 
conjunctiva,  626 
cornea,  616 
hyaloid,  623 
iris,  619 
Jacob's,  621 
retina,  620 
sclerotic,  615 
pupil  of,  619 
tunics  of,  615 
uvea  of,  619 
vessels  of  globe  of,  624 
Eyeball,  614 
„  muscles  of,  243 
nerves  of,  625 
tunics  of,  615 
veins  of,  625 
Eyebrows,  625 
Eyelashes,  626 
Eyelids,  625 

cartilages  of,  625 
Meibomian  glands  of,  625 
muscles  of,  242.  625 
structure  of,  625 
tarsal  ligament  of,  626 
Eye-teeth,  646 

Face,  arteries  of,  374 

bones  of,  57,  80 

lymphatics  of,  484 

muscles  of.  242 

nerves  of,  542 

veins  of,  458 
Facial  bones,  57,  80 
Falciform  process  of  fascia  lata, 

769 
Fallopian  tubes,  752 

fimbriated  extremity  of,  752 

lymphatics  of,  492 

nerves  of,  755 


Fallopian  tubes — 
structure  of,  752 
vessels  of,  755 
Falx  cerebelli,  508 

cerebri,  508 
Fangs  of  teeth,  645 
Fascia  or  Fasciae,  235,  236 
anal,  786 
aponeurotic,  237 
of  arm,  302 
cervical,  deep,  254 

superficial,  253 
costo-coracoid,  296 
cremasteric,  740,  762 
cribriform,  768 
deep,  237 
dentata,  525 
dorsal,  of  foot,  350 
of  face,  238 
fibro-areolar,  237 
of  foot,  349 
of  forearm,  305 
of  hand,  316 
of  head,  238 
iliac,  325 

infundibuliform,  763 
intercolumnar,  283,  760 
intercostal,  288 
intermuscular,  of  arm,  302 

of  foot,  349 

of  thigh,  328 
ischio-rectal,  775,  786 
lata,  328,  768 

falciform  process  of,  769 

iliac  portion  of,  768 

pubic  portion  of,  769 
of  leg,  340 
lumbar,  285 
lumborum,  285 
of  mamma,  294 
of  neck,  253 
obturator,  786 
palmar,  316 
pelvic,  785 

obturator  layer,  786 

parietal  layer,  786 

visceral  layer,  786 
perineal,  deep,  780 

superficial,  777 
plantar,  349 
propria,  740 
recto-vesical,  786 
spermatic,  760 
superficial,  237 

of  epicranial  region,  240 

of  inguinal  region,  758 

of  ischio-rectal  region,  775 

perineal,  777 

of  thigh,  327 
'    of  thoracic  region,  294, 298 

of   upper  extremity,   294. 
298 
temporal,  250 
of  thigh,  deep,  328 

superficial,  327 
of  thorax,  293,  294 
transversalis,  763 
Fasciculi  graciles.  511 

teretes,  514,  532 
Fasciculis  unciformis,  518 
Fauces,  isthmus  of,  653 


796 


INDEX. 


Female  organs   of  generation, 
746 

bulbi  vestibuli,  747 

carunculae  myrtiformes,  747 

clitoris,  747 

fossa  navicularis,  747 

fraenulum  pudendi,  747 

glands  of  Bartholine,  747 

hymen,  747 

labia  majora,  746 
minora,  747 

nympliae,  747 

praeputium  clitoridis,  747 

uterus,  750 

vagina,  749 

vestibule,  747 
Femoral  hernia.    See  Hernia, 

femoral. 
Femur,  158 

articulations  of,  163 

attachment  of  muscles  to,  163 

development  of,  163 

fracture  of,  above  condyles, 
355 
below  trochanters,  355 
of  neck  of,  355 

structure  of,  162 
Fenestra  ovalis,  633,  639 

rotunda,  633,  639 
Ferrein,  pyramids  of,  726 

tubes  of,  726 
Fibrae  arciformes,  511,  513 

transversa?,  532 
Fibrin  of  muscle,  235 
Fibro-cartilage,  183 

acromio-clavicular,  209 

circumferential,  183 

connecting,  183 

interarticular,  183.     See  In- 
terarticular. 

intercoccygean,  205 

interosseous,  183 

intervertebral,  189 

of  knee,  225 

of  lower  jaw,  197 

pubic,  206 

radio-ulnar,  214 

sacro-coccygeal,  205 

semilunar,  225 

sterno-clavicular,  208 

stratiform,  183 

triangular,  214 
Fibrous  nervous  matter,  495 
Fibula,  168 

articulations  of,  170 

attachment    of    muscles   to, 
170 

development  of,  170 

fracture  of,  with  dislocation 
of  the  tibia,  357 
Fibrous  rings  of  heart,  697 
Fifth  pair  of  nerves,  545 

ventricle  of  brain,  525 
Fimbriae  of  Fallopian  tube,  752 
Fissura  palpebrarum,  625 
Fissure,  auricular,  71 

of  cerebellum,  horizontal.  531 

of  cranial  bones,  congenital, 

80 
of  ductus  venosus,  677 

for  gall-bladder,  677 


Fissure — ■ 

Glaserian,  68,  632 
of  helix,  629 
of  liver,  677 

longitudinal,     of    cerebrum, 
515,  517 
of  liver,  676 
of  lung,  718 
maxillary,  83 
of  medulla  oblongata,  511 
palpebral,  625 
portal,  677 
posterior  lateral,  503 

median,  503 
pterygo-maxillary,  106 
spheno-maxillary,  106 
sphenoidal,  75,  101 
of  spinal  cord,  anterior  late- 
ral, 503 
median,  503 
of  Sylvius,  518 
of  tragus,  629 
transverse,  of  cerebrum,  525 

of  liver,  677 
umbilical,  of  liver,  677 
for  vena  cava,  677 
Floating  ribs,  116 
Flocculus,  532 

Foetus,  circulation  in,  699,  700 
Eustachian  valve  in,  693 
foramen  ovale  in,  693 
liver  of,  distribution  of   its 

vessels,  699 
ovaries  in,  755 

peculiarities  of  vascular  sys- 
tem in,  699 
relics  in  heart  of,  693 
Folds,   aryteno  -  epiglottidean, 
705, 710 
recto-uterine,  750 
recto-vesical,  730 
vesico-uterine,  750 
Follicle  of  hair,  606 
Follicles,  dental,  650 
gastric,  666 
sebaceous,  607 
Follicular  stage  of  development 

of  teeth,  650 
Fontanelles,  60,  62,  79 
anterior,  62,  79 
posterior,  60,  62,  79 
Foot,  arteries  of,  448,  452 
bones  of,  170 
development  of,  179 
dorsal  region  of,  muscles  of, 

350 
fascia  of,  349 

ligaments  of,  228,  229,  230 
nerves  of,  589 
plantar  region  of,  muscles  of, 

350 
vessels  of,  448,  452,  473 
veins  of,  473 
Foramen.     See  also  Foramina, 
caecum  of  frontal  bone,  69, 
100 
of  medulla  oblongata,  511 
of  tongue,  609 
carotid,  70 
condyloid,  59 
inferior  dental,  98 


Foramen — 

incisive,  102 

infra-orbital,  83 

intervertebral,  57 
jugular,  101 

lacerum  anterius,  101 
medium,  101 
posterius,  101 

magnum,  58,  60 

mastoid,  69 

mental,  93 

of  Monro,  523,  526 

obturator,  154 

optic,  73,  100 

ovale  of  heart,  699 
of  sphenoid,  74,  101 

palatine,  anterior,  85,  102 
posterior,  88 

parietal,  61 

pterygoid,  75 

pterygopalatine,  74 

rotundum,  74,  101 

sacro-sciatic,  great,  152, 154, 
205 
small,  152,  154,  205 

of  Sbmmering,  621 

spheno-palatine,  110 

spinosum,  74,  101 

sternal,  114 

stylo-mastoid,  71 

supra-orbital,  64 

thyroid,  154 

vertebral,  42 

Vesalii,  74,  101 

of  Winslow,  661 
Foramina  of  diaphragm,  291 

external  orbitar,  74 

malar,  87 

olfactory,  77 

sacral,  51 

Thebesii,  479,  693 
Forearm,  arteries  of,  410 

bones  of,  133 

fascia  of,  305 

lymphatics  of,  488 

muscles  of,  305 

nerves  of,  569 

veins  of,  466 

vessels  of,  410,  466,  488 
Foreskin.  736 
Fornix,  524,  525 

body  of,  526 

bulb  of,  519 

crura  of,  526 
Fossa  of  antihelix,  629 

canine,  82 

cerebral,  100 

condyloid,  59 

cystidis  fellege,  677 

digastric,  59 

digital,  159 

glenoid,  68 

of  helix,  629 

iliac,  150 

infra-spinous,  124 

incisive,  82,  92 

innominata,  629 

ischio-rectal,  776 

jugular,  104 

lachrymal,  65 

myrtiform,  82 


INDEX. 


797 


rossa — 
navicular  of  urethra,  733 

of  vulva,  747 
occipital,  inferior,  60 
ovalis,  693 

palatine,  anterior,  85, 102 
pituitary,  73 
pterygoid  of  sphenoid,  75 

of  lower  jaw,  95 
scaphoid,  75 
ecaphoidea,  629 
spheno-maxillary,  106 
of  skull,  anterior,  100 
middle,  100 
posterior,  101 
sublingual,  93 
submaxillary,  94 
subscapular,  123 
supra-spinous,  124 
temporal,  105 
trochanteric,  159 
zygomatic,  106 
Fossae,  cranial,  100 

nasal.    See  Nasal  fossae. 
Fourchette,  747 
Fourth  nerve,  538 

ventricle,  532 
Fovea  centralis  retinae,  621 
hemispherica,  638 
semi-elliptica,  638 
Fracture  of  acromion  process, 
321 
clavicle,  320 

acromial  end  of,  321 
centre  of,  320 
sternal  end  of,  321 
Colles's,  323 
coracoid  process,  321 
coronoid  process  of  ulna,  322 
femur  above  condyles,  355 
belbw  trochanters,  355 
neck  of,  355 
fibula,  with  dislocation  of  ti- 
bia, 357 
humerus,  321,  322 
anatomical  neck,  321 
shaft  of,  322 
surgical  neck,  321 
olecranon  process,  322 
patella,  356 
Pott's,  357 
radius,  323 

lower  end  of,  323 
neck  of,  323 
shaft  of,  323 
and  ulna,  323 
tibia,  shaft  of,  356 
ulna,  323 
shaft  of,  323 
Fraena  of  ileo-ccecal  valve,  671 
Fraenulum  cerebri,  529 
pudendi,  747 
of  Vieussens's  valve,  529 
Fraenum  clitoridis,  747 
labii  inferioris,  643 

superioris,  643 
praeputii,  736 
Frontal  bone,  63 

articulations  of,  66 
attachment  of  muscles  to, 
66 


Frontal  bone — 

development  of,  66 
structure  of,  66 
Fundus  of  bladder,  731 

of  uterus,  750 
Funiculi  of  nerve,  498 
Funiculus,  498 

Furrow,    auriculo- ventricular, 
691 
interventricular,  691 
Furrowed  band  of  cerebellum, 
531 

Galactophorous  ducts,  756 
Gall-bladder,  681 

duct  of,  681 

fissure  for,  677 

structure  of,  681 

valve  of,  681 
Ganglia,  497.     See  Ganglion. 

cardiac,  596 

cephalic,  551,  594 

of  fifth  nerve,  551 

lumbar,  600 

lymphatic,  482 

mesenteric,  599 

renal,  598 

sacral,  600 

semilunar  of  abdomen,  598 

solar,  598 

of  spinal  nerves,  562 

of  sympathetic  nerve,  592 
branches  from,  592 

thoracic,  597 
Ganglion,  Arnold's,  554,  594 

of  Andersch,  555 

carotid,  595 

Casserian,  546 

cervical,  inferior,  595 
middle,  594 
superior,  594 

ciliary,  551 

on  circumflex  nerve,  569 

diaphragmatic,  598 

on  facial  nerve,  541 

glossopharyngeal,  555 

impar,  592,  600 

inferior  cervical,  595 

intercarotid,  595 

on  interosseous  nerve,  pos- 
terior, 576 

jugular,  555,  557 

lenticular,  551 

lingual,  594 

Meckel's,  552,  594 

middle  cervical,  595 

ophthalmic,  551,  594 

otic,  554,  594 

petrous,  556 

pharyngeal,  557,  594 

pneumogastric,  557,  558 

of  portio  dura,  541 

of  Ribes,  592 

of  root  of  vagus,  558 

semilunar  of  fifth  nerve,  546 
of  sympathetic.  598 

spheno-palatine,  552.  594 

submaxillary,  555,  &94 

superior  cervical,  594 

supra-renal,  598 

temporal,  594 

4 


Ganglion — 
thyroid,  595 

of  trunk  of  vagus,  557,  558 
of  Wrisberg,  597 
Ganglion  corpuscles,  497 
Generative  organs,  female,  747. 

See  Female  organs  of  gene- 
ration, 
male,  735.    See  Male  organs. 
Genu  of  corpus  callosum,  521 
Germinal  spot  of  ovum,  754 

vesicle  of  ovum,  754 
Gimbernat's  ligament,  281,  760, 

770 
Ginglymus,  186 
Gladiolus,  114 
Gland  or  Glands — 
absorbent,  482 
accessory  of  parotid,  654 
aggregate,  669 
agminate,  669 
arytenoid,  711 
of  Bartholine,  747 
of  biliary  ducts,  681 
Brunner's,  669,  781 
buccal,  644 
ceruminous,  632 
Cowper's,  736 
duodenal,  669 
ductless,  684,  721,  722,  727 

spleen,  684 

supra-renal,  727 

thymus,  722 

thyroid,  721 
epiglottic,  711 
gastric,  666 
of  Havers,  184 
kidney,  724 
labial,  643 
lachrymal,  628 
of  larynx,  711 
lingual,  610 
of  Littre,  733 
liver,  675 
lumbar,  435 
lymphatic,  482 

anterior  tibiaf,  488 

auricular,  484 

axillary,  487 

bronchial,  494 

buccal,  484 

cervical,  485 

conglobate,  482 

gluteal,  489 

iliac,  490 

inguinal,  488 

intercostal,  493 

internal  mammary,  4C3 

ischiatic,  489 

of  large  intestine,  493 

lumbar,  490 

mediastinal,  493 

mesenteric,  493 

of  neck,  485 

oesophageal,  494 

occipital,  484 

parotid,  485 

popliteal,  489 

sacral,  490 

of  spleen,  493 

of  stomach,  492 


798 


INDEX. 


Gland  or  Glands — 
submaxillary,  484 
thoracic,  493 
zygomatic,  484 

mammary,  756 

Meibomian,  626 

molar,  644 

mucilaginous  of  Havers,  184 

odoriferoe,  736 

oesophageal,  658 

of  Pacchioni,  507 

palatine,  652 

pancreas,  683 

parotid.     See  Parotid  gland. 

peptic,  666 

Peyer's,  670 

pharyngeal,  656 

pineal,  528 

pituitary,  519 

prostate.  See  Prostate  gland. 

salivary,  653 

sebaceous,  607 

solitary,  669,  675 

sublingual.      See  Sublingual 
gland. 

submaxillary.     See  Submax- 
illary gland. 

sudoriferous,  607 

supra-renal,  727 

sweat,  607 

thymus,  722 

thyroid.     See  Thyroid  gland. 

of  tongue,  610 

tracheal,  713 

of  Tyson,  736 

uterine,  754 

of  vulva,  747 
Glandulse  odorifera;,  736 

Pacchioni,  463,  507 

solitariae,  669 

Tysonii,  736 
Glans  clitoridis,  747 

penis,  736 
Gliding  movement,  187 
Glisson's  capsule,  662,  678 
Globus   major    of    epididymis, 
739 

minor  of  epididymis,  739 
Glottis,  707 

rinia  of,  707 
Gomphosis,  185 
Graafian  vesicles,  753,  754 

membrana  granulosa  of,  754 

ovicapsule  of,  754 

structure  of,  753 
Granules,  seminal,  744 
Gray  matter  of  cerebellum,  533 

of  cerebrum,  495,  515 
chemical  analysis  of,  495 

of  fourth  ventricle,  533 

of  medulla  oblongata,  513 

of  spinal  cord,  505 

of  third  ventricle,  528 
Greater  wings  of  sphenoid,  74 
Groin,  758 

cribriform  fascia  of,  760 

cutaneous  vessels  and  nerves 
of,  758 

region  of,  758 

superficial  fascia  of,  758 

surgical  anatomy  of,  758 


Groove,    auriculo  -  ventricular, 
691 

bicipital,  129 

cavernous,  73,  100 

dental,  649 

infra-orbital,  83 

lachrymal,  84 

mylo-hyoid,  94 

nasal,  81 

occipital,  69 

optic,  73 

subclavian,  118 
Grooves  in  the  radius,  140 

ventricular,  691 
Growth  of  bone,  40 
Gubernaculum  testis,  745 
Gums,  644 
Gyri  operti,  518 
Gyrus  fornicatus,  517,  521 

Hairs,  606 

follicles  of,  606 
structure  of,  606 

medulla  of,  606 

root  of,  606 

shaft  of,  606 

sheath  of,  606 
Ham,  region  of  the,  443 
Hamstring    tendons,    surgical 

anatomy  of,  340 
Hand,  arteries  of,  411,  414 

bones  of,  140 

development  of,  148 

fascia  of,  349 

ligaments  of,  217 

muscles  of,  350 

nerves  of,  from  median,  571, 
573 
from  radial,  575 
from  ulnar,  573,  574 

veins  of,  466 
Hard  palate,  652 
Harmonia,  185 
Havers,  glands  of,  184 
Head,  muscles  of,  240 
veins  of,  458 

of  scapula,  127 

of  ulna,  135 
Heart,  691 

annular  fibres  of  auricles,  698 

arteries  of,  699 

auricles  of,  691,  692 

circular  fibres  of,  698 

component  parts  of,  691 

endocardium,  697 

fibres  of  the  auricles,  698 
of  the  ventricles,  698 

fibrous  rings  of,  697 

fcetal  relics  in,  693 

infundibulum  of,  694 

left  auricle,  695 
ventricle,  696 

looped  fibres  of  auricles,  698 

lymphatics  of,  494,  699 

muscular  structure  of,  698 

nerves  of,  560,  596,  699 

openings  into,  693 

peculiarities  of,  in  foetus,  699 

position  of,  691 

right  auricle,  692 
ventricle,  694 


Heart — 

septum  ventriculorum,  694 
size  and  weight,  691 
spiral  fibres  of,  698 
structure  of,  697 
subdivision  into  cavities,  691 
valves  of,  693,  694,  695 
veins  of,  699 
vortex  of,  698 
Helicotrema  of  cochlea,  640 
Helix,  629 
fossa  of,  629 
muscles  of,  630 
process  of,  629 
Hernia,  congenital,  765 
direct  inguinal,  761,  765 
comparative  frequency  of, 

766 
course  of,  765 
coverings  of,  765 
diagnosis  of,  766 
incomplete,  766 
femoral,  complete,  773 
cutaneous      vessels      and 

nerves  of,  766 
coverings  of,  773 
descent  of,  773 
dissection  of,  766 
incomplete,  773 
seat  of  stricture  in,  774 
superficial  fascia  of,  766 
surgical  anatomy  of,  700 
varieties  of,  773 
infantile,  765 
inguinal,  758,  764 
dissection  of,  758 
external,  764 
internal,  764 
surgical  anatomy  of,  758 
oblique  inguinal,  764 
course  of,  764 
coverings  of,  764 
scrotal,  765 
Hesselbach's  triangle,  765 
Hey's  ligament,  769 
Hiatus  Fallopii,  69,  101 
Highmore,  antrum  of,  83 
Hilton's  muscle,  710 
Ililus  of  kidney,  724 

of  spleen,  684 
Hip  joint,  221 

muscles  of,  334 
Hippocampus  major,  524 

minor,  523 
Humerus,  129 
anatomical  neck,  fracture  of, 

320 
articulations  of,  133 
attachment  of  muscles  to,  133 
development  of,  132 
head  of,  129 
neck  of,  129 
nutrient  arterv  of,  409 
shaft  of,  fracture  of,  322 
surgical  neck,  fracture  of,  321 
tuberosities  of,  129 
Humors  of  the  eye,  622 
Hyaloid  membrane  of  eye,  623 
Hymen,  747 
Hyoid  bone,  111 

attachment  of  muscles  to,  112 


INDEX. 


799 


ITyoid  bono — 

development  of,  112 

Ileo-c^cal  valve,  673 

-colic  valve,  G73 
Ileum,  608 
Ilium,  149 

attachment  of  musclesto, 155 
Impressio  colica,  678 

renalis,  678 
Incisor  teeth,  646 
of  lower  jaw,  646 
of  upper  jaw,  646 
Incisura  cerebelli,  anterior,  531 
posterior,  531 
intertragica,  629 
Santorini,  631 
Incus,  635 
ligament  of,  636 
suspensory,  636 
Infantile  hernia,  765 
Inferior  maxillary  bone,  92.  See 
Jaw,  lower, 
meatus  of  nose,  111,  613 
turbinated  bones,  91 
articulations  of,  91 
development  of,  91 
Infundibula  of  kidney,  726 
Infundibulum  of  brain,  628 
of  cochlea,  639 
of  ethmoid,  79 
of  heart,  694 
Inlet  of  pelvis,  155 
Innominate  bone,  149 
articulations  of,  155 
attachment  of  muscles  to, 

155 
development  of,  154 
structure  of,  154 
Inorganic  constituent  of  bone, 

33 
Interarticular    fibro- cartilage, 
183 
of  jaw,  197 
of  knee,  225 
of  pubes,  206 
of  radio-ulnar  joint,  214 
of  sacro-coccvgeal  joint, 

205 
of  scapuloclavicular  joint, 

209 
of  sterno-clavicular  joint, 
208 
Intercellular  substance  of  car- 
tilage, 182 
Intercclumnar  fibres,  760 
Intercostal  spaces,  116 
Interlobular  biliary  plexus,  680 
Interpeduncular  space  of  brain, 

519 
Interstitial  lamella;,  36 
Intertubular  tissue  of  teeth,  648 
Intervertebral  notches,  41 

substance,  189 
Intestine,  large,  670 

cellular  coat  of,  674 
ca;cum,  670 
colon,  672 

ileo-caecal  valve,  671 
mucous  membrane  of,  674 
muscular  coat  of,  673 


Intestine — 

rectum,  672 
serous  coat  of,  673 
structure  of,  673 
small,  667 

cellular  coat  of,  668 
divisions  of,  667 
duodenum,  667 
ileum,  668 
jejunum,  668 
glands  of,  669 
mucous  coat  of,  668 
muscular  coat  of.  668 
serous  coat  of,  668 
simple  follicles  of,  669 
structure  of,  668 
submucous  coat  of,  668 
valvuloe  conniventes,  668 
villi  of,  668 
Intra-cartilaginous  ossification, 
39 
-membranous    ossification, 
39 
Intumescentia  gangliformis,  541 
Involuntary  muscles,  234 
Iris,  619 

arteries  of,  620 
structure  of,  619 
Ischium,  152 

attachment  of  muscles  to,  155 
Island  of  Reil,  518 
Isthmus  of  the  fauces,  653 
of  the  thyroid  gland,  721 
Iter  ad  infundibulum,  528 

e  tertio  ad  quartum  ventri- 
culum,528 
Ivory  of  tooth,  648 

Jacob's  membrane,  621 
Jacobson's  nerve,  556 

canal  for,  71 
Jaw,  lower,  92 

articulations  of,  97 
attachments  of  muscles  to, 

97 
changes  produced  by  age 

in,  95 
development  of,  95 
ligaments  of,  195 
oblique  line  of,  92 
rami  of,  94 
symphysis  of,  92 
upper.     See  Superior  Maxil- 
lary bone. 
Jejunum,  668 
Joint.     See  Articulations. 

Kerkrino,  valves  of,  668 
Kidney,  724 

calyces  of,  726 

cortical  substance  of,  724 

ducts  of,  726 

hilus  of,  724 

infundibula  of,  726 

lymphatics  of,  727 

Malpighian  bodies  of,  726 

mammillae  of,  725 

medullary  substance  of,  724 

nerves  of,  727 

papillae  of,  725 

pelvis  of,  726 


Kidney — ■ 

pyramids  of  Ferrcin,  726 
of  Malpighi,  724 

relations  of,  724 

renal  artery,  726 

sinus  of,  726 

tubes  of  Ferrein,  726 

tubuli  uriniferi,  725 

veins  of,  726 

weight  and  dimensions  of,  724 
Knee-joint,  223 

Kurschner,    on     structure     of 
heart's  valves,  694 

Labia  cerebri,  521 

pudendi  majora,  746 
minora,  747 
lymphatics  of,  488 
Labyrinth,  637 

arteries  of,  642 

fibro-serous  membrane  of,  639 

membranous,  640 

nerves  of,  642 

veins  of,  642 
Lachrymal  apparatus,  027 

bones,  86 

articulations  of,  86 
attachment  of  muscles  to, 

86 
development  of,  86 
Lacteals,  493,  069 
Lactiferous  ducts,  756 
Lacuna  magna,  733 
Lacunae  of  bone,  36 
Lacus  lacrymalis,  625,  626 
Lamella,  articular,  181 
of  bone,  36 

circumferential,  36 

horizontal,  of  ethmoid,  77 

interstitial,  36 

perpendicular,  of  ethmoid,  77 
Lamina  cinerea,  518 

cribrosa  of  sclerotic,  616 

denticulate  of  cochlea,  640 

fusca  of  sclerotic,  015 

membranacea,  040 

spiralis  of  cochlea,  040 
Laminae  of  cornea,  clastic,  616 

of  the  vertebrae,  41 
Laminated  tubercle  of  cerebel- 
lum, 531 
Laryngis  sacculus,  712 
Laryngo-tracheotomy,  713,  714 
Laryngotomy,  713,  714 
Larynx,  703 

arteries  of,  711 

cartilages  of,  703 

cavity  of,  707 

glands  of,  711 

glottis,  707 

interior  of,  706 

ligaments  of,  705 

lymphatics  of,  711 

mucous  membrane  of,  710 

muscles  of,  708 
actions  of,  708 

nerves  of,  711 

pouch  of,  708 

rima  glottidis,  707 

veins  of,  711 

ventricle  of,  708 


800 


INDEX. 


Larynx — 

vocal  cords  of,  false,  707 

inferior,  708 

superior,  708 

true,  708 
Lateral  ginglymus,  186 
masses  of  ethmoid,  78 
Leg,  arteries  of,  446 
bones  of,  163 
fascia  of,  340 

deep,  345 
ligaments  of,  226 
lymphatics  of,  488 
muscles  of  front  of,  341 

back  of,  343 
nerves  of,  588 
veins  of,  473 
Lens,  crystalline,  623 
capsule  of,  623 
changes  produced  in  by  age, 

624 
structure  of,  624 
suspensory  ligament  of,  624 
Lesser  lachrymal  bone,  86 
Lieberkuhn,  crypts  of,  669 
Ligament  or  Ligaments,  struc- 
ture of,  183 
accessory,  211 

acromio-clavicular,  superior, 
208 

inferior,  208 
alar  of  knee,  226 
of  ankle,  anterior,  228 

lateral,  228 
annular  of  ankle,  348 

anterior,  348 

external,  348 

internal,  348 

of  radius  and  ulna,  213 

of  stapes,  636 

of  wrist,  anterior,  315 
posterior,  315 
anterior  of  knee,  223 
arcuate,  291 
aryteno-epiglottic,  707 
astragalo-scaphoid,  2-2 
atlo-axoid,  anterior,  191 

posterior,  192 
of  bladder,  false,  731 

true,  730 
broad  of  liver,  676 

of  uterus,  750 
calcaneo-astragaloid      exter- 
nal, 230 
posterior,  230 
calcaneocuboid,  internal,  231 

long,  231 

short,  231 

superior,  231 
calcaneo-scaphoid,     inferior, 
231 

superior,  231 
capsular  of  atlo-axoid,  193 

of  costo-sternal,  200 

of  crico-thyroid,  206 

of  hip,  221 

of  intercostal,  202 

of  jaw,  197 

of  knee,  224 

of  occipito-atloid,  194 

of  ribs  with  spine,  198 


Ligament  or  Ligaments — 

of  shoulder,  210 

of  thumb,  218 

of  vertebrae,  190 
carpo-metacarpal,  218 
of  carpus,  217 
central,  of  spinal  cord,  502 
check,  195 
ciliary  of  eye,  620 
common  vertebral,  anterior, 
188 

posterior,  189 
conoid,  209 
coraco-acromial,  210 

-clavicular,  209 

-humeral,  211 
coracoid,  210 
coronary  of  knee,  226 

of  liver,  676 
costo-clavicular,  208 

-sternal,  anterior,  200 
posterior,  200 

-transverse,  anterior,  199 
middle,  199 
posterior,  200 

-vertebral,  198 

-xiphoid,  201 
cotyloid,  222 
crico-arytcnoid,  706 

-thyroid,  706 
crucial  of  knee,  224 

external,  224 

internal,  224 
cruciform,  193 
deltoid,  228 

dorsal,  of  carpo-metacarpal, 
218 

of  carpus,  217 

of  metacarpus,  219 

of  metatarsus,  233 

tarso-metatarsal,  233 

of  tarsus,  230 
of  elbow,  212 

anterior,  212 

external  lateral,  212 

internal  lateral,  212 

posterior,  212 
falciform  of  liver,  676 
femoral,  769 
gastro-phrenic,  664 
Gimbernat's,  281,  760,  770 
glenoid,  211 

glosso-epiglottidean,  705 
Hey's  769 
of  hip, 221 

hyo-epiglottic,  705,  706 
ilio-femoral,  222 

-lumbar,  203 
of  incus,  636 

interarticular  of  ribs,  198 
interclavicular,  208 
intercostal,  201 
internal  lateral  of  lower  jaw, 
196 

of  knee,  224 
interosseous,   calcaneo-astra- 
galoid, 230 

calcaneocuboid,    internal, 
231 

carpal,  217 

carpo-metacarpal,  218 


Ligament  or  Ligaments— 

metacarpal,  219 

metatarsal,  233 

radio-ulnar,  214 

of  ribs,  199 

tarsal,  230 

tarso-metatarsal,  233 

tibio-fibular,  inferior,  22T 
inter-spinous,  190 
inter-transverse,  191 
intervertebral,  189 
of  jaw,  lower,  195, 196 

lateral,  external,  195 

internal,  196 
of  knee,  223 
of  larynx,  705 

extrinsic,  705 

intrinsic,  705 
lateral  of  ankle,  228 

of  bladder,  730 

of  carpus,  218 

of  elbow,  212 

of  jaw,  195 

of  knee,  224 

of  liver,  676 

of  tarso-metatarsal,  233 
longitudinal  of  liver,  676 
lumbo-iliac,  203 

-sacral,  203 
of  malleus,  635 
metacarpal,  219 
metacarpo-phalangeal,  220 

anterior,  220 

lateral,  220 
metatarsal,  233 
metatarso-phalangeal,  233 
mucosum,  226 
nucha?,  270 
oblique,  214 
obturator,  207 
occipito-atloid,  anterior,  194 
lateral,  194 
posterior,  194 

-axoid,  195 
odontoid,  195 
orbicular,  213 
of  ossicula,  635 
of  ovary,  755 
palmar,  217,  218 
palpebral,  626 
peritoneal,  662 
of  patella,  223 
of  pelvis,  204 

of  the  phalanges  of  the  hand, 
220 
anterior,  220 
lateral,  220 

of  the  foot,  234 
of  the  pinna,  629 
plantar,  230,  233 

long,  231 
posterior  of  knee,  224 

sternal,  203 
posticum  Winslowii,  224 
Poupart's,  281,  760,  769 
pterygo-maxillary,  249 
pubic,  anterior,  206 

posterior,  206 

superior,  206 
pubo-prostatic,  730,  735 
radio-carpal,  216 


INDEX. 


801 


Ligament  or  Ligaments — 
radioulnar,  anterior,  21-1 

middle,  214 

posterior,  214 
recto-uterine,  750 
rhomboid,  208 
round,  of  hip,  222 

of  liver,  GT6 

of  radius  and  ulna,  214 

of  uterus,  755 
sacro-coccygeal,  anterior,  205 

posterior,  205 
sacro-iliac.  anterior,  204 

oblique,  204 

posterior,  204 
sacro-sciatic,  anterior,  great- 
er, 204 

lesser,  204 

posterior,  204 
sacro-vertebral,  203 
of  scapula,  210 
of  shoulder,  210 
of  stapes,  G36 
stellate,  198 

sterno-clavicular,      anterior, 
207 

posterior,  208 
of  sternum.  202 
stylo-maxillary,  196 
subflavous,  190 
subpubic,  206 
supra-spinous,  190 
suspensory,  of  incus,  636 

of  lens,  024 

of  liver,  676 

of  malleus,  636 

of  mamma,  294 

of  penis,  736 

of  spleen,  684 
sutural,  181 
tarsal,  180 

of  eyelids,  626 
tarso-metatarsal,  233 
teres,  of  hip.  222 
of  thumb,  220 

thyro-arytcnoid,  inferior,  708 
superior,  707 

-epiglottic,  705,  706 

-hyoid,  705 
tibio-fibular,  227 

-tarsal,  228 
transverse  of  atlas,  193 

of  hip,  222 

of  knee,  225 

of  metacarpus,  219 

of  scapula,  210 

of  tibio-fibular,  227 
trapezoid,  209 
triangular,  infrapubian,  781 

of  urethra,  781 
of  tympanic  bones,  635 

of  incus,  636 

of  malleus,  635 

of  stapes,  636 
of  urethra,  781 
of  uterus,  750 
of  vertebra;,  188 
vesico-uterine,  750 
of  Winslow,  224 
of  wrist,  216 

anterior,  216 
51 


Ligament  or  Ligaments — 
lateral,  external,  216 

internal,  216 
posterior,  216 
of  Zinn,  244 
Ligamenta  alaria,  226 

subflava,  190 
Ligamentum    arcuatum    exter- 
num, 291 
internum,  290 
denticulatum,  502 
latum  pulmonis,  715 
patella;,  223 
teres  of  hip,  222 
See  also  Ligaments. 
Ligation  of  arteries.    See  Ope- 
ration. 
Limbus  luteus,  620 
Linea  alba,  287 
aspera,  160 
ilio-pectinea,  153 
quadrati,  160 
splcndens,  502 
Linea;  semilunares,  287 

transversa;  of  abdomen,  287 
of  fourth  ventricle,  532 
Lingual  bone,  111 
Linguetta  laminosa,  529 
Lips,  643 
arteries  of,  375 
structure  of,  643 
Liquor  Cotunni,  640 
Morgagnii,  623 
Scarpa;,  641 
seminis,  744 
Lithotomy,  parts  avoided  in,  784 
parts  concerned  in,  783 
divided  in,  784 
Liver,  675 

arteries  of,  678 

changes  of  position  in,  675 

distribution  of  vessels  to,  in 

foetus,  701 
ducts  of,  680,  681 
fibrous  coat  of,  679 
fissures  of,  676 

of  ductus  venosus,  677 
for  gall-bladder.  677 
longitudinal,  677 
portal,  677 
transverse,  677 
umbilical,  677 
for  vena  cava,  677 
hepatic  artery,  678,  679,  680 
cells,  679,  680 
duct,  679,  681 
veins,  G78,  679,  680 
ligaments  of,  675 
broad,  676 
coronary,  676 
falciform.  676 
lateral,  676 
longitudinal,  676 
round,  675, 676 
suspensory,  676 
lobes  of,  677 
left,  678 
right,  677 

lobus  caudatus,  678 
quadratus,  678 
Spigelii,  678 


Liver — 

lobules  of,  679 
lymphatics  of,  492,  678 
nerves  of,  678 
portal  vein,  678,  680 
situation,  size,  and  weight,  675 
structure  of,  678 
surfaces  and  borders  of,  675 
veins  of,  678 
Lobes  of  cerebellum,  531 
digastric,  532 
inferior,  posterior,  532 
pneumogastric,  532 
slender,  532 
subpeduncular,  532 
of  cerebrum,  517.     See  Cere- 
brum, 
of  liver,     See  Liver, 
of  lung,  718 
optic,  529 
of  prostate,  735 
of  testis,  742 
of  thymus,  722 
of  thyroid,  721 
Lobular  biliary  plexus,  680 
Lobule  of  the  ear,  629 
Lobules  of  liver,  679 

of  lung,  719 
Lobuli  testis,  742 
Lobulus  centralis  of  cerebellum, 

531 
Lobus  caudatus,  678 
quadratus,  678 
Spigelii,  678 
Locus  ca;ruleus,  532 
niger,  520 

perforatus  anterior,  519 
posterior,  5 1 9 
Lower  extremity,  arteries   of, 
438 
bones  of,  149 
fascia  of,  324 
ligaments  of,  221 
lymphatics  of,  488 
muscles  of,  324 
nerves  of,  580 
veins  of,  473 
Lower,  tubercle  of,  693 
Lumbar  vertebra;,  47 
development  of,  49 
Lungs,  717 
air-cells  of,  720 
bronchial  arteries,  720 

veins,  720 
capillaries  of,  720 
in  foetus,  701 
lobes  and  fissures  of,  718 
lobules  of,  7 1 9 
lymphatics  of,  494,  721 
nerves  of,  721 
parenchyma  of,  719 
pulmonary  artery,  720 

veins,  720 
root  of,  718 
structure  of,  719 
subdivision  of  bronchi  in,  71 3 
weight,  color,  etc.,  719 
Lunula;  of  nails,  605 
Lymphatic  duct,  right.  484 
Lymphatic  glands,  482 
anterior  mediastinal,  493 


802 


INDEX. 


Lymphatic  glands —  ' 
auricular,  posterior,  484 
axillary,  487 
brachial,  487 
bronchial,  494 
buccal,  484 
cervical,  deep,  485 

superficial,  486 
in  front  of  elbow,  486 
gluteal,  489 

of  head,  superficial,  484 
iliac,  external,  490 

internal,  490 
inguinal,  deep,  489 

superficial,  488 
intercostal,  493 
internal  mammary,  493 
ischiatic,  489 
of  large  intestine,  493 
of  lower  extremity,  488 
lumbar,  490 
mammary,  493 
mediastinal,  posterior.  493 
mesenteric,  493 
of  neck,  485 
occipital,  484 
parotid,  484 
of  pelvis,  490 

deep,  490 
popliteal,  deep,  489 
radial,  487 
sacral,  490 

of  small  intestine,  493 
of  spleen,  493     • 
of  stomach,  492 
submaxillary,  488 
of  thorax,  493 
tibial,  anterior,  488 
ulnar,  487 

of  upper  extremity,  486 
zygomatic,  484 
Lymphatics,  481 
coats  of,  481 
origin  of,  481 
plexus  of,  481 
subdivision  of,  481 

deep,  481 

superficial,  481 
valves  of,  482 
vessels  and  nerves  of,  482 

abdomen,  490 
afferent,  482 
arm,  487 
bladder,  492 
bone,  38 

broad  ligaments,  492 
cardiac,  494 
cerebral,  484 
cervical,  deep,  486 

superficial,  486 
chest,  494 
clitoris,  491 
cranium,  deep,  485 
diaphragm,  494 
efferent,  482 
face,  484 

deep,  485 

superficial.  484 
Fallopian  tubes.  492 
gluteal  region,  490 


Lymphatics — 
head,  484 

superficial,  484 
heart,  494 
intercostal,  494 
internal  mammary,  494 
intestines,  493 
kidneys,  492,  727 
labia,  491 
lacteals,  493 
large  intestine,  493 
leg,  489 
liver,  492,  678 . 
lower  extremity,  488,  489 

deep,  489 

superficial,  489 
lung,  494,  721 
meningeal,  485 
mesentery,  494 
mouth,  485 
neck,  485 
nose,  485 
nymphae,  491 
oesophagus,  494 
ovaries,  492 
pancreas,  493 
pelvis,  490,  491 
penis,  490 
perineum,  490 
pharynx,  485 
pia  mater,  485 
prostate,  492 
radial,  487 
rectum,  492 
scrotum,  490 
small  intestine,  493 
spleen,  493 
stomach,  492 
testicle,  492 
thoracic  duct,  483 
thorax,  494 
thymic,  494 
thyroid,  494 
upper  extremity,  486 

deep,  487,  488 

superficial,  487,  488 
uterus,  492 
vagina,  492 
Lyra  of  fornix,  526 

Macula  cribrosa,  638 
Magnum  (os)  of  carpus,  145 
Malar  bones,  87 

articulations  of,  88 
attachment  of  muscles  to, 

88 
development  of,  88 
Malleolus,  external,  169 

internal,  167 
Malleus,  635 

suspensory  ligament  of,  636 
Malpighi,  pyramids  of,  725 
Malpighian   bodies   of  kidney, 
726 
corpuscles  of  spleen,  686 
relation  with  arteries,  686 
veins,  686 
Mamma,  756 
areola  of,  756 
lobules  of,  756 
mammilla  of,  756 


Mamma — 
nerves  of,  757 
nipple,  756 
structure  of,  756 
vessels  of,  757 
Mammary  gland.     See  Gland, 

mammary. 
Mammilla  of  breast,  756 

of  kidney,  725 
Manubrium  of  sternum,  112 

of  malleus,  635 
Marrow  of  bone,  38 

spinal,  502  • 
Mastoid  cells,  openings  of,  633 
portion  of  temporal  bone,  69, 
631 
Matrix  of  nail,  605 
Maxillary  bone,  inferior,  92 

superior,  81 
Meatus  auditorius  externus,  69 
internus,  70 
of  nose,  inferior,  111,  613 
mucous    membrane     of, 
613 
middle,  111,  613 

mucous    membrane     of, 
613 
superior,  110,  613 
mucous    membrane    of, 
613 
urinarius,  female,  747 
male,  733,  736 
Meckel's  ganglion,  550 
Mediastinum,  715,  716 
anterior,  716 
middle,  716 
posterior,  715,  716 
testis,  741 
Medulla  oblongata,  510 

anterior  pyramids  of,  511, 512 
back  of,  512 

corpora  pyramidalia  of,  511 
fasciculi  graciles  of,  511 
fissures  of,  511 
gray  matter  of,  513 
lateral  tract  of,  511 
olivary  body,  511 
pyramids  of,  anterior,  511 

posterior,  511 
restiform  bodies,  511 
septum  of,  513 
structure  of,  512 
Medulla     spinalis,     502.      Set 

Spinal  cord. 
Medullary  canal  of  bone,  35 
membrane  of  bone,  38 
substance  of  brain,  495 
of  kidney,  725 
of  supra-renal  capsules,  725 
velum,  posterior,  of  cerebel- 
lum, 531 
Meibomian  glands.  626 
Membrana  fusca,  615 
granulosa,  621 
limitans,  622 
nictitans,  627 
pupillaris,  620 
sacciformis,  215 
tympani,  6:54 

structure  of,  634 
secundaria,  633,  639 


INDEX. 


803 


Membrane  of  aqueous  chamber, 
623 

arachnoid,  cerebral,  508 
spinal,  501 

choroid,  018 

costo-coracoid,  290 

crico-thyroid,  700 

fenestrated,  359 

hyaloid,  023 

hyoglossal,  010 

Jacob's  021 

limiting,  022 

pituitary,  013 

pupillary,  020 

Schneiderian,  013 

thyro-hyoid,  705,  700 

vitelline,  754 
Membranes  of  spinal  cord,  500 

of  brain,  507 
Membranous  labyrinth,  040 
structure  of,  041 

portion  of  urethra,  733 

semicircular  canals,  041 

zone,  040 
Meninges,  cerebral,  500 

spinal,  507 
Menisci,  183 
Mesentery,  002,  003 
M6soc6pliale,  514 
Mesocascum,  003 
Mesocolon,  ascending,  003 

descending,  003 

sigmoid,  003 

transverse,  003,  072 
Mesorchium,  745 
Mesorectum,  003 
Metacarpal  bones,  140 
Metacarpus,  140 

common  characters  of,  140 

development  of,  148 

peculiar  bones  of,  140 
Metatarsus,  177 

bones  of,  177 

development  of,  179 
Middle  ear  or  tympanum,  032 
Milk  teeth,  045,  047 
Mitral  valve,  097 
Modiolus  of  cochlea,  039 
Molar  teeth,  040 

peculiar,  047 
Mons  Veneris,  740 
Monticulus  cerebelli,  531 
Morsus  diaboli,  7.">2 
Motor  oculi  nerve,  537 
Mouth,  043 

mucous  membrane  of,  043 

muscles  of,  248 
Movement  admitted  in  joints, 

187 
Multicuspidate  teeth,  040 
Muscles,  General  Anatomy  of, 
235 

of  animal  life,  235 

aponeuroses  of,  237 

arrangement  of  fibres  of,  230 

bipenniform,  230 

bloodvessels  of,  230 

derivation  of  names  of,  230 

fasciculi  of,  235 

fibrils  of,  235 

form  of,  230 


Muscles — 
fusiform,  230 
insertion  of,  237 
involuntary,  230 
lymphatics  of,  230 
mode    of    connection,    with 

bone,  &c,  230 
nomenclature  of,  230 
of  organic  life,  235 
origin  of,  237 
penniform,  237 
primitive  fasciculi  of,  235 

fibrils  of,  235 
radiated,  237 
sarcous  elements  of,  235 
sheath  of.  230 
size  of,  237 
striped,  235 
structure  of,  230 
tendons  of,  237 
unstriped,  235 
voluntary,  235 
Muscle  or  Muscles,  Descriptive 

Anatomy  of,  238 
of  abdomen,  281 
abductor  indicis,  319 

minimi  digiti  of  foot,  351 
of  hand,  318 

pollicis  of  foot,  351 
of  hand,  310 
accelerator  urinae,  778 
accessorius   ad  sacro-lumba- 
lem,  270 

orbicularis  oris,  248 

pedis,  270 
of  acromial  region,  299 
adductor  brevis,  333 

longus,  333 

magnus,  333 

pollicis  of  hand,  318 
of  foot,  353 
anconeus,  312 
anomalus,  240 
antitragicus,  030 
of  anus,  770 
of  arm,  302 

arytacno-epigiottideus      infe- 
rior, 710 

superior,  710 
arytaenoideus,  709 
attollens  aurem,  241 

oculi,  244 
attrahcns  aurem,  242 
of  auricular  region,  241 
azygos  uvulae,  205 
of  back,  209 
basio-glossus,  201 
biceps  of  arm,  303 

of  leg,  339 
biventer  cervicis,  277 
brachial  region,  anterior,  300 

posterior,  312 
brachialis  anticus,  304 
buccinator,  249 
caninus.  217 
cerato-glossus,  201 
cervicalis  ascendens,  270 
of  chest,  294 
chondro-glossus,  201 
ciliary  of  eye,  020 
circumflexus  palati,  205 


Muscle  or  Muscles — 
coccygeus,  782 
cochlcaris,  040 
complexus,  277 
compressor  naris,  240 
narium  minor.  240 
sacculi  laryngis,  708,  710 
urethra,  733 
constrictor  isthmi    faucium, 
205 
pharyngis  inferior,  202 
medius,  203 
superior,  203 
urethra,  781 
coraco-brachialis,  303 
corrugator  supercilii.  243 
cremaster,  702 
crico-arytaenoideus    lateralis, 
709 
posticus,  708 
crico-thyroid,  708 
crureus,  331 
deltoid,  299 
depressor  alae  nasi,  240 
anguli  oris,  248 
epiglottidis,  710 
labii  inferioris,  248 
diaphragm,  289 
digastric,  259 
dilator  naris  anterior,  240 

posterior,  240 
dorsum  of  foot,  350 
of  epicranial  region,  239 
erector  clitoridis,  780 
penis,  779 
spinae,  270 
of  external  ear,  241 
external  sphincter,  770 
extensor    brevis    digitorum, 
350 
carpi  radialis  brevior,  311 
longior,  310 
ulnaris,  312 
coccygis,  279 
communis  digitorum,  312 
indicis,  314 
longus  digitorum,  342 
minimi  digiti,  312 
ossis  metacarpi  pollicis,  313 
primi    internodii    pollicis. 

313 
proprius  pollicis,  342 
secundi  internodii  pollicis. 
313 
of  eyelids,  242 
of  face,  240 

femoral  region,  anterior,  327 
internal,  332 
posterior,  339 
fibular  region,  347 
flexor  accessorius,  352 
brevis  minimi  digiti  of  foot, 
353 
of  hand,  318 
brevis  digitorum.  351 
pollicis  of  foot,  353 

of  hand,  317 
carpi  radialis,  300 

ulnaris,  307 
digitorum  profundus,  303 
sublimis,  307 


804 


INDEX. 


Muscle  or  Muscles — 

longus  digitorum,  346 
pollicis  of  foot,  346 
of  hand,  309 
ossis    metacarpi    pollicis, 

316 
profundus  digitorum,  308 
sublimis  digitorum,  307 
of  foot,  348 
of  forearm,  305 
gastrocnemius,  343 
gemellus  inferior,  338 

superior,  337 
genio-hyo-glossus,  2G0 

-hyoid,  259 
gluteus  maximus,  334 
medius,  335 
minimus,  336 
of  gluteal  region,  334,  335, 

336 
gracilis,  332 
of  hand,  315,  316 
of  head  and  face,  238 
helicis  major,  630 

minor,  630 
Hilton's,  710 
of  hip,  334 
humeral  region,  anterior,  302 

posterior,  304 
hyo-glossus,  260 
of   hyoid  bone   and  larynx, 

256,  258 
iliac  region,  325 
iliacus,  326 
ilio-costalis,  276 
infra-costal,  289 
infra-spinatus,  300 
intercostal,  288 
external,  288 
internal,  288 
of  intermaxillary  region,  248 
interossei,  319,  354 
dorsal,  319 
palmar,  320 
plantar,  354 
inter-spinales,  279 
inter-transversales,  279 
labial,  248 
of  larynx,  705 
latissimus  dorsi,  270 
laxator  tympani  major,  G36 

minor,  636 
of  leg,  340 

levator  anguli  oris,  247 
scapulae,  272 
ani,  781 

glandulae  thyroidea?,  721 
labii  inferioris,  247 
superioris,  247 
akvque  nasi,  246 
proprius,  247 
proprius  alee  nasi  ante- 
rior, 246 
posterior,  246 
menti,  247 
palati,  265 
palpebral  243 

superioris,  243,  625 
prostatas,  735 
levatores  costarum,  289 
lingualis,  261 


Muscle  or  Muscles — 

superficialis,  610 
of  lips,  248 
of  liver,  678 
longissimus  dorsi,  276 
longus  colli,  267 
of  lower  extremity,  324 
lumbricales  of  foot,  352 

of  hand,  319 
masseter,  249 
of  mouth,  248 
multifidus  spina?,  278 
mylo-hyoid,  259 
myrtiformis,  246 
naso-labialis,  248 
of  neck,  252 
of  nose,  246 

oblicpius  externus  abdominis, 
281,  760 
internus,  283,  761 

ascendens,  283,  761 

auris,  631 

capitis  inferior,  280 
superior,  280 

cervicis  inferior,  280 
superior,  280 

descendens,  281,  760 

oculi  inferior,  245 
superior,  245 
obturator  externus,  338 

internus,  337 
occipito-frontalis,  239 
omo-hyoid,  258 
opponens  minimi  digiti,  319 

pollicis,  316 
orbicularis  oris,  248 

palpebrarum,  242 
of  orbit,  243 
nalate,  264 
palato-glossus,  262,  265 

pharyngeus,  265 
palmaris  brevis,  318 

longus,  307 
of  palpebral  region,  242 
pectineus,  332 
pectoralis  major,  294 

minor,  296 
of  penis,  779 
of  perineum,  female,  781 

male,  779 
peroneus  brevis,  347 

longus,  347 

tertius,  342 
of  pericranium,  240 
of  pharynx,  260 
of  pinna,  630 
plantaris,  344 
platysma  myoides,  253 
popliteus,  345 
pronator  quadratus,  309 

radii  teres,  306 
psoas  magnus,  326 

parvus,  326 
pterygoid,  external,  252 

internal,  251 
pyramidalis  abdominis,  287 

nasi,  246 
pyriformis,  336 
quadratus  femoris,  338 

lumbornm,  287 

menti,  248 


Muscle  or  Muscles — . 

quadriceps   extensor   cruris, 

330 
radial  region,  310 
rectus  abdominis,  286 

capitis  anticus  major,  266 
minor,  267 
posticus  major,  279 
minor,  279 

femoris,  330 

lateralis,  267 

oculi,  244 
externus,  244 
inferior,  244 
internus,  244 
superior,  244 
retrahens  aurem,  242 
rhomboideus,  246 

major,  273 

minor,  272 
risorius  of  Santorini,  249 
rotatores  spina?,  278 
sacro-lumbalis,  276 
sartorius,  329 
scalenus  anticus,  268 

medius,  268 

posticus,  268 
scapular  region,  anterior,  299 

posterior,  300 
semi-membranosus,  340 
serratus  magnus,  298 

posticus  inferior,  274 
superior,  273 
semi-spinalis  colli,  278 

dorsi,  278 
semi4endinosus,  339 
sole  of  foot.  350 

first  layer,  350 

second  layer,  352 

third  layer,  353 
soleus,  344 

sphincter  ani,  external,  77G 
internal,  776 

vagina;,  780 
spinalis  cervicis,  277 

dorsi,  277 
splenitis,  274 

capitis,  274 

colli,  274 
stapedius,  636 
sterno-cleido-mastoid,  251 

-hyoid,  256 

-thyroid,  257 
stylo-glossus,  261 

-hyoid,  259 

-pharyngeus.  2G3 
subanconeus,  305 
subclavius,  296 
subcrureus,  331 
subscapularis.  299 
supinator  brevis,  313 

longus,  310 
Bupra-epinales.  279 
supra-spinatus',  300 
temporal,  251 
tensor  palati,  265 

tarsi,  243 

tympani.  636 

vagina?  femoris,  329 
teres  major,  301 

minor,  301 


INDEX. 


805 


Muscle  or  Muscles — 
of  thigh.  327 

of  thoracic  region,  anterior, 
294 
lateral,  298 
of  thorax,  288 
of  thumb,  316 
thyro-arytamoideus,  709 
-epiglottideus,  710 
-hyoid,  258 
tibialis  anticus,  341 

posticus,  340 
tibio-fibular  region,  anterior, 
341 
posterior,  343 
of  tongue,  2G0 
trachelo-mastoid,  277 
tragicus,  630 

transvcrsalis  abdominis,  284, 
762 
colli,  277 
transversus  auriculae,  630 
pedis,  353 
perinei,  779 
in  female,  780 
trapezius,  269 
triangularis  sterni,  289 
triceps  extensor  cruris,  330 
cubiti,  304 
femoralis,  331 
of  trunk,  269 
of  tympanum,  636 
of  upper  extremity,  293 

surgical  anatomy  of,  320 
of  ureters,  731 
of  urethra,  778 
vastus  externus,  330 

internus,  330 
vertebral  region,  anterior, 215 

lateral,  217 
zygomaticus  major,  247 
minor,  247 
Musculi  papillares  of  left  ven- 
tricle, 697 
of  right  ventricle,  695 
pectinati,  in  left  auricle,  696 
in  right  auricle,  693 
Musculus.    See  Muscle. 

Nails,  605 
chemical  composition  of,  606 
lunula  of,  605 
matrix  of.  605 
root  of,  605 
structure  of,  605 
Nares,  anterior,  109 
posterior,  106,  656 
septum  of,  110,  612 
Nasal  bones,  81 

articulations  of,  81 
development  of,  81 
fossae,  109,  613 
arteries  of,  614 
mucous  membrane  of,  613 
nerves  of,  614 
veins  of,  614 
Nates  of  brain,  531 
Navicular  bone,  141.  175 
Neck,  muscles  of,  253 
triangle  of,  anterior,  382 
posterior,  384 


Neck — 

surgical  anatomy  of,  382 
veins  of,  458 
Nerve  or  Nerves,  496 
General  Anatomy  of — 
afferent,  500 
centrifugal,  500 
centripetal,  500 
cerebro-spinal,  498 

composition  of,  498 

junction  of  funiculi  of, 
498 

neurilemma  of,  498 

origin  of,  498 

apparent,  499,  500 
real,  500 

plexus  of,  498 

sheath  of,  498 

structure  of,  498 

subdivision  of,  497 

termination  of,  498 

vessels  of,  498 
cells,  497 

compound,  535,  545 
corpuscles,  497 
efferent,  500 
excito-motory,  500 
fibres,  496 
mixed,  535 
of  motion,  535 
motor,  500 
reflex,  500 
sensitive,  500 
of  special  sense,  535 
spinal,  roots  of,  560 
sympathetic,  592 
Descriptive  Anatomy  of — 
abducens,  539 
accessory  obturator,  582 

spinal,  560 
acromial,  564 
of  arachnoid,  509 
articular,  of  elbow,  573 

hip,  482,  588 

knee,  582,  584,  590 

shoulder-joint,  568,  569 

wrist,  573 
auditory,  537,  642 
auricular,    of    auricularis 
magnus,  564 

of  auriculo-temporal,  250 

posterior,  from  facial, 542 

of  second  cervical,  566 

of  small  occipital,  564 

of  vagus,  558 
auricularis  magnus,  564 
axillary,  565 
of  bone,  38 
buccal,  550 

of  facial,  543 

of  inferior  maxillary,  550 
cardiac,  596 

inferior,  596 

middle,  596 

posterior,  566 

of  pneumogastric,  569 

superior,  596 
cardiacus  magnus,  596 

minor,  596 
carotid,  §57 
cavernous,  large,  691 


Nerve  or  Nerves — 
cavernous,  small,  601 

of  penis,  601 
cervical,  roots  of,  562 
anterior  branches  of,  563 
posterior  branches  of,  56(5 
superficial  branches  of,  564 
cervico-facial,  543 
chorda  tympani,  542,  637 
ciliary,  long,  547 

short,  548 
circumflex,  569 
clavicular,  564 
coccygeal,  584 
anterior,  585 
posterior,  585 
cochlear,  642 
communicans  noni,  565 

peronei,  589 
of  Cotunnius.  553 
cranial.     See  Cranial  nerves, 
crural,  580 

anterior,  582 
cutaneous,  of  abdomen,  ante- 
rior, 579 
lateral,  579 
accessory  obturator,  582 
of  arm,  external,  569 
internal,  570 
lesser  internal,  570 
of  buttock  and  thigh,  580 
of  cervical  plexus,  564 
circumflex,  569 
coccygeal,  584 
crural,  anterior,  582 
dorsal  nerves,  576 
dorsalis  pedis,  586 
hemorrhoidal,  inferior,  586 
ilio-hypogastric,  580 

-inguinal,  580 
of  inguinal  region,  758 
intercostal,  577 
of  ischio-rectal  region,  777 
lateral  of  dorsal,  578 
of  intercostal,  577 
lumbar,  578 
median,  571 

musculo-cutaneous,     5G9, 
591 
-spiral,  575 
obturator,  580 
palmar,  575 
of  patella,  583 
perineal,  586 
peroneal,  590 
plantar,  589 
popliteal,  external,  590 

internal,  588 
radial,  575 
sacral,  584 
sciatic,  lesser,  588 

small,  588 
of  thigh,  external,  580 
internal,  583 
middle,  583 
of  thorax,  anterior,  577 

lateral,  577 
tibial,  anterior,  591 

posterior,  589 
ulnar,  573 
cutaneus  patella?,  583 


806 


INDEX. 


Nerve  or  Nerves — 

dental,  anterior,  549,  614 

inferior,  551 

posterior,  549 
descendens  noni,  545 
digastric,  from  facial,  543 
digital  of  foot,  dorsal,  590, 591 
plantar,  589 

of  hand,  dorsal,  574,  575 
palmar,  median,  573 

radial,  575 

ulnar,  574 
dorsal,  576,  577 

anterior  branches  of,  576 
peculiar,  577 
posterior  branches  of,576 
roots  of,  576 

of  penis,  586 
dorsi-lumbar,  578 

-spinal,  576 
of  dura  mater,  507 
eighth  pair,  555 
of  eyeball,  625 
facial,  540 

branches  of,  541 

communications  of,  541 

in  temporal  bone,  540 
of  femoral  artery,  580 
fifth,  545 

ganglia  connected  with,  551 
fourth,  538 
frontal,  546 
ganglionic  branch  of  nasal, 

547 
gastric  branches  of  vagus,  560 
genital,  580 
genito-crural,  580 
glosso-pharyngeal,  555 
gluteal,  inferior,  588 

superior,  586 
gustatory,  550 
of  heart,  564,  596,  699 
hemorrhoidal,  inferior,  586 
hepatic,  599,  678 
hypogastric,  580 
hypoglossal,  544 
iliac,  580 
ilio-hypogastric,  579 

-inguinal,  580 
incisor,  563 
infra-maxillary,  543 
of  facial,  543 

-orbital  of  facial.  543 

-trochlear,  547 
intercostal,  576 

lower,  577 

upper,  576 
intercosto-humeral,  577 
interosseous,  anterior,  571 

posterior,  575 
of  intestines,  599 
'ischiadic,  great,  588 

small,  586 
Jacobson's,  556,  637 
of  kidney,  727 
labial,  549 
of  labyrinth,  642 
lachrymal,  546 
of  Lancisi,  522 
large  cavernous,  601 
laryngeal,  external,  559 


Nerve  or  Nerves — 
laryngeal,  inferior,  559 

internal,  559 

recurrent,  559 

superior,  559 

from  sympathetic,  594 
lesser  sciatic,  586 

splanchnic,  598 
lingual,  of  fifth,  550 

of  glosso-pharyngeal,  557 
long  saphenous,  583 
lumbar,  578 

anterior  branches  of,  578 

posterior  branches  of,  578 

roots  of,  578 
lumbo-sacral,  578 
malar  branch  of  facial,  543 

of  orbital  nerve,  548 
masseteric,  549 
mastoid,  564 
maxillary,  inferior,  549 

superior,  547 
median,  571 
mental,  551 
motor  oculi,  common,  537 

external,  539 
musculo-cutaneous    of   arm, 
569 
inferior,  580 
from  peroneal,  591 
superior,  579 
musculo-spiral,  574 
mylo-hyoid,  551 
nasal,    from    Meckel's    gan- 
glion, 553 

of  ophthalmic,  547,  614 

from    superior    maxillary, 
549 

from  Yidian.  553 
naso-palatine,  553,  614 
ninth,  544 
obturator,  580 

accessory,  582 
occipital  of  facial,  543 

great,  566 

small,  564 

of  third  cervical,  566 
occipitalis  major,  566 

minor,  564 
oesophageal,  560 
olfactory,  518,  614 

peculiarities  of,  476 
ophthalmic,  546 
optic,  536 
orbital,  548 

relations  of,  539 

in  cavernous  sinus,  540 
in  orbit,  540 
in  sphenoidal  fissure,  540 
palatine,  552 

anterior,  552 

external,  552 

large,  552,  614 

middle,  552 

posterior,  553 

small,  553 
palmar  cutaneous,  571,  574 

deep,  573 

of  median,  571 

superficial,  573 

ulnar,  574 


Nerve  or  Nerves — 
palpebral,  549 
parotid,  550 
par  vagum,  557 
pathetic,  538 
perforans  Gasserii,  569 
perineal,  586 

superficial,  586 
peroneal,  553,  590 
petrosal,  great,  551 

large,  541,  553 

small,  superficial,  541 

superficial    external,   541, 
553 
from  Vidian,  553 
petrosus  superficialis  major, 

553 
pharyngeal,  from  external  la- 
ryngeal, 558 

from     glosso-pharyngeal, 
557 

from    Meckel's    ganglion. 
554 

from  pneumogastric,  558 

from  sympathetic,  594 
phrenic,  565 
plantar,  cutaneous,  589 

external,  590 

internal,  589 
pneumogastric,  557 
popliteal,  external,  590 

internal,  588 
portio  dura,  540 

inter  duram  et  mollem,  540 

mollis,  537 
pterygoid,  550 
pterygopalatine,  553,  554 
pudendal,  inferior,  588 
pudic,  586 
pulmonary,  anterior,  559 

posterior,  560 

from  vagus,  559 
radial,  575 
recurrent  laryngeal,  559     - 

to  tentorium,  539 
renal  splanchnic,  598 
respiratory,  external,  568 

internal,  565 
sacral,  584 

anterior  branches  of,  585 

posterior  branches  of,  584 

roots  of,  584 
saphenous,  external,  589 

internal.  583 

long,  583 

short,  589 
sciatic,  great,  588 

lesser,  586 

small,  586 
seventh,  537,  540 
sixth,  539 
spermatic,  599 
spheno-palatine,  549 
spinal.     See  Spinal  nerves. 

accessory,  560 
splanchnic,  great,  597 

lesser,  598 

renal,  598 

smallest,  598 
splenic,  599 
sternal,  564 


INDEX. 


801 


Nerve  or  Nerves — 

stylohyoid  of  facial,  543 
subclavian,  5G8 
suboccipital,  562 

posterior  branch  of,  566 
subscapular,  569 
superficialis  colli,  564 

cordis,  596 
supra-clavicular,  564 

-maxillary  of  facial,  543 

-orbital,  547 

-scapular,  568 

-trochlear,  546 
sympathetic,  cephalic  portion 
of,  594 

cervical  portion  of,  594 

cranial  portion  of,  594 

lumbar  portion  of,  600 

pelvic  portion  of.  600 

thoracic  portion  of,  599 
tarsal,  591 

temporal,  of  auriculo-tempo- 
ral,  550 

deep, 549 

of  facial,  543 

of  orbital  nerve,  548 
temporo-facial,  543 

-malar  or  orbital,  548 
third  or  motor  oculi,  537 
thoracic,  anterior,  568 

cardiac,  559 

long,  568 

posterior,  568 
thyro-hyoid,  545 
tibial,  anterior,  590 

posterior,  589 
of  tongue,  611 
tonsillar,  557 
trifacial,  545 
trigeminus,  545 
trochlear,  538 
tympanic  of  facial,  541 

of  glosso-pharyngeal,  556, 
037 
ulnar.  573 
uterine,  601      , 
vaginal,  601 
vagus,  557 

branches  of,  558 

ganglion  of  root  of,  557 
of  trunk  of,  557 
vestibular.  642 
Vidian,  553,  614 
of  Wrisberg,  570 
Nervi  nervorum,  499 
Nervous    substance,   chemical 
analysis  of,  495 
microscopic    appearance    of, 
496 
Nervous  System,  General  Ana- 
tomy of.  495 
of  animal  life,  594 
cerebro-spinal  axis,  495 
cortical  substance,  495 
division  of,  495 
fibrous  nervous  matter,  495 
ganglia,  497 
gray  or  cineritious  substance, 

495 
nerves,  497 
of  organic  life,  495 


Nervous  System — 

sympathetic,  499 
composition  of,  499 
gelatinous  fibres  of,  499 
structure  of,  499 
tubular  fibres  of,  499 

vesicular  matter,  495 

white  or  medullary  substance 
of,  495 
Neurilemma,  498 

of  cord,  502 
Nidus  hirundinis,  531 
Nipple,  756 

Nodule  of  cerebellum,  531 
Noduli  Arantii,  695 
Nodulus,  531 
Nose,  611 

arteries  of,  613 

bones  of,  81 

cartilages  of,  612 
of  septum  of,  612 

fossae  of,  109,  613 

mucous  membrane  of,  613 

muscles  of,  246,  612 

nerves  of,  613 

veins  of,  435,  613 
Notch,  cotyloid,  153 

ethmoidal,  77 

intercondyloid,  162 

nasal,  64 

pterygoid,  75 

sacro-sciatic,  greater,  152 
lesser,  152 

sigmoid,  95 

spheno-palatine,  91 

supra-orbital,  64 
-scapular,  126 
Nuck,  canal  of,  745,  755 
Nummular  layer  of  retina,  621 
Nyniphae,  747 

lymphatics  of,  491 

Oblique  inguinal  hernia.     See 
Hernia, 
line  of  the  clavicle,  121 
of  lower  jaw,  93 
of  radius,  139 
Occipital  bone,  57 

articulations  of,  61 
attachment  of  muscles  to, 

61 
crests  of,  58 
development  of,  61 
structure  of,  60 
(Esophagus,  656 
lymphatics  of,  494 
relations  of,  in  neck,  657 

in  thorax,  657 
structure  of,  657 
surgical  anatomy  of,  657 
Oesterlen,  on  supra-renal   cap- 
sules, 728 
Olfactory  bulb.     See  Bulb,  ol- 
factory, 
nerve.    See  Nerve,  olfactory. 
Olivary  bodies  of  medulla  ob- 
longata, 511,  512 
Omenta,  662 

Omentum,  gastro-colic,  662 
gastro-hepatic,  660,  662 
-splenic,  662,  684 


Omentum — 
great,  662 
lesser,  660,  662 
sac  of,  661 
Opening,  aortic,  in  diaphragm, 
291 
in  left  ventricle.  697 
caval  in  diaphragm,  291 
of  coronary  sinus,  693 
of  inferior  cava,  693 
left  auriculo-ventricular,  690, 

697 
oesophageal    in    diaphragm, 

291 
of  pulmonary  artery,  694 

veins,  696 
right  auriculo-ventricular,693 
saphenous,  769 
of  superior  cava,  693 
Operation  for  club-foot,  348 
of  laryngotomy,  714 
of  laryngo-tracheotomy,  714 
ligation  of  the  anterior  tibial, 
447 
over  instep,  447 
in  lower  third  of  leg,  447 
in  upper  part  of  leg,  447 
axillary  artery,  406 
brachial  artery,  408 
common  carotid  artery,  371 
above  omo-hyoid,  371 
below  omo-hyoid,  371 
iliac  artery,  429 
dorsalis  pedis  artery,  449 
external  carotid,  372 

iliac  artery,  437 
femoral  artery,  440 
innominate  artery,  367 
internal  iliac  artery,  431 
lingual  artery,  374 
popliteal  artery,  445 
in    lower     part    of    its 

course,  445 
in  upper  part,  445 
posterior  tibial,  450 
at  ankle,  451 
in  lower  third  of  leg,  451 
in  middle  of  leg,  451 
radial  artery,  411 
subclavian  artery,  394 
superior  thyroid  artery,  373 
ulnar  artery,  414 
of  lithotomy,  783 
of  cesophagotomy,  657 
of  staphylorraphy,  266 
for  strabismus,  245 
tracheotomy,  714 
for  wryneck,  256 
Opercula    of    dental    grooves 

650 
Optic  commissure.     See  Com 
missure.  optic 
lobes.     See  Lobes,  optic. 
Ora  serrata,  620 
Orbicular  bone,  635 
Orbits,  108 
arteries  of,  387 
muscles  of,  243 
relation  of  nerves  in,  5-10 
Organs  of  circulation,  691 
of  deglutition,  056 


808 


INDEX. 


Organs — 

ot'  digestion,  643 

of  generation,  female,  746 
male,  735 

of  respiration,  703 

of  sense,  602 

urinary,  724 

of  voice,  703  * 

Organic  constituent  of  bone,  33 
Orifice,    auriculo  -  ventricular, 
692,  694 
oesophageal,   of    stomach, 
663 

of  prostatic  ducts,  733 

pyloric,  of  stomach,  663 

of  uterus,  750 

of  vagina,  747 
See  also  Openings,  Apertures, 

and  Ostium. 
Os  calcis,  170 

hyoides,  111 

innominatum,  149 

magnum  of  carpus,  145 

orbiculare,  635 

planum,  78 
See  also  Bone. 

uteri,  750 
Ossa  triquetra,  80 
Ossicles  of  ear,  634 
Ossicula  of  tympanum,  634 

ligaments  of.  635 
Ossification  of  bone,  38 
intramembranous,  39 
intracartilaginous,  39 
of  spine,  progress  in,  49 
period  of,  39 
Osteo-dentine,  649 
Osteology,  33 

Ostium  abdominale  of  Fallopian 
tube,  752 

uteri  internum,  750 

uterinum,  750 
Otoliths,  642 
Outlet  of  pelvis,  157 
Ovary,  752 

corpus  luteum  of,  754 

Graafian  vesicles  of,  753 

ligament  of,  755 

lymphatics  of,  492 

nerves  of,  755 

ovisacs  of,  753 

shape,  position,  and    dimen- 
sions of,  753 

situation  of,  in  foetus,  755 

stroma  of,  753 

structure  of,  753 

tunica  albuginca  of,  753 

vessels  of,  755 
Ovicapsule  of  Graafian  vesicle, 

754 
( Oviducts,  752 
Ovisacs  of  ovary,  753 
Ovula  of  Naboth,  751 
Ovum,  754 

discharge  of,  754 

discus  proligerus,  754 

germinal  spot,  754 
vesicle,  754 

vitelline  membrane  of,  754 

yolk  of,  754 

zona  pellucida,  754 


Pacchionian'  depressions,  62 
Palate,  652 

arches  of,  652 
hard,  652 
muscles  of,  264 
pillars  of,  653 
soft,  652 
bone,  88 

articulations  of,  90 
attachment  of  muscles  to, 

91 
development  of,  90 
Palmar  arch.  See  Arch,  palmar. 
Palpebrae,  626 
Pampiniform  plexus  of  veins, 

755 
Pancreas,  682 
duct  of,  683 
structure  of,  684 
vessels  and  nerves  of.  684 
Papilla,  lacrymalis,  625 
Papillae,  conjunctival,  627 
of  kidney,  725 
of  skin,  603 
of  tongue,  609 

circumvallatae,  609 
conicse,  609 
filiformes,  609 
fungiformes,  609 
maximae,  609 
media;,  609 
minimae,  609 
structure  of,  610 
of  tooth,  649 
Papillary  stage  of  development 

of  teeth,  649 
Par  vagum,  558 
Parietal  bones,  61 

articulations  of,  63 
attachment  of  muscles  to, 

63 
development  of,  63 
Parotid  gland,  653 

accessory  portion  of,  654 
duct  of,  654 
nerves  of,  655 
vessels  of,  655 
Patella,  164 

articulations  of,  164 
attachment  of  muscles  to,  164 
development  of,  164 
fracture  of.  356 
structure  of,  164 
Pecquet,  cistern  of,  483 

reservoir  of,  483 
Pectiniform  septum,  737 
Pectoral  region,  dissection  of, 

293 
Pedicles  of  a  vertebra,  41 
Peduncles  of  cerebellum,  533 
of  cerebrum,  519 
of  corpus  callosum,  522 
of  pineal  gland,  532 
Pelvic  fascia.  See  Fascia,  pelvic. 

bones.  155.     See  Pelvis. 
Pelvis,  155,  728 
arteries  of,  429 
articulation  of,  204 

with  spine,  203 
axes  of,  157 
boundaries  of,  728 


Pelvis — 

brim  of,  115 
cavity  of,  156,  728 
diameters  of,  155 
false,  155 
inlet  of,  155 
ligaments  of,  204 
lymphatics  of,  490 
male    and    female,    differ- 
ences of,  158 
outlet  of,  157 
position  of,  157 

of  viscera  at  outlet  of,782 
true,  155 
of  kidney,  726 
Penis,  736 

arteries  of,  738 
body  of,  736 
corpora  cavernosa,  737 
corpus  spongiosum,  737 
dorsal  artery  of,  434 

nerve  of,  586 
extremity  of,  736 
glans,  7H6 

lymphatics  of.  490,  738 
muscles  of,  779 
nerves  of,  591,  738 
prepuce  of,  736 
root  of,  736 

suspensory  ligament  of,  736 
Penniform  muscles,  236 
Perforans  Casserii  nerve,  569 
Perforated  space,  anterior,  519 

posterior,  519 
Perforating  arteries,  413 
from  mammary  artery,  400 
from  plantar,  452 
from  profunda,  443 
inferior,  443 
middle,  443 
superior,  443 
Pericardium,  689 
relations  of,  689 
structure  of,  690 
fibrous  layer  of,  690 
serous  layer  of,  690 
vessels  of,  691 
Perilymph,  640 
Perineum,  777 

abnormal  course  of  arteries 

in,  785 
deep  boundaries  of,  777 
fascia,  deep,  780 
superficial,  777 
lymphatics  of,  483 
muscles  of,  778 
surgical  anatomy  of,  775 
Perineal  space,  777 
Periosteum,  38 
Peritoneum,  660 
folds  of,  662 
lesser  cavity  of,  661 
ligaments  of,  662 
mesenteries  of,  662 
omenta  of,  662 
reflections  of,  660 
Pes  accessorius,  525 

hippocampi,  525 
Petit,  canal  of,  624 
Petrous    portion    of   temporal 
bone,  69 


IXPEX. 


8«0 


Peyer'a  glands,  070 
Phalanges  of  foot,  178 
articulations  of,  234 
development  of,  179 
of  hand,  147 

a  rt  it-  ulations  of,  220 
development  of,  148 
Pharynx,  C.">6 
aponeurosis  of,  G56 
arteries  of,  378 
mucous  membrane  of,  656 
muscles  of,  262 
openings  into,  G5G 
structure  of,  656 
Phlebolites,  475 
Pia  mater  of  brain,  509 

vessels  and  nerves  of,  509 
of  oord,  502 

structure  of,  502 
testis,  741 
Pigment  cells  of  iris,  620 
Pigmentary  layer  of  choroid, 

618 
Pillars  of  external  abdominal 
ring,  760 
of  diaphragm,  561 
of  fauces,  653 
of  fornix,  526 
Pineal  gland,  528 

peduncles  of,  528 
Pinna  of  ear,  628 
cartilage  of,  629 
ligaments  of,  629 
muscles  of,  630 
nerves  of,  631 
structure  of,  629 
vessels  of,  631 
Pisiform  bone,  143 
Pituitary  body,  519 
Plate,  cribriform  of  ethmoid,  77 
external  pterygoid,  75 
perpendicular,  of  ethmoid, 
77 
Pleura.  715 

cavity  of,  715 
parietal  layer  of,  715 
reflections  of,  715 
vessels  and  nerves  of,  716 
visceral  layer  of,  715 
costalis,  715 
pulmonalis,  715 
Pleurae,  715 
Plexus  of  Nerves,  49o 
aortic,  599 
brachial,  566 

branches  above  clavi- 
cle, 567 
below  clavicle,  568 
cardiac,  anterior,  597 
deep.  596 
great,  596 
superficial,  597 
carotid.  595 

external,  594 
cavernous.  595 
cerebral,  595 
cervical,  563 

deep  branches  of,  565 

posterior,  564 
superficial     branches 
of,  564 


Plexus  of  Ncrves- 
coeliac,  599 
colic,  left,  599 

middle,  599 

right,  599 
coronary,  anterior,  597 

posterior,  597 
cystic,  699 
diaphragmatic,  598 
epigastric,  598 
facial,  594 
gastric,  599 
gastro-duodcnal,  599 

epiploic,  599 

left,  599 
great  cardiac,  596 
hemorrhoidal      inferior, 
601 

superior,  599 
hepatic,  601 
hypogastric,  600 

inferior,  600 
ileo-colic,  599 
infra-orbital,  550 
lumbar,  578 

branches  of,  579 
magnus  profundus,  596 
meningeal,  595 
mesenteric,  inferior,  599 

superior,  599 
oesophageal,  560 
ophthalmic,  595 
ovarian.  599 
pancreatic,  599 
pancreatico-duodcnal, 

599 
patellar,  584 
pelvic,  600 
pharyngeal,  561,  595 
phrenic,  598 
prostatic,  601 
pulmonary,  anterior,  560 

posterior,  560 
pyloric,  599  ' 
renal,  598 ' 
sacral,  585 
sigmoid.  599 
solar,  598 
spermatic,  599 
splenic,  599 

superficial  cardiac.  597 
supra-renal,  598 
tonsillar,  557 
tympanic,  561,  637 
vaginal,  601 
vertebral,  596 
vesical,  601 
of  Yeins,  455 

choroid.     See  Choroid, 
hemorrhoidal,  475 
ovarian.  476 
pampiniform,  476,  755 
prostatic,  475 
pterygoid,  459 
spermatic,  476 
thyroid,  658 
uterine,  475 
vaginal,  475 

of  portal  vein,  679 
vesico-prostatic,  475 
Plica  semilunaris,  627 


Points  of  ossification,  38 
Pomum  Adami,  703 
Pons  hepatis,  (JT7 
Tarini,  519 
Varolii,  514 

longitudinal  fibres  of,  514 
septum  of,  515 
structure  of,  514 
transverse  fibres  of,  514 
Popliteal   space.      See   Space, 

popliteal. 
Pores  of  the  skin,  607 
Portio  dura  of  seventh  nerve, 
540 
inter  duram  et  mollem,  540 
mollis,  577 
Porus  opticus  of  sclerotic,  616 
Pott's  fracture,  357 
Pouches,  laryngeal,  708 
Poupart's   ligament,  281,  760, 

769 
Praeputium  clitcridis,  747 
Prepuce,  736 

Process    or    Processes,    acro- 
mion, 126 
fracture  of,  321 
alveolar,  85 
angular,  external,  64 

internal,  65 
auditory,  69 
basilar,  59 
ciliary,  618 

structure  of,  619 
clinoid,  anterior,  75 
middle,  73 
posterior,  73 
cochleariform,  634 
condyloid  of  lower  jaw,  95 
coracoid,  127 

fracture  of,  321 
coronoid,  of  lower  jaw,  94 
of  ulna,  135 
fracture  of,  322 
ethmoidal,  of  inferior  turbi 

nated,  91 
falciform,  769 
frontal,  of  malar,  87 
hamular,  of  cochlea,  640 
of  lachrymal,  86 
of  sphenoid,  75 
of  helix,  629 
of  Ingrassias,  75 
jugular,  59 
lachrymal,  of  inferior  turbi 

nated  bone,  91 
malar  of  superior  maxillarv- 

84 
mastoid,  69 

maxillary,  of  inferior  turbi- 
nated, 91 
of  malar  bone,  88 
mental,  92 
nasal.  84 

odontoid,  of  axis,  44 
olecranon.  135 
fracture  of,  322 
olivary,  73 

orbital,  of  frontal,  65 
of  malar,  87 
of  palate,  89 
of  superior  mayulary,  82 


810 


INDEX. 


^Process  or  Processes — 

palate,  88 

palatine,  of  superior  maxil- 
lary, 85 

pterygoid,  of  palate  bone,  89 
of  sphenoid,  75 

sphenoidal,  of  palate,  90 

spinous,  of  ilium,  150 
of  sphenoid,  74 
of  tibia,  1G5 
of  vertebra?,  41 

styloid,  of  radius,  139 
of  temporal,  71 
of  ulna,  136 

transverse,  of  vertebra,  41 

unciform,  145 
of  ethmoid,  78 

vaginal  of  sphenoid,  74 
of  temporal,  71 

vermiform  of  cerebellum,  infe- 
rior, 531 
superior,  530 

zygomatic,  67 
Processus  ad  medullam,  534 

ad  pontem,  534 

ad  testes,  529 

brevis,  of  malleus,  635 

caudatus,  629 

clavatus,  512 

cochleariformis,  71,  634 

e   cerebello   ad   testes,   529, 
533 

gracilis,  of  malleus,  635 
Promontory  of  sacrum,  50 

of  tympanum,  633 
Prostate  gland,  735,  782 

lobes  of,  735 

levator  muscle  of,  735,  782 

position  of,  735,  782 

secretion  from,  736 

size  and  shape  of,  735 

structure  of,  735 

surgical  anatomy  of,  782 

vessels  and  nerves  of,  736 
Prostatic  fluid,  736 

secretion,  736 
Protuberance,  occipital,  exter- 
nal, 58 

internal,  60 
Pubes,  153 

articulations  of,  205 

attachment  of  muscles  to,  155 

development  of,  154 

structure  of,  154 

symphysis  of,  153 
Pudendum,  746 
Puncta  lacrymalia,  625 

vasculosa,  520 
Pulp  cavity  of  tooth,  648 

development  of,  648 

dental,  050 
Pupil  of  eye,  619 

dilator  muscle  of,  620 

membrane  of,  620 

sphincter  muscle  of,  620 
Pylorus,  665 
Pyramid  of  cerebellum,  531 

of  thyroid  gland,  721 

of  tympanum,  633 

in  vestibule  of  ear,  G38 
Pyramids,  anterior,  511 


Pyramids,  anterior — 
decussation  of,  51 1 
of  Ferrein,  726 
of  Malpighi,  725 
posterior,  511 
of  the  spine,  55 

Qcadrigeminal  bodies,  529 

Radiating  fibres  of  retina,  622 
Radius,  138 

articulations  of,  140 
development  of,  140 
fracture  of,  323 

of  lower  end  of,  324 
of  neck  of,  323 
of  shaft  of,  323 
muscles  attached  to,  140 
structure  of,  140 
and  ulna,  fracture  of,  323 
Ramus  of  ischium,  153 
of  lower  jaw,  94 
of  pubes,  153 
Raphe  of  corpus  callosum,  522 
of  palate,  652 
of  perineum,  777 
of  tongue,  609 
Receptaculum  chyli,  481 
Rectum,  672 
columns  of,  673 
folds  of,  674 
lymphatics  of,  492 
relations  of,  in  female,  749 

male,  672 
surgical  anatomy  of,  783 
Region  of  abdomen,  281,  658 
acromial,  muscles  of,  299 
auricular,  muscles  of,  241 
of  back,  muscles  of,  269 
brachial,  anterior,  muscles  of, 
306,  308 
posterior,  312,  313 
cervical,  superficial,  muscles 

of,  253 
diaphragmatic,  289 
dorsal,    of  foot,  muscles    of, 

350 
epicranial,  muscles  of  239 
epigastric,  659 
femoral,  anterior,  muscles  of, 
327 
internal,  332 
posterior,  339 
fibular,  347 
foot,  dorsum  of,  350 

sole  of,  350 
gluteal,  lymphatics  of,  435 

muscles  of,  334 
groin,  758 

of  hand,  muscles  of,  316 
humeral,  anterior,  302 

posterior,  304 
hypochondriac,  659 
left,  659 
right,  659 
hypogastric,  659 
iliac,  muscles  of,  325 
infrahyoid,  muscles  of,  256 
inguinal,  659,  758 
left,  659 
right,  659 


Region — 

intermaxillary,    muscles     of, 

248 
ischio-rectal,  surgical  anato- 
my of,  775 
laryngotracheal.        surgical 

anatomy  of,  713 
lateral,  of  skull,  105 
lingual,  muscles  of,  260 
lumbar,  659 

left,  659 

right,  659 
maxillary,    inferior,   muscles 
of,  247 

superior,  muscles  of,  247 
nasal,  muscles  of,  246 
orbital,  muscles  of,  243 
palatal,  muscles  of,  264 
palmar,  middle,  muscles  of, 

319 
palpebral,  muscles  of,  242 
pectoral,  muscles  of,  293 
of  perineum,  777 
pharyngeal,  muscles  of,  262 
plantar,  muscles  of,  350 
popliteal,  443 
pterygo  -  maxillary,    muscles 

of,  251 
pubic,  659 

radial,  muscles  of,  310,  316 
scapular,    anterior,   muscles 
of,  299 

posterior,  300 
Scarpa's  triangle,  4",8 
of  skull,  anterior,  106 
supra-hyoid,  muscles  of,  258 
temporo-  maxillary,  muscles 

of,  249 
thoracic,  muscles  of,  288, 294, 
298 

anterior,  294 

lateral,  298 
tibio-fibular,  anterior,  341 

posterior,  343,  345 
ulnar,  muscles  of,  318 
umbilical,  659 

vertebral,   anterior,   muscles 
of,  266 

lateral,  268 
Reservoir  of  Pecquet,  483 

of  thymus,  722 
Respiration,  organs  of,  717 
Restiform  bodies   of    medulla 

oblongata,  511,  513 
Rete  mucosum  of  skin,  604 

testis,  742 
Reticular  cartilage,  182 
Retina,  620 

arteria  centralis  of,  390,  622 
external  layer  of,  621 
fovea  centralis  of,  621 
granular  layer  of,  621 
internal  layer  of,  621 
Jacob's  membrane  of,  621 
limbus  luteus  of,  625 
membrana  limitans  of,  622 
middle  layer  of,  621 
nervous  layer  of,  621 
nummular  layer  of,  621 
radiating  fibres  of,  622 
structure  of.  621 


INDEX. 


811 


Retina — 

yellow  spot  of,  G21 
Retinacula  of  ileo-caecal  valve, 

671 
Rhomboid  impression,  122 
Bibs,  116 

attachment   of   muscles    to, 
118 

common  characters  of,  117 

development  of,  118 

false,  116 

floating,  116 

ligaments  of,  198 

peculiar,  118 

structure  of,  118 

true,  116 

vertebral,  116 

vertebro-costal,  116 
-sternal,  116 
Rickets,  34 
Ridge,  internal  occipital,  60 

mylo-hyoidean,  93 

pterygoid,  74 

superciliary,  64 

temporal,  64 
Rima  glottidis,  707 
Ring,  abdominal,  external,  282, 
760 
internal.  763 

crural,  771 

femoral,  771 

position  of  parts  around, 
771 

fibrous,  of  heart,  697 
Root  of  lung,  719 

of  spinal  nerves,  561 

of  teeth,  645 

of  zygomatic  process,  67 
Rostrum   of  corpus  callosum, 
521 

of  sphenoid  bone,  74 
Rotation,  187 
Rugae  of  stomach,  666 

of  vagina,  749 
Rupture    of    urethra,     course 
taken  by  urine  in,  778 

Sac,  dental,  650 
lachrymal,  628 

structure  of,  650 
of  omentum,  622 
Sacculus  laryngis,  707,  708 

of  vestibule,  641 
Sacrum,  50 

articulations  of,  54 
attachment  of   muscles    to, 

54 
cornua  of,  51 
development  of,  54 
peculiarities  of,  53 
in  female,  53 
in  male,  53 
structure  of,  53 
Salivary  glands,  653 

structure  of,  666 
Santorini,  cartilages  of,  705 
Sarcolemma,  235 
Sarcous    elements    of   muscle, 

235 
Scala  tympani  of  cochlea,  640 
vestibuli  of  cochlea,  640 


Scake  of  cochlea.  640 
Scaphoid  bone  of  foot,  175 

of  hand,  141 
Scapula,  123 

articulations  of,  128 

attachment  of  muscles  to,  128 

development  of,  127 

dorsum  of,  124 

glenoid  cavity  of,  127 

ligaments  of,  210 

muscles  of,  299 

spine  of,  126 

structure  of,  127 

venter  of,  123 
Scarfskin,  604 
Scarpa's  triangle,  438 
Schindylesis,  185 
Schneiderian  membrane,  613 
Schreger's  analysis  of  bone,  34 
Schwann,  white   substance  of, 

496 
Sclerotic,  615 

structure  of,  616 

vessels  and  nerves  of,  616 
Scrotal  hernia.      See   Hernia, 

scrotal. 
Scrotum,  739 

dartos  of,  739 

lymphatics  of,  490 

nerves  of,  739 

septum  of,  739 

structure  of,  739 

vessels  of,  739 
Sella  turcica,  73,  100 
Semen,  744 

liquor  seminis  of,  744 

seminal  granules  of,  744 

spermatozoa  of,  744 
Semicircular  canals,  638 
external,  638 
horizontal,  638 
membranous,  641 
posterior,  638 
superior,  638 
Semilunar  bone,  141 

valves.     See  Valves,   Semi- 
lunar. 
Seminal  vesicles.      See    Vesi- 

cuhe  seminales. 
Seminiferous  tubes,  742 
Senac,  on  structure  of  heart's 

valves,  694 
Senses,  organs  of  the,  602 
Septum  auricularum.  691,  695 

between  bronchi,  712 

crurale,  772 

lucidum,  525 

of  medulla  oblongata,  513 

of  nose,  110 
cartilage  of,  612 

pectiniforme,  737 

of  pons  Varolii,  515 

scroti,  739 

subarachnoid,  501 

of  tongue,  610 

ventriculorum,  694 
Sesamoid  bones,  179 
Shaft  of  a  bone,  structure  of,  35 
Sheath  of  arteries,  360 

crural,  770 

femoral,  770 


Sheath —  » 

of  muscles,  236 

of  nerves,  498 
Shoulder,  121 
Shoulder-joint,  210 

muscles  of,  299 

vessels  and  nerves  of,  211 
Sigmoid  flexure.     See  Colon. 
Simon,  on  supra-renal  capsules. 

728 
Sinus,  cavernous,  465 

circular,  465 

circularis  iridis,  620 

coronary,  479,  693 

opening  of,  in  heart,  693 

of  dura  mater,  463 

of  jugular  vein,  461 

of  kidney,  724 

lateral,  464 

longitudinal,  inferior,  4G4 
superior,  463 

maxillary,  84 

occipital,  464 

petrosal,  inferior,  466 
superior,  466 

pocularis,  733 

prostatic,  733 

of  right  auricle,  691 
of  left,  695 

straight,  464 

transverse,  466 
Sinuses,  455,  463 

of  the  aorta,  362,  695,  697 

confluence  of  the,  i64 

ethmoidal,  78 

frontal,  66 

maxillary,  84 

pulmonary,  695 

sphenoidal,  73 

of  Valsalva,  aortic,  362,  697 
pulmonary,  695 
Skeleton,  33 

number  of  pieces  in,  40 
Skin,  anatomy  of,  602 

appendages  of,  605 

areolae  of,  603 

arteries  of,  605 

color  of,  605 

corium  of,  603 

cuticle  of,  604 

derma  of,  602 

epidermis  of,  604 

furrows  of,  604 

hairs,  606 

lymphatics  of,  605 

muscular  fibres  of,  603 

nails,  605 

nerves  of,  605 

papillary  layer  of,  603 

rete  mucosum  of,  604 

sebaceous  glands  of,  607 

sudoriferous  or  sweat  gland» 
607 

true,  602 

vessels  of,  605 
Skull,  57,  98 

anterior  region  of,  106 

base  of,  99 

bones  of,  57 

cerebral  surface  of,  100 

external  surface,  102 


w  4 


812 


IXDEX. 


Skull- 
fossa  of,  anterior,  100 
middle,  100 
posterior,  101 
spheno-raaxillary,  106 
temporal,  105 
zygomatic,  10G 
internal  surface  of,  100 
lateral  region  of,  105 
tables  of,  35 
vertex  of,  98 
vitreous  table  of,  35 
Socia  parotidis,  654 
Soft  palate,  652 
aponeurosis  of,  653 
arches  of,  652 
muscles  of,  653 
pillars  of,  652 
structure  of,  652 
Sole  of  foot,  muscles  of,  first 
layer,  350 
second  layer,  352 
third  layer,  353 
Space,  anterior  perforated,  519 
axillary.     See  Axilla. 
Haversian,  38 
intercostal,  116 
popliteal,  443 

boundaries  of.  444 
contents  of,  444 
position  of  contained  parts 
in,  444 
posterior  perforated,  519 
Spermatic  cord,  740 
arteries  of,  740 
course  of,  740 
lymphatics  of,  740 
nerves  of,  740 
relation  of  to  femoral  ring, 

771 
relations  of,  in  inguinal  ca- 
nal, 742,  762 
veins  of,  740 
Spermatozoa,  744 
Sphenoid  bone,  72 
articulations  of,  76 
attachment  of  muscles  to,  76 
development  of,  76 
greater  wings  of,  74 
lesser  wings  of,  75 
processes  of  Ingrassias  of,  75 
pterygoid  processes  of,  75 
spinous  process  of,  74 
vaginal  processes  of,  74 
Sphenoidal  spongy  bones,  76 
Sphincter  ani,  776 
of  bladder,  731 
of  rectum,  external,  776 

internal,  776 

of  vagina,  780 

Spinal  column,  40,  55 

Spinal  cord,  500,  502 

arachnoid  of,  501 

arrangement    of    gray    and 

white  matter  in,  504 
central  canal  of,  506 

ligament  of,  502 
columns  of,  503 
dura  mater  of,  500 
filum  tcrminale  of,  502 
fissure  of,  503 


Spinal  cord — 

foetal  peculiarity  of,  506 

gray  commissure  of,  504 
matter  of,  504,  505 

ligamcntum  denticulatum  of, 
502 

membranes  of,  500 

neurilemma  of,  502 

pia  mater  of,  502 

sections  of,  504 

structure  of,  504 

substantia  cinerea  gelatinosa, 
503 

white  commissure  of,  503 
matter  of,  504 
Spinal  nerves,  561 

arrangement  into  groups, 

561 
branches  of,  anterior,  562 

posterior,  562 
ganglia  of,  562 
roots  of,  anterior,  561 
posterior,  561 
Spine,  40 

See  also  Process,  spinous. 

of  bone,  35 

ethmoidal,  72 

of  ilium,  150 

of  ischium,  152 

nasal,  65 
anterior,  85 
posterior,  88 

pharyngeal,  59 

of  pubes,  153 

of  scapula,  126 
Spleen,  684 

artery  of,  688 

capillaries  of,  688 

fibrous  elastic  coat  of,  685 

fissure  of.  684 

hilus  of,  684 

lymphatics  of,  493,  688 

Malpighian  corpuscles  of,  686 

nerves  of,  688 

proper  substance  of,  685 

relations  of,  684 

serous  coat  of,  685 

size  and  weight  of,  684 

structure  of,  685 

suspensory  ligament  of,  684 

trabecular  of,  685 

veins  of,  688 
Spongy  bones,  91 

cartilage,  182 

portion  of  urethra,  733 

tissue  of  bone,  34 
Squamous  portion  of  temporal 

bone,  67 
Stapes,  635 

annular  ligament  of,  636 
Steno's  duct,  654 
Sternum,  112 

articulations  of,  116 

attachment  of  muscles  to,  11 6 

development  of,  114 

ligaments  of,  202 

structure  of,  114 
Stomach,  663 

alteration  in  position  of,  664 

alveoli  of,  666 

cardiac  orifice  of,  663 


Stomach — 

cellular  coat  of,  666 
curvatures  of,  663 
fundus  of,  663 
gastric  follicles  of,  666 
ligaments  of,  664 
lymphatics  of,  498,  666 
mucous  glands  of,  666 
mucous  membrane  of,  666 
muscular  coat  of,  665 
oesophageal  orifice  of,  663 
peptic  glands  of,  666 
pyloric  end  of,  663 

orifice  of,  663 
pylorus,  665 
serous  coat  of,  6/55 
simple  follicles  of,  667 
splenic  end  of,  663 
structure  of,  665 
submucous  coat  of,  666 
surfaces  of,  664 
vascular  coat  of,  666 
vessels  and  nerves  of,  666 
Striae  laterales,  522 

longitudinales,  522 
Stricture,  seat  of,  in  direct  in 
guinal  hernia,  765 
in  femoral  hernia,  774 
in  oblique  hernia,  764 
Stroma  of  ovary,  753 
Subarachnoid  fluid,  509 
septum,  501 
space  of  brain,  509 
of  cord,  501 
Sublingual  gland.  655 
duct  of,  655 

vessels   and    nerves   of, 
655 
Submaxillary  gland,  655 
duct  of,  655 
nerves  of,  655 
vessels  of,  655 
Subpeduncular  lobe  of  cerebel- 
lum, 532 
Sub-peritoneal   areolar    tissue, 

660 
Substantia   cinerea  gelatinosa, 

505 
Sulci  of  cerebrum,  516 
Supcrcilia,  625 
Superior  maxillary  bone.  81 
articulations  of,  86 
attachment  of  muscles  to, 

86 
development  of,  85 
Supra-renal  capsules,  727 

cortical  substance  of,  728 
medullary  substance  of,  728 
nerves  of,  728 
relations  of,  728 
structure  of,  728 
vessels  of,  728 
Surgical  anatomy,  33 
of  abdominal  aorta.  420 
anterior  tibial,  447 
arch  of  aorta,  364 
axilla,  401 
axillary  artery,  404 
base  of  bladder,  7s:'> 
bend  of  elbow,  1(17 
brachial  artery,  408 


IXDEX. 


813 


Si.rgical  anatomy — 

jf  common   carotid   artery, 
370 
iliac  artery,  429 
dorsalis  pedis,  449 
external  carotid,  372 

iliac,  437 
facial  artery,  376 
femoral  artery,  440 

hernia,  766 
hamstring  tendons,  340 
innominate  artery,  367 
inguinal  hernia,  758 
internal  carotid,  386 

iliac,  431 
ischio-rectal  region,  775 
laryngo  -  tracheal     region, 

713 
lingual  artery,  374 
muscles  of  eye,  242 
lower  extremity,  354 
soft  palate,  266 
upper  extremity,  320 
oesophagus,  657 
perineum,  775 
popliteal  artery,  445 
posterior  tibial,  450 
prostate  gland,  782 
radial  artery,  411 
Scarpa's  triangle,  438 
sterno-mastoid  muscle,  256 
subclavian  artery,  401 
superior  thyroid,  373 
talipes,  348 
temporal  artery,  379 
thoracic  aorta,  417 
triangles  of  neck,  382 
ulnar  artery,  414 
Sustentaculum  tali,  172 
Sutura,  184 

dentata,  185 

harmonia,  185 

iimbosa,  185 

notha,  185 

serrata,  185 

squamosa,  185 

vera,  184 
Suture,  basilar,  97 

coronal,  97 

cranial.  97 

ethmo-sphenoidal,  100 

ethmoido-frontal,  100 

frontal,  66,  97 

fronto-malar,  10.7 
-parietal,  97 
-sphenoidal,  100 

intermaxillary,  85 

internasal,  107 

interparietal,  97 

lambdoid,  97 

malo-maxillary,  108 

masto-occipital,  98 
-parietal.  '.17 

naso-maxillary,  105 

occipito-parietal,  97 

petro-occipital.  97 
-sphenoidal,  98 

sagittal,  97 

spheno-parietal,  97 

squamo-paiietal.  97 
-sphenoidal,  98 


Suture — 

temporal,  69 

transverse.  96 
Swallow's  nest  of  cerebellum, 

531 
Sweat-glands,  007 
Symphysis  of  jaw,  92 

pubis,  153 
Synarthrosis,  184 
Synchondrosis,  sacro-iliac,  204 
Synovia,  184 
Synovial  membrane,  183 

ankle,  229 

articular,  183 

astragalo-scaphoid,  232 

atlo-axoid,  193 

bursal,  184 

calcaneo-astragaloid,  230 
-cuboid,  231 

carpal,  217,  218 

carpo-metacarpal,  218 

of  cartilage  of  ribs  with  each 
other,  202 

chondro-sternal,  200 

costo-transverse,  199 
-vertebral,  198 

elbow,  212 

hip,  222 

intercostal,  200 

interpubic,  206 

knee,  226 

metacarpal,  218,  219 

occipito-atloid,  193 

phalanges,  220 

radio-ulnar,  inferior,  215 
superior,  213 

sacro-coccvgeal,  205 
-iliac,  204 

scapulo-clavicular,  210 

shoulder,  211 

sterno-clavicular,  208 

tarsal,  232 

tarso-metatarsal,  233 

temporo-maxillary,  197 

thumb,  197 

tibio-fibular,  inferior,  227 
superior,  227 

vaginal,  184 

wrist,  216 
System,  Haversian,  37 
portal,  477 

Tables  of  the  skull,  35 
Tenia  hippocampi,  524,  525 
semicircularis,  523 
violacca,  532 
Tarsus,  170 

development  of,  178 
Teeth,  645 

bicuspid,  645,  646 
body  of,  645 
canine,  645,  646 
of  lower  jaw,  93 
of  upper  jaw,  82 
cement  of,  649 
chemical  composition  of,  648, 

649 
cortical  substance  of,  649 
crown  of,  ('>!."> 
crusta  petrosa  of,  648 
cuspidate,  G4G 


Teeth- 
deciduous,  G45 

dental  tubuli  of,  648 

dentine  of,  648 

development  of,  649,  650,  651 

enamel  of,  649 

eruption  of,  G51 

eye,  6  !6 

false  molars,  646 

fang  of,  645 

general  characters  of,  645 

growth  of,  651 

incisors,  646 

iutertubular  tissue  of,  G48 

ivory  of,  648 

large  molars,  646 

milk,  645,  647 

molar,  645,  G4G 

multicuspidate,  646 

permanent,  645.  646 

pulp  cavity  of,  648 

roots  of,  645 

small  molars,  646 

structure  of,  618 

temporary,  645,  647 

true  molars,  64G 

wisdom,  647 
Temporal  bone,  67 

articulations  of,  72 
attachment  of  muscles  to, 

72 
development  of,  71 
mastoid  portion  of,  69 
petrous  portion  of,  69 
squamous  portion  of,  67 
structure  of,  71 
Tendo  Achillis,  344 

oculi,  242 

palpebrarum,  242 
Tendon,  central,  of  diaphragm, 
291 

conjoined,  of  internal  obliqu* 
and  transversalis,  284, 
761 

cordiform,  of  diaphragm,  291 

structure  of,  237 
Tentorium  cerebelli,  508 
Testicle.     See  Testis. 
Testis,  738 

aberrant  duct  of,  741 

coni  vasculosi  of.  741 

coverings  of,  739,  740 
tunica  albuginca,  740 
vaginalis,  740 
vasculosa,  740 

gubernaculum  testis,  745 

investments  of,  740 

lobules  of,  741 

lymphatics  of,  492 

mode  of  descent  of,  744 

pia  mater  of,  741 
'  rete  of,  741 

size  and  weight  of,  739 

structure  of,  741 

tubuli  seminiferi  of.  71 1 

vas  deferens  of,  742 

vasa  efferentia  of,  741 
recta,  741 

vasculum  aberrans  of,  741 

vessels  and  nerves  of.  742 
Theca  vertebralis,  500 


814 


INDEX. 


Thalami  optici,  526 
Thigh,  bone  of,  158 
fascia  of,  327 
deep,  328 
lata,  328 
muscles  of  back  of,  288 
of  front  of,  276 
Thorax,  689 
base  of,  689 
bones  of,  112 
boundaries  of,  689 
cutaneous  nerves  of,  577 
fasciae  of,  294,  298 
muscles  of,  294 
openings  of,  689 
parts  passing  through  upper 

openings  of,  689 
viscera  contained  in,  689 
Thumb,  muscles  of,  316 
Thymus  gland,  722 

chemical  composition  of,  723 
lobes  of,  722 
lymphatics  of,  494,  723 
reservoir  of,  722 
structure  of,  722 
vessels  and  nerves  of,  723 
Thyro-hyoid  membrane,  705 
Thyroid  axis,  398 
cartilage,  703 
gland,  721 

chemical  composition,  722 
isthmus  of,  721 
lymphatics  of,  494,  722 
situation  of,  721 
structure  of,  721 
vessels  and  nerves  of,  721 
Tibia,  165 
articulations  of,  168 
attachment  of  muscles  to,  168 
development  of,  168 
fracture  of  shaft  of,  356 
structure  of,  168 
Tongue,  608 
arteries  of,  611 
cutis  of,  609 
dorsum,  609 
epithelium  of,  610 
fibrous  septum  of,  610 
follicles  of,  610 
mucous  glands  of,  610 

membrane  of,  609 
muscular  fibres  of,  610 
muscles  of,  260 
nerves  of,  611 

papilla?  of,  609.    See  Papillae, 
tip  of,  609 
Tonsils,  653 

nerves  of,  653 
vessels  of.  653 
of  the  cerebellum,  531,  532 
Tooth.    Bee  Teeth. 
Torcular  Herophili,  60,  464 
Trabecular  of  corpus  cavcrno- 
sum,  737 
of  spleen,  685 
of  testis,  741 
Trachea,  711 

cartilages  of,  712 
glands  of,  713 
relations  of,  712 
structure  of,  713 


Trachea — 

surgical  anatomy  of,  713 

vessels  and  nerves  of,  713 
Tracheotomy,  713,  714 
Tract,  optic,  536 
Tractus    intermedio    lateralis, 
505 

opticus,  536 
Tragus,  629 
Trapezium  bone,  143 
Trapezoid  bone,  143 
Triangle  of  Hesselbach,  765 

inferior  carotid,  383 

of  neck,  anterior,  382 
posterior,  384 
surgical  anatomy  of,  382 

occipital,  384 

Scarpa's,  438 

subclavian,  384 

submaxillary,  383 

superior  carotid,  383 
Tricuspid  valves,  694 
Trigeminus  nerve,  545 
Trigone  vdsicale,  732 
Trigonum  vesicae,  732 
Triquetral  bones,  80 
Trochanters,  greater  and  lesser, 

159 
Trochlea  of  humerus,  131 
Trunk,  muscles  of,  269 
Tube,  auditory,  631 

Eustachian,  634 

Fallopian,  752 
Tuber  cinereum,  519 

ischii,  152 
Tubercle  of  bone,  35 

of  the  clavicle,  121 

of  the  femur,  160 

genial,  93 

lachrymal,  43,  625 

laminated,  of  cerebellum,  531 

of  Lower,  693 

for  odontoid  ligaments,  59 

of  ribs,  117 

of  scaphoid,  141 

of  the  tibia,  166 

of  ulna,  135 

of  zygoma,  68 
Tubercula  quadrigemina,  529 
Tuberculo  cinereo,  514 
Tuberculum  Loweri.  693 
Tuberosities  of  humerus,greater 
and  lesser,  129 

of  tibia,  165 
Tuberosity  of  bone,  35 

of  ischium,  152 

maxillary,  82 

of  palate  bone,  89 

of  radius,  138 
Tubes,  bronchial,  712 

structure  of,  in  lung,  719 
Tubuli,  dental,  648 

of  Ferrein,  726 

galactophori,  756 

lactiferi,  756 

recti,  741 

seminiferi,  741 

uriniferi,  725 
Tubulus  centralis  modioli,  639 
Tuft,  vascular,  in  Malpighian 
bodies  of  kidney,  726 


Tunica  albuginea,  740 
of  ovary,  753 

Ruschiana,  618 

vaginalis,  740 
propria,  740 
reflexa,  740 

vasculosa  testis,  740 
Turbinated  bone,  inferior,  91 

middle,  78 

superior,  78 
Tutamina  oculi,  625 
Tympanic  bone,  71,  635 
Tympanum,  632 

arteries  of,  636 

cavity  of,  632 . 

membrane  of,  634 

mucous  membrane  of,  636 

muscles  of,  636 

nerves  of,  637 

ossicula  of,  634.  See  Ossicula. 

veins  of,  637 

Ulna,  133 

articulations  of,  138 
development  of,  138 
fracture  of  coronoid  process 
of,  322 
of  olecranon  process,  322 
of  shaft,  323 
muscles  attached  to,  138 
Umbilicus,  287 
Unciform  bone,  145 
Ungual  phalanges,  147 
Upper  extremity,  arteries   of, 
391 
articulations  of,  207 
bones  of,  121 
fascia  of,  293 
ligaments  of,  207 
lymphatics  of,  486 
muscles  of,  293 
nerves  of,  566 
surgical  anatomy  of,  320 
veins  of,  466 
Urachus,  730 
Ureters,  726,  727 
muscles  of,  731 
nerves  of,  727 
relations  of,  727 
structure  of,  727 
vessels  of,  727 
Urethra,  female,  relations  of, 748 
structure  of,  748 
male,  732 

bulbous  portion  of,  733 
caput  gallinaginis  of,  733 
external  aperture  of.  733 
membranous     portion     of, 

733 
prostatic  portion  of,  732 

sinus  of,  733 
rupture  of,  course  taken  by 

urine  in,  778 
sinus  pocularis  of,  733 
spongy  portion  of,  733 
structure  of,  733 
veru  montanum  of,  732 
vesicula  prostatica  of,  733 
Urinary  organs,  724 
Uterus,  750 

appendages  of,  752 


Uterus — 

arbor  vita;  of,  751 

body  of,  750 

cavity  of,  750 

cervix  of,  750 

in  foetus,  752 

fundus  of,  750 

ligaments  of,  750,  754 

lymphatics  of,  492,  751 

during  menstruation,  752 

in  old  age,  752 

orifices  of,  750 

after  parturition,  752 

during  pregnancy,  752 

at  puberty.  752 

shape,  position,   dimensions, 
&c,  of,  686 

structure  of,  751 

vessels  and  nerves  of,  751 
Uterus  masculinus,  733 
Utricle  of  vestibule,  641 
Utriculus,  641 
Uvea,  619 
Uvula,  652,  656 

of  cerebellum,  531 

vesicae,  732 

Vagina,  749 
columns  of,  749 
direction  of,  749 
dimensions  of,  749 
lymphatics  of,  492 
orifice  of,  747 
relations  of,  749 
shape  of,  749 
situation  of,  749 
structure  of,  749 
Valve  or  Valves — 
of  Bauhin,  671 
of  cystic  duct,  682 
of  gall-bladder,  682 
of  heart,  693,697 
coronary,  693 
Eustachian,  693 
mitral,  697 
of  right  auricle,  693 
semilunar,  aortic,  697 

pulmonic,  695 
tricuspid,  694 
ileo-cajcal,  671 
of  Kerkring,  668 
of  veins,  457 
of  Vieussens,  529 
Valvula  Bauhini,  671 
Valvukc  conniventes,  668 
Vas  aberrans,  742 
deferens,  742 
structure  of,  742 
Vasa  aberrantia  of  brachial  ar- 
tery, 407 
afferentia     of     lymphatic 

glands,  482 
brevia  arteries,  422 

veins,  477 
efferentia  of  testis,  741 

of  lymphatic  glands,  482 
inferentia,  482 
intestini  tenuis,  424 
recta,  741 

vasorum  of  arteries,  360 
of  veins,  457 


INDEX. 

Vascular  system,  changes  in, 

at  birth,  702 
peculiarities  of,  in  foetus,  699 
Vasculum  aberrans,  741 
Vein  or  Veins — 

General  Anatomy  of,  455 
anastomoses  of,  455 
arrangement  into  groups, 

457 
coats  of,  456 
muscular  tissue  of,  457 
plexus  of,  455.   See  Plexus 

of  veins, 
sinuses  of,  455 
size,  form,  etc.,  of,  455 
structure  of,  457 
valves  of,  457 
vessels  and  nerves  of,  457 
Vein  or  Veins — 

Descriptive  Anatomy  of,  457 
of  alas  nasi,  458 
angular,  458 
articular,  of  knee,  474 

of  jaw,  458 
auricular,  anterior,  458 

posterior,  459 
axillary,  468 
azygos,  470 

left  lower,  470 
upper,  471 

right,  470 
basilic,  467 
basi-vertebral,  472 
of  bone,  37 
brachial,  468 
brachio-cephalic,  468 
bronchial,  471,  720 
buccal,  458 
cardiac,  479 

anterior.  479 

great,  479 

posterior,  479 
cava,  inferior,  475,  693 

superior,  470,  693 
cephalic,  467 
cerebellar,  463 
cerebral,  462 

deep,  463 

inferior  anterior,  463 
lateral,  463 
median,  463 

superficial,  462 

superior,  462 
cervical,  ascending,  461 

deep,  461 
choroid  of  brain,  463 
circumflex  iliac,  474 

superficial,  473 
comites,  455 

of  brachial,  468 

interosseous,  467 

radial,  467 

ulnar,  467 
condyloid,  posterior,  461 
coronary,  479 

of    corpora    cavernosa, 
738 

of   corpus   spongiosum, 
738 

striatum,  463,  523 
cutaneous,  -155 


815 

Vein  or  Veins — 
cystic,  478 
deep,  455 

dental,  inferior,  459 
diaphragmatic,  476 
digital  of  hand,  467 
of  diploe,  461 
dorsal,  of  penis,  475 
dorsalis  nasi,  458 

pedis,  474 
dorsi-spinal,  471 
epigastric,  474 

superficial,  473 
of  eyeball,  625 
facial,  459 
femoral,  474 

relation  of  to  femoral  arte* 
ry,  440 
to  femoral  ring,  771 
frontal,  458 
of  Galen,  463,  523,  526 
gastric,  477 

gastro-epiploic,  left,  477 
gluteal,  474 
hemorrhoidal,  inferior,  475 

middle,  475 

superior,  475 
of  head,  457 
hepatic,  477,  678 
iliac,  common,  475 

peculiarities  of,  475 

external,  474 

internal,  474 
ilio-lumbar,  475 
innominate,  468 

left,  468 

peculiarities  of,  469 

right,  468 
intercostal,  superior,  470 

left,  470 

right,  470 
interlobular,  679 
interosseous,  of  forearm,  467 
intralobular,  679 
jugular,  anterior,  460 

external,  460 
posterior,  460 

internal,  460 
sinus  of,  461 
of  kidney,  726 
labial,  inferior,  459 

superior,  459 
laryngeal,  461 
lateral  sacral,  475 
lingual,  461 
of  liver,  678 
longitudinal,  inferior,  464 

superior,  463 
of  lower  extremity,  473 
lumbar,  476 

ascending,  476 
mammary,  internal,  469 
masseteric,  458 
mastoid,  430 
maxillary,  internal,  459 
median,  467 

basilic,  467 

cephalic,  467 

cutaneous,  467 
medulli-spinal,  471,  472 
meningeal,  459 


m 


81G 


INDEX. 


Vein  or  Veins — 
meningo-raekidian,  471 
mesenteric,  inferior,  477 

superior,  477 
nasal,  458 
of  neck,  460 
oblique,  479 
obturator,  474 
occipital,  459 
oesophageal,  470 
ophthalmic,  465 
ovarian,  476 
palatine,  inferior,  458 
palmar,  deep,  468 
palpebral,  inferior,  459 

superior,  459 
pancreatic,  477 
pancreatico-duodenal,  477 
parotid,  474 
peroneal,  459 
pharyngeal,  461 
phrenic,  476 
plantar,  external,  474 

internal,  474 
popliteal,  474 
portal,  677,  678,  679 
profunda  femoris,  474 
from  pterygoid  plexus,  459 
pudic,  external,  473 

internal,  474 
pulmonary,  455,479,  696,720 
radial,  467 
ranine,  459 
renal,  476,  726 
sacral,  lateral,  475 

middle,  475 
salvatella,  467 

saphenous,  external  or  short, 
473 

internal  or  long,  473 
sciatic,  474 
spermatic,  476,  676 
sphenopalatine,  461 
spinal,  471,  472 

anterior  longitudinal,  471 

posterior  longitudinal,  471 
splenic,  477 
stylo-mastoid,  459 
subclavian,  468 
sublobular,  679 
submaxillary,  459 
submental,  459 
superficial,  455 
supra-orbital,  458 
supra-renal,  476,  728 
supra-scapular,  460 
sural,  -174 
systemic,  455 
temporal,  459 

middle,  4.">0 
tcmporo-maxillary,  459 
Thehesii,  479 
of  thorax,  466 

thyroid,  inferior,  469 
middle,  461 
superior,  461 


Vein  or  Veins — 
tibial,  anterior,  474 

posterior,  474 
transverse  cervical,  460 

facial,  459 
ulnar,  anterior,  466 

deep,  466 

posterior,  467 
umbilical,  699,  701,  702 

how  obliterated,  702 
of  upper  extremity  and  tho- 
rax, 466 
vaginal,  of  liver,  680 
vasa  brevia,  477 
ventricular,  463 
of  vertebra,  461 

of  bodies  of,  472 
Vidian,  461 

See  also  Vena  and  Vena?. 
Velum  interpositum,  523,  526 

arteries  and  veins  of,  526 
pendulum  palati,  652 
Vena  cava,  inferior,  475 
peculiarities  of,  476 

superior,  470 
corporis  striati.  463 
innominata,  468 
porta;,  477,  677,  678 
salvatella,  467 
See  also  Vein. 
Venaa  basis  vertebrarum,  471 
comites,  455,  474 
Galeni.    See  Veins  of  Galen. 
minima3  cordis,  479 
Thebesii,  479 
vorticosa?,  618 
See  also  Vein.  I 
Venter  of  ilium,  150 

of  scapula,  123 
Ventricle  of  brain,  third,  527 
gray  matter  of,  527 

fourth,  532 

lining  membrane  of,  532 

fifth,  524 

lateral,  522 
of  corpus  callosum,  521 
of  heart,  left,  696 

right,  691 
of  larynx,  707,  708 
Vertebra  dentata,  43 

prominens,  44 
Vertebra;,  40 

attachment  of  muscles  to,  49 

cervical,  41 

coccygeal,  50 

development  of,  48 

dorsal,  44 

false,  50 

general  characters  of,  40 

ligaments  of,  188 

lumbar,  47 

ossification  of,  49 

peculiar,  42,  45,  47 

pedicles  of,  41 

sacral,  50 

structure  of,  47 


Vertebral  column,  40,  55 

ossification  of,  49 
Vertex  of  skull.  98 
Vera  montanum,  732 
Vesicles,  Graafian.     See  Graa 

fian  vesicles. 
Vesicula  prostatica,  733 
Vesicuke  scminales,  form  and 
size  of,  743 
nerves  of,  744 
relations  of,  744 
1  structure  of,  744 
vessels  of,  744 
Vesicular  nervous  matter,  495, 

496 
Vestibule  of  car,  687 
acpieduct  of,  70,  638 
of  vulva,  747 
Vibrissa;  of  nose,  fill   • 
Vieussens,  valve  of,  529 
Villi,  669 

Viscera,  abdominal,  position  of 
in  regions.  659 
pelvic,  position  of  at  outlet  of 

pelvis,  782 
thoracic,  689 
Vitelline  membrane,  754 
Vitreous  body,  623 
humor  of  the  eye,  623 
table  of  the  skull,  35 
Vocal  cords,  false,  707 
inferior,  708 
superior,  707     ■ 
true,  708  » 

Voice,  organs  of,  702 
Voluntary  muscles,  235 
Vomer,  92 
ala3  of,  92 
articulations  of,  92 
development  of,  92 
Vortex  of  heart,  698 
Vulva,  747 

Wharton's  duct,  655 
White  substance  of  brain,  che- 
mical analysis  of,  495 
of  Schwann,  496 
Willis,  circle  of,  397 
Winslow,  foramen  of,  661 
Wirsung,  canal  of,  683 
Wisdom  tooth,  647 
Womb.     See  Uterus. 
Wormian  bones,  80 
Wrisberg,  cartilages  of,  705 

nerve  of,  570 
Wrist-joint,  216 

Xiphoid  appendix,  114 

Y-shaped   centre   of    acetabu- 
lum, 155 
Yelk  of  ovum,  754 
Yellow  spot  of  retina,  620 

Zona  pellucida,  754 
Zygoma,  67 


T  n  E    EJfD, 


■ — w 


V 


